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A Survey of Colonially-breeding Birds on
Mud Islands, Port Phillip, Victoria; with an
annotated list of all terrestrial vertebrates
P. Menkhorst
July 2010
Arthur Rylah Institute for Environmental Research
Technical Report Series Number 206
Arthur Rylah Institute for Environmental Research Technical Report Series Number 206
A Survey of Colonially-breeding Birds on Mud Islands,
Port Phillip, Victoria, with an annotated list of all
terrestrial vertebrates
Peter Menkhorst
Arthur Rylah Institute for Environmental Research
123 Brown Street, Heidelberg, Victoria 3084
July 2010
Arthur Rylah Institute for Environmental Research
Department of Sustainability and Environment
Heidelberg, Victoria
Report produced by:
Arthur Rylah Institute for Environmental Research
Department of Sustainability and Environment
PO Box 137
Heidelberg, Victoria 3084
Phone (03) 9450 8600
Website: www.dse.vic.gov.au/ari
© State of Victoria, Department of Sustainability and Environment 2009
This publication is copyright. Apart from fair dealing for the purposes of private study, research, criticism or review as
permitted under the Copyright Act 1968, no part may be reproduced, copied, transmitted in any form or by any means
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Citation: Menkhorst, P. (2010). A Survey of Colonially-breeding Birds on Mud Islands, Port Phillip, Victoria, with an
annotated list of all terrestrial vertebrates. Arthur Rylah Institute for Environmental Research Technical Report Series
Number 2006. Department of Sustainability and Environment, Heidelberg, Victoria
ISBN 978-1-74242-779-9 (print)
ISBN 978-1-74242-780-5 (online)
Disclaimer: This publication may be of assistance to you but the State of Victoria and its employees do not guarantee
that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore
disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in
this publication.
Front cover photo: Australian Pelican breeding colony, Mud Islands 13 July 2008 (photographer P. Menkhorst).
Authorised by: Victorian Government, Melbourne
ii
A Survey of Colonially-breeding Birds on Mud islands, Port Phillip, Victoria
Contents
List of tables and figures .................................................................................................................. 4
Acknowledgements ........................................................................................................................... 5
Acknowledgements ........................................................................................................................... 5
Summary ........................................................................................................................................... 6
Introduction ...................................................................................................................................... 7
1.1 Location ................................................................................................................................... 7
1.2
Geomorphology ....................................................................................................................... 7
1.3
Vegetation ................................................................................................................................ 8
1.4
Changes to Vegetation ............................................................................................................. 9
1.5
Land status ............................................................................................................................. 10
11
2
2.1
Purpose and scope ................................................................................................................ 13
Objectives............................................................................................................................... 13
3
3.1
Methods ................................................................................................................................. 14
Monitoring breeding birds by foot ......................................................................................... 14
3.2
Monitoring breeding birds from the air .................................................................................. 14
3.3
Previous bird counts at Mud Islands ...................................................................................... 15
3.4
Historical literature search ..................................................................................................... 16
4
4.1
Results ................................................................................................................................... 17
Colonially-breeding birds, 2008-2010 ................................................................................... 17
4.1.1
Australian Pelican ................................................................................................... 17
4.1.2
Pied Cormorant ....................................................................................................... 19
4.1.3
Little Egret .............................................................................................................. 20
4.1.4
Straw-necked Ibis ................................................................................................... 20
4.1.5
Australian White Ibis .............................................................................................. 21
4.1.6
Royal Spoonbill ...................................................................................................... 23
4.1.7
Caspian Tern ........................................................................................................... 23
4.1.8
Crested Tern ........................................................................................................... 24
4.1.9
Silver Gull............................................................................................................... 25
4.1.10
Summary of colonially-breeding birds ................................................................... 26
4.2
Other breeding birds............................................................................................................... 26
4.3
Non-breeding visitors ............................................................................................................. 26
4.4
Historical records ................................................................................................................... 27
5
5.1
Discussion.............................................................................................................................. 28
Sources of error in population estimates ................................................................................ 28
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A Survey of Colonially-breeding Birds on Mud Islands, Port Phillip, Victoria
5.2
Significance of Mud Islands for birds .....................................................................................28
5.2.1
Waterbirds ...............................................................................................................29
5.2.2
Shorebirds ................................................................................................................29
5.2.3
Seabirds ...................................................................................................................30
5.2.4
Threatened Species ..................................................................................................30
5.3
Changes to the Bird Fauna ......................................................................................................31
5.4
Other terrestrial fauna .............................................................................................................33
5.5
History of bird study on Mud Islands .....................................................................................33
6
Conclusions and Recommendations ....................................................................................34
7
References ..............................................................................................................................35
8
Appendix 1 – Maps of breeding colonies ............................................................................38
38
Appendix 2 - Annotated List of Species .......................................................................................41
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A Survey of Colonially-breeding Birds on Mud islands, Port Phillip, Victoria
List of tables and figures
List of tables
Table 1. Numbers of bird counts conducted by the author at Mud Islands per month before the
present study and during the present study. ........................................................................... 14
Table 2. Monthly distribution of nests with eggs (E), nests with nestlings (N) and crèches of
juvenile Australian Pelicans (C), on Mud Islands between February 2008 and March 2010.
See Map 2 for location of colonies. ....................................................................................... 18
Table 3. Monthly numbers of nests of the Australian Pelican on Mud Islands that contained eggs
between February 2009 and April 2010 when counts were made. e – estimated. ................. 18
Table 4. Summary of colonially-breeding birds at Mud Islands. ..................................................... 26
Table 5. Threatened species that utilize Mud Islands, excluding species recorded only once or
twice. FFG – Flora and Fauna Guarantee Act 1988; EPBC – Commonwealth Environment
Protection and Biodiversity Conservation Act 1999; DSE – Advisory List of Threatened
Vertebrate Fauna in Victoria 2007; f – listed under Flora and Fauna Guarantee Act; ce –
critically endangered; e – endangered; v – vulnerable. .......................................................... 30
Table 6. Bird species that have declined in population number on Mud Islands since 1982 and
possible reasons for the declines. ........................................................................................... 31
Table 7. Bird species that have increased in population number on Mud Islands since 1982 and
possible reasons for the increases. ......................................................................................... 32
List of figures
Map 1. Aerial viw of Mud Islands showing the major vegetation communities and place names
used in the text. ........................................................................................................................ 9
Figure 1. Erosion of Leucopogon parviflorus scrub, Northern Island, 8 March 1964 (photographer
F.T.H. Smith) ......................................................................................................................... 11
Figure 2. Herbfield on ‘the airstrip’, East Island, January 1972 (photographer T. Pescott). This area
now carries a dense shrubland dominated by Atriplex cinerea and Lavatera plebia (Figure
3). ........................................................................................................................................... 11
Figure 3. Dense shrubland dominated by Atriplex cinerea and Lavatera plebia which has replaced
the open herbfield on ‘the airstrip’ (Figure 2) (photographer P. Menkhorst, 20 June 2010). 12
Figure 4. Shorebirds and shipping, Mud Islands, 22 February 2009 (photographer P. Menkhorst) 12
Figure 5. Example of aerial photograph used to estimate numbers of breeding ibis (photographer P.
Menkhorst) ............................................................................................................................. 15
Figure 6. Nestling Pied Cormorants, East Island, 1 October 2009 (photographer P. Menkhorst) ... 19
Figure 7. Breeding Straw-necked Ibis, 13 September 2009 (photographer P. Menkhorst) .............. 21
Figure 8. Nests of Australian White Ibis, 13 July 2008 (photographer P. Menkhorst) .................... 22
Figure 9. Caspian Tern nest, Boatswain Island, 13 September 2009 (photographer P. Menkhorst) 24
Figure 10. Crested Terns nesting amongst Spinifex sericeus, 13 December 2009 (photographer P.
Menkhorst) ............................................................................................................................. 25
Map 2. Locations of breeding colonies of Australian Pelican at Mud Islands, 2009-2010. ............. 38
Map 3. Locations of breeding colonies of other colonially-breeding birds at Mud Islands, 20092010........................................................................................................................................ 39
Map 4. Locations of ibis colonies at Mud Islands, 2009-2010......................................................... 40
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Acknowledgements
This project is a component of the Migratory Bird Species and Port Phillip (Western Shoreline)
and Bellarine Peninsula Ramsar Site Project managed by DSE through Biodiversity and
Ecosystem Services. I thank Karen Weaver, Yvette Baker and Bill O’Connor for their assistance
with program management and administration.
Many people have assisted in counting birds on Mud Islands over the years and I am grateful to all
of them for their help and company. Particular thanks are due to Fisheries Victoria and Parks
Victoria for providing boat transport to the islands in the early years, to The Friends of Mud
Islands for taking me along on their regular working bees yet not expecting me to work!, and to
David and Linda McKeown for so generously providing their boat and boating skills, and helping
to count pelicans during the last two years of the survey. David Middleton generously made
available his time, expertise, camera gear and aeroplane to allow the aerial photography to take
place. David Cameron (ARI) and Jeff Yugovic (Biosis Research) kindly answered questions
relating to flora. Steve Sinclair (ARI) provided the base image for the maps and the estimates of
the area of each vegetation community. Clive Minton of the Victorian Wader Study Group
provided information on the size and production of tern breeding colonies from the group’s
database. Finally, Canran Lui (ARI) provided statistical advice.
A draft of this report was improved by Richard Loyn (ARI) and Yvette Baker for which I am most
grateful.
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A Survey of Colonially-breeding Birds on Mud islands, Port Phillip, Victoria
Summary
Mud Islands in southern Port Phillip, Victoria, provide important breeding habitat for waterbirds
and significant feeding and roosting habitat for shorebirds. Because of these values the islands are
included in the Port Phillip Bay (Western Shoreline) and Bellarine Peninsula Ramsar Site. Over
recent decades there have been significant changes to the bird communities of Mud Islands but
information about these changes has not been collated or comprehensively documented. This
report attempts to achieve that, and also to provide a complete listing of the terrestrial vertebrate
fauna of the islands, using information collected by the author during 64 opportunistic visits over
26 years and more systematically during 22 visits during 2008-2010. The historical literature
relating to birds at Mud Islands has also been reviewed.
Before the late 1950s only one species of colonially-breeding bird was known to breed on Mud
Islands, the White-faced Storm-Petrel, although anecdotal reports suggest breeding by Australian
Pelicans and cormorant species in earlier times. Silver Gulls were found breeding in small
numbers in 1959 and Crested Terns in 1966. During the 1980s small breeding colonies of
Australian Pelican and Pied Cormorant became established, and in the 1990s Australian White Ibis
and, surprisingly in a marine environment, Straw-necked Ibis formed breeding colonies. These
have been followed in recent years by small colonies of Royal Spoonbill and Little Egret.
Meanwhile, the Silver Gull colony had grown exponentially to an unknown and perhaps
unknowable size, probably several tens of thousands of nests at any one time between July and
December each year. Similarly, the ibis and pelican colonies have grown steadily over the last 15
years.
Mud Islands now support the largest Victorian breeding colonies of White-faced Storm-Petrel,
Australian Pelican, Straw-necked Ibis and Silver Gull, and significant breeding colonies of Pied
Cormorant, Royal Spoonbill, Australian White Ibis, Caspian Tern and Crested Tern. Numbers of
nests of both ibis species were estimated by the analysis of aerial photographs, revealing that the
Straw-necked Ibis colony is far larger than previously realised – estimated at 56 000 nests in
October 2010.
Mud Islands are also an integral component of the complex of shorebird habitats in southern Port
Phillip. This complex includes Swan Bay and its islands, Lake Victoria and Lake Connewarre, as
well as Mud Islands. The number of migratory shorebirds using Mud Islands has declined over
recent decades, reflecting a trend across most sites in Australia where shorebirds are monitored
(Gosbell and Clemens 2006), including other sites around Port Phillip (Herrod 2010). Despite this
decline in usage by some species, Mud Islands still supports significant numbers, at the State level,
of Grey Plover, Double-banded Plover, Bar-tailed Godwit, Grey-tailed Tattler, Ruddy Turnstone,
Great Knot, Red Knot and Sharp-tailed Sandpiper.
The key management issues for maintaining the bird breeding colonies on Mud Islands relate to
ensuring that mammalian predators do not become established, and controlling the activities of
human visitors to ensure that breeding is not disrupted at critical times of the year.
