I was a member of the Australasian Wader
Study Group’s expedition to
I drove from
We started seeing Oriental
Pratincoles about 50km north of Anna Plains Station flying low over the
scrub. They weren’t large numbers
(up to 50), but enough for people to comment about them being there and about
them flying low. We continued to see
small groups as we drove to the station. Several
large flocks of Oriental Pratincoles flew past
close to the homestead from the scrub west out over the plain.
The largest flock was at least 1,000.
In the afternoon people reconnoitred several potential mist netting sites
on the plain. We saw ‘smokes’ of
many thousand Oriental Pratincoles and one group
saw very large numbers low over the plain close to dusk.
The numbers were so high that a decision was made at the meeting that
evening to set mist nets and cannon nets on the plain the following evening.
Normally you would think that this would be a futile exercise, but the
numbers were such that expectations were high.
We made our first cannon net catch on
Eighty Mile Beach the next day (Tuesday) 2km north of the Anna Plains Station
entrance. We saw a few Oriental
Pratincoles on the beach. As
planned, we set a line of mist nets and two cannon nets on the plain in the late
afternoon. The pratincoles
were in large numbers over the plain (flocks of 1,000s to 10,000+), but those
close to the mist nets almost all flew parallel to the nets.
Seven birds were caught in daylight and eight more in the fading light
after sunset. The AWSG had only
caught about 200 Oriental Pratincoles in the past,
and never before by mist net.
We cannon netted on Wednesday morning 5km
south of the Anna Plains Station entrance and there were good numbers of Oriental
Pratincoles on the beach prior to the catch.
We normally aim for a catch of about 150 to 200 birds, but because the
AWSG only had very limited data on Oriental Pratincoles,
we fired when we only had about 30 Oriental Pratincoles
in front of the net. We cleared the
net quickly, and fired the second net catching another 60+ Oriental
Pratincoles. As we drove back
along the beach after the catch we began to realise that we were witnessing
something very unusual. The informal
estimates of Oriental Pratincoles roosting on the
mud flats along the 5km stretch varied from 100,000 to 250,000.
My estimate was 160,000 +/- 50,000. They
far outnumbered the ‘grey waders’. This
generated some discussion at the evening meeting, and there was agreement that
somehow we had to make an estimate of the numbers of Oriental
Pratincoles. The possibility
of an aerial count of the full beach was floated.
On Thursday 5th February the
cannon netting site was 9km south of the Anna Plains Station entrance.
When we arrived at the beach it was clear that the numbers of Oriental
Pratincoles had increased. We
caught a further 120 Oriental Pratincoles between
the two nets that we fired. After
the catch, one vehicle went to investigate the Oriental
Pratincoles. They found
several hundred thousand including 46,000 in the southern most kilometre, and
similar numbers could be seen in the distance to the south.
There was considerable discussion at the meeting that night and a
decision was made to do a count of the northern most 71km of Eighty
On Friday 6th February the
cannon netting site was 16km south of the
Friday also saw the possibility of an
aerial count come to fruition. Clive
Minton (the expedition leader) had mentioned the idea to John Stoate, the owner
or Anna Plains Station. John knew of
a pilot who would make the flight for free, if we could charter an aircraft that
was available. Clive contacted Grant
Pearson from CALM in
Three experienced wader counters made the
flight on Saturday 7th February.
Peter Collins counted the birds on the southward flight.
Humphrey Sitters counted the birds on the northern flight.
Brian Etheridge was the recorder. Peter’s
count was 2.45 million, and Humphrey’s count was 2.88 million.
There was considerable thought given about reasons for the difference in
the counts, and about how accurate the counts were.
There were good reasons to believe that both counts were reasonably
accurate, with the first count being augmented by the continued arrival of birds
from the north and inland, and that the counts were more likely to be
conservative than overestimated. The
vast majority of birds in both counts were around the mouths of several creeks
on Mandora Station where the sands and mud flats were much wider than anywhere
else. The full details of the events
and counts are soon to be published in the International Wader Study Group
Bulletin (Sitters et al. 2004).
I left Broome on Sunday 15th
February to return to Perth. I
started to see Oriental Pratincoles in small
numbers near Pardoo Roadhouse and I saw the last on the following day near Whim
Creek. The biggest numbers totalling
almost 45,000 Oriental Pratincoles were near South
Hedland flying over grass and spinifex plains and acacia scrub.
