Birds of the Cocos (Keeling) Islands, Indian Ocean

2006·4.7 MB·English

by  D Hopton

BIRDS OF THE COCOS (KEELING) ISLANDS,
INDIAN OCEAN
By D. HOPTON
P.O. Box 56, Ashbourne, South Australia 5157
SUMMARY
This paper reports on bird observations made on two trips
to the Cocos (Keeling) Islands including the remote and
difficult-to-access Pulu Keeling National Park in May and
June/July 2003. Although additional species new to the
island that I recorded as well as some of my other sightings
have been included in Johnstone and Storr (2004), this
paper expands on my observations during my time on the
islands. I have included a list of all previous species sighted
on the islands although a review of all previous records can
be found in Johnstone and Storr (2004).
INTRODUCTION The southern atoll consists of 26
The Cocos (Keeling) Islands are islands surrounding a lagoon.
situated in the north-eastern North Keeling Island (only 1.2
Indian Ocean (12° 12' S, 96° 54’ E). square kilometres in size) is 24
The closest island is Christmas km to the north. The total land
Island (see Figure 211 in area of the two atolls is 14 square
Johnstone and Storr 2004), which kilometres. A narrow submarine
is 975km to the east-north-east. bank at a depth of 700-800m
Java Head is just over 1,000 km to connects the atolls while the
the northeast while Perth is depth of the surrounding ocean
2900km to the southeast (Parks is approximately 5000m. There is
Australia 1999). The annual no fresh water on North Keeling
climate is tropical with an Island. Bechet Besar freshwater
average rainfall of 1976 mm. The swamp on West Island is the only
islands have an average daily fresh water above ground on the
maximum of 28.9 C, high islands, although Horsburgh
humidity and a predominant Island has a small brackish lake
wind direction of east to south¬ on its northern side. The
east with average daily speeds of islanders rely on the freshwater
16 to 30 km/hr for most of the lenses on the two largest islands,
year (Director of National Parks West Island and Home Island, for
2004). water.
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There are about five hundred Coconut dominate the
Cocos-Malay people living on vegetation on North Keeling
Home Island and one hundred Island. Octopus Bush (Argusia
people, mostly public servants, argentea) shrublands are common
live on West Island (Parks on the eastern shore while Tea
Australia 1999). The islands are Shrub (Pemphis aciclula) and
very low lying, the highest point smaller patches of Ironwood
being on South Island where a (Cordia subcordata) form dense
sand dune reaches 9m above sea thickets around the margin of
level. the lagoon, interspersed with
open grassy areas (Parks Australia
Even before settlement in the
1999).
early nineteenth century
Coconuts (Cocos nucifera) were The vegetation is affected by
abundant on the islands. cyclones that pass through the
However, since then coconut area occasionally. The shallow
plantations have replaced most rooted Pisonia trees are easily
of the original vegetation on the blown over and reshoot where
southern atoll. The vegetation they fall. Cyclone Walter, which
on North Keeling Island remains passed through the area on 5
pristine due mainly to its April 2001, felled 14 percent of
inaccessibility (Parks Australia the trees on North Keeling and
1999). destroyed 61 percent of the
canopy (Director of National
North Keeling Island was
Parks 2004). The resulting
proclaimed Pulu Keeling
regrowth and original root
National Park in 1995 and is
systems and old trunks form
Australia's smallest Common¬
formidable barriers as well as
wealth national park. The island
ideal habitat for the endemic
is 2km long and 1.3km wide. The
Cocos Buff-banded Rail
shore rises steeply to a height of
3-5 m and then slopes gradually (Gallirallus philippensis andreivsi).
to the central lagoon. The Park Apart from birds a few other
includes the land area of the vertebrates occur on the Cocos
island as well as a marine area (Keeling) Islands.
extending 1.5km around the The Mourning Gecko
perimeter. As well as the Park's (Lepidodactylus lugubris) occurs on
value as an unspoiled coral atoll
North Keeling Island while on
ecosystem it supports one of the the southern atoll the
largest breeding colonies in the introduced House Gecko
world of the Red-footed Booby (Hemidactylus frenatus) and a
(Sula sulci) (Parks Australia 1999). blind snake (Ramphotyphlops sp.)