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A Survey of Colonially-breeding Birds on Mud Islands, Port Phillip, Victoria
Introduction
Mud Islands forms a unique low-lying and dynamic environment in shallow waters in southern
Port Phillip, close to the ocean entrance. It has long been renowned as an important habitat for
migratory shorebirds, which feed from the inter-tidal mudflats and roost at high tide on sandbars
and in the central lagoon. It also provides important breeding habitat for colonially-breeding
seabirds and other waterbirds. These fall into three groups. Firstly, one pelagic seabird, the
White-faced Storm-Petrel breeds in burrows on Mud Islands and nearby South Channel Fort
Island. Secondly, several species that feed in coastal waters nest on Mud lslands: Australian
Pelican, Pied Cormorant, Silver Gull, Crested Tern, Caspian Tern and Fairy Tern (not in recent
years). Thirdly, three species that more typically breed in freshwater wetlands (Australian White
Ibis, Straw-necked Ibis and Royal Spoonbill) have established large breeding colonies on Mud
Islands from the early 1990s, with many thousands of ibis commuting between nesting colonies on
the islands and feeding habitat on the mainland fringe of Port Phillip. There was also evidence in
early 2010 of an incipient breeding colony of Little Egrets.
There have been many changes over time in the size of these breeding colonies, including a
progressive increase in numbers of Silver Gulls (from zero in the mid 1950s to tens of thousands
now), erratic changes and disappearance in Fairy Terns, and establishment of breeding colonies of
Australian Pelicans, Pied Cormorants, Royal Spoonbills and massive ibis colonies during the
1990s. Mud Islands support significant numbers of most of these species in the State or national
context. There have been no formal assessments of numbers of these species, with the exception
of the White-faced Storm-Petrel. This report attempts to document these historical changes and
provide baseline data on the location and size of current breeding colonies.
1.1 Location
Mud Islands lie 8 km east of Queenscliff at the southern end of Port Phillip. This places the islands
12 km inside Port Phillip Heads and exposed to tidal movements through the Heads and, to a lesser
extent to swells from Bass Strait.
1.2 Geomorphology
Mud islands are an elipse of low sand dune islands separated by tidal channels and encircling a
shallow tidal lagoon (Map 1). In the central lagoon, the positions of current and past tidal channels
are indicated by sandy tidal deltas. The total land area (including saltmarsh) is approximately 60
ha. Mud Islands are the high point of the Great Sand, part of an extensive series of shoals at the
southern end of Port Phillip that comprise a tidal delta formed by currents pushing into Port Phillip
through the Port Phillip Heads. These shoals are separated by natural channels gouged out by the
tidal flows that take vast volumes of water into and out of Port Phillip twice daily. The Great Sand
is bounded to the south by the South Channel [dredged to allow passage of ships], Pinnace
Channel to the south-east and Symonds Channel to the north-west.
Mud Islands are misnamed – they are composed almost entirely of sand and shell grit, and there
are no muddy sediments on the islands themselves, although areas of silt have accrued within the
lagoon and in surrounding waters. The sand has accumulated by wind and wave action around
outcrops of a soft ‘rock’ called Calcarenite. Calcarenite is formed by the action of phosphate,
leached from bird guano, on underlying shell deposits to form calcium phosphate. The highest and
most stable part of the island system (to about 3 m above sea level), at the southern end of
Boatswain Island, corresponds to the point where the largest outcrops of Calcarenite occur.
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A Survey of Colonially-breeding Birds on Mud islands, Port Phillip, Victoria
Deposits of guano and phosphate-rich rock on Middle Island were mined intermittently between
1860 and 1902 to be used as fertilizer (for details of the extent and duration of mining see Yugovic
1998). Mining ceased when a campaign by the Royal Australasian Ornithologists Union to protect
the White-faced Storm-Petrel colony succeeded in having Middle Island (now incorporated into
East Island) declared a sanctuary for the storm-petrel (Townsend 1903).
Mudflats surrounding the western and northern shoreline are important feeding areas for
shorebirds on falling and low tides, as are the tidal deltas within the lagoon. Shorebirds congregate
at high tide in dense mixed-species flocks on the higher parts of the tidal deltas at the northern end
of the lagoon, or on exposed sand islands along the western shore and on the extensive sand spit
that has recently developed at the south inlet.
The conformation and shape of the islands are constantly changing (Bird 1973). For example,
during the 1900s there were at various times three or four islands (Boatswain, Western, Middle
and East) separated by four inlets (North, East, South and West), all of which except South Inlet
have been periodically closed by shifting sand. Only Boatswain and East Islands, and the deep
South Inlet separating them, have remained stable, being well anchored to the underlying
Calcarenite. During the late 1970s erosion of the former North Cape shore resulted in closure of
the Northern Inlet, uniting East and Northern Islands. With continuing erosion from the western
and northern shores, and deposition in the east and south, East Inlet closed completely in the 1980s
and north Inlet re-opened to be once again a deep channel. Finally, in 2005, the channel between
Boatswain Island and North Island was closed by sand deposits leaving only two islands (hereafter
referred to as Boatswain and East Islands). Wave action on the exposed western and north-western
shore of Boatswain Island has resulted in significant erosion in recent years. However, sand is
being deposited elsewhere so that the eastern-most point of East Island has accreted significantly
over the past 15 years and sandbanks extending from the south of Boatswain Island have resulted
in an extension of the southern outlet channel by some 100 m to the east. These sorts of changes in
shape and conformation have occurred continuously since the islands were first charted by HMS
Rattlesnake in 1836 (Bird 1973).
1.3 Vegetation
The modern vegetation of Mud Island was comprehensively surveyed by Yugovic (1998) and the
saltmarsh component was further categorised and mapped by the Victorian Saltmarsh Study Group
(2010). Map 1 provides an aerial view of the vegetation communities. The terrestrial vegetation
covers some 26.6 ha and comprises dune shrubland dominated by Coast Saltbush Atriplex cinerea
to the seaward, and Coast Hollyhock Lavatera plebia var. tomentosa on the dune ridges. Coast
Hollyhock is one of very few Australian plants adapted to bird colonies with their high
phosphorous and nitrogen levels, and regular disturbance. The stand of Coast Hollyhock on Mud
Islands is one of the largest known and is of high conservation significance (Yugovic 1998). In
recent decades the spread of gull and ibis colonies has resulted in the establishment of a diverse
weed flora through increased nutrients, soil disturbance and the transport of seeds by birds. In
contrast, the saltmarsh communities on Mud Islands, totalling 33.9 ha, are notable for their nearpristine condition, having been protected from introduced grazing mammals and trampling by
people (the European Rabbit Oryctolagus cuniculus is the only herbivorous mammal known to
have been present and that species had died out by 1988). An extensive stand of saltmarsh
dominated by Shrubby Glasswort Tecticornia arbuscula, interspersed with herbfields of Beaded
Glasswort Sarcocornia quinqueflora, occurs on the inward edge of Boatswain Island; other
saltmarshes occupy former tidal deltas at various points around the lagoon and are currently
expanding in area.
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A Survey of Colonially-breeding Birds on Mud Islands, Port Phillip, Victoria
Extensive stands of the sea-grasses Zostera muelleri and Z. tasmanica occur in the surrounding
shallow waters providing important feeding habitat for Black Swans and fish-eating species such
as the Hoary-headed Grebe and cormorants.
Map 1. Aerial view of Mud Islands showing the major vegetation communities and place names
used in the text.
1.4 Changes to Vegetation
Tall stands of coastal scrub dominated by Coast Beard-heath Leucopogon parviflorus formerly
occurred on dunes at the north-west end of Boatswain Island and on Northern Island (summarised
by Yugovic 1998). This scrub provided a sheltered camp site for parties of visiting naturalists
(Figure 1) but has now completely disappeared due to erosion. A violent storm about 1913 is said
to have been responsible for the destruction of large Leucopogon bushes along the western shore,
and for creating a break in the islands at the northern end (presumably the western inlet)
(Campbell 1933). Wheeler (1980) implicates the deepening of The Rip (the entrance to Port
Phillip) during the Second World War in the high tides that washed away the Leucopogon scrub on
Western Island. In 1960, old stumps of Leucopogon could be seen standing in the water at both
ends of the islands. A major storm on 27 September 1962 caused further erosion of the coast scrub
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A Survey of Colonially-breeding Birds on Mud islands, Port Phillip, Victoria
on Northern Island – the fallen trunks of some of these trees persisted in the sea until the 1990s
providing important perching sites for cormorants and Common Terns.
The introduced European Rabbit has had a profound influence on the vegetation and the bird fauna
by maintaining areas of low herbfield through intensive grazing. The largest area of rabbitdominated, low herbfield was a long flat dune on the inward side of East Island, which has been
known as the ‘airstrip’ (Figure 2). The ‘airstrip’ has supported the largest breeding colony of
White-faced Storm-Petrel since records began in 1907. These rabbit-maintained herbfields also
provided habitat for White-fronted Chat and Eurasian Skylark. The Rabbit population was targeted
for eradication by the Fisheries and Wildlife Division during the 1970s and was greatly reduced.
Rabbit numbers then slowly dwindled to zero through the 1980s. Once rabbits declined the
herbfields were invaded by shrubs, notably Atriplex cinerea and Lavatera plebia var. tomentosa
(Figure 3) and there is now no low open vegetation on the islands. These shrublands now provide
breeding substrate for ibis and shelter for breeding Silver Gulls, probably to the detriment of the
storm-petrels which still burrow amongst the roots of the shrubs.
1.5 Land status
Mud Islands were recognized as an important bird breeding area from the beginnings of European
settlement of Melbourne – they were originally called Swan Isles [a name that remains entirely
appropriate] by Acting Lieutenant John Murray of H.M.S. Lady Nelson in February 1802, and
breeding swans and pelicans provided a source of protein for the first settlement at Sorrento in
1803 (Knopwood quoted in Campbell and Mattingley 1907). The name Mud Islands was conferred
by Lieutenants Symonds and Henry of H.M.S. Rattlesnake who mapped the islands in 1836. Mud
Islands were reserved as a ‘site for Public Purposes’ by Order of the Governor in Council on 12
January 1872. The White-faced Storm-Petrel colony on Middle Island was protected from guano
mining in 1903 and the islands were proclaimed a sanctuary for all native game in 1931. Mud
Islands were added to the Register of the National Estate in October 1980. They form part of the
Port Phillip Bay (Western Shoreline) and Bellarine Peninsula Ramsar site, recognizing that they
form part of a wetland of international significance. Mud Islands were included in the Harold Holt
Marine Reserves proclaimed in February 1979, the first marine reserves in Victoria. Finally, in
2002 Mud Islands and a 625 ha square of surrounding waters were included as part of the newly
proclaimed Port Phillip Heads Marine National Park. Uniquely, the land above high tide is also
included in the Marine National Park, for administrative and management convenience.
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A Survey of Colonially-breeding Birds on Mud Islands, Port Phillip, Victoria
Figure 1. Erosion of Leucopogon parviflorus scrub, Northern Island, 8 March 1964
(photographer F.T.H. Smith)
Figure 2. Herbfield on ‘the airstrip’, East Island, January 1972 (photographer T. Pescott). This
area now carries a dense shrubland dominated by Atriplex cinerea and Lavatera plebia (Figure
3).
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A Survey of Colonially-breeding Birds on Mud islands, Port Phillip, Victoria
Figure 3. Dense shrubland dominated by Atriplex cinerea and Lavatera plebia which has
replaced the open herbfield on ‘the airstrip’ (Figure 2), 20 June 2010 (photographer P.
Menkhorst).
Figure 4. Shorebirds and shipping, Mud Islands, 22 February 2009 (photographer P. Menkhorst)
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A Survey of Colonially-breeding Birds on Mud Islands, Port Phillip, Victoria
2 Purpose and scope
This project aimed to document the location, size and significance of waterbird breeding colonies
on Mud Islands over two breeding seasons, 2008-09 and 2009-10. Colonies were located, and
their size estimated, by ground-based counts and by analysis of photographs taken from a light
aircraft. The project also aimed to document what is known of changes in recent decades in the
numbers of breeding waterbirds on Mud Islands. Together, this information provides important
base-line data for managing this unique low-lying part of the Port Phillip Bay (Western Shoreline)
and Bellarine Peninsula Ramsar Site. Note that this proposal does not include work on the Whitefaced Storm-Petrel, as data already exist (studied by Megan Underwood, Deakin University) and
there are several logistical constraints: the Storm-Petrels only visit their burrows at night, and
examination of burrows involves risk of causing them to collapse.
2.1 Objectives
The objectives of this study were to:



Document numbers and locations of breeding waterbirds (gulls, terns, pelicans,
cormorants, ibis and spoonbills) breeding on Mud Islands in two breeding seasons, 200809 and 2009-10.
Document known historical changes in numbers and locations of breeding waterbirds on
Mud Islands from the 1960s.
Provide comments on any other aspects (e.g. habitat use or change) that may be relevant to
management
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3 Methods
3.1 Monitoring breeding birds by foot
During this study the numbers of each bird species on the islands were counted or estimated during
22 visits by boat between 17 February 2008 and 18 April 2010. Access to the islands depended on
the availability of a suitable boat and boat handler, combined with favourable weather (forecast
winds below 20 knots). Spring and summer tended to be the most problematic seasons because of
prevailing northerly winds. These months are also the peak breeding times of colonially-breeding
species on the islands. The monthly distribution of these visits is shown in Table 1. During each
visit particular attention was given to locating breeding colonies and estimating the number of
active nests of each species by direct count of nests containing eggs or young.