The largest flock was about 20,000. This
was in stark contrast to when I had driven north.
What is the significance of this count?
Firstly, the accepted number of Oriental
Pratincoles in the Australasian East Asian Flyway prior to our discovery
was only 75,000 (Bamford et al. 2003).
We subsequently learnt of an unpublished report of nearly 400,000 in
April 1975 by John Darnell near
Why were they at Anna Plains Station and
Eighty Mile Beach? We asked
ourselves this question while we were at Anna Plains Station.
The conditions were excellent. There
had been good rains just before New Year, which led to the plain having a
generally good cover of grass, but there had been little follow up rain until a
couple of days before we arrived, so the grass was not very high or dense.
There were large numbers (but not plague proportions) of Yellow-winged
Locusts (Gastrimargus musicus).
The pratincoles appeared to be feeding on
the locusts. We never saw one catch
a locust, but we could feel them in the crops of some of the pratincoles
we caught, and the beach also had a lot of wings from the locusts, which we felt
must have been discarded by the pratincoles while
they were roosting on the mud flats.
are largely considered to be crepuscular feeders.
That is, they feed mostly early in the morning and late in the afternoon,
possibly even after sunset when there is a full moon. (McNeil et
al. 1992). The days became
increasingly hotter during the week leading up to the aerial survey.
We felt that the pratincoles were feeding in
the morning until it became too hot, and then flew out to Eighty Mile Beach to
rest during the hottest part of the day, before returning inland in the late
afternoon to feed again and to roost. We
have observed this behaviour on previous expeditions with Oriental
The best reason for the Oriental
Pratincoles being at Anna Plains Station came when someone read the
species account in HANZAB (Higgins & Davies 1996) which indicated that Oriental
Pratincoles may move into an area after rainfall, but that they may leave
after persistent heavy rain. They
followed this up by contacting the Australian Government Bureau of Meteorology
who provided a rainfall map for the three months prior to our sighting
highlighting the areas that were above and below average.
The area from the
Why had Oriental
Pratincoles never been recorded in such numbers before?
The areas of northern Australia where Oriental
Pratincoles occur are largely inaccessible, especially in the wet season.
In normal years, it could be expected that they are very widespread.
It could be possible that much of the population may not normally migrate
all the way to Australia, but perhaps remains spread out across Indonesia or the
Phillippines. We caught 250 Oriental
Pratincoles and only 16 (6%) were aged as juveniles, so the numbers were
not due to an extraordinary breeding season.
We happened to be in the right place at the right time to witness the
event. If we had been there a week
later when the Oriental Pratincoles had moved
further south, we would have missed the event.
A week or two earlier and the birds would not have arrived.
The AWSG is most grateful to John Stoate
of Anna Plains Station for inviting us to work on the station, for providing us
with accommodation and for all that he does to encourage and support our
research, and especially on this occasion for arranging the hire of an aircraft
and finding a volunteer pilot Phil O’Driscoll at extremely short notice.
We thank the Western Australian Department of Conservation of Land
Management (CALM), through the offices of Grant Pearson and Allan Gross,
who paid for the aircraft hire. I personally thank Dr Clive Minton who is
the driving force behind the AWSG expeditions, and all the volunteer expedition
members who made this and every other expedition so successful.
M.J., Watkins, D.G., Bancroft, W. & Tischler, G.
In prep 2003. Migratory Shorebirds of the
East-Asian Australasian Flyway; Population Estimates and Important Sites.
Wetlands International, Oceania.
P.J. & Davies, S.J.J.F. (Eds) 1996. Handbook
of Australian, New Zealand and Antarctic Birds. Vol. 3: Snipe to Pigeons.
Oxford University Press, Melbourne.
R., Drapeau, P. & Goss-Custard, J.D. 1992. The occurrence and adaptive
significance of nocturnal habits in waterfowl. Biol.
Rev. 67: 381-419.
H., Minton, C., Collins, P., Etheridge, B., Hassell, C. & O’Connor, F.
In prep 2004. Extraordinary numbers of Oriental Pratincoles in NW Australia. Wader
Study Group Bull. 103: XX-XX.
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