The mouth of the lagoon on the also occur (Director of National
east coast has been blocked for
Parks 2004). Green Turtles
the last few years and the water (Chelonia mydas) and Hawksbill
level in the lagoon is falling. Turtles (Eretmochclys imbricata)
Pisonia (Pisonia grandis) forest and are common, the Green Turtle
73
nesting on the northern atoll May 2003 and 26 June-14 July
(Director of National Parks 2004). 2003. During the first period 1
A Dugong (Dugong dugon) has searched the entire outer
been resident in the lagoon since perimeter of the southern atoll
May 2002 (Director of National and a small portion of the inner
Parks 2004). Rabbits were lagoon area as well as accessible
introduced to the islands some areas within the islands. During
time ago and there are still the second period 1 was
occasional reports of sightings by employed by Parks Australia to
locals on Direction Island (W. undertake a bird survey of Pulu
Murray pers. comm.). Keeling National Park. 1 visited
the National Park twice, in the
Gibson-Hill (1949) cited an
company of park staff, from 30
“immense number" of marine
June 2 July and from 7-10 July.
birds on the main atoll in 1828-
The trip from the southern atoll
29 and stated that Charles
to Pulu Keeling takes one hour
Darwin, visiting the area in April
by boat. There is only one
1836, referred to the trees on the
landing place on the island,
main atoll as being “occupied by
reached by a 50m swim.
many nests of seabirds”.
On both trips the island and the
Most of the birds had been
lagoon were circumnavigated.
eliminated from the southern
Approximately 5 hours was also
atoll by 1885 because of habitat
spent searching the forested
change, density of human
areas, mainly using set transect
habitation, intense hunting
lines, which are used for Red¬
pressure and predation by cats
footed Booby counts. The lagoon
and rats. Today there are still
area was also thoroughly
very few birds on the southern
investigated.
atoll (Stokes 1982).
The Wedge-tailed Shearwater
Carter (1994) recorded
nesting area was checked three
approximately sixty species of
times in the evenings with the
birds from the islands, however,
intent of determining the
the number was increased to 72
presence of the Herald Petrel
species (Johnstone & Storr 2004).
The inclusion of the Northern (Pterodroma arminjoniana), which
was observed in this area once
Giant Petrel recorded by Park
before. The area was observed for
staff in 2003 (Murray, pers.
a period of one hour on each
comm) now increases the
occasion until fading light made
number to 73.
bird identification impossible.
The taxonomy and
METHODS nomenclature of this list
My bird observations were made generally follows Christidis and
over two separate periods, 4-15 Boles (1994).
74
BIRD SPECIES OF THE COCOS to breed birds for cock fighting. I
(KEELING) ISLANDS saw no obvious evidence of
crossbreds occurring on the
islands although given the
Green Junglefowl Callus varius
number of both feral chickens
The former owner of the Cocos
and Green Junglefowl seen this
Keeling Islands, George Clunies-
would seem to be likely to occur.
Ross, introduced these birds to
the southern atoll, probably Feral chickens are restricted to
around 1800 (Gibson-Hill 1950). I the southern atoll and are not
found these birds common along found in Pulu Keeling National
the roads and the runway on Park.
West Island. Some were observed
with one to three chicks. On one Helmeted Guineafowl Numida
meleagris
occasion 42 individuals were
counted from the northern end Stokes et al (1984) stated that a
pair had been seen in the
of the runway.
transmitter area on West Island
Green Junglefowl are decreasing
for a number of years probably
in number in their own home
derived from domestic stock
range in Indonesia due to habitat
from the Clunies-Ross estate.
loss and capture for the pet trade
These birds have not been seen
but as an introduced species on
recently.
West Island appear to be doing
well. While considered a pest by Hardhead Aythya australis
locals in gardens and farms this
I observed one adult male in the
population could become an
brackish lake on Horsburgh
important gene pool for the
Island on 11 May 2003. This was
species. This species does not occur
the first record for the Cocos
in Pulu Keeling National Park.
(Keeling) Islands. The bird was
not sighted on my second visit.
Red Junglefowl Gallusgallus
Chickens derived from this Northern Giant-Petrel
species are kept by many of the Macronectes halli
islanders and many escape their
A Northern Giant Petrel was
cages or are deliberately let loose
found on Home Island and
around the pondoks (local
handed to park staff in May/
shacks). 1 noticed the occasional
June 2003 in an emaciated
bird around dwellings and also
condition. It died but
along the road on West Island as
unfortunately the bird was not
well as on Home, South and
kept as a specimen (Murray, pers.
Horsburgh Islands.
comm.).
The domestic chicken is capable
of interbreeding with the Green Herald Petrel Pterodroma
Junglefowl and in some arminjoniana
countries is deliberately crossed Approximately ten birds were
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seen on North Keeling around (Gibson-Hill 1949). This specimen
the Wedge-tailed Shearwater was later identified as D. c. bassii
colony, possibly breeding, from (Johnstone and Storr 2004).
