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Little Tern Survey, Wells Harbour, 2013
James McCallum
Little Tern Survey, Wells Harbour, 2013
Contents
Introduction and Method
page 3
Results
page 4 - 12
Summary of the 2012 Breeding Season
page 13
2012 Breeding Totals
page 13 - 15
Summary of Tern Feeding Activity
page 15 - 16
Summary of Dredging Activity
page 16
Acknowledgements
page 16
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Little Tern Breeding Survey Wells Harbour 2013
From the start of June to the end of August 2013 I was contracted to survey Little Tern
breeding activity in Wells Harbour. The area I was asked to concentrate on was the shingle
and shell ridges to the east of the main channel on Bob Hall’s Sands and the new Outer
Harbour Wall.
The work was funded by Wells Harbour Commissioners and I was asked to follow the same
method used in the 2011 & 2012 WHC Little Tern survey, however this year it was decided
that the observation time should be reduced to one day per week. The methodology was
originally set out by Royal Haskoning who commissioned a similar survey in 2010. The
survey started at the beginning of June 2013 and continued until the final two Common
Tern chicks fledged on the 21st of August.
My brief, as outlined in 2010 by Royal Haskoning, was to simply record Little Tern behaviour
and breeding attempts. The long hours of repeated observation were to be condensed into
short summaries highlighting each week’s observations. In addition I have included details
of all other nesting species and the fishing activities of Common Terns. Although this
information was not required it was straightforward to collect during the Little Tern
observation and forms a greater resource of information which may be useful in future
years.
Little Terns are a schedule one breeding bird and are therefore legally protected. To avoid
any disturbance to them on their nesting areas they were watched from a distance using a
telescope with a 15x-40x zoom lens.
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Results
4th June 2013
Little Tern. 47 birds counted in the harbour at high tide – Most activity was centred around
Outer Harbour Wall and up to 11 birds were fishing in the Channel north of The Lifeboat
House. 29 pairs were incubating and an additional pair was scraping on the Outer harbour
Wall.
Common Tern. 49 birds were recorded in the harbour at high tide – Most activity was
centred around the Outer Harbour Wall where 36 birds were counted.
Breeding Ridges.
Little Tern. No Little Terns were recorded on the ridges.
Common Tern. Up to 9 birds were counted from the Lifeboat House and at least 3 pairs
seemed to be incubating.
Oystercatcher. 5 pairs incubating - 3 on the Southern Ridge and 2 on the Northern Ridge.
Black-headed Gull. Up to 22 pairs of which at least 11 incubating – all on the Northern
Ridge.
Common Gull. 3 pairs present, two of which incubating on the Northern Ridge.
Outer Harbour Wall
Little Tern. Up to 30 pairs. 29 pairs incubating and an additional pair scraping.
Common Tern. 21 pairs present. 13 incubating and up to 8 additional pairs seen displaying
and scraping.
Arctic Tern. 1 pair incubating. The first breeding record for the Outer Harbour Wall.
Oystercatcher. 3 pairs present. 2 pairs incubating and 1 pair with three newly-hatched
chicks.
Ringed Plover. 2 pairs present. I pair scraping.
Black-headed Gull. 93 pairs nesting, with at least 17 of these having chicks.
Common Gull. 1 pair incubating. The first breeding record for the Outer Harbour Wall.
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Mediterranean Gull. Up to 3 birds present. A pair of adults displaying and a single 2 nd
summer bird.
11th June 2013
Breeding Ridges.
A walk out over Bob Hall’s Sands showed no breeding birds on the Northern Ridge and 3
incubating Oystercatchers on the Southern Ridge. *A closer look at the Northern Ridge
revealed fresh Fox tracks which accounted for the lack of nesting birds.*
Oystercatcher 3 pairs incubating on Southern Ridge.
12th June 2013
Outer Harbour Wall
Little Tern. Up to 43 pairs present. 40 pairs incubating and a single pair with two newlyhatched chicks.
Common Tern. 25 pairs present. 22 incubating and up to 3 additional pairs seen displaying
and scraping.
Arctic Tern. 1 pair incubating.
Oystercatcher. 3 pairs incubating but no sign of the pair with three newly-hatched chicks –
predated?
Ringed Plover. 3 pairs present. 2 pairs incubating and I pair scraping and mating.
Black-headed Gull. 108 pairs nesting, 92 incubating and 16+ pairs with chicks (some
predation).
