Each year, songbirds head south for warmer climates, some of them travelling up to 15,000 kilometres. And yet, every spring, they return home — sometimes even to the same tree.

A new study from the University of British Columbia's Department of Zoology has identified a small cluster of genes that could be responsible for this epic journey.

"They undergo one of the most iconic migrations of all the organisms that migrate — because some of them are really small, like under 20 grams," said Kira Delmore, lead researcher on the project.

Migrate alone and at night

Delmore's team studied the Swainson's Thrush — a bird commonly found in British Columbia.

The birds were outfitted with 'light level geolocators', which Delmore described as tiny "backpacks" which measure the amount of light every 10 minutes, allowing the researchers to determine latitude and longitude.

Geolocator on swainson's thrush

A Swainson's Thrush wearing a geolocator — a device that measures the amount of light during the day in 10-minute intervals. The backpacks weigh about one gram, and the bird weighs about 30 grams. (Kira Delmore/UBC)

The results suggest the songbirds migrate alone and at night, which Delmore said is key to supporting the idea that the birds' migration patterns are genetic.

"We know that it's genetically determined because it's not like they're flying with mom and dad," she explained.

Tiny region of DNA

Delmore's team was able to narrow in and map the exact section of DNA that controls songbird migration.

"We know the timing of migration is strongly linked to changes in daylight. So this could suggest that this behaviour is associated with genes that are controlling circadian rhythm," she said.

Swainson's thrush migratory routes

Delmore's research found that in British Columbia, birds from the Vancouver area travel directly south, while birds from the interior travel in a more easterly direction. (Boreal Songbird Initiative)

Delmore said scientists can begin to understand other species — such as salmon, for example.

In fact, Delmore's team mapped a gene in the Swainson Thrush that was similar to one found in the rainbow trout.

"That's really fantastic that such disparate groups of animals could have migration controlled by the same gene," she said.

With files from The Early Edition.


To listen to the audio, click on the link labelled UBC study finds small handful of genes control direction and route of songbird migration