30 December, 2008

Broome W. A.

I recently made a trip to Broome in Western Australia to help in the count of shorebirds. South of Broome lies Roebuck Bay and 80 Mile Beach, two of the most important shorebird habitats in Australia. Our team was comprised of 26 people,mostly volunteers.
It was at 80 Mile Beach that it was realised that the population of Oriental Pratincole was greater than the estimated 700 000 when 2.88 million of the birds turned up one year. We did not see that number but they are the dominant bird in the foreground. As the tide comes in it forces the birds into small groups along the shore. This makes counting easier than when they are dispersed across the mudflats. The difficulty lies in the dense flocks hiding smaller birds. At the site above I missed 96% of the Sanderlings on the first count. When the tide receded the birds spread out a little and we could recount. This produced higher numbers of all the smaller birds. We were glad that the bigger bird counts were the same; it boosted our confidence. The aim is to count each bird once.Hundreds of thousands of waders leave the muddy flats of Roebuck Bay as the 8 metre tides flood the rich muds. They roost on sandy beaches, rocky headlands and even behind the mangroves.
Some areas such as Gordon Bay had not been surveyed before while the well known and richer sites are counted twice a year.
Sometimes an onshore wind increases the height of the tide in this wide shallow bay. This makes prediction of roosting sites difficult and this flock is getting away. A quick count of the overall numbers and a rough allocation of proportions was all that could be done and then hope we can find then elsewhere.
I learnt a lot about identification of not only waders but tern subspecies. The Gull-billed Tern above comes from Asia.
We had workshops and this excursion to a freshwater wetland acted as a training session.
I was pleasantly surprised that most of our counts came in within 5-10% of the median figure but each of us had the odd count which was way off the mark. Except for missidentification the miscount was always under the true total. The birds move, they hide and some come in while others leave.
We had professionals and amateurs from China, Korea and Australia. The Koreans and Chinese were most interested to see where "their" birds go during the northern winter. All of us are most concerned about where our birds will feed between their southern feeding grounds in Australia and their breeding areas in Siberia and Alaska. Wetlands around the Yellow Sea are being "reclaimed" to produce industrial and commercial land. This has already put hundreds of fishermen out of work and is robbing the birds of their staging posts during their long migration.
Once the data are collected it is necessary to enter and store it for later analysis. These experienced counters could manage four plus species at once and still handle totals in the thousands.
Two kilometres is not very far to walk but...
through soft sand...in forty-two degrees (in what shade?) and with lots of flies...
it is thirsty, tiring work.With a little protection, some good management and the nations of the East Asian, Australasian flyway honouring the agreements they have signed, generations to come will also be able to enjoy the wonders of thousands of shorebirds wheeling through the sky: seeing the flocks turn from grey to white as they alter direction and observe the colours of the birds change as they develop their bright breeding plumage.

1 comment:

James said...

It would be very awseome and spectacular to observe waders in such large numbers. Enjoyed this blog entry, thanks for sharing!