Common Gull. 1 pair incubating.
Mediterranean Gull. Single adult loafing with non-breeding Black-headed Gulls. Frequently
mobbed by the breeding Black-headed Gulls.
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19th June 2013
Breeding Ridges.
Oystercatcher. 5 pairs incubating – 4 pairs on the Southern Ridge and 1 pair on Northern
Ridge.
Otherwise only 4 pairs of Black-headed Gulls and a single pair of Common Gulls on territory
on the Northern Ridge.
Outer Harbour Wall
Little Tern. Up to 44 pairs present. 34 pairs incubating, 7 pairs with chicks and 3 additional
pairs displaying.
Common Tern. 27 pairs present. 23 incubating and up to 4 additional pairs seen displaying
and scraping.
Arctic Tern. No sign of the breeding pair so the eggs have clearly been predated.
Oystercatcher. 3 pairs incubating but there was still no sign of the pair with three newlyhatched chicks so these were presumably predated.
Ringed Plover. 3 pairs incubating.
Black-headed Gull. C.108 pairs nesting but very difficult to count as lots of non-breeding
birds present. 22 pairs with chicks.
Common Gull. 1 pair with 3 newly-hatched chicks.
Mediterranean Gull. 3 adults, including 1 pair displaying. Frequently mobbed by the
breeding Black-headed Gulls.
26th June 2013
A quick check of the colony on the morning of the 21 st June showed all to be well but on the
25th June, depressing news reached me that there were no signs of any Little Terns on the
Outer Harbour Wall. As the majority of other nesting species were still present it appears
that a predator targeted the Little Tern colony some time from the morning of 22 nd to the
evening of the 24rd. The predation has the hallmarks of a gull but without observation we
can only surmise. On the 26th a 2nd summer Mediterranean Gull was seen diving down
towards two pairs of displaying Little Terns then after the terns took to the air the gull was
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actively searching around vegetation close to where the terns had been resting. It darted
from one clump to the nest as if searching for chicks. Although this is not hard proof, the
behaviour suggested that this bird may have been the culprit. The same 2nd summer bird
was also twice observed killing and eating a Black-headed Gull chick.
Breeding Ridges.
Little Tern. 21 Little Terns roosting on the Northern Ridge at high-tide (Marsh tide and very
little of the ridges exposed).
Common Tern. Up to 7 birds counted on the Northern Ridge at high-tide
Oystercatcher. No signs of any of the incubating birds and no signs of chicks.
Black-headed Gull. 2 pairs on territory on the Northern Ridge.
Common Gull. 1 pair incubating on the Northern Ridge.
Outer Harbour Wall
Five hours continuous observation failed to show any evidence of Little Tern pairs with
young. (However, a fledged juvenile was photographed on the Outer Harbour Wall on the
28th June – see entry under that date).
Little Tern. All young and eggs had gone from the nesting areas. A maximum of 4 pairs were
recorded. These were displaying and scraping so it was hoped that they would attempt to
breed again.
Common Tern. 23 pairs present. 21 pairs nesting of which 4+ pairs had newly-hatched
chicks. 2 additional pairs seen displaying.
Arctic Tern. 1 pair incubating – the same pair making a second nesting attempt.
Oystercatcher. 2 pairs present both with newly-hatched chicks.
Ringed Plover. 4 pairs present – 2 still incubating and 2 pairs displaying. (1 pair obviously
had their eggs predated).
Black-headed Gull. 77 pairs nesting. 53 pairs incubating and 24+ pairs with chicks. Clearly
some young have been predated, however, as many of the young are now quite large and
well feathered it is likely that some have already dispersed on foot accompanied by their
parents.
Common Gull. 2 pairs. 1 pair with 3 chicks and an additional pair displaying.
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Mediterranean Gull. 2nd summer bird present – see above.
28th June 2013
Little Tern A single recently-fledged juvenile Little Tern was photographed on the Outer
Harbour Wall on this date (per Cy Campbell) – lots of observation on the 26th June and 3rd
July failed to show any evidence of young so the observation comes as a complete and very
welcome surprise.
A check with Natural England indicated that at the same time as this fledgling was observed
all nesting attempts by Little Terns in neighbouring colonies had failed so it certainly
originated from the Wells Outer Harbour Colony.
3rd July 2013
Breeding Ridges.