Table 1. Numbers of bird counts conducted by the author at Mud Islands per month before the
present study and during the present study.
MONTH
J
F
No. visits pre Feb 2008
1 21 0
J
A S O N D TOTALS
0
1
8 19 4
4
3
1
2
64
2
1
4
1 2
2
1
1
1
1
22
4 24 2
1
5
9 21 6
5
4
2
3
86
No. visits post Feb 2008 3 3
Total visits
M A M J
3.2 Monitoring breeding birds from the air
Two flights using a Cessna 172S aircraft were also made – a preliminary trial flight in November
2008 to test the efficacy of aerial photography for identifying and counting active nests, and a data
collection flight on 9 October 2009. A Canon 400 mm telephoto lens, combined with a Canon
digital SLR camera, was assessed as providing the best combination of ease of use within the cabin
of the Cessna and resolving power necessary to distinguish active ibis and spoonbill nests (as
compared to 300 mm and 600 mm Canon lenses).
The data collection flight on 9 October 2010 was intended to coincide with a peak of breeding by
the colonially-breeding species that are most difficult to estimate – ibis species (because of the
large number of nests) and the Royal Spoonbill (because of the habitat damage involved in
accessing its nests). A visit to the islands before the flight allowed the setting up of a scale for later
calibration of the aerial photographs. The scale consisted of two red buckets set 10 m apart in a
clear area above the high tide line, filled with sand and upturned so that they would remain in
place. This scale was photographed from the aeroplane in the same manner as the nesting colonies
and allowed the construction of a grid of known area (5 m x 5 m) to be placed over a computer
monitor so that nest densities in each image could be calculated.
During the flight ‘continuous’ (within the capacity of the camera to process and store the data)
photographs were taken, in a roughly vertical plane, of the terrestrial parts of the island system
while the aircraft circled at an altitude of 1500 feet. This resulted in some 400 images of the
breeding habitat that were available for analysis. Digital cameras automatically assign a number to
each image and these numbers were used to select a random sample of images for analysis by
electronically generating random numbers within the range of numbers assigned by the camera to
these 400 images.
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A Survey of Colonially-breeding Birds on Mud Islands, Port Phillip, Victoria
The first 60 images in the random list which were sharp enough to allow identification of large
wading birds and their nests were analysed (n = 1083 5x5 m cells). These images covered 2.7 ha of
terrestrial habitat, some 10.2% of the terrestrial vegetation on the islands (26.565 ha).
Using the 5 x 5 m grid overlay, each grid cell that contained > 50% coverage of terrestrial habitat
was selected for counting of the number of nests of each species. The mean number of nests per ha
was then calculated. Because of the clumped distribution of nests (for example see Figure 5), a
non-parametric bootstrap procedure was used to calculate 95% confidence intervals around the
mean. This density was then scaled to the area of nesting habitat (derived from the vegetation
mapping component of the Victorian Saltmarsh Study (Steve Sinclair ARI, unpublished data)) to
yield an estimate of the total number of nests of each species.
3.3 Previous bird counts at Mud Islands
The author has made numerous trips to Mud Islands beginning in July 1982. During a majority of
these visits an attempt was made to record all bird species present and to count or, where
impracticable, to estimate the numbers of each. Only species that actually used the islands and
surrounding mudflats are included here; seabirds utilizing surrounding waters, and beach-cast
records are excluded. Data collected on 86 trips are summarised in Appendix 1 and used to inform
the discussion of colonially-breeding birds, as appropriate. Although the 64 visits made before
February 2008 (the beginning of this project) occurred during all months except March and April,
most occurred in either February (21 visits, 33%) or July (19 visits, 30%) (Table 1) to coincide
with the summer and winter wader counts conducted by the Australasian Wader Study Group.
Figure 5. Example of aerial photograph used to estimate numbers of breeding ibis
(photographer P. Menkhorst)
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A Survey of Colonially-breeding Birds on Mud islands, Port Phillip, Victoria
3.4 Historical literature search
Local natural history and birding journals were searched for reports of visits to Mud Islands. These
include The Victorian Naturalist, Geelong Naturalist, The Bird Observer and its predecessor Bird
Observers Club Monthly Notes, VORG Notes, Australian Bird Watcher and Emu. A previous
compilation (Menkhorst 1982) was used as a basis for the literature search.
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4 Results
Throughout this report bird names and taxonomic sequence follow Christidis and Boles (2008).
4.1 Colonially-breeding birds, 2008-2010
Nine species of colonially-breeding bird were monitored between 22 February 2008 and 18 April
2010. This timing covered part of the 2007/08 breeding period for some species and all of the
subsequent two breeding seasons for all species. Each species is treated separately below.
4.1.1
Australian Pelican
Australian Pelicans were found to breed almost continuously at Mud Islands during this two-year
period. Colonies have been sited on all islands and vary from small groups of about 15 nests to
large sites with about 300 nests (see cover photograph), all located in Coast Saltbush or Coast
Hollyhock shrubland. Colony sites are regularly abandoned at the end of a breeding event, perhaps
due to destruction of the shrub cover by the birds themselves (the presence of a pelican colony
often results in the destruction of Coast Saltbush on the site and its replacement with Coast
Hollyhock, a species highly adapted to disturbed sites with high nutrient concentrations (Yugovic
1998).
Nests and nest contents were counted during 17 visits to the islands between 15 February 2009
and18 April 2010. (On four previous visits between February 2008 and February 2009 nesting
colonies were not entered because the levels of disturbance that breeding pelicans will tolerate
were unknown, so only qualitative descriptions of breeding stage were obtained.) Active nests or
dependent young could be found somewhere on the islands in all months except April. Breeding
was extraordinarily protracted, beginning in April and May when groups of adults with full
breeding colour in their gular pouches gathered on sandbanks at the northern end of the islands. By
mid-May in both years a large colony of about 200 nests had formed at the north end of East
Island. The final breeding activity was evident in late March when downy young in the last
remaining crèche moulted into immature plumage and dispersed to the central lagoon. Colonies of
varying size formed at 10 separate locations during the survey period (Map 2, Table 2) and these
formed consecutively eastwards and southwards from the first colony along the outer edge or inner
edge of East Island (Map 2), except for colony 7 which was on the main dune at the northern end
of East Island (formerly known as the ‘airstrip’). The maximum number of nests found during
field surveys across all sites in the 2009/10 breeding period was 784, but this is likely to be an
underestimate because many unsuccessful nesting attempts would have been missed between
visits.
As far as can be determined from the frequency of visits achieved in this study, egg laying was
fairly constant between mid-May and mid-November with peaks in early winter (May-June) and
spring (September-November) (Table 3), but peaks in laying are likely to be strongly influenced
by seasonal conditions and may vary between years. There is no information on the level of relaying after a successful breeding event or whether there is a succession of pairs forming and
breeding through the breeding season. Therefore, it is not possible to estimate the numbers of
breeding pairs without having a proportion of breeding birds individually tagged.
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Table 2. Monthly distribution of nests with eggs (E), nests with nestlings (N) and crèches of
juvenile Australian Pelicans (C), on Mud Islands between February 2008 and March 2010. See
Map 2 for location of colonies.
COLONY NO. OF
J
NUMBER NESTS
(MAX.
COUNT)
F
M
AP
M
J
J
N
A
E
S
O
N
E
E
E
D
1
20
2
30
E
E
E
N
N,
C
C
3
58
E
E
E,
N,
C
E,
N,
C
E,
N,
C
C
4
300
E,
N,
C
E,
N,
C
E,
N,
C
E,
N,
C
C
C
5
32
E
E,
N,
C
C
6
53
E
E
7
120
N,
C
8
54
C
9
105
E,
N,
C
10
12
C
E
E,
N
N
E,
N,
C
E
E,
N
E,
N,
C
E
N
C
E,
N
E,
N,
C
E
E,
N
C
Table 3. Monthly numbers of nests of the Australian Pelican on Mud Islands that contained eggs
between February 2009 and April 2010 when counts were made. e – estimated.
MONTH
J
F
M A M
No. of nests with eggs 0 11 0
0
J
J
A S
200e 300e 80 0
O
N
D
160 308 163 13
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4.1.2
Pied Cormorant
A discrete colony of 40-50 pairs of the Pied Cormorant bred on the easternmost point of Mud
Islands (Map 3) (Figure 6) in the winters of 2008 and 2009, as has occurred since July 1986. Nests
are constructed in Atriplex cinerea adjacent to the beach. Breeding begins with the refurbishment
of nests in late June and is completed by mid-November.
Observations are summarised below:
17 Feb and 4 May 2008 – no breeding
13 July 2008 – estimate 50 nests with eggs on East Point; 120 adults present.
3 May and 31 May 2009 – no breeding
21 June 2009 – no breeding
30 July 2009 – 18 nests with eggs, 16 others refurbished but not laid in.
30 August 2009 – estimate 40 nests, about 2/3 with eggs, 1/3 with nestlings.
13 September 2009 – 42 nests, contents range from eggs to large downy chicks.
1 October 2009 – nests with large young – prone to jump so didn’t inspect closely.
18 Nov 2009 – breeding finished
December 2009-18 April 2010 – no breeding
There is only one other regular breeding colony of the Pied Cormorant in Victoria, at the Western
Treatment Plant on the western shore of Port Phillip. Curiously, breeding at this colony occurs
mainly in summer and autumn (R. Loyn and R. Swindley pers comm.).
Figure 6. Nestling Pied Cormorants, East Island, 1 October 2009 (photographer P. Menkhorst)
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4.1.3
Little Egret
The first record of this species breeding on Mud Islands came in December 2009 when a small
colony of three nests was located amongst ibis nests built in Atriplex cinerea shrubs on the eastern
edge of the south outlet (Map 3). The only other regular breeding site in southern Victoria for this
species is in cypress trees at Geelong Grammar on the edge of Limeburners Lagoon, Corio (e.g.
Hewish 2006).
Observations are summarised below:
13 December 2009 – 8 birds perched in Coast Saltbush at south entrance on East Island. One nest
with 3 eggs and 2 nests with 3 nestlings were found, but the search was incomplete. At least one,
possibly more, of the perched birds had a yellow bill (a juvenile characteristic for a percentage of
birds).
4 January 2010 – only 4 birds present and no active nests found. At least one of the egrets, which
was photographed in flight, had a yellow bill with a dusky tip – indicating that it is juvenile. This
raises the distinct possibility that it was hatched here in preceding months, i.e. earlier breeding by
this species may have been missed.
24 January 2010 – one adult at South Inlet with remnants of breeding plumes.
28 March and 18 April 2010 – no Little Egrets observed.
4.1.4
Straw-necked Ibis
Straw-necked Ibis bred between July and November in the terrestrial shrubland dominated by
Atriplex cinerea. Mixed colonies of this species and the Australian White Ibis occupied virtually
the entire available habitat (Map 4) (Figures 5 and 7), though nest densities were variable. The
relative proportions of both ibis species in the colony changed over time. Australian White Ibis
were first to begin nesting and were estimated to be four times as numerous during August.
However, by October the number of Straw-necked Ibis breeding in the colony had increased
dramatically and they were by far the most numerous species.
Observations are summarised below:
31 May 2009 – no breeding or prospecting, small groups flying over.
30 July 2009 – nests being guarded by approx. 3000 adults, laying not confirmed.
30 August 09 – many thousands of nests with eggs. Outnumber White ibis by 4:1 but White ibis
more advance with their breeding.
13 September 2009 – many nests now with well developed young.
1 October 2009 – some runners, but also many nests still with eggs.
18 November 2009 – many 1000s of runners and free-flying young across the entire island
complex.
13 December 2009 – breeding effectively finished, many thousands of free-flying young still
present.
4 January 2010 – as above, still several thousand flying young standing around lagoon and on
sandbars.
24 January – only 4 birds counted at south end. Breeding finished.
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A Survey of Colonially-breeding Birds on Mud Islands, Port Phillip, Victoria
Figure 7. Breeding Straw-necked Ibis, 13 September 2009 (photographer P. Menkhorst)
28 March 2010 – no birds observed
18 April 2010 – no breeding, one small group flying over
The estimation of nest densities derived from aerial photographs taken on 9 October 20009
indicate a mean nest density of 2114.28 +/- 289.5 nests/ha of terrestrial shrubland, and a colony
size of 56 166 nests (95% CI 40 963 – 71 223).
4.1.5
Australian White Ibis
This species nested in much lower numbers than the Straw-necked Ibis but had a more protracted
breeding period and there were several laying events, beginning in July and continuing through
October, November and January. Dense clumps of Australian White Ibis nests were scattered
through the more widespread and dispersed nests of Straw-necked Ibis. These dense clusters of
nests constructed of woody branches of Atriplex cinerea form solid nest platforms that survive
between breeding seasons and are renewed and reinforced each year (Figure 8).
