Thursday, July 16, 2009

Alaska - the catching

As you can see from the photo below, the Alaskan tundra is a vast expanse of low lying vegetation, pocky mounds, typically moist and below which lies a layer of permafrost. In this vastly different habitat from the inter-tidal mud flats, godwits nest... somewhere. We had to find that somewhere. Our job had four key steps: 1. Find the birds. 2. Find the nest 3. Catch the birds on the nest 4. Process and release the birds. However, both step 1 and 2 required hours upon hours of work each, mixed with a large measure of good luck. Once we had established typical "Godwit habitat", finding the birds became less problematic, but finding breeding birds was always a challenge. We needed birds on the nest to capture because Godwits typically sit tight on the net and don't flush until a person is remarkably close, in fact, in all cases we could lower the net over the bird and it would stay on the nest!

Locating the nest typically involved relying on viewing a nest exchange (where the male swaps with the female to incubate the eggs, or vice versa). Working on the assumption of 12 hour shifts we would observe foraging individuals to work out schedules and predict when an exchange might occur. Sometimes this worked perfectly, other times not at all... maybe the 12 hour shift idea was a good assumption, maybe not? Once the nest was located however, the next steps of catching and processing the bird could be completed within an hour.

The photo above shows Jesse and I taking the net to lower over a Godwit. The photo below is of a female Godwit still on the nest, look carefully and you can see the net at the top of the photo!
Once the eggs had hatched, catching relied on an entirely different approach and involved catching the young chicks briefly so that the parents would swoop in and be caught by a mist net being flicked up with perfect timing. We also tried various other strategies, such as using recorded chick calls and decoys (to little effect mind you). All up we caught 9 Godwits and 3 Red Knots. This might seem like small numbers, but it has been known for people to be out for up to 6 weeks and not catch a single bird on the breeding grounds. They can be very illusive.

1 comment:

Anonymous said...

How much did u catch........??????

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