Little Tern. 16 pairs incubating on the Northern Ridge, presumably many if not all of these
pairs originate from the Outer Harbour Colony.
Common Tern. 1 pair incubating on the Northern Ridge.
Black-headed Gull. 1 pair incubating on the Northern Ridge.
Common Gull. 1 pair incubating on the Northern Ridge.
Ringed Plover. 1 pair scraping on Northern Ridge.
Outer Harbour Wall
Little Tern. 1 pair briefly scraping was the only record during several hours of concentrated
observation.
Common Tern. 25 pairs present. 10 pairs incubating and 15 pairs with chicks. 3 additional
pairs seen displaying.
Arctic Tern. 1 pair incubating.
Oystercatcher. 2 pairs present, both with chicks.
Ringed Plover. 2 pairs incubating, one of the adults sitting high on the nest and calling as if
the young were hatching.
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Black-headed Gull. 81 pairs nesting. 43 pairs incubating. Clearly some of the young and
eggs have been predated. 12 young now capable of flight and some may well have
dispersed.
Common Gull. 2 pairs - 1 pair with 3 chicks and an additional pair displaying.
Mediterranean Gull. 8 present. 6 adults and two 2nd summers. The adult birds were paired
and were regularly displaying, sometimes with nesting material stolen from the nests of
incubating Black-headed Gulls. Some of the birds were regularly sitting as if on nests but
none were seen to be nesting.
10th July 2013
Breeding Ridges.
Little Tern. Only 3 pairs incubating on the Northern Ridge - 13 pairs predated.
Black-headed Gull. 2 pairs on the Northern Ridge, one pair with chicks and one pair
incubating.
Common Gull. 1 bird seemingly incubating on the Northern Ridge but no sign of any eggs.
Ringed Plover. 2 pairs incubating. 1 pair on the Northern Ridge and 1 pair on Southern
Ridge.
Outer Harbour Wall
Little Tern. No birds observed on the Outer Harbour Wall for the first time this season.
Common Tern. 21 pairs present. 10 pairs incubating and 11 with chicks. Clearly some of the
young have been predated. 2 additional pairs were displaying.
Arctic Tern. 1 pair incubating.
Oystercatcher. 4 pairs present - 1 pair with near fledged young just south of the Outer
Harbour, 1 pair with half-grown chicks, 1 pair incubating and 1 pair scraping.
Ringed Plover. 1 pair incubating. (The other pair watched last week have seemingly
hatched their brood and have either dispersed or the young have been predated. These are
best recorded as ‘outcome unknown’.
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Black-headed Gull. 42 pairs incubating. 12+ pairs with chicks. In addition several fullyfledged and independent juveniles on the sands around the Outer Harbour indicating that
many have already left the area. Several juveniles capable of strong flight.
Common Gull. 2 pairs. 1 pair with 3 chicks and an additional pair displaying.
Mediterranean Gull. 1 pair present loafing with non breeding gulls.
17th July 2013
Outer Harbour Wall
Little Tern. Several adults and a single fledged young were fishing in the channel and
regularly resting on the Outer Harbour Wall.
Common Tern. 13 pairs present. 6 pairs incubating and 7 pairs with chicks. A minimum of
11 juveniles were counted – brood sizes 3+2+2+1+1+1+1. The overall numbers are down on
last week’s count indicating that some of the young have been predated. 5 additional pairs
seen displaying.
Arctic Tern. 1 pair with newly-hatched chicks.
Oystercatcher. 2 pairs with young present. 1 pair with near fledged young and 1 pair with 2
large chicks.
Ringed Plover. No signs of any nesting activity.
Black-headed Gull. 47 fledged young in the immediate area – many of which will have
originated from the Outer Harbour Colony but as ever with so much dispersal from other
nesting areas it is impossible to be sure of the exact origins of all the young birds. 11 pairs
incubating and 13+ pairs with small chicks within the colony.
Common Gull. 1 pair with 3 large young and 2 additional pairs displaying.
Mediterranean Gull. 1 adult with two fledged chicks on the Outer Harbour Wall. After two
hours this family group got up and headed off westwards. This observation highlights the
need for regular visits to sites as it would be very easy to assume an observation such as this
was evidence of successful breeding at the site.
*In addition on the 15th July a pre-roost gathering of 53 Mediterranean Gulls, mainly adults,
were counted on the Outer Harbour Wall.*
18th July 2013
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Breeding Ridges.