Observations are summarised below:
1 July 07 – nest building has commenced
25 May 2008 – no breeding
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A Survey of Colonially-breeding Birds on Mud islands, Port Phillip, Victoria
13 July 2008 – 200+ nests with eggs, mostly at north end of Boatswain Island and north of East
Point, East Island.
31 May 2009 – no breeding
21 June 2009 – small groups occupying nest platforms within colony sites.
30 July 2009 – clusters of nests with eggs on the Airstrip and Leg of Mutton.
30 August 2009 – breeding well advanced, many large nestlings; nests concentrated at north end of
Boatswain Island, on Airstrip and across southern end of both islands, including Leg of Mutton.
13 September 2009 – breeding in full swing; nest contents range from eggs to runners.
1 October 2009 – as above, new round of laying may be happening.
18 November 2009 – much new laying had occurred.
13 December 2009 – still several thousand active nests.
4 January 2010 – as above, new clutches being laid on north east side of ‘airstrip’.
24 January 2010 – still estimated 200 nests with nestlings/near runners on east side of ‘airstrip’.
21 February 2010 – no sign of breeding observed by David McKeown or Ash Herrod (pers. com)
28 March 2010 – only 15 birds flying over
18 April 2010 – only one group flying over
The estimation of nest densities derived from aerial photographs taken on 9 October 20009
indicate a mean nest density of 286.7 +/- 78.03 nests/ha of terrestrial shrubland, and a colony size
of 7616 nests (95% CI 3924 – 11986).
Figure 8. Nests of Australian White Ibis, 13 July 2008 (photographer P. Menkhorst)
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4.1.6
Royal Spoonbill
Royal Spoonbills were not observed to breed at Mud Islands during the 2008/09 summer but did
so in the following summer when at least 31 nests were found in a tall stand of Shrubby Glasswort
Tecticornia arbuscula east of the north outlet (Map 3). A few pairs are suspected to have bred in
the same area in previous years but breeding was not confirmed: thus, the breeding event in the
summer of 2009/10 is the first definite breeding record by this species on Mud Islands.
Observations are summarised below:
1 October 2009 – birds in breeding plumage noted standing guard on Tecticornia bushes, north
end of East Island. Nests not distinguished from those of ibis.
9 October 2009 – aerial survey indicates at least 18 nests present (by presence of adults perched in
Tecticornia beside nests).
18 November 2009 – 31 nests counted by presence of adults perched in Tecticornia; some with
eggs, others with small nestlings.
13 Dec 2009 – some young have fledged (can fly a little) but still spending time on nest.
4 January 2010 – 11 adults standing guard at nests (did not investigate further)
24 January 2010 – 3 adults guarding nests
28 March 2010 – no spoonbills observed
18 April 2010 – no spoonbills observed
4.1.7
Caspian Tern
A small colony of Caspian Terns breeds annually during spring and early summer at the top of the
beach along the northern shore of Boatswain Island (Map 3) (Figure 9). In 2009 the maximum nest
count was 24 on 23 November. The Victorian Wader Study Group (VWSG) subsequently banded
15 juveniles which is likely to be close to the total production of young (Clive Minton, VWSG,
pers. comm.). Since 1987/88 the estimated number of breeding pairs at this colony has varied
between 7 and 30 (mean 18.8, sd 6.5) (VWSG unpublished data).
Observations are summarised below:
17 February 2008 – 2 juveniles swam off from the beach – non-flying?
13 Sept 2009 – 3 nest scrapes, one with 2 eggs
1 October 2009 – nests from 13 Sept gone; 6 new scrapes, no eggs.
18 November 2009 – 17 nests, 2 with nestlings, 15 with 2 eggs.
23 November 2009 – 24 nests, 21 with eggs, some hatching; 3 with nestlings; 2 runners.
13 December 2009 – 15+ nests with nestlings/runners; 4+ free-flying young.
4 January 2010 – one new nest with 2 eggs, 12 runners on beach and 6 free-flying young on
sandbank offshore.
24 January 2010 – 10 free-flying young on sandbank offshore.
28 March 2010 – no birds present
18 April 2010 – no birds present
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Figure 9. Caspian Tern nest, Boatswain Island, 13 September 2009 (photographer P. Menkhorst)
4.1.8
Crested Tern
A colony of Crested Terns breeds annually between October and January on a flat, sand bench
about 1 m above high tide mark on Boatswain Island (Map 3) (Figure 10). In the 2009 breeding
season the colony was estimated to total 1300 nests and 676 juveniles were banded by the VWSG
with an estimated total chick production of 700-800 (Clive Minton pers. comm.). Since 1986/87
the estimated number of breeding pairs at this colony has varied between 800 and 2600 (mean
1490, sd 452) (VWSG unpublished data). In recent years the number of nests may have been
constrained by the available space as beach erosion has steadily reduced the width of Boatswain
Island and of the sand bench on which the colony forms. Breeding habitat at this colony has been
actively managed since 1985 by volunteers from the VWSG and Friends of Mud Islands through
the annual removal of encroaching shrubs to maintain an open area with only low grassy
vegetation, the preferred breeding habitat. One of three regular Victorian breeding colonies, only
that on The Nobbies, Phillip Island, is larger, and it was started by birds that had been born (and
banded) at Mud Islands (Peter Dann pers. com).
Observations are summarised below:
30 August 09 – adults in breeding plumage congregating on mudflat.
13 September 2009 – as above, courtship displays on beach.
1 October 2009 – birds milling around colony site, courtship displays etc.
22 October 2009 – egg laying has begun
18 November 2009 – hundreds of nests with eggs.
23 November 2009 – 1100 nests each with 1 egg estimated by VWSG.
13 December 2009 – many nests with a nestling/runner.
4 January 2010 – breeding almost finished, some runners still being fed in the saltbush at northern
end, several hundred free-flying young on nearby sandbanks.
24 January 2010 – breeding completed
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A Survey of Colonially-breeding Birds on Mud Islands, Port Phillip, Victoria
Figure 10. Crested Terns nesting amongst Spinifex sericeus, 13 December 2009 (photographer
P. Menkhorst)
4.1.9
Silver Gull
During the study, Silver Gulls bred continuously between late June and early January each year. It
was not possible to estimate numbers from the ground or from the air because of the small size of
nests and the fact that most are hidden beneath shrubs and not readily visible. Further, new nests
with eggs constantly appear through that six month breeding period. Without a large sample of
marked pairs, the level of re-nesting by a given pair cannot be estimated, so neither the total
number of nest attempts, nor the total number of breeding pairs can be estimated. It is clear,
however, that the species nests on all dry sandy portions of the islands, including beaches above
high tide mark, and that the total number of breeding attempts is in the 10’s of thousands. An
estimate of 30 000 nests at any one time during the height of the breeding period (August to
December) is tentatively suggested, but more accurate estimates were not possible within the time
and resources available in this study.
Observations are summarised below:
1 July 2007 – some nests with eggs
17 Feb 2008 – no breeding, few birds present.
13 July 2008 – many nests with eggs
15 February 2009 – no breeding
21 June 2009 – large numbers of adults present, nest site defence taking place.
30 July 2009 – many thousands of nests with eggs.
1 October 2009 – all stages of breeding, many free-flying young.
18 November 2009 – very few nests with eggs, many free-flying young.
13 December 2009 – no eggs noticed, but not a thorough search.
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A Survey of Colonially-breeding Birds on Mud islands, Port Phillip, Victoria
4 January 2010 – some adults still seem to be territorial but no eggs or non-flying young seen
24 January 2010 – breeding completed
4.1.10 Summary of colonially-breeding birds
The results summarised in Table 4 indicate that during the late winter and spring of 2008 and 2009
the number of breeding birds at Mud Islands was in the order of 90 000 pairs. If, as seems likely,
different pairs of ibis and Silver Gulls lay sequentially through their protracted breeding season
then the actual number could be significantly higher.
Table 4. Summary of colonially-breeding birds at Mud Islands.
SPECIES
COLONY SIZE
(PAIRS)
BREEDING
PERIOD
COMMENTS
White-faced
Storm-Petrel
? 1000
Sept- Feb
One of 3 Victorian breeding colonies,
numbers steadily declined through 20th
century
Pied Cormorant
50-100
July-Nov
One of 2 regular breeding colonies in
Victoria
Australian
Pelican
700-800
May-Feb
One of 2 regular breeding colonies in
Victoria (O’Brien et al. 2010)
Little Egret
?3+
Dec
Possibly an incipient colony
Australian
White Ibis
7 000
Jul-Dec
Now probably Victoria’s largest regular
breeding colony
Straw-necked
Ibis
55 000
Jul-Jan
Now probably Victoria’s largest regular
breeding colony
Royal Spoonbill
30
Sept-Jan
Numbers of breeding pairs is increasing
Caspian Tern
19
Nov-Dec
One of 3 regular breeding colonies in
Victoria
Crested Tern
1500
Nov-Dec
Victoria’ second largest breeding colony
Silver Gull
?30 000
July-Feb
One of the largest breeding colonies of
this species.
4.2 Other breeding birds
Evidence of breeding by a few other species which breed as isolated pairs was also gathered
during the survey. These include Black Swan, Swamp Harrier, Red-capped Plover, Pied
Oystercatcher and Buff-banded Rail (for further details see Appendix 2).
4.3 Non-breeding visitors
Mud Islands is also recognised as an important feeding and roosting site for migratory shorebirds,
and 22 species were recorded during this survey. At a State level, Mud Islands is particularly
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A Survey of Colonially-breeding Birds on Mud Islands, Port Phillip, Victoria
important as a feeding site and high-tide roost for Grey Plover, Bar-tailed Godwit, Great Knot,
Red Knot and Grey-tailed Tattler. It also supports significant numbers of Common Greenshank,
Sharp-tailed Sandpiper, Red-necked Stint, Ruddy Turnstone and Double-banded Plover. This is
true for both summer, when the entire population of trans-equatorial migrants is present for their
non-breeding period, and winter when immature birds remain on the wintering grounds until they
reach sexual maturity in their second year of life or later.
The seagrass beds surrounding Mud Islands and inside the tidal lagoon provide feeding habitat for
large numbers of Black Swans, particularly in summer and autumn when around 1000 birds are
regularly present.
4.4 Historical records
Historical records of interest are summarised in the Annotated List of Species (Appendix 2).
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5 Discussion
5.1 Sources of error in population estimates
The population numbers presented for colonially-breeding species are estimates only, with several
sources of potentially significant error. To overcome these sources of error would require far
greater resources than were available for this project, including individually marking a large
number of breeding birds and their nests for all species, and a greater frequency of visits to the
colonies. Species with relatively small populations were estimated by direct counts of nests so
estimates are likely to be accurate snapshots of the situation on the survey day. For species with a
tightly defined breeding season (such as the Royal Spoonbill, Crested Tern and Caspian Tern)
counts of nests and chicks late in the breeding cycle will give an underestimate of the total number
of pairs that attempted to breed because failed nests from earlier in the season will have been
missed. However, a reasonable estimate of the production of young may be derived. Species with a
protracted breeding season (Australian Pelican, Pied Cormorant, ibis and Silver Gull) present
particular difficulties because re-laying by the same pair cannot be distinguished from nests
commenced by newly arrived pairs. This means that we cannot reliably estimate the number of
pairs of these species that breed on the islands. Rather, the figures presented represent a minimum
number of nest attempts. This is particularly so for the once-off aerial survey.
Sources of error in interpretation of the aerial photographs relate mainly to three causes
1. the assumption that the area sampled by each image is constant, that is, that the
aeroplane’s altitude was constant during the photo session. Depending on whether the
aeroplane edged above or below the desired altitude, this error would be positive or
negative, and therefore any differences may tend to cancel each other out.
2. the clumped distribution of the ibis nests resulted in high variability in counts and large
confidence intervals around the estimates (95% CI is 54% of the estimate for Strawnecked Ibis and 96% for Australian White Ibis). It was not practicable, within the
resources available for this project, to analyse enough images to significantly tighten
these CIs.
3. the ability to distinguish active nests from old nests, and incubating birds from standing
birds not actually incubating. In patches of high ibis nest density over-counting may
have occurred if both members of a pair were present at the nest site and this was scored
as two nests rather than one. Care was taken to only count sitting birds and exposed
nests with obvious contents (eggs or young), however, there may have been a level of
double counting, or the counting of abandoned nests where unhatched eggs remain.
Both of these factors would inflate the population estimate by unknown amounts.
5.2 Significance of Mud Islands for birds
Results of this survey indicate that in recent years in the order of 95 000 nests belonging to 10
species of colonially-breeding bird occurred at Mud Islands during spring (Table 4). This
represents one of the highest concentrations of breeding birds in Victoria. The high populations of
several species are likely to reflect a local abundance of food, from both natural and humanderived sources. Fish are among the main foods attracting Australian Pelicans, Pied Cormorants
and terns. Australian Pelicans also scavenge at places where fishermen clean their catch and at
refuse tips near the shores of Port Phillip, along with Australian White Ibis and large numbers of
Silver Gulls. Straw-necked Ibis feed extensively in pastures around Port Phillip, including the
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A Survey of Colonially-breeding Birds on Mud Islands, Port Phillip, Victoria
Western Treatment Plant (Macak et al. 2002, Loyn et al. 2008), while Australian White Ibis and
Royal Spoonbills forage in both tidal and non-tidal areas.
