Monday, November 26, 2007

Australia - Roebuck Bay and Broome Bird Observatory, WA, January 14, 2007

Hermit crabs are plentiful on Roebuck Bay

Over the last two days we made two catches of over 300 birds each. On each catch the skill of both Chris and Clive, and the growing capability of the team, helped to make well executed and safe catches. Yesterday we made a catch of 378 birds including Red-necked Stint, Great Knot, Red Knot, Oriental Plover, Bar-tailed Godwit, Greater and Lesser Sand Plovers, Curlew Sandpiper, Terek Sandpiper, and Broad-billed Sandpiper. I was especially grateful to work with Frank O’Connor on Terek Sandpipers, a species I had never seen let alone handled and banded. The technique was similar to the first day, a net set high just above the high tide line and a second several meters down-beach meant to catch birds two hours before high tide. In this, our second catch at Roebuck Bay we caught on the low net; on the third catch we caught on the high net.

A net set on Roebuck Bay beach (the three cannons and net are just visible on the beach as three sandy "lumps" and a mildly-disturbed area just right of the lumps in the foreground)

The latter catch (our third) was thwarted by all that could go wrong. At first, we had a nice potential catch of Grey-tailed Tattlers and Ruddy Turnstones, a rarity that would improve species coverage. Frank O’Connor, Nik Ward, and Naoko Takeuchi, operating on beaches as far as 2 km away, slowly moved (or “twinkled”) the birds to the net position; when close to firing, an Osprey flew low over the beach and landed right in the catch area flushing birds in all directions. The advancing tide forced us to rescue the low net necessitating a switch to the high net. After some quick-but-judicious twinkling we soon had birds in front of the net only to see a young aboriginal boy, fishing with his father, walk over to the flock chasing it away.

Still we persisted and, after a short problem with Brahminy Kites, we once again had about 400 birds in front of the net. This time Pete Collins occupied the young boy, we fired and made a good catch of Bar-tailed Godwits, Great Knots, Red Kots, Red-necked Stints, Greater and Lesser Sand Plovers, Red-capped Plover and Curlew Sandpiper.

Two Brahminy Kites looking over the birds in front of the net

Although one would have to be impressed by the skill of the leaders and the group during the entire process, the real expertise comes after the catch. Envisage a heat so great that you could actually fry eggs on a rock, a soft wind that feels cooling actually drains you of all your liquids so much so that you don’t pee all day despite drinking gallons of water. Now imagine hundreds of birds struggling under the net under the searing tropical sun. On any catch one must be concerned with the usual problems: safety of the birds from the powerful leading edge of the net, a “wet catch” where birds are captured at the tide edge and could drown if not quickly secured, birds escaping from an improperly secured net, birds suffering stress because of slow post-catch handling or covering. Here at Broome, you still have those difficulties, but the greatest threat for human and bird is the heat. Over the last 30 years Clive, and more recently Chris, have developed strategies and methods to prevent problems, many of which we have copied on Delaware Bay. With experience, it looks like a well-choreographed dance. As soon as the net is fired, the team races to the front (or seaward side) of the net. With the leaders at the back (or beach side) of the net barking instructions, the team – shoulder-to-shoulder -- uses their arms like a long, linear fork lift to swiftly move the net up and away from the tide. With a small-mesh net, birds do not become entangled, and the team lifts (or “tents”) the net so the birds can run up-beach toward the back of the net. Then a large shade cloth, like that used to shade greenhouses, is spread over the birds and net -- the immediate effect is to first calm the birds and then shade them from the sun.

Holly Sitters, Assistant Warden at the Broome Bird Observatory, transporting Red-necked Stints to keeping cages

While this is happening, a smaller group erects keeping cages of coarse cloth that are high enough to allow easy movement of taller birds, like godwits or curlews, and are well-ventilated to allow the body heat of the birds inside to be dissipated. The team then extracts all birds and places them in separate compartments according to species. Within minutes of securing the catch in keeping cages, Chris directs the team to cover all the cages with shade cloth. Immediately afterward, the team erects shade tents that will shade both the keeping cages and the team during processing. This whole procedure is usually complete in 30 to 40 minutes. By the time processing (banding, weighing, measuring) occurs the birds have preened and are cooler than if they were roosting on the beach. Processing can then take place without hurry and with the care and precision necessary for good science to occur.

The keeping cages are first covered with shade cloth . . . .

. . . .then a shelter of shade cloth is erected to cover the keeping cages and crew

Chris Hassell measures head and bill of an individually color-marked Bar-tailed Godwit -- a new bird for his ongoing research

Yahkat Barshep from Nigeria, a Ph.D. Student at the University of Cape Town, South Africa, and David Melville of New Zealand processing Great Knots

Peter Jenkins weighing a Red Knot

We were grateful to Chris and Maylee for taking us to Lake Eda for an early-morning field trip. The lake is one of few freshwater habitats and so attracts thousands of shorebirds, waterbirds, waterfowl, and raptors. We were also grateful to both Clive for his lecture on on Australia-Asia migration range mapping and to Dick Holmes for a talk on shorebird breeding ecology.

Nailed-tailed Wallaby near Lake Eda

Australian Pratincole at Lake Eda

Dick Holmes presenting an evening lecture on the evolution of shorebird breeding behavior


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