Little Tern. 3 pairs with newly-hatched chicks. 5 additional pairs in the area.
Black-headed Gull. 3 pairs on the Northern Ridge, two pairs with chicks and one pair
incubating.
Common Gull. 1 pair on the Northern Ridge but no sign of the eggs.
Oystercatcher One pair incubating two eggs.
Ringed Plover. 1 pair incubating on the Northern Ridge.
24th July 2013
Breeding Ridges.
Further signs of predation this time probably by Gulls rather than by a Fox.
Little Tern. All young predated
Black-headed Gull. 2 pairs on the Northern Ridge with large young.
Oystercatcher Nest predated.
Ringed Plover. Nest predated.
Outer Harbour Wall
Little Tern. Up to 3 adults recorded fishing in the Channel.
Common Tern. 10 pairs present – 7 pairs with young and 3 pairs incubating. 11 fledged
juveniles counted. Also a big congregation of 41 non breeding adults resting on the Outer
Harbour Wall.
Arctic Tern. The chicks had been predated but the adults were still present and busy
displaying and nest-scraping. It was too late in the season to make another nesting attempt.
Oystercatcher. 1 pair with 2 fledged young.
Ringed Plover. No signs
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Black-headed Gull. Only 10 nesting pairs remaining – 6 incubating and 4 with young. Most
of the flying young have dispersed.
Common Gull. 1 pair with 3 fledged young.
Mediterranean Gull. 1 adult.
31st July 2013
Outer Harbour Wall
Common Tern 2 pairs present – 1 with newly-hatched chicks and one incubating.
Black-headed Gull Colony virtually finished now just a few adults remaining with small
chicks. Very difficult to count as vegetation is quite high and dense in many places.
7th August 2013
Outer Harbour Wall
Common Tern 2 pairs present both with chicks.
Black-headed Gull A few pairs with young remaining but very difficult to count in the tall
vegetation.
14th August 2013
Outer Harbour Wall
Common Tern 2 pairs present both with chicks.
Black-headed Gull A few pairs with young remaining but mainly post breeding birds present.
21st August 2013
Outer Harbour Wall
Common Tern 2 pairs present each with a single fledged young.
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Black-headed Gull Nesting season virtually finished with last few pairs with young
remaining.
Summary of the 2013 Breeding Season
The 2013 breeding season started extremely well with the Outer Harbour Wall, in particular,
proving to be a very attractive breeding area – the highlights being an impressive count of
41 pairs of nesting Little Terns and the first ever nesting pair of Arctic Terns for the site.
The season was however, dominated by high levels of natural predation and only a single
young Little Tern fledged. Poor breeding success in 2013 was mirrored at most other sites
along the North Norfolk Coast. The count of 41 nesting pairs of Little Terns on the Outer
Harbour Wall showed that the site had developed into one of Norfolk’s larger and most
important colonies of this rare and threatened species. Gulls were the main predator of
Little Terns on the Outer Harbour and this season Mediterranean Gulls, a recent colonist,
were thought to have been responsible - one 2nd summer plumaged bird perhaps
accounting for the predation of the majority of the young and eggs. On Bob Hall’s Sands the
breeding ridges were also hit by predation; initially by a Fox then later by gulls.
In spite of the high predation suffered by the Little Terns, the Common Terns did much
better and successfully fledged 13 young.
Fledged Little Tern
Summary of the 2013 Breeding Totals
Little Tern 41 pairs nested on the Outer Harbour Wall. The first chicks were seen on the 12th
June. During the period from 22nd to 24th June the colony was targeted by gulls, almost
certainly Mediterranean Gulls and one 2nd summer bird in particular. A full day of
observation on the 26th June failed to show any evidence of chicks surviving however on the
28th June a single fledged chick was seen and photographed from a boat. The chick had
somehow escaped predators and presumably remained hidden in tall, dense vegetation on
the north-eastern edge of the wall. A very welcome surprise.
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Many of the nesting pairs relocated to the breeding ridges on Bob Hall’s Sands were 16 pairs
were found incubating on the Northern Ridge on the 3rd of July. The next visit on the 10th
July showed that only 3 nests remained the rest had been predated (possibly by Common
Gulls). The 3 pairs hatched their eggs but a visit on 24th July showed that these too had been
predated.
Young Fledged Bob Hall’s Sands 0. Outer Harbour 1.
