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Archived Postings

June 25, 2007 – July 1, 2007

The end of June marks the mid-way point of the Monitoring Avian Productivity and Survivorship (MAPS) program. We have now visited each MAPS site three times and have banded 144 birds, which is a respectable banding total. American redstarts, white-throated sparrows, Tennessee warblers, and ovenbirds have been the top banded species so far in the MAPS banding. A Blackburnian warbler was heard singing at one of the banding sites, but he was high up in a spruce tree so we couldn’t catch him. Slave Lake is at the very western tip of the Blackburnian warblers breeding range; it would have been a great catch. Only two juvenile birds have been banded so far: a hermit thrush and a winter wren. We have seen the signs that indicate that many more young birds are on their way. Quite a few adults have been observed carrying food to their chicks and all of the young from the Canada warbler nests we have found and have been monitoring have fledged. Soon there will be hatch-year birds everywhere and banding will become quite busy. Adult birds will continue feeding their young until they are capable of foraging for themselves. Once the young are well on their way to becoming independent, the adults have the energy to begin their prebasic moult. This moult occurs before they begin fall migration and involves replacing all body and flight feathers. Old feathers are dropped which frees the follicle allowing the new feather to grow in. The prebasic moult goes through stages, a few feathers are replaced at a time, and takes a few weeks to complete. If the birds lost all of their feathers at once, they would lose the ability to fly and would look rather ridiculous. Some of the birds we have banded are already in the mid-stages of their prebasic moult. These birds have either had a nest that failed or is a floater. Floaters are individuals that migrated all the way up here with the intent to breed, but were unable to find a mate. They have spent their summer roaming the forest without a territory, a nest, or young. Without young to care for, they have the energy to begin their moult earlier and prepare for fall migration. Just think of floaters as the ones who leave the party early because they can’t find anyone to dance with. American redstarts are frequently encountered floaters. American redstarts have a moult strategy which puts the first year breeding males at a distinct disadvantage in attracting a mate. Males do not obtain their striking breeding plumage until their second breeding year. A male in its first year breeding plumage more closely resembles a female. Plumage colouration is critical because the bright plumage is a sign of good genes which attracts the females. But females are not just superficial when it comes to mate selection, there are other factors involved that makes the mating system a complicated matter. For instance, females will find a male who is able to claim and defend a suitable breeding habitat. The male American redstarts who were unable to breed this season can rest easy. When they return to breed next summer they will be a little older, a little wiser, and will finally have that stunning plumage that will improve their chances of impressing a girl.

2010