April to June in 1986 (Stokes and
Goh 1987). No petrels were sighted Red-tailed Tropicbird Phaethon
during my visit despite checking rubricauda
the area on three evenings. Breeding birds have been
Previous attempts at sighting this recorded on South Island, West
species by park staff have also Island and on North Keeling
been unsuccessful. Visits to the Island (previous records
island are limited and as this summarised by Johnstone and
species can only be sighted at Storr 2004).
dusk and observers are few there
may be a possibility that this White-tailed Tropicbird Phaethon
species still visits the island. Upturns
1 observed up to 14 birds at a time
Wedge-tailed Shearwater Puffinus in Pulu Keeling National Park
pacificus usually high above the other
1 observed these birds entering birds and always late in the day.
burrows in the early evenings in One bird was observed possibly
the area adjacent to the inlet on leaving a nesting hollow in an
Pulu Keeling National Park. The ironwood and others were
fact that they were still present observed flying among trees in
in July when breeding should be the centre of the forest. 1 also
well completed was interesting. observed one individual at
Previous records indicate Trannies Beach on West Island.
breeding occurs between Small numbers have been
October and November (Gibson- recorded on West Island
Hill 1950) (Carter 1994) and (Johnstone and Storr 2004).
possibly up to January (Stokes et
al. 1984). Four birds were seen to Masked Booby Sula dactylatra
circle, land and enter burrows This species breeds throughout
one evening and on subsequent the year in Pulu Keeling National
evenings two and then one bird Park but winter is the prime
were observed. About 20 active nesting time. Birds are only
or recently used burrows were in occasionally recorded from the
the area. A few breeding birds southern atoll (Johnstone and
have also been recorded from Storr 2004). During my visit I
West Island (Johnstone and Storr observed approximately 50 pairs
2004). nesting on the coast on south¬
eastern Pulu Keeling National
Yellow-nosed Albatross Diomedca Park and two birds were
chlororhynchos observed nesting in the open
One bird was found in an grassy area near the inlet. Most
emaciated condition, 2 July 1941 nests contained eggs although
76
there was one large chick at the chicks being present. Birds are
inlet near the Wedge-tailed occasionally sighted near the
Shearwater nesting area. southern atoll.
Little Pied Cormorant
Red-footed Booby Sula sula
Phalacrocorax melanoleucos
In 1941, 3,500-4,000 pairs were
1 observed one bird at the
estimated to be present (Gibson-
northern end of the runway,
Hill 1950), 30 000 individuals
West Island on 7 May 2003. This
were recorded in 1982 (Stokes et
was the first sighting for the
al. 1994) and 'tens of thousands’
islands of this species.
breeding birds were sighted in
1999 (Johnstone and Storr 2004).
Little Black Cormorant
The resident population of this
Phalacrocorax sulcirostris
species on the northern atoll is
Four birds were observed on the
now estimated by park staff to
edge of the lagoon on the
number 30 000 pairs (Director of
southern end of the runway on
National Parks 2004). The
29 June 2003. This was another
population of Red-footed Booby
first record for the island.
appears to have grown under
protection. Great Frigatebird Fregata minor
On both my visits to Pulu Keeling During my visits to Pulu Keeling
National Park, the birds 1 National Park, a number of small
observed nesting were mainly in pockets of nesting birds were
the lagoon area and Pisonia trees observed between the Lesser
in the centre of the island but Frigatebirds and many birds were
many were also nesting over roosting in the trees on the
other areas of the island, even in eastern side of the lagoon. Only
low bushes. Some birds were eggs were observed. Although 1
collecting nesting material while made no estimation of numbers
others had eggs or chicks up to they were noticeably less
approximately eight weeks old. common than the Lesser
Dark plumaged immature birds Frigatebird. At the time of my
were also common. Many birds visit the Lesser Frigatebirds
were nesting close to the outnumbered Greater Frigate-
frigatebirds. 1 also observed a few birds by about ten to one. This
birds out to sea from Home Island. was considerably less than
Carter’s (1994) estimation in 1994
Brown Booby Sula leucogaster of two to one. Breeding is
Evidently this species fluctuates confined to the northern atoll
widely in numbers (Johnstone although birds are occasionally
and Storr 2004) but during my sighted around the southern
visit approximately 20 pairs were atoll (Johnstone and Storr 2004).