5.2.1
Waterbirds
Colonially-breeding waterbirds are known to have bred at Mud Islands since records were first
made in 1803 (Campbell and Mattingley 1907), however, there appears to have been a long period
of absence through much of the twentieth century. There are anecdotal reports of pelican and
cormorant colonies through the early- mid-1900s, including attempts to destroy them by fishermen
concerned that the birds were competing with them for fish. These attempts may have succeeded
because such colonies did not exist in the early years of this survey – Australian Pelicans were first
found breeding at Mud Islands in 1983 (Menkhorst et al. 1983) when 10 nests were present. The
number of nests has steadily increased to the current 700-800 nesting attempts per year. Similarly,
Crested Terns were not known to breed on the islands until 1966 but have bred annually since
then, as have Pied Cormorants since their first recorded breeding in 1986.
In recent decades there has been a remarkable colonisation of the islands by a succession of
colonially-breeding species. It began with the Silver Gull in the late 1950s (Menkhorst et al. 1984),
continued with the Crested Tern (1960s), Australian Pelican and Pied Cormorant (1980s), two
species of ibis (1990s) and Royal Spoonbill and Little Egret (early 2000s). One species of
colonially-breeding bird has ceased breeding at Mud Islands – the Fairy Tern. It probably
attempted to breed annually until the late 1980s when, as elsewhere in Port Phillip, breeding
became intermittent, and declined to nothing by the late 1990s. The last recorded breeding event
on Mud Islands was in 1997 when only a couple of young were fledged.
The Silver Gull colony is by far the largest in Victoria and, on a world scale, is rivalled only by the
Five Islands colony off Newcastle, New South Wales (Higgins and Davies 1996). The Silver Gull
is a scavenger with a varied diet. It probably plays an important role in the removal of dead animal
matter from the Port Phillip ecosystem, as well as from the surrounding urban environments. There
are no obvious reasons to consider the species to be ‘over-abundant’, rather the population has
increased in proportion to the availability of food provided by the surrounding human population.
The number of nests on Mud Islands is likely to have declined over the last decade as the ibis
colonies have increased and usurped much of the area previously available for nesting by the
Silver Gull. Although Silver Gulls continue to nest amongst the ibis nests, there may be a level of
predation on their chicks by Australian White Ibis which are known to eat a range of small
vertebrates (Higgins and Davies 1996).
The colony of Straw-necked Ibis is by far the largest reported for Victoria (Cowling and Lowe
1981, Marchant and Higgins 1990), at least in recent decades when some former large breeding
colonies in the Kerang Lakes have declined due to a lack of water. Ibis are widely recognised to
play a significant role in the control of large insect pests of pasture, and farms on the Bellarine and
Mornington Peninsulas, and beyond, are likely to have benefited from the presence of this colony.
5.2.2
Shorebirds
In a review conducted in the early 1980s (Lane et al. 1984), Mud Islands was considered to be of
national significance because it supported greater than 1% of the Australian populations of 4
shorebird species: Pacific Golden Plover (3.0%), Ruddy Turnstone (1.4%), Lesser Sand Plover
(1.3%) and Grey Plover (1.2%). Since that time our understanding of shorebird numbers in northwestern Australia and elsewhere has rendered early assessments of significance for shorebirds
redundant, and it is doubtful that any shorebird species at Mud Island would now meet that
criterion for national significance. However, four shorebird species are regularly recorded in
numbers that represent a significant proportion of the Victorian population: Great Knot, Red Knot,
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Grey Plover and Bar-tailed Godwit. Numbers of the Grey-tailed Tattler, although small, are also of
significance at the State level as this species is now rarely found in Victoria.
There is qualitative evidence of a decline in tidal influence in the central lagoon and a steady
expansion of saltmarsh vegetation onto the sandflats at the northern end, particularly since the
closure of the western inlet. The increasing frequency of filamentous green algae in the lagoon is
suggestive of enhanced nutrient levels, possibly associated with excrement from the increasing
numbers of ibis and pelicans. Both of these habitat changes may be affecting the quality of habitat
for shorebirds within the lagoon and may have led to an apparent decrease in shorebird usage of
the central lagoon in recent years.
5.2.3
Seabirds
One species of pelagic seabird breeds at Mud Islands – the White-faced Storm-Petrel (Menkhorst
et al. 1984) and has done so since at least 1882 (Campbell 1901). Harris (1979) estimated the
number of pairs at 5600 but there appears to have been a steady decline since that time and the
total breeding population is now unknown, but thought to be considerably less, probably less than
1000 pairs (M. Underwood pers. comm., author pers. obs.). There are two other small breeding
colonies of this species in Victoria, on the nearby South Channel Island and Tullaberga Island in
East Gippsland (Harris 1979). The species breeds at many islands around southern Australia and
the Victorian colonies are small compared to many off Tasmania, South Australia and Western
Australia (Marchant and Higgins 1990).
5.2.4
Threatened Species
Threatened species recorded at Mud Islands are listed in Table 5. The Orange-bellied Parrot and
Hooded Plover no longer make use of the islands, although the islands were an important site for
the Orange-bellied Parrot until the early 1970s (Appendix 2). At the State level the islands provide
important feeding habitat for Royal Spoonbill, Grey-tailed Tattler, Great Knot, Little Tern and
Fairy Tern.
Table 5. Threatened species that utilize Mud Islands, excluding species recorded only once or
twice. FFG – Flora and Fauna Guarantee Act 1988; EPBC – Commonwealth Environment
Protection and Biodiversity Conservation Act 1999; DSE – Advisory List of Threatened
Vertebrate Fauna in Victoria 2007; f – listed under Flora and Fauna Guarantee Act; ce – critically
endangered; e – endangered; v – vulnerable.
SPECIES
FFG EPBC DSE
Little Egret
f
-
e
Royal Spoonbill
-
-
v
Lewin’s Rail
f
-
v
Black-tailed Godwit
-
-
v
Whimbrel
-
-
v
Grey-tailed Tattler
f
-
c
Great Knot
f
-
e
Lesser Sand Plover
-
-
v
Greater Sand Plover
-
-
v
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Hooded Plover
f
-
e
Little Tern
f
-
v
Fairy Tern
f
-
e
ce
ce
Orange-bellied Parrot f
5.3 Changes to the Bird Fauna
In addition to the colonisation of Mud Islands by colonially-breeding waterbirds (section 4.2.1),
population fluctuations have been observed in several species, probably in response to changes in
vegetation and habitat structure. These changes are summarised in Tables 6 and 7. The loss of
coastal scrub during the 1960s has led to the loss of two honeyeaters that formerly inhabited or
visited that vegetation community – White-eared Honeyeater and New Holland Honeyeater, and
the Silvereye was a more abundant and regular visitor when coastal scrub was still present on the
islands. The loss of open herbfield habitat following the extinction of the European Rabbit
population has resulted in a decline in birds that require low open herbfield – White-fronted Chat
and the introduced Eurasian Skylark.
Partly in accord with a sharp decline in shorebird populations within the East Asian-Australasian
Flyway (Gosbell and Clemens 2006, Nebel et al. 2008), the number and diversity of shorebirds
using Mud Islands has declined during recent decades. Species that are no longer recorded there,
or are rare and unpredictable, include the East Curlew, Whimbrel, Grey-tailed Tattler, Large Sand
Plover and Lesser Sand Plover.
Table 6. Bird species that have declined in population number on Mud Islands since 1982 and
possible reasons for the declines.
SPECIES
POSSIBLE CAUSES
Chestnut Teal (see
Appendix 2)
unknown
Little Penguin
Establishment of St Kilda breakwater colony provided superior
nesting sites?
White-faced StormPetrel
Interference and possible predation from breeding gulls and ibis?
Eastern Curlew
Consistent with general decline in numbers using Port Phillip.
Changing substrate in tidal lagoon?
Grey-tailed Tattler
Consistent with general decline in numbers using Port Phillip.
Changing substrate in tidal lagoon?
Pied Oystercatcher
Increasing disturbance of breeding pairs as human visitation rate
increases?
Lesser Sand Plover
Consistent with general decline in numbers using Port Phillip,
changing substrate in lagoon?
Greater Sand Plover
Consistent with general decline in numbers using Port Phillip,
changing substrate in lagoon?
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Hooded Plover
Never primary habitat
Red-capped Plover
Increased predation by Silver Gulls?
Common Tern
Decline in availability of suitable resting perches with the decay of
remnants of eroded coastal scrub?
Fairy Tern
Consistent with general decline of Port Phillip breeding colonies.
Orange-bellied Parrot
Reduction in bare ground and potential food plants following the
decline of the rabbit population and increasing weed flora introduced
by breeding gulls?
White-eared and New
Holland Honeyeaters
Formerly associated with the tall coastal shrubland that was present
on Northern Island until mid 1960s.
White-fronted Chat
Formerly associated with ‘the airstrip’ – a site of guano mining in the
late 19th century that was maintained as a low herbfield through heavy
grazing by European Rabbits. With the extinction of the rabbit
population during the mid 1980s the vegetation rapidly converted to a
dense shrubland dominated by Lavatera plebia.
Silvereye
Formerly associated with the tall coastal shrubland of Leucopogon,
Leptospermum and Acacia that was present on Northern Island until
mid 1960s.
Eurasian Skylark
Formerly associated with ‘the airstrip’ – a site of guano mining in the
early 20th century that was maintained as a low herbfield through
heavy grazing by European Rabbits. With the removal of rabbits
during the mid 1980s the vegetation rapidly converted to a dense
shrubland dominated by Lavatera plebia.
Australasian Pipit
Formerly associated with ‘the airstrip’ – a site of guano mining in the
early 20th century that was maintained as a low herbfield through
heavy grazing by European Rabbits. With the removal of rabbits
during the mid 1980s the vegetation rapidly converted to a dense
shrubland dominated by Lavatera plebia.
European Goldfinch
Reduction in bare ground and potential food plants following the
decline of the rabbit population and increasing weed flora introduced
by breeding gulls?
Table 7. Bird species that have increased in population number on Mud Islands since 1982 and
possible reasons for the increases.
SPECIES
PROBABLE CAUSE
Pied Cormorant
Establishment of a breeding colony on East Point in 1986.
Australian Pelican
Establishment of a breeding colony in 1983. Increasing level of
commensualism with humans in this species – increased food
availability via recreational fishing and human usage of southern Port
Phillip.
Australian White Ibis
Establishment of a breeding colony in 1990. Increasing level of
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commensualism with humans in this species.
Straw-necked Ibis
Establishment of a breeding colony in 1991.
Silver Gull
Establishment of a breeding colony in 1959. Increasing level of
commensualism with humans in this species.
Crested Tern
First breeding record in Port Phillip – Mud Islands 1966. Active
management of breeding habitat since 1986 by Victorian Wader
Study Group – through removal of vegetation on a suitable shore
platform on Boatswain Island.
Golden-headed Cisticola
Recent colonization?
5.4 Other terrestrial fauna
Only one non-avian terrestrial vertebrate species has successfully colonised Mud Islands, the
Metallic Skink Niveoscincus metallicus. It may have been inadvertently introduced by fishermen
who lived for par of the year on Mud Islands during the first half of the twentieth century, for
example, transported in a load of firewood. This species occupies the sand dunes under dense
ground vegetation such as provided by Galenia Galenia sp. It is likely to be eaten by ibis and gulls
if it was to venture into the open.
There are no indigenous terrestrial mammals recorded for the islands. Mud Islands are apparently
too far offshore to have been colonized by the Water Rat Hydromys chrysogaster which is known
from Swan Bay, about 7 km to the west. Campbell and Mattingley (1907) and Mattingley (1907)
suggested that common rats (Rattus rattus or R. norvegicus?) had been introduced to the islands by
guano miners. However, their evidence for this statement is unconvincing, being based upon
finding burrows reminiscent of those made by rats and upon finding partially eaten White-faced
Storm-Petrels. The burrows could have belonged to crabs and remains of storm-petrels are
regularly found to this day, with the Barn Owl being a likely culprit.
It is not clear when or why European Rabbits were introduced to the islands, but they were present
in 1902 (Townsend 1903) and remained common until the 1970s when some control was
undertaken by the Fisheries and Wildlife Division. The population then seemed to slowly decline
and the last sighting of a living animal was in 1988.
5.5 History of bird study on Mud Islands
Mud Islands has attracted Victorian ornithologists for over a century. Early visitors include S. P.
