Download Yellow Chat (Alligator Rivers)

Subspecies Conservation Summary
Yellow Chat (Alligator Rivers)
Epthianura crocea tunneyi Mathews, 1912
Meliphagidae
Conservation status
Endangered B2ab(ii,iii,iv,v), C2a(ii)
Reasons for listing
Population of 250–2500 mature individuals occupying
an area <500 km2 in a single subpopulation at <5
locations with a continuing decline in area occupied,
habitat quality, no. locations and no. mature individuals,
probably from a combination of introduced weeds, feral
animals and saline intrusion
Status 2000
Endangered B2ab(ii,iii,iv,v), C2a(ii)
Status 1990
Endangered B2ab(ii,iii,iv,v), C2a(ii)
Taxonomy
E. c. macgregori (Capricorn) is Endangered, E. c. crocea
(inland northern Australia) is Least Concern, as is the
species
Taxonomic uniqueness: medium (43 genera/family, 4
species/genus, 3 subspecies/species)
Range
Recorded from a small number of sites in Adelaide R.,
Mary R., Wildman R., South Alligator R. and East Alligator R. floodplains in the Northern Territory (Keast 1958;
Armstrong 2004). Most records are from within Kakadu
National Park but the relative importance of the different
floodplains is unknown. Occasional records elsewhere,
mostly from Darwin to Oenpelli, are probably of dispersive individuals which make up what is presumed to be a
single subpopulation.
Abundance
Based on recording 96 individuals in 32 observations over
2 weeks, Armstrong (2004) estimated a population of
<300 in Kakadu National Park. Anecdotally the subspecies was more widespread in the past and a continuing
decline is inferred from the nature of the threats and their
expanding influence on chat habitat.
Ecology
Inhabits alluvial coastal and subcoastal grassy floodplains, primarily near floodplain depressions and channels, typically sparsely vegetated with a small number of
grasses, sedges and forbs, and aggregates around refugial
waterholes in the late dry season (Armstrong 2004). Also
recorded from tall grasslands and samphire shrublands
(Woinarski et al. 2007). The habitat is frequently burnt
and is flooded every wet season. It feeds in small groups
on insects, mainly on the ground, in grassy or open areas
including the muddy edges of wetlands, and amongst low
vegetation (Higgins et al. 2001; Armstrong 2004). A generation time of 5.8 years (BirdLife International 2011) is
derived from an age at first breeding of 1.5 years (extrapolated from Manorina and Phylidonyris) and a maximum
longevity in the wild of 10.1 years (extrapolated from
other Meliphagidae).
Threats
Threatened by habitat degradation caused by exotic
plant species, grazing, feral pigs Sus scrofa, altered fire
regimes and saltwater intrusion. Invasion by the weeds
Mimosa pigra, Para Grass Urochloa mutica, Gamba Grass
Andropogon gayanus and perhaps Aleman Grass Echinochloa polystachya and Olive Hymenachne Hymenachne
amplexicaulis, which are established across much of the
chat’s range may render the habitat unsuitable, although
the relationship between these weeds and chat abundance has not been established and the largest population of E. c. macgregori occurs on grazed land dominated
by H. amplexicaulis (Houston and Melzer 2008).
However, while grazing by cattle does not seem to affect
E. c. macgregori, wallowing by feral Water Buffalo
Bubalus bubalis will degrade habitat of E. c. tunneyi if
buffalo numbers are allowed to return to high densities.
Armstrong (2004) did not record the species in otherwise suitable habitats where mud-banks had been significantly disturbed by pig-rooting. At the end of the
dry season, both feral pigs and chats concentrate in relatively small areas of suitable habitat. Regular patch
burning of parts of the floodplain may be necessary to
maintain habitat diversity (Lucas et al. 1997). The plains
are also at risk from saltwater incursion as a result of sea
level rise, though this is not straightforward as mobilisation of sediments by rising sea levels can lead to reemergence of freshwater wetlands at a higher level
(Winn et al. 2006). Predation by feral cats Felis catus has
been suggested as a threat (Woinarski et al. 2007). Given
the threats of weeds and saltwater intrusion, the subspecies is assessed as having 5 locations: the floodplains of
© Birds Australia 2011
Published by CSIRO Publishing, http://www.publish.csiro.au/
Citation: Garnett ST, Szabo JK, Dutson G (2011) The Action Plan for Australian Birds 2010. CSIRO Publishing, Melbourne.
