Sometimes it’s tough to find the perfectplace to live, or even a place to live at all. During these times of scant housing, have you ever considered moving into an occupied house? Why not just set up camp in the third floor of someone else’s nice home?
Whitehorse’s Dr. Kathryn Aitken, instructor/coordinator of the BSc in Northern Environmental & Conservation Sciences Program at Yukon College tells me that in the cut-throat world of forest real estate some birds do just that.
“Starlings are not native to Canada but were introduced by Europeans 120 years ago,” says Aitken, “They will build a nest right on top of other birds’ nestlings. Starlings aggressively use pre-existing cavities for nesting.”
Oh, like one of those pre-existing cavities I’ve been looking at on Kijiji? Not exactly. Aitken, who is giving a free talk on November 26 as part of Yukon College’s Brown Bag Lunch Speaker series, explains how cavity houses are created, passed along, and competed for, in the forest.
“Woodpeckers excavate cavities in trees by working at the softer, decaying patches of the tree,” says Aitken. “After the woodpeckers leave their nest in that cavity, other birds and animals nest there or use it for shelter, because they can’t make their own.”
Aitken became “hooked on birds” while studying for her Master’s degree at Simon Fraser University. She has also worked for Canadian Wildlife Service (part of Environment Canada) in the Yukon, and holds her PhD from University of British Columbia, Faculty of Forestry.
Among other things, she studies the nest-web.
“The nest web,” says Aitken, “is a complex set of interactions like a food chain or food web, but is instead centered on nest sites.”
A Yukoner since 2007, Aitken’s Brown Bag Lunch talk will explore the nest-web of cavity-nesting birds such as owls, starlings, woodpeckers, bluebirds, swallows, kestrels, and ducks. Small mammals such as red squirrels, northern flying squirrels, bushy-tailed woodrats, deer mice, and bats also nest in cavities and will be discussed.
“Birds are small and around us all time, which makes them easy to study,” says Aitken, who worked extensively on a survey project near Williams Lake and Riske Creek, B.C. “They are so different from mammals, yet birds have parallels with mammals’ behaviour and evolution. Things like language, dietary behaviours, and hunting [in the bird kingdom] are similar to human behaviour, but were arrived upon through different, but equally complex, evolutionary paths.”
Take for example, the features of a good nesting cavity or house. Aitken has observed that the keys to cavity popularity are similar to things people look for in homes.
“It boils down to how many babies can be produced there,” says Aitken, “At the Williams Lake study site, I wondered why some cavities were used over and over again year after year, and others were not used. The most popular cavities were close to food, were more protected from the elements, and safer from predators.”
The neighbourhood counts too. Aitken is currently studying cavities in the Fox Lake burn.
“Burned areas in the Yukon provide habitat similar to the grassland area I studied in B.C. The stressed and dead trees provides habitat for many species to use like kestrels and mountain tree swallows,” says Aitken.
And speaking of burnt wood, Aitken suggests, “when you are cutting firewood, it’s a good idea to leave trees with pre-exiting cavities uncut.”
Aitken’s Brown Bag Lunch Speaker series talk is entitled, “Cut-throat Competition: How birds and small mammals in our forests manage a real estate crunch” and is on Tuesday November 26 from 12:00 p.m. — 1:00 p.m. in room A2103 at Yukon College, Ayamdigut campus.
For more information about the Brown Bag Lunch Series visit: www.yukoncollege.yk.ca/hub/brownbag.