Townsend (1903) who campaigned successfully to protect the storm-petrel colony on Middle
island from guano and phosphate mining. Some of the first banding of birds in Australia took
place on Mud Islands during six trips by members of the Bird Observers Club between 1914 and
1919 when home-made bands were placed on White-faced Storm-Petrels (Mattingley 1942,
Chandler 1959). Annual trips during the Australia Day long-weekend to band White-faced StormPetrels began in 1955 under the auspices of the Altona Survey Group. The Victorian
Ornithological Research Group then assumed responsibility until 1975, after which the Geelong
Field Naturalists Club took over until the project ceased in 1980. During this 25 year effort 12 652
storm-petrels were banded and about 2% were recovered, the great majority back at Mud Islands
(Menkhorst et al. 1984).
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6 Conclusions and Recommendations
Mud Islands provide one of the most important breeding locations in Victoria for waterbirds and
the presence of these birds provides significant benefits for Port Phillip and its hinterland.
There appear to be few management issues for conserving the bird values of Mud Islands. The
primary threats relate to human disturbance, but this is mitigated by its status as a marine national
park, its relative isolation, and the surrounding shallow waters, mudflats and sandbars which make
access difficult. Additionally, there are few enticements for visitors to leave the outside beaches.
However, with increasing levels of recreational boating in Port Phillip (boat registrations in
Victoria increased by 21% between 1994 and 2005 (CCB 2007)), the rate of visitation can be
expected to increase, particularly with the popularity of personal watercraft such as jet skis. It is
important that visitation rates and activities are carefully monitored, particularly in spring when
terns are breeding on or adjacent to the western beaches.
The greatest threat is to species which breed on or adjacent to beaches. The Caspian Tern colony
on Boatswain Beach and the Pied Cormorant colony on East Point are by far the most susceptible
to disturbance by humans, and the number of Pied Oystercatchers breeding at Mud Islands has
already declined, probably due to this cause, as is true for many Victorian beaches. The Crested
Tern colony, although immediately adjacent to the beach, appears to be large enough and robust
enough to not be seriously impacted by people walking the beach. However, it is important that
visitors remain on the lower portion of the beach and do not enter the colony or flush incubating
birds from their nests, as this exposes eggs and young to predation by gulls and ibis. There is a
need for improved signage and educational material at the main landing point at the south-east end
of the islands, and at strategic points on Boatswain beach, north and south of the tern colonies.
The current program of annual removal of encroaching shrubs from the Crested Tern breeding site
is supported. There may be a need to also remove the Hairy Spinifex Spinifex sericeus that is now
well-established on the site, but further monitoring of its growth and the tern’s response is
warranted before making a decision.
A potentially significant threat is the establishment of mammalian predators on the islands. Given
that there are active bird breeding colonies in almost all months, it is conceivable that the islands
could support a population of the Black Rat Rattus rattus or Brown Rat R. norvegicus, both of
which are known predators of nest contents, though the months of little breeding activity would
likely limit the size of any rat population. A single Cat Felis catus survived on the islands for
many months in the mid 1980s (author pers obs.) and survived attempts to trap it (L. Jackson,
Parks Victoria pers comm.). A contingency plan to remove any populations of introduced
mammals that may become established is warranted.
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7 References
Anonymous, 1974. Mud Island campout – 27-29 January 1973. V.O.R.G. Notes 10(1): 7-10.
Barrett, N. 1938. Leach Memorial Club. Visit to Mud Island. Bird Observer’s Club monthly notes,
February 1938.
Barrett, N. 1940. Leach Memorial Club’s visit to Mud Island. Bird Observer’s Club monthly
notes, February 1940.
Bird, E. C. F. 1973. Physiographic changes at Mud Islands, Port Phillip Bay. Victorian Naturalist
90: 157-165.
Campbell, A. G. 1933. The White-faced Storm-Petrel. Emu 33:86-92.
Campbell, A. G. and Mattingley, A. H. E. 1907. A rookery of storm-petrels. Emu 6: 185-192.
Campbell, A.J. 1901. Nests and Eggs of Australian Birds, including the Geographical Distribution
of Species and Popular Observations Thereon. The author, Sheffield, England.
Carter, M. J. 1970. Birds at Mud Islands, 24, 25 and 26 January 1970. V.O.R.G. Notes 8(6): 5-9.
Central Coastal Board, 2007. Boating Coastal Action Plan. Central Coastal Board, Melbourne.
Chandler, L. G. 1959. The first banding of birds in Victoria. Australian Bird Watcher 1: 11-14.
Christidis L. and Boles W.E. 2008. Systematics and Taxonomy of Australian Birds. CSIRO
Publishing, Melbourne.
Cowling, S.J. and Lowe, K.W. 1981. Studies of ibises in Victoria, 1: Records of breeding since
1955. Emu 81: 33-39.
DSE 2007. Advisory List of Threatened Vertebrate Fauna in Victoria, 2007. Department of
Sustainability and Environment, Melbourne.
Garnett, S., Lane, B., Schulz, M. and Wood, K. 1986. Birds of Port Phillip Bay. Ministry for
Planning and Environment, Melbourne.
Gosbell, K. and Clemens, R. 2006. Population monitoring in Australia: Some insights after 25
years and future directions. Stilt 50: 162-175.
Harris, M. P. 1979. The seabirds of the Victorian islands. Report to the Ministry for Conservation,
Victoria. Institute for Terrestrial Ecology project report number 588.
Heathcote, W. 1936. Mud Island. Bird Observer’s Club Monthly Notes, February 1936.
Herrod, A. 2010. Migratory Shorebird Monitoring in the Port Phillip Bay (Western Shoreline) and
Bellarine Peninsula Ramsar Site, 1981-2010. Birds Australia report, Melbourne.
Hewish, M. (ed). 2006. Geelong Bird Report 2005. Geelong Field Naturalists Club, Geelong.
Higgins, P.J. and Davies, S.J.J.F. (eds) 1996. Handbook of Australian, New Zealand and Antarctic
Birds Volume 3. Snipe to Pigeons. Oxford University Press, Melbourne.
Lane, B.A., Schulz, M. and Wood, K.L. 1984. Birds of Port Phillip Bay. Coastal Unit Technical
Report Number 1, Ministry for Planning and Environment, Melbourne.
Loyn, R.H. and Kinhill Planners 1980. Historical records of Orange-bellied Parrots. Unpublished
report to ICI Australia, November 1980.
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A Survey of Colonially-breeding Birds on Mud islands, Port Phillip, Victoria
Loyn, R.H., Macak, P., Gormley, A. and McCormick, P. 2008. Requirements for land and water
by ibis at the Western Treatment Plant. Report to Melbourne Water by Arthur Rylah Institute for
Environmental Research.
Macak, P., Loyn, R.H. and lane, B.A. 2002. Investigation into use of filtration paddocks by ibis
and other waterbirds at the Western Treatment Plant. Report to Melbourne Water by Arthur Rylah
Institute for Environmental Research in Association with Brett Lane & Associates Pty Ltd.
Marchant, S. and Higgins, P.J. (eds) 1990. Handbook of Australian, New Zealand and Antarctic
Birds Volume 1 Ratites to Ducks. Oxford University Press, Melbourne.
Mattingley, A. H. 1907. A trip to Mud Island, Port Phillip. Victorian Naturalist 24: 4-12.
Mattingley, A. H. E. 1942. History of the banding of birds in Australia. Bird Observer’s Club
Monthly Notes, May 1942.
Menkhorst, P.W. 1982. A bibliography of research by the Victorian Ornithological Research
Group, 1962-1981. Corella 6: 105-113.
Menkhorst, P. and Knight, F. 2010. A Field Guide to the Mammals of Australia. 3rd (revised)
edition. Oxford University Press, Melbourne.
Menkhorst, P.W., Davey, G. & Nicholls, D.G. 1983. Australian Pelicans breeding at Mud Islands,
Port Phillip Bay. Victorian Ornithological Research Group Notes 19(2): 43-44.
Menkhorst, P.W., Kerry, K. & Hall, F. 1988. Seabird Island series - Mud Islands. Corella 12:7277.
Menkhorst, P.W., Pescott, T.W. & Gaynor, G.F. 1984. Results of banding White-faced StormPetrels Pelagodroma marina at Mud Islands, Victoria. Corella 8: 53-60.
Nebel, S., Porter, J. and Kingsford, R. 2008. Long-term trends of shorebird populations in eastern
Australia and impacts of freshwater extraction. Biological Conservation 141: 971-980.
O’Brien, M., Corrick, A. and Lacey, G. 2010. Breeding sites of the Australian Pelican Pelicanus
conspicillatus in Victoria. Australian Field Ornithology 27: 19-30.
Pescott, T. 1966. Mud Island storm-petrel survey. V.O.R.G. Notes 3(12): 5-9.
Pescott, T. 1968. Mud Island campout, 1967. V.O.R.G. Notes 6(2): 3-7.
Pescott, T. 1975. Mud Islands campout, January 25, 26, 27 1975. Geelong Naturalist 12: 92-100.
Pescott, T. 1977. Mud Islands campout, 1977. Geelong Naturalist 14(2): 46-48.
Pescott, T. 1983. Birds of Geelong. Neptune Press, Newtown.
Robertson, P. and Coventry, A. (in press). Reptiles of Victoria. CSIRO Publications, Melbourne.
Smith, F. T. H. 1965. Birds recorded at Mud Island January 30, 31 and February 1, 1965.
V.O.R.G. Notes 2(12): 7-10.
Smith, F. T. H. 1968. Birds of Mud Islands. V.O.R.G. Notes 6(5): 11-14.
Tarr, H. E. 1952. Notes from Mud Island, Victoria. Emu 52: 220.
Tarr, H. E. 1954. Mud Island revisited. Bird Observer February 1954.
Townsend, S. P. 1903. A trip tp Mud Island, Port Phillip Bay: with notes on the White-faced
Storm-Petrel, Pelagodroma marina. Victorian Naturalist 19: 165-170.
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A Survey of Colonially-breeding Birds on Mud Islands, Port Phillip, Victoria
Victorian Saltmarsh Study Group (2010). Mangroves and coastal saltmarsh of Victoria:
distribution, condition, threats and management. Institute for Sustainability and Innovation,
Victoria University, Melbourne.
Weston, M. A. and Peter, J. M. 2004. The occurrence of Hooded Plovers in Port Phillip Bay.
Victorian Naturalist 121: 274-283.
Wheeler, R. 1958. Mud Island visited by the group. Bird Observer No. 321.
Wheeler, R. 1959. Mud Island revisited. Bird Observer No. 333.
Wheeler, R. 1960. The Grey Plover on Mud Islands, Victoria. Australian Bird Watcher 1:107-109.
Wheeler, R. 1960. Mud Island revisited. Bird Observer No. 346: 2.
Wheeler, R. 1980. Mud Island. Geelong Naturalist 16(4): 65-66.
Yugovic, J. 1998. Vegetation dynamics of a bird-dominated island ecosystem: Mud Islands, Port
Phillip Bay, Australia. PhD thesis, Monash University, Melbourne.
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8 Appendix 1 – Maps of breeding colonies
Map 2. Locations of breeding colonies of Australian Pelican at Mud Islands, 2009-2010.
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Map 3. Locations of breeding colonies of other colonially-breeding birds at Mud Islands, 2009-2010.
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A Survey of Colonially-breeding Birds on Mud islands, Port Phillip, Victoria
Map 4. Locations of ibis colonies at Mud Islands, 2009-2010.
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Appendix 2 - Annotated List of Species
This list and the species summaries were compiled from bird counts conducted by the author
during 86 visits to Mud Islands over the 28 years between July 1982 and April 2010 (see Methods
for the monthly distribution of visits), supplemented with historical records from the literature and
the Atlas of Victorian Wildlife. During each visit, an attempt was made to record all bird species
present and to count or, where impracticable, to estimate the numbers of each. Incidental sightings
of mammals and reptiles were also recorded. Only species that actually used the islands and
surrounding mudflats are included; seabirds utilizing surrounding waters, and beach-cast records
are excluded. Nomenclature and taxonomy for birds follow Christidis and Boles (2008), for
mammals Menkhorst and Knight (2010) and for reptiles Robertson (in press). The percentage
value following each species name is the proportion of my visits during which the species was
recorded. * indicates introduced species.
Class Aves
Phasianidae
Brown Quail Coturnix ypsilophora
10.5%
Small coveys in Coast Hollyhock shrubland. First recorded 1987, therefore likely to have benefited
from the development of dense weedy Hollyhock shrubland following expansion of bird breeding
colonies. Max. count, 6 on 25 June 1987.
Anatidae
Musk Duck Biziura lobata
0%
Early records of ones or twos only – Campbell and Mattingley (1907), Heathcote (1940), Wheeler
(1958, 1959). Not recorded during the present survey.
Black Swan Cygnus atratus
96%
Always present, numbers peak in summer and autumn when up to 1000 may be present. Scattered
pairs build their nests in Atriplex cinerea shrubland around the outer perimeter of East Island
during July, early reports suggest larger breeding aggregations in the past. The seagrass flats
surrounding Mud Islands are a major feeding ground for Black Swans.