nesting along the coast in Pulu
Keeling National Park. Nests were Lesser Frigatebird Fregata arid
at various stages, eggs to large Estimations in 1999 by park staff
77
from surveys indicate a resident 1 observed Little Egrets opposite
population of approximately the meteorological station on the
3000 pairs (Parks Australia 1999). edge of the lagoon, in the North
In November 1999 J. Reid Park area and on the oval on
estimated 10000 birds on the Home Island. Up to four birds
island (Johnstone and Storr were observed at a time and all
2004). 1 found these birds were were longer legged and more
very abundant in Pulu Keeling upright and slender than the
National Park; nests were located Eastern Reef Egrets. They had
in loose groups mainly around blackish bills grading to
the lagoon area in tea shrub or greenish/yellow at the base.
ironwood and most contained Those that 1 observed closely had
eggs. Some birds were also dark legs with yellow feet. There
observed off the coast on the is a possibility that these birds
southern atoll. may be the subspecies E. garzetta
garzetta. The Australian
Christmas Frigatebird Fregata subspecies E. g. nigripes has black
andreivsi feet with yellow to grey soles
An adult female was recorded while the subspecies garzetta,
from North Keeling in 1986 which occurs in Europe, Asia,
(Stokes and Goh 1987) and two Japan, Philippines and Africa, has
more birds were seen on North yellow feet (Marchant and
Keeling in 1993 (Carter 1994). 1 Higgins 1990). A specimen would
observed three adult female birds be needed for confirmation of
near South Island flying with subspecies.
Lesser Frigatebirds on my first
visit. Eastern Reef Egret Egretta sacra
Reef egrets are reported to breed
White-faced Heron Egretta on the southern atoll in coconut
novaehollandiae trees around January (Gibson-
One bird was recorded in January Hill 1949, Stokes ct al 1994). I
1992 (Stokes eta/. 1982). encountered these birds often on
the rocky shore, inland lagoon
Little Egret Egretta garzetta and grassy areas on West Island as
well as most of the smaller
A specimen taken in 1879 from
West Island was identified as the islands. They were often in the
company of the Little Egrets.
Indonesian race nigripes (Forbes
Mainly white morphs were seen.
1885). Carter (1994) observed a bird
Few were seen on Pulu Keeling
with yellow feet on West Island
National Park probably due to
on 4 November 1993. J. Reid
lack of suitable habitat.
recorded two birds in November
1999 with nuchal plumes and On 5 July 2003 1 observed a light
bare part colouring consistent ash grey bird in the company of
with the subspecies nigripes two dark phase birds and four
(Johnstone and Storr 2004). white phase birds in the swampy
78
area around the towers just as early as 1879 but regarded as a
south of North Park. This visitor in 1949 (Forbes 1885,
particular bird had a pale Gibson-Hill 1949). 1 found these
coloured bill, white head and birds common on West Island
neck, pale ash grey body and especially in open grassy areas.
wings, darker towards the They are also commonly seen on
primaries. The legs were darkish. lawns around buildings. On 29
On 11 July 2003 a light ash grey June 2003 I observed 34 birds
bird in company of one dark from the northern end of the
phase and five white phase birds runway. They nest in the
was observed on the lagoon side Pemphis shrubs on the small
of central South Island. This bird offshore islands of the southern
appeared similar to the bird seen atoll (Murray, pers. comm.).
on West Island. 1 am fairly Three birds were also observed
confident that this was an roosting in Pulu Keeling
Eastern Reef Egret but have National Park amongst nesting
never before heard of this colour frigatebirds and Red-footed
variation. Boobies and four birds were seen
on Home Island.
Great Egret Ardea alba
On 6 July 2003 1 flushed three Glossy Ibis Plegadis falcinellus
birds from Beshet Besar Four birds were recorded on the
freshwater swamp. The yellow airstrip in May 1990 (Stokes 1994).
bills, dark legs (trailing in flight), J. Reid recorded three birds at
long kinked neck and large size Bechet Besar swamp on 18
of these birds, compared to the November 1999 (Johnstone and
two reef herons also in the Storr 2004).
swamp, clearly identified these On 6 May 2003 1 observed seven
birds. The birds were seen again birds on the northern end of the
on 13 July 2003. This was a new runway. Probably the same birds
record for the islands. were present in various places
including Bechet Besar
Cattle Egret Ardea ibis freshwater swamp on my second
Two birds were observed in visit.
breeding plumage on 14 January
1982 (Stokes etai 1982). Greater Flamingo Phoenicopterus
ruber
Black-crowned Night Heron One bird was seen on North
Nycticorax nycticorax Keeling during 26 April to 15
One specimen was taken on 13 June 1988 (Marchant and Higgens
October 1941 (Gibson-Hill 1950). 1990).
