Northern breeding