Australian Shelduck Tadorna tadornoides
5.8%
Rare, occasional small groups. Max. count 7, 13 February 2005.
Pacific Black Duck Anas superciliosa
1.2%
Very rare (contra Garnett et al. 1986), one record only – 3 on 29 June 1997. Also listed by
Campbell and Mattingley (1907).
Australasian Shoveler Anas rhynchotis
1.2%
Rare, occasional reports of small groups. One record only – 3 on 16 Feb 1997.
Chestnut Teal Anas castanea
29.1%
Formerly regularly present, not recorded during the last 10 years. Numbers highly variable, from
zero to 120 on 22 June 1986. Last recorded 11 July 1999.
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Grey Teal Anas gracilis
1.2%
Very rare, one record only; 6 on 7 July 1991. Also listed by Campbell and Mattingley (1907),
Wheeler (1958, 1959), Pescott (1977).
Pink-eared Duck Malacorhynchus membranaceus
0%
One record only (1961 Australia Day camp, Wheeler 1964)
Podicipedidae
Hoary-headed Grebe Poliocephalus poliocephalus
7%
Irregular in winter, small flocks offshore. Does not enter the lagoon.
Great Crested Grebe Podiceps cristatus
0%
One record only – Campbell and Mattingley (1907)
Columbidae
*Rock Dove Columba livia
1.2%
One record only – single bird resting on beach, July 1996.
*Spotted Dove Streptopelia chinensis
0%
One record only (Wheeler 1958).
Spheniscidae
Little Penguin Eudyptula minor
12.8%
Formerly bred in small numbers but not in every year – last breeding record October 1988.
Hydrobatidae
White-faced Storm-Petrel Pelagodroma marina
15.1%
Regular breeding migrant though in decreasing numbers. Birds return September, laying occurs in
October and November and young have fledged by late February (Menkhorst et al. 1984a).
Population estimates: 1907 – 24 000 burrows (Mattingley 1907), 1959 – 10 000 burrows (Wheeler
1959), 1966 – 2500 pairs (Pescott 1966), 1978 – 5 600 burrows (95% confidence interval 44006900) (Harris 1979). Now thought to be < 1000 pairs (M. Underwood pers. comm.).
Phalacrocoracidae
Little Pied Cormorant Phalacrocorax melanoleucos
81.4%
Common, regularly rests on sandbars. Max. count, 153 on 9 February 1992.
Pied Cormorant Phalacrocorax varius
81.4%
Common, regularly rests on sandbars. Known to have bred during the 1940s and 1950s but
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fishermen destroyed the nests (John Reed in lit. to R. Wheeler) leading to desertion of the site for
about three decades. Breeding colony on East Point first recorded in late July 1986, active most
years since, up to 250 nests. One of only two regular Victorian breeding colonies (the other is at
the Western Treatment Plant, Werribee). Max. count 500 birds on 18 July 2004.
Little Black Cormorant Phalacrocorax sulcirostris
33.7%
Occasional large flocks rest on sandbars, particularly those at north and south ends. Largest flock
estimated at 1500 on 29 July 1990 in rough weather.
Great Cormorant Phalacrocorax carbo
19.8%
Rare. Occasional singles or small group resting on sandbar (contra Garnett et al. 1986). Max.
count 8 on 27 July 1986. May have once been a breeding species on North Island (Pescott 1983).
Pelecanidae
Australian Pelican Pelecanus conspicillatus
91.9%
Common breeding species, max. count 650 adults, July 2006. Breeding known to have occurred in
the past (to 1940s?) but persecution by fishermen may have led to the demise of the colony.
During this survey, breeding first recorded in September 1983 when 10 nests were present on
North Island (Menkhorst et al. 1983). Now almost continuous breeding by up to 450 pairs in up to
10 sites spread across the island complex. One of only two regular breeding colonies in Victoria,
the other being Lake Corangamite (O’Brien et al. 2010). The rise of the Mud Islands colony
partially coincides with the decline of a colony on the north coast of French Island since 1999 (P.
Dann pers comm., O’Brien et al. 2010)
Ardeidae
White-faced Heron Egretta novaehollandiae
70.9%
Common, regularly present in the lagoon and saltmarsh with largest counts in winter. Max. count,
80 on 25 June 2006.
Little Egret Egretta garzetta
12.8%
First recorded on 22 August 2004 when 3 birds present; intermittently present since. Three nests
with 3 eggs (1 nest) and 3 young (2 nests) found beside South Inlet on 13 December 2009.
Apparently abandoned subsequently.
White-necked Heron Ardea pacifica
0%
One old record (Mattingley 1907) and one recent sighting of a single bird in January 1973 (Anon.
1974).
Nankeen Night Heron Nycticorax caledonicus
0%
One record only – 2 immature birds seen by D. Robinson in 1982 (pers. comm.)
Threskiornithidae
Australian White Ibis Threskiornis molucca
67.4%
An occasional visitor in small numbers until 1990 when suddenly began breeding - about 100
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A Survey of Colonially-breeding Birds on Mud islands, Port Phillip, Victoria
nests were constructed at north end of Boatswain Is. Now nests annually in Coast Saltbush
shrubland throughout the islands. Apart from a small impermanent colony at Point Henry, the Mud
Islands colony is the only Victorian colony in a marine environment. Arrives in July and breeding
occurs through to January. Estimated that 7 600 nests were present in October 2009. Some feeding
occurs in the lagoon and on sandbars exposed at low tide, but most birds commute regularly to the
Bellarine and Mornington Peninsulas.
Straw-necked Ibis Threskiornis spinicollis
38.4%
Not recorded before September 1991 when a breeding colony formed on Boatswain Island.
Originally less common than Australian White Ibis but now nests in far greater numbers –
estimated at 57 000 nests in October 2009. By far the largest Straw-necked Ibis colony ever
reported in Victoria (Marchant and Higgins 1990) and the only one anywhere in a marine
environment. Does not feed on the islands – flocks commute to the Bellarine and Mornington
Peninsulas, and the Geelong-Werribee region to forage in pastoral land.
Royal Spoonbill Platalea regia
68.6%
Almost always a flock of between 18 and 40 birds present in the lagoon. Max. count 44 on 11
September 2005. Occasionally the flock flies towards Swan Bay. In recent years a few pairs have
bred amongst breeding ibis on North Island and East Island, and in 20009-10 a distinct scattered
breeding colony formed in tall Tecticornia shrubland at the north end of East island. Maximum
nest count 31 on 18 November 2009.
Accipitridae
Whistling Kite Haliastur sphenurus
7.0%
Not recorded until 9 July 2000, between one and 4 birds fairly regularly present since, perhaps the
expanding waterbird colonies have provided a reliable food source. A probable migrating flock of
22 birds observed passing over from south to north on 3 May 2009. Also listed by Barrett (1938).
White-bellied Sea-Eagle Haliaeetus leucogaster
2.3%
First recorded on 23 July 1989, intermittent records of single birds passing over since then.
Swamp Harrier Circus approximans
69.8%
Regularly one or two birds, and up to four. Has nested in Poa poiformis tussock grassland on
Boatswain Island and courtship flights observed in January of 2009 and 2010.
Brown Goshawk Accipiter fasciatus
1.2%
Rare visitor, one present on 26 May 1984.
Falconidae
Brown Falcon Falco berigora
2.3%
Rare visitor, recorded January 1958 (Wheeler 1958) and one present on 24 June 1984.
Australian Hobby Falco longipennis
1.2%
Rare visitor, one record in September 1984.
Black Falcon Falco subniger
0%
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A Survey of Colonially-breeding Birds on Mud Islands, Port Phillip, Victoria
One recorded in January 1968 (Smith 1968).
Peregrine Falco peregrinus
0%
One record, 1960 (Wheeler 1964).
Nankeen Kestrel Falco cenchroides
0%
One record, 1957 (Wheeler 1968).
Rallidae
Buff-banded Rail Gallirallus philippensis
4.6%
Probably resident in saltmarsh and adjacent vegetation. Nests in Coast Hollyhock shrubland (M.
Underwood pers comm.). Eggs found in Coast Saltbush shrubland on East Island, 4 January 2010.
Recorded breeding by Campbell and Mattingley (1907).
Lewin's Rail Rallus pectoralis
1.2%
One record only (one on 26 November 1984) but possibly resident in saltmarsh. Wheeler (1959)
reported the finding of two dead chicks in January 1959.
Australian Spotted Crake Porzana fluminea
7%
Listed by Heathcote (1936). One record only – a single bird on the lagoon edge adjacent to the
Boatswain Island saltmarsh, 5 February 2006, but calls occasionally heard and possibly resident in
saltmarsh.
Haematopodidae
Pied Oystercatcher Haematopus longirostris
98.8%
Regular breeding species, but numbers declining. Largest aggregations occur in winter - max.
count 33 on 24 July 1983 and 20 June 1987. Tarr (1952) recorded at least 20 juveniles and, in
November 1953, counted 50 individuals Tarr (1954). Smith (1965) reported a flock of 62 and
Smith (1968) recorded ‘over 100 about the islands.’ Max. count during this survey 14 on 17
February 2008.
Sooty Oystercatcher Haematopus fuliginosus
46.5%
Between one and three individuals were present on most visits. Throughout the late 1970s and
1980s one bird was paired with a Pied Oystercatcher and several hybrid chicks were produced. An
apparent pairing of a Sooty oystercatcher and a hybrid bird was observed frequently and
photographed during this survey at the northern end of Boatswain Island. A hybrid captured and
banded by the VWSG at The Spit Nature Conservation Reserve in March 1980 was subsequently
observed on Boatswain Beach on numerous occasions until at least late 2002 when it was 23 years
of age. Tarr (1954) and Smith (1968) also reported a mixed pair and a hybrid at Mud Islands.
Recurvirostridae
Black-winged Stilt Himantopus himantopus
0%
One record only of a single bird seen during the 1960 Australia Day weekend campout (Wheeler
1960). Wrongly described as common at Mud Islands by Garnett et al. (1986).
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A Survey of Colonially-breeding Birds on Mud islands, Port Phillip, Victoria
Banded Stilt Cladorhynchus leucocephalus
1.2%
One record only – six present at the north end of the lagoon on 13 February 2005
Charadriidae
Pacific Golden Plover Pluvialis fulva
30.2%
Infrequent in highly variable numbers, but overall decline in numbers and frequency of
occurrence; max. count 180 on 17 February 1985.
Grey Plover Pluvialis squatarola
58.1%
Regular in larger numbers than Pacific Golden Plover; highest count 450 on 9 February 1986.
Small numbers – 10 to 20 – over-winter. Mud Islands is one of the two most important sites for
this species in Victoria (Wheeler 1960, Lane et al. 1984), the other being Corner Inlet.
Red-capped Plover Charadrius ruficapillus
51.2%
Probable resident; breeds. Max. count 38 on 6 February 1994; population appears to have declined
based on earlier reports of between 100 and 200 (e.g. Carter 1970).
Double-banded Plover Charadrius bicinctus
30.2%
Winter migrant in inconsistent numbers. Max. count 400 on 25 May 2008.
Lesser Sand Plover Charadrius mongolus
26.7%
Uncommon summer migrant in declining numbers. Max. count, 44 on 11 February 1984.
Greater Sand Plover Charadrius leschenaultii
4.6%
Rare summer migrant. Max. count 3 on 16 February 1997.
Hooded Plover Thinornis rubricollis
0%
Not recorded during this survey. Barrett (1940) recorded 10 individuals, last recorded in the early
1960s (Weston and Peter 2004).
Masked Lapwing Vanellus miles
16.3%
Formerly regular in small numbers; now rarely present and only in ones or twos.
Scolopacidae
Bar-tailed Godwit Limosa lapponica
69.8%
Flocks regularly present. Max. count 1500, 5 February 2006. Up to 250 first year birds overwinter. Feeds and roosts in the lagoon and on surrounding sandbars.
Black-tailed Godwit Limosa limosa
4.6%
Rare visitor; four records of ones or twos.
Hudsonian Godwit Numenius haemastica
1.2%
Vagrant, one bird present in flock of Bar-tailed Godwits, February 2009.
Little Curlew Numenius minutus
0%
Two birds were observed over three days in early Nov 1953 by two observers (Tarr 1954).
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A Survey of Colonially-breeding Birds on Mud Islands, Port Phillip, Victoria
Whimbrel Numenius phaeopus
5.8%
Regular in ones and twos until 1986 – last record 27 July 1986. Max. count 4 on 17 February
1985.
Eastern Curlew Numenius madagascariensis
8.1%
Uncommon during survey period – max. count 6 on 14 February 1999. Tarr (1954) reported 2000
birds present during gale force winds in early Nov 1953 and flocks of up to 200 were regular in the
1970s. Now uncommon and in small numbers – only two records of single birds during this
survey.
Marsh Sandpiper Tringa stagnatilis
7.0%
Rare visitor in small flocks. Max. count 13 on 13 February 2005.