Common Tern minimum of 29 pairs breeding in Wells Harbour – 4 pairs on Bob Hall’s Sands
and 25 pairs on the Outer Harbour Wall.
Young Fledged Bob Hall’s Sands 0. Outer Harbour Wall 13.
Arctic Tern A single pair nested for the first time on the Outer Harbour Wall. The eggs from
the first nest were predated but the pair re-laid in the same spot and hatched two chicks but
these were sadly also predated.
Young Fledged 0
Oystercatcher
Bob Hall’s Sands - 6 pairs
Outer Harbour Wall - 4 pair
Young Fledged Bob Hall’s Sands 0. Outer Harbour 3.
Ringed Plover
Bob Hall’s Sands 4 laid eggs.
Outer Harbour Wall 4 pairs laid eggs, 1 brood of chicks seen but probably predated.
Young Fledged Bob Hall’s Sands 0. Outer Harbour Wall unknown but not thought to have
fledged young.
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Black-headed Gull
Bob Hall’s Sands 11 pairs laid eggs of which 2 pairs each fledged a single young.
Outer Harbour Wall 108 nesting pairs were counted on a single date however, as predation
levels were reasonably high this figure almost certainly doesn’t reflect the true number of
nesting attempts. A figure of 135 nesting pairs is more realistic.
Young Fledged Bob Hall’s Sands 0. Outer Harbour Wall – without dedicated observation
arriving at actual figures is impossible. Many young disperse ‘by foot’ and due to the
gregarious nature of gulls many fledged young from nearby colonies will frequent other
nesting colonies. The breeding season was fairly good one for Black-headed Gulls on the
Outer Harbour and an estimate of 70 fledged young seems realistic.
Common Gull
6 pairs nested on Bob Hall’s Sands but all were predated.
A single pair nested on the Outer Harbour for the first time and raised 3 fledged young.
Young Fledged Bob Hall’s Sands 0. Outer Harbour Wall 3
Tern Feeding Activity
The feeding behaviour of the Little and Common Terns followed a clear pattern that
mirrored the findings of the previous three surveys. As in 2012 the occurrence of trapped
shoals of both Whitebait and Lesser Sandeels during ebb tides was also noted. The trapped
fish quickly attracted the attention of both terns and gulls and a summary of this is listed
below under ‘Additional Tern Feeding Activity’.
As noted in past surveys fishing activity has so far formed a definite pattern. The pattern
has applied to both Little and Common Terns.
At high tide many birds are seen to be resting or small numbers fishing around The Bar or in
the open sea. During rising and falling tide there is far more feeding activity. Much of this
activity occurs in the lower reaches of the channel (particularly on the eastern shore)
especially around The Bar or in the open sea. Smaller numbers of both species may be seen
south of the Lifeboat House. The Common Terns can often be seen fishing as far up the
channel as the Whelk Sheds and Little Terns regularly frequent the smaller creeks. The
channel north of the Lifeboat House is, however by far the most important feeding area in
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Wells Harbour. At low tide the majority of both Little and Common Tern fishing activity
takes place in the open sea.
Whitebait and Lesser Sandeels were the most commonly recorded prey items for both
species.
Additional Tern Feeding Activity
Although a regular feeding cycle had been noted in previous surveys the presence of
Whitebait and Sandeels trapped in shallow pools by the receding tide was again noted in
Wells Harbour - as in 2012. Whitebait were unusually abundant in Wells Harbour especially
during the period from mid July to mid August. Just before low tide shoals of Whitebait and
Sandeels were frequently concentrated in shallow water by the falling tide. Gulls and Terns
were quick to identify this food source and large feeding groups frantically fed on the
trapped fish until the supply was exhausted. These feeding groups were sometimes joined
by Little Egrets.
This situation was most often observed just to the south of the Outer Harbour.
Lesser Sandeels and Whitebait.
Dredging Activity. Both species have been noted fishing in the channel when the dredger is
working but neither species feeds closer than 90-100 metres. Other than terns not feeding
in close proximity, the working dredger didn’t appear to trouble either species of tern.
Acknowledgements.
Many thanks to Wells Harbour Commissioners, particularly Chris Rose for his regular
updates during the periods in between my scheduled visits.
The Wells Harbour Commissioners have very effectively fenced off the Outer Harbour Wall
and placed a series of signs requesting people to stay away from the nesting areas. This
extra protection has been of great benefit to the nesting birds.
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