Current eligibility against IUCN Red List Criteria
IUCN
category
A
Criteria eligibility
Not applicable: past, current or future population
declines are thought unlikely to exceed 20% in any
3-generation period
B
Endangered: AOO <500 km2, at ≤5 locations with
plausible future threat, inferred continuing decline in
AOO, habitat quality, no. individuals
C
Endangered: population 250–2500 mature individuals,
suspected continuing decline, >95% mature individuals
in 1 subpopulation
D
Vulnerable: population <1000 mature individuals
E
Not applicable: no population viability analysis
undertaken
the Adelaide R., Mary R., Wildman R., South Alligator
and East Alligator Rivers.
Conservation objectives
1. A viable population
2. Evidence-based management of chat habitat
Information required
1. Population trends
2. Movements, habitat and threats
3. Effect of management actions
Management actions required
1. Survey population and establish a monitoring
protocol
2. On pastoral properties maintain grazing at levels that
do not cause habitat deterioration
3. Manage pests, particularly feral pigs
4. Control or eradicate invasive weeds that are affecting
taxon
Bibliography
IUCN Red List assessment data
Estimate
Reliability
Extent of occurrence
trend
1700 km2
stable
medium
low
Area of occupancy
trend
170 km2
decreasing
low
low
No. of mature individuals
trend
500
decreasing
medium
medium
No. subpopulations
1
high
No. locations
5
medium
Generation time
Global population share
5.8 years
low
100%
high
Houston W and Melzer A (2008) ‘Yellow chat (Capricorn subspecies) Epthianura crocea macgregori recovery plan’. Report
to Department of the Environment, Water, Heritage and the
Arts, Canberra. Queensland Environmental Protection
Agency, Brisbane.
Keast A (1958) The relationship between seasonal movements
and the development of geographic variation in the Australian chats Epthianura Gould and Ashbyia North (Passeres:
Muscicapidae, Malurinae). Australian Journal of Zoology 6,
53–68.
Lucas D, Gapindi M, Russell-Smith J (1997) Cultural perspectives of the South Alligator River floodplain: continuity and
change. In Tracking Knowledge in North Australian Landscapes: Studies in Indigenous and Settler Ecological Knowledge
Systems. (Eds DB Rose and A Clarke) pp. 120–140. North
Australia Research Unit, Darwin.
Winn KO, Saynor MJ, Eliot MJ, Eliot (2006) Saltwater intrusion
and morphological change at the mouth of the East Alligator River, Northern Territory. Journal of Coastal Research 22,
137–150.
Armstrong M (2004) ‘The Yellow Chat Epthianura crocea tunneyi in Kakadu National Park’. Unpublished report. Parks
Australia (North).
Woinarski J, Pavey C, Kerrigan R, Cowie I, Ward S (Eds) (2007)
Lost from Our Landscape: Threatened Species of the Northern
Territory. Northern Territory Government, Darwin.
BirdLife International (2011) ‘Species factsheet: Epthianura
crocea’. Retrieved 17 January, 2011 from <http://www.birdlife.org/>.
Comments received from
Martin Armstrong, Peter Kyne, Simon Ward,
John Woinarski
Higgins PJ, Peter JM, Steele WK (Eds) (2001) Handbook of Australian, New Zealand and Antarctic Birds. Volume 5: TyrantFlycatchers to Chats. Oxford University Press, Melbourne.
© Birds Australia 2011
Published by CSIRO Publishing, http://www.publish.csiro.au/
Citation: Garnett ST, Szabo JK, Dutson G (2011) The Action Plan for Australian Birds 2010. CSIRO Publishing, Melbourne.