Bird Detective by Bridget Stutchbury

Author:Bridget Stutchbury [Bridget Stutchbury]
Language: eng
Format: epub
ISBN: 9781443400992
Publisher: HarperCollins Canada

7 EMPTY NEST

Finding a First Home

Eventually, young birds must leave their parents’ territory and find their own breeding territory. In many cases, high-quality territories or territories of any kind are in short supply and young birds attain sexual maturity but cannot breed for lack of resources. One of the first studies to demonstrate the existence of a non-breeding population was conducted in the late 1940s, but the study was originally designed to answer the practical question of how important songbirds are in controlling spruce budworm. This native insect pest periodically breaks out and the larvae defoliate tens of square kilometres of spruce forest. The experiment seemed simple enough, though draconian: shoot all the songbirds in a forest plot and compare the budworm numbers with those in a comparable control plot where none of the birds have been removed. This experiment didn’t work because the dozens of bay-breasted warblers, magnolia warblers, Cape May warblers, and blackburnian warblers that were shot were quickly replaced by young birds looking for a chance to breed.

My first study on birds, when I was an undergraduate student in the mid-1980s, looked at how young tree swallows find their first home. Tree swallows breed in tree cavities and have a delicate beak, so they must use old woodpecker cavities or nest boxes that humans provide. The short supply of cavities makes for fierce competition, and older females, who arrive first in spring, claim almost all the nest sites. First-year females are brown, instead of iridescent blue, and only a small number get to breed.

I was not a birdwatcher as a child, and neither were my parents, but I did love the outdoors, so as a college student I leapt at the opportunity to work outside all summer catching tree swallows and checking their nest boxes. In the spring I helped to set up grids of nest boxes in fields at the Queen’s University Biological Station, near Kingston, Ontario, one of which was soon dubbed “Bridget’s Grid.” My job was to check the nest boxes twice a week to keep track of eggs and nestlings and to catch all the breeding adults. I learned how to take birds out of the mist nets that we placed in front of the nest boxes; there was so much fighting over the boxes that we caught dozens of swallows even though the nets were in the open and usually flapping in the cool May wind.

My favourite trick was feather tossing; male tree swallows will do just about anything for a luxurious downy feather. After installing nest traps that shut when a bird enters, I teased males by tossing up large white feathers that floated enticingly across the field. A male would swoop over and grab the feather in his beak, then, curiously, fly around the field with his gleaming prize to attract attention. Other males were soon in hot pursuit, often stealing the feather from the lead male in mid-air. The high-speed chase could go on for five minutes or more before one of the males finally delivered the feather safely home.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.