Common Greenshank Tringa nebularia
60.5%
Regularly present in the lagoon throughout the year. Frequently 30-40 individuals; usually some
over-winter and max. count occurred, perhaps surprisingly, on 23 July 2006 when 100 individuals
were estimated to be present.
Terek Sandpiper Xenus cinereus
0%
One record (1961) listed by Wheeler (1964).
Common Sandpiper Actitis hypoleucos
0%
Two records – listed by Heathcote (1936) and Barrett (1940).
Grey-tailed Tattler Heteroscelus brevipes
13.9%
Formerly regular in flocks of up to 33 (Smith 1968), now irregular and in small numbers – max.
count during survey 8 birds on 26 June 1988
Ruddy Turnstone Arenaria interpres
70.9%
Regularly present foraging on the outside beaches, sandbars and exposed seagrass beds, and in the
lagoon. Max. count 200 on 21 December 1983 and 18 February 1990.
Asian Dowitcher Limnodromus semipalmatus
0%
One record, first observed in December 1974 (M. Carter, A. Isles, P. Menkhorst and D. Robinson).
Remained until at least the end of January 1975 and was also seen at Swan Island (Pescott 1975).
Great Knot Calidris tenuirostris
47.7%
Regular summer migrant; max. count 700 on 11 February 1984. Small numbers over-winter in
most years. Mud Islands is possibly the most important site for this species in Victoria.
Red Knot Calidris canutus
67.4%
Regular summer migrant; max. count 600 in February 1991 and 1994. Up to 120 over-winter.
Sanderling Calidris alba
3.5%
Rare summer migrant in ones and twos. Three records - 2 birds on 15 February 2004 and 5
February 2005, and one bird on 18 April 2010.
Red-necked Stint Calidris ruficollis
76.7%
The most abundant shorebird – regularly 800-1000 (and up to 2500) counted in summer and up to
260 in winter.
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A Survey of Colonially-breeding Birds on Mud islands, Port Phillip, Victoria
Sharp-tailed Sandpiper Calidris acuminate
48.8%
Abundant summer migrant feeding around edges of saltmarsh and on sandbars. Max. count 620 on
15 February 2004. Does not over-winter.
Curlew Sandpiper Calidris ferruginea
62.8%
Regular summer migrant. Max. count 600 on 17 February 1985 and 9 February 1992. Numbers
have declined since the late 1990s. Small numbrs overwinter (<20).
Broad-billed Sandpiper Limicola falcinellus
1.2%
Rare summer migrant - three records – 2 birds on 4 November 1953 (Tarr 1954), one bird 29-31
January 1977 (Pescott 1977) and one on 17 February 2008.
Laridae
Pacific Gull Larus pacificus
76.7%
Small numbers rest on sandbanks; highest counts in winter (up to 100, mostly immatures).
Kelp Gull Larus dominicanus
9.3%
Not recorded before 1970 (2 present in January 1970 (Carter 1970)), now a regular winter visitor
in small numbers, mostly immature and sub-adult birds. Max. count 10 on 1 July 2007.
Silver Gull Larus novaehollandiae
100%
Abundant breeding species. First recorded breeding in 1959 (8 nests); colony then increased
exponentially - 250 pairs in 1962, 1000 in 1970, tens of thousands in 1978, stabilising at perhaps
50 000 nests through the 1980s (Menkhorst et al.1988). Numbers of breeding pairs may have
fallen as a consequence of the ibis colonies taking over much of the available breeding habitat. By
far the largest breeding colony in Victoria and possibly the largest anywhere.
Caspian Tern Sterna caspia
41.9%
Fifteen-thirty pairs breed annually in Nov-Dec. on the Boatswain Island beach. One of only three
regular breeding colonies in Victoria (the others are in Corner Inlet and at Mallacoota). Eggs and
hatchlings may be eaten by Silver Gulls if the parent birds are disturbed by people on the beach.
Max. count 35 on 13 December 2009.
Crested Tern Sterna bergii
77.9%
Breeding first recorded in 1966 (Pescott 1983) and has bred in all or most years since. Formerly
nested at several sites including on the shore terrace beside the south entrance and along the
western beach. Since 1986 has bred only on Boatswain Island in an area kept clear of vegetation
by volunteers from the Victorian Wader Study Group and Friends of Mud Islands. Up to 2000
pairs breed during November-December.
Common Tern Sterna hirundo
4.6%
First recorded in January 1964. Apparently present in large numbers during the 1970s, e.g. 206
counted in late January 1975 (Pescott 1983). Infrequently present during study period and then
only in small numbers. Max. count, 10 on 11 February 2001. Claim by Garnett et al. (1986) that
Mud Island is a major roosting site for this species with flocks of up to 260 does not accord with
my observations or with the literature.
White-fronted Tern Sterna striata
2.3%
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A Survey of Colonially-breeding Birds on Mud Islands, Port Phillip, Victoria
Rare winter visitor, 2 observations of single birds resting on sandbars, July 1997 and 2010.
Little Tern Sterna albifrons
11.6%
Regular non-breeding visitor, in small numbers (< 20). Unconfirmed reports of small numbers
breeding, including one pair as recently as February 2001 (M. Carter pers comm.).
Fairy Tern Sterna nereis
59.3%
Previously a regular breeding species on both Boatswain and East Islands and, most recently, on
the sandbar in the lagoon near northern entrance. Not recorded breeding since 1997. Now regular
outside the breeding season. Max. count, 85 on 13 February 1985.
Whiskered Tern Chlidonias hybridus
1.2%
One record only - single bird resting on sand bar at north end of lagoon on 11 September 2005.
White-winged Black Tern Chlidonias leucopterus
1.2%
One record only – single bird resting on sand bar at north end of lagoon on 11 February 2001.
Psittacidae
Eastern Rosella Platycercus eximius
0%
One record only of a single bird in gale conditions in November 1953 (Tarr 1954)
Blue-winged Parrot Neophema chrysostoma
2.3%
Surprisingly few records – one female on 25 February 2007 and one flying over on 18 April 2010.
Orange-bellied Parrot Neophema chrysogaster
2.3%
Previously probably regular winter visitor, at times in large flocks; e.g. flocks of between 80 and
40 recorded between 1953 and 1973 (summarized by Loyn and Kinhill Planners 1980). Since then
the largest number recorded is 7 birds in 1978. Only two records of a single bird during survey
period – July-September 1983 and September 1985, both in Tectocornia saltmarsh on Boatswain
Island.
Cuculidae
Horsfield's Bronze-Cuckoo Chrysococcyx basalis
1.2%
Only one record during survey – single on 9 February 1992. Previous records through the 1950s
and 1960s.
Tytonidae
Barn Owl Tyto alba
1.2%
Judging by characteristic remains, probably a regular visitor to prey on White-faced Storm-Petrels.
Two birds flushed on 29 October 1987 from the ground in Coast Hollyhock shrubland on ‘the
airstrip’. Also reported to be present by Mattingley (1907) who also reported finding storm-petrel
remains but ascribed these to rats.
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A Survey of Colonially-breeding Birds on Mud islands, Port Phillip, Victoria
Acanthizidae
Chestnut-rumped Heathwren Hylacola pyrrophygia
0%
One record only – Tarr (1954) claimed to have had protracted, close views of a single individual.
Striated Fieldwren Calamanthus fuliginosus
0%
Only one record - (Wheeler 1964).
Meliphagidae
White-eared Honeyeater Lichenostomus leucotis
0%
Listed by Wheeler (1964). Possibly formerly present in coastal scrub on Boatswain and Northern
Islands.
White-fronted Chat Epthianura albifrons
0%
Formerly present in large numbers, particularly on ‘the airstrip’ (Tarr 1954, Wheeler 1958, 1959);
now absent with a lack of suitable open habitat. Last record January 1978 when a pair was present
on the ‘airstrip’ (GFNC 1978).
Dicaedae
Mistletoebird Dicaeum hirundinaceum
0%
Old records of occasional birds (Wheeler 1964) in the coastal scrub that was formerly present on
North Island.
Rhipiduridae
Grey Fantail Rhipidura fuliginosa
0%
One record only – January 1967 (Pescott 1968).
Willie Wagtail Rhipidura leucophrys
4.6%
Occasional winter records of single birds.
Petroicidae
Flame Robin
1.2%
One record only – of 2 birds on s. Boatswain Is beach on 23 May 2010
Alaudidae
*Skylark Alauda arvensis
20.9%
Formerly present and breeding on ‘the airstrip’ but declined as the low herbfield became
dominated by shrubs following the eradication of rabbits. Max. count 25; last record 25 July 1993.
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A Survey of Colonially-breeding Birds on Mud Islands, Port Phillip, Victoria
Cisticolidae
Golden-headed Cisticola Cisticola exilis
34.9%
Common breeding resident though apparently not always so – first record is of one bird seen in
late January 1970 (Carter 1970). Not recorded during the first 10 years of this survey – first record
was on 25 July 1993; max. count 25.
Megaluridae
Little Grassbird Megalurus gramineus
62.8%
Breeding resident in saltmarsh. Max. count 22 0n 9 February 2003.
Timalidae
Silvereye Zosterops lateralis
1.2%
One record only – 5 birds on 6 February 1994 in Coast Saltbush shrubland. Formerly regular
summer visitor to feed on Leucopogon berries (Wheeler 1964).
Hirundinidae
Welcome Swallow Hirundo neoxena
36.0%
Usually a few present and up to 100. Recorded breeding under the eaves of an old hut by
Mattingley (1907).
Tree Martin Hirundo nigricans
0%
Several records of small groups during the 1960s.
Turdidae
*Common Blackbird Turdus merula
0%
Listed by Wheeler (1964).
Sturnidae
*Common Starling Sturnus vulgaris
32.6%
Present since at least 1906 (Campbell and Mattingley 1907). Formerly regular with flocks feeding
in Hollyhock shrubland. Max. count 100 on 24 July 1994. Last recorded in February 2005.
Passeridae
*House Sparrow Passer domesticus
65.1%
Present since at least 1906 (Mattingley 1907). Small flock regularly present in Coast Saltbush and
Coast Hollyhock shrubland. Probably a breeding resident. Max. count 35 on 11 July 1999.
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A Survey of Colonially-breeding Birds on Mud islands, Port Phillip, Victoria
*Eurasian Tree Sparrow Passer montanus
0%
Recorded only by Townsend (1903).
Motacillidae
Australasian Pipit Anthus novaeseelandiae
1.2%
Recorded only by Mattingley (1907) until two birds present on mudflats inside the north inlet on
18 April 2010.
Fringillidae
*European Goldfinch Carduelis carduelis
2.3%
Formerly an infrequent visitor; max. count 30 on 11 July 1982; not recorded since 1983.
*Common Greenfinch Carduelis chloris
2.3%
Rare visitor, two records only – 50 on 18 Feb 1990 and 2 on 18 April 2010. A single bird also
reported by Wheeler (1958) and Anon (1974).
Records requiring confirmation
Latham’s Snipe Gallinago hardwickii
One record by the Altona Survey Group, January 1961 – seems doubtful because this species does
not occur in marine environments.
Pin-tailed Snipe Gallinago stenura
Claimed to have been seen during the Australia Day weekend campout, 1940 (Barrett 1940) – not
recorded from southern Australia.
Wood Sandpiper Tringa glareola
One record only (Barrett 1938) – seems unlikely as this species is not usually associated with
marine environments.
Pectoral Sandpiper Calidris melanotus
One record only (Barrett 1940) – seems unlikely as this species is not usually associated with
marine environments.
White-plumed Honeyeater Lichenostomus penicillatus
Only one record – listed by Heathcote (1936) but considered doubtful because of the complete lack
of suitable habitat on the islands.
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A Survey of Colonially-breeding Birds on Mud Islands, Port Phillip, Victoria
Class Mammalia
There are no native terrestrial mammals recorded for Mud Islands, and only an occasional fur seal
hauls out on the beach.
Otaridae
Australian Fur Seal Arctocephalus pusillus
Occasional individuals found resting on the beach, usually in poor condition and probably unlikely
to survive.
Leporidae
*European Rabbit Oryctolagus cuniculus
Introduced to the islands sometime before 1902 (Townsend 1903). Individuals commonly seen by
visitors during the 1960s and 1970s. An eradication program undertaken by the Fisheries and
Wildlife Department in the late 1970s reduced the population to low numbers and the population
steadily dwindled, with the last sighting of a living animal in December 1988.
Class Reptilia
Only one species of terrestrial reptile is found on Mud Islands, probably unintentionally introduced
to the islands by the semi-resident fisherman of former decades.
Scincidae
Metallic Skink Niveoscincus metallicus
Present wherever dense, matted ground cover provides protection from predatory birds such as ibis
and gulls. Usually found beneath mats of Galenea.
Arthur Rylah Institute for Environmental Research Technical Report Series No. 206
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ISSN 1835-3827 (print)
ISSN 1835-3835 (online)
ISBN XXXXXXXX (print)
ISBN XXXXXXXX (online)