Nankeen Night Heron Nycticorax Swamp Harrier Circus approximans
caledonicus One specimen was taken on 6
Observed nesting on the islands July 1941 (Gibson-Hill 1950).
79
Nankeen Kestrel Falco cenchroides species has been on the islands at
A pair was seen for several weeks least since 1998 when a specimen
on West Island on 5 June 1990 was hit by a plane on the runway
(Stokes 1994). and eventually identified in May
2000 by J. Reid (Johnstone and
Buff-banded Rail Gallirallus Storr 2004). I observed single
philippensis birds on West Island at the
northern end of runway, in a
This endemic subspecies G.
swampy area on the lagoon side
philippcnsis andrewsi was once
of West Island, as well as near the
common on all islands in the
Quarantine Station and just
group but now is almost
south of North Park.
confined to Pulu Keeling
National Park where it is said to
have been introduced in the late Pin-tailed Snipe Gallinago stenura
1800s, although it may already This species is considered an
have been present (Gibson-Hill uncommon visitor (Johnstone
1948). It appears that a small and Storr 2004).
population may be surviving on
West Island as an adult with five Little Curlew Numenius minutus
chicks was seen at the southern One bird seen near the airstrip
end of the runway in July 2002 on West Island on 12 and 15
(Director of National Parks March 1983 and three birds on 26
2004). March 1983 (Stokes et al. 1984).
On my visit to Pulu Keeling
National Park 1 found these birds Whimbrel Numenius phaeopus
very common along the edge of Recorded as an uncommon
the lagoon with up to 20-30 visitor from both atolls
individuals within sight (Johnstone and Storr 2004). Park
simultaneously. They were also staff regularly see this species on
encountered frequently in the the coastal side of South Island,
forested area. Fewer were however, during my visit no
encountered around the coast. birds were seen there on 9 May
One chick, only a few days old, 2003, the birds probably having
was observed in the large grassy migrated north.
area opposite the inlet in the
central lagoon region. Four half- Common Redshank Tringa totanus
grown chicks were also present Johnstone and Storr (2004)
in the same area. considers this species to be a rare
visitor.
White-breasted Waterhen
Amaurornis phoenicurus Common Greenshank Tringa
Local rangers have previously nebularia
recorded this species on the This species is considered an
islands and have seen adults with uncommon visitor (Johnstone
chicks (Murray, pers. comm.). The and Storr 2004).
80
Common Sandpiper Actitis black nape was clearly visible
hypoleucos identifying it as the Australian
This species is considered a subspecies leucocephalus. Possibly
regular visitor (Johnstone and the same bird was observed
Storr 2004). several times at the northern end
of the runway on my second visit.
Ruddy Turnstone Arenaria
interpres Pacific Golden Plover Pluvialis
Ruddy Turnstones are regular fulva
visitors to the islands (Johnstone This species is considered an
and Storr 2004). Up to 12 birds in irregular visitor (Johnstone and
breeding or part breeding Storr 2004).
plumage were observed by me in
the central lagoon area near inlet Grey Plover Pluvialis squatarola
on Pulu Keeling National Park One was seen on the airstrip on 4
and on the rocky eastern shore November 1993 (Carter 1994).
near the inlet on both visits.
Greater Sand Plover Charadrius
Sanderling Calidrisalba leschenaultii
This species is considered an This species is considered a
irregular visitor (Johnstone and regular visitor (Johnstone and
Storr 2004). Storr 2004).
Sharp-tailed Sandpiper Calidris Oriental Plover Charadrius veredus
acuminata One bird was seen on 17 October
One bird seen on West Island on 1941 (Gibson-Hill 1950).
4 November 1993 (Carter 1994).
Oriental Pratincole Glareola
Curlew Sandpiper Calidris maldivarurn
ferruginea This species is considered a
J. Reid observed a single bird on regular visitor (Johnstone and
the shore of Pulu Keeling Storr 2004). Park staff have noted
National Park on 9 November their annual visits in the late dry
1999 (Johnstone & Storr 2004). season each year (Director of
National Parks 2004).
Black-winged Stilt Himantopus
himantopus Lesser Black-backed Gull Larus
E. Alfred recorded a bird of the fuscus
nominate subspecies from Afro- A bird was banded as a chick at
Eurasia at Bechet Besar swamp on Simo, Lapland, Finland on 13 July
28 November 1958 (Johnstone 1957 and recovered freshly dead,
and Storr 2004). On 14 May 2003 1 presumedly killed by islanders,
observed one bird at the on South Island at the end of
southern end of runway in a September 1959 (Johnstone and
shallow salt-water pond. The Storr 2004).
81