Wednesday, August 4, 2010

The Hudsonian Godwits of Churchill

After all of the posts about Churchill that I've written, I realized that I've written very little about the bird that has taken me here for the past two summers: the Hudsonian Godwit, Limosa haemastica. The Hudsonian Godwit is a mid to large sized shorebird, and is a well known long-distance migrant. The godwits' breeding distribution is still not entirely understood, but is known to be found in isolated pockets across the sub-arctic and arctic of Canada and Alaska. They typically breed in fens, bogs, and marshes with abundant sedge cover as well as a few trees (such as Larch, Larix laricina and spruces, Picea sp.) and shrubs (in Churchill, mostly Dwarf Birch, Betula glandulosa). Hudsonian Godwits are particularly famous for their long-distance migration, which takes the birds from Churchill first to staging grounds around James Bay. From there, many godwits make a direct flight from James Bay south to South America, perhaps stopping off for a day or two somewhere in the Amazon before finally making it to the southern coast of Argentina and Tierra del Fuego. Godwits that breed in Alaska winter mostly on the island of Chiloe. On the northward journey, godwits again make very long flights, some flying all the way from Argentina to Texas and Nebraska before stopping.

In Churchill, godwits typically return to the area sometime between May 20 and May 25, however there can be variation in this depending on local conditions. For example, the first godwits in 2009 did not show up until June 3, and even then were restricted to a limited number of locations due to snow conditions. In a typical year, after the birds arrive, males usually spend almost a week establishing territories and displaying. Its during this period when we start walking through the breeding grounds, looking for returning birds from previous years, and getting an idea of where territories are so we know where to look for nests.

Upon arrival, godwits will hang around, perhaps going to areas where they will later breed. In these pictures, a female Hudsonian Godwit is loafing around the Fen with a Short-billed Dowitcher

In addition to inspecting the breeding grounds, godwits also spend a lot of time feeding when they first arrive. Often they will feed in areas close to their future territories. This male, feeding in a roadside pool, later nested about 300 meters away in the marsh.

During the first week or so after arrival, male godwits spend a lot of time displaying and setting up territories. This male, banded 2 years ago is seen here displaying in the top of a tree. The display flight of godwits consist of a slow, "butterfly-like" flight over their territories, calling consistently "god-wit, god-wit, god-wit."

Beginning sometime during the first week of June, godwits will begin nesting. During the summer of 2008, the first nest was found June 5, while this year, the first nest was found June 8. In any particular year, most nesting is fairly synchronous, and within about a week, most birds that are nesting will be on eggs. Incubation of eggs does not begin full time until a full clutch (usually of 4) is laid, although males will incubate sporadically even when two eggs are laid. Males incubate for the entire day after the last egg is laid, while females feed. After that first day, males and females share incubation tasks, with females typically incubating during the day, and males incubating at night (although there is considerable variation in this schedule).

A Hudsonian Godwit nest with a full clutch of 4 eggs. While 4 eggs is the maximum clutch size, and also the most typical, complete clutches of 3, and occasionally 2 eggs are also laid. If a godwit renests after losing the eggs to a predator, the replacement clutch is more frequently smaller.

Female Hudsonian Godwit incubating eggs. Godwits are very reluctant to flush from their nest, which can make nests particularly difficult to find. Their cryptic coloration allows them to hide incredibly well among the sedges.

Female godwit sitting very tight on her nest.

After about 17 or so days of incubation, the eggs begin to get star cracks, which are the first signs of hatching. The appearance of star cracks usually indicate that the eggs are within 3 or 4 days of hatch. The day before hatch, the chicks begin to pip the eggs, making small holes in the wider end of the egg. Hatching of all the eggs occurs on the same day, although there can be several hours delay between the first and last chick hatching. Oftentimes, the first chicks to hatch will disperse from the nest site by the time the last chick hatches. During this entire period, both adults stay very close to the nest, and incubating birds sit very tight on the nest, and are very reluctant to flush from the nest. Since chicks leave the nest only a couple of hours after hatch, it is very important for us to get to the nest at hatch if we want to band all the chicks. Otherwise, it can be very, very difficult to find all of the chicks of a brood once they have dispersed.

A godwit nest that is getting very close to hatching. If you look closely, all the eggs have fine "star-cracks" around the wide end of the egg.

A detail of "star-cracks" on an egg.

A godwit chick in the final stages of hatching. This particular chick hatched right in front of us while we were banding his siblings, which had already hatched. It was quite incredible.

Recently hatched godwit chick, this bird is still not completely dry.

Hudsonian Godwit chick that is less than one day old. It's difficult to see, but this chick has a tiny radio transmitter on his back, which we use to track them as they grow. This allows us to determine what habitats they use to feed in, how far they wander, and also check survival.

When chicks are very young, the parent godwits are very aggressive. This pair was constantly attacking us and yelling at us while we were banding their newly hatched chicks. Notice the white flags on the legs of each of these birds, as well as a plastic color band beneath the flag. The orange color band on the male indicates that he was first banded in 2009, while the blue color band indicates this female was banded this year. Also note the brightness of this female, compared with the female pictured in the first 2 pictures of the post.

Male Hudsonian Godwit brooding his recently hatched chicks while we finish banding the last of the brood.

After hatch, chicks and adults wander very far from the original territory. Just three days after hatching, we tracked one family over 2 kilometers from the original nest site. Parents stay with the chicks until they can fly, which is about 24 days after hatching. Females may leave before the chicks are fledged, but males stay with the chicks. Parents will defend their chicks vigorously against predators, and will brood them for the first several days after hatching, but do not feed them.

A godwit chick that is about 2 weeks old. Notice the wing feathers which are in pin, and the back feathers which have come in on this bird.

A 3-week old godwit chick. Notice the wing feathers are growing in nicely, and have already started breaking out of their sheaths. This is likely the latest age that we can capture godwit chicks, since after this they run too fast.

A 3-week old godwit chick running away from us after we banded it. In another 5 days, this godwit chick will be able to fly. At 26 days after hatching, godwit chicks are able to fledge. It is at this point when the adults leave the chicks.

After fledging at about 26 days after hatch, godwit chicks are completely on their own. Adult birds leave the chicks once they have fledged. Adults will continue to the staging grounds around James Bay, and the chicks will remain around Churchill for a little while longer before continuing to James Bay. If all goes well, 2 years from now, we will see "EC" return to Churchill. Young birds will spend their first "summer" on the non-breeding grounds in South America.

To see pictures of Hudsonian Godwits on their winter grounds in South America, see my posts from Chile, where I was able to see and catch some godwits.


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  2. and my email is Astrid Kant