Monday, July 27, 2009

Alaska - the nests & chicks

While wandering across the tundra on the hunt for godwit nests we would regularly stumble across nests of other birds. Often this discovery arose following the heart-stopping flush of bird from the nest as we stepped only centimetres away. Ptarmigan often gave the most dramatic flush from the nest. Nest discoveries sometimes proved useful for other researchers in the area at the time, such as those working on Short-eared Owls or Pacific Golden Plovers. The size of a clutch would vary - all Godwit nests we found had 4 eggs, long-tailed Jaegers 2 eggs, but Ptarmigan nests typically had over 10 eggs, the largest I found had 14. There was also a variety of nest type and colouration of eggs. Here's a few examples

Ptarmigan Nest

Godwit Nest

Short-eared Owl Nest

We were also fortunate enough to still be around as the chicks hatched. It was always a delightful sight seeing a chick bumbling its way across the tundra, in the company of the adult or hunkered down on a nest.

Short-eared Owl

Of particular interest was the fact that due to the abundance of voles and lemmings the clutches of some birds, such as Rough-legged hawks, was unusually large. In the photo below you can see a picture of a Rough-legged hawk chick, one of 6 in the nest. According to Ted Swem, a biologist who has been studying rough-legged hawks for 25 years, the typical clutch is 2-3. He had seen only two clutches of 6 in the past 25 years.

Thursday, July 16, 2009

Alaska - the other wildlife

So there's no denying that one of the major perks of being in Alaska was being able to see such amazing wildlife every day we headed out into the field. While the bears stayed at a comfortable distance, I did find myself wishing for a closer encounter (though not too close!). Winning us over the most were the Musk Ox. We saw them every day, with one exception, and delighted in observing them with their young.

Reindeer were a common site in the area and we were told by a local Inupiat how they would round them up using helicoptors and remove their antlers for sale to overseas markets, a valuable source of income for the indigenous communities. The Red Fox we saw were few and far between, but we did encounter depredated nests (why not predated one asks?) which could have fallen victim to a fox visit.

The Arctic ground squirrels were great little companions, popping up in all sorts of places as if to say Hi. I love New Zealand and I love our birds, but I sometimes wish the country had evolved with a few mammals present so we could have our own encounters in the bush, as they really add to the whole experience out there. I'm not sure our introduced possums, deer & pigs cut it I'm afraid. That said, we probably wouldn't have such iconic birds like kiwi, kakapo and takahe had that been the case. I suppose it means I just have to keep travelling!

Alaska - collecting data

During our time in Alaska, the focus was on catching male Godwits, such as this gorgeous male with the most stunning breeding plumage. Unfortunately, despite a number of treks across the tundra to this male's breeding area, we never managed to catch him. He was just too clever.

However, of the ones we did catch we recorded typical data such as mass, bill length, wing length, and plumage details. We also collected feather samples to analyse for melanin content and to score the degree of wear.

Before releasing the birds we would add Aplha numeric flags and metal bands so they can be identified in the future, hopefully this summer back in New Zealand! So keep an eye out for J6, J8, J9, K0, K1, K2, K3 and K4, coming to an estuary near you soon.

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.