Tiny song bird makes record migration, U of G study proves

By Staff Reporter

Mar 20, 2019 08:07 AM EDT

Blackpoll warbler wearing tiny 'backpack.'

It's an epic journey for a tiny bird.

For the first time, University of Guelph biologists have tracked an annual migration of up to 20,000 kilometres made by the 12-gram blackpoll warbler, one of the fastest declining songbirds in North America.

The bird's trek between its breeding grounds in the central and western boreal forest of North America and its winter home in the Amazon Basin - one of the longest songbird migrations recorded -- is the topic of a new paper by a research team headed by U of G biologist Ryan Norris.

The paper was published today in the journal Ecology.

Describing a "great circle route" arcing across North America and including a transoceanic flight to South America, the study confirms an epic migration journey that scientists had long suspected but not yet proved.

In 2015, Norris and other biologists were the first to show that blackpolls breeding in the Maritimes and New England complete a non-stop transoceanic flight of up to three days and about 2,700 km along the eastern coast of the United States.

For this new study, they looked at the full migration of birds from central and western breeding populations.

"It's amazing," said Norris, who worked on the study with Hilary Cooke, associate conservation scientist with Wildlife Conservation Society Canada. "A bird weighing a couple of loonies travels from the western edge of North America all the way to the Amazon basin - and, in between, traverses the Atlantic Ocean."

Other co-authors were integrative biology professor Amy Newman and U of G grad students Bradley Woodworth, Nikole Freeman and Alex Sutton, as well as researchers from other universities, conservation groups and national parks in Canada, the U.S. and Australia.

For the study, researchers tracked birds outfitted with tiny geolocators from four boreal forest sites across northern Canada and Alaska.

Total southward migration took about 60 days on average over distances ranging from 6,900 km for birds breeding in Churchill, Manitoba, to 10,700 km for populations on the western edge of the continent in Nome, Alaska.

Blackpolls from Nome took 18 days to fly across North America to the Atlantic coast of the Carolinas. There, the birds spent almost a month fattening up to double their body weight before a non-stop, 2 ½-day flight across open water to overwintering grounds in northern Colombia, Venezuela and Brazil.

They covered between 2,250 and 3,400 km for that transoceanic hop.

Continued