A winter thrush rush from Kamloops to Central America
Birds of a feather might not always flock together after all.
That’s what a University of B.C. researcher discovered after studying data collected from a Kamloops-specific group of songbird.
Kira Delmore, a PhD student in zoology at UBC, attached 38 “backpacks” to birds in two groups of Swainson’s thrushes — a medium-sized songbird found in forested areas across North America.
One group was in the Vancouver area; the other in and around Kamloops.
“We wanted to see whether these two groups are taking different routes to get to their wintering grounds,” Delmore told KTW, explaining the birds spend the cold months in Central America.
“And, we found these guys really were taking very different routes.”
Not only that, they also fly solo.
Delmore said thrushes fly alone and at night, unlike other birds that migrate in groups.
While the Lower Mainland birds flew south along the Pacific Coast, following the water to their winter hangout, the heartier Interior thrushes took a route east over the Rocky Mountains and south, stopping in Alabama before crossing the Gulf of Mexico and heading to Central America.
That determination — something Delmore said had already been a common belief among zoologists — was just the first part of the research, though.
Now, she’s looking at a “hybrid-zone” group of Swainson’s thrushes west of Kamloops, where the two groups have been interbreeding and creating a new group.
“The routes the birds are taking are genetically determined,” she said.
“They’re not getting help from their friends. So, this hybrid group, rather than going east or south, we think maybe they’ll go somewhere in between.”
That in-between route might be over the Cascade Mountains, Delmore said.
And, it won’t be long before she knows for sure.
“We have the data back and I’m just in the middle of analyzing it,” she said.
“Hopefully, we’ll know within a few months.”
Delmore said the information will be passed on to conservation officials along the birds’ routes.
For instance, she said, authorities in Alabama will be notified about the pit stop the Kamloops thrushes make, with the goal of having the data considered when new conservancy projects are planned.
How do you get backpacks on little birds? Very carefully . . .
Fitting locator units on birds that weigh between an ounce and 1.5 ounces is no easy task, Delmore said, so researchers had to think outside the box.
Swainson’s thrushes, she said, are not big enough to support a GPS unit.
Instead, researchers fastened tiny light-detecting geo-locators to the birds’ backs.
“It measures the intensity of the light,” Delmore said.
“Basically, it tells us how long the day was and when noon was.
“From there, we can determine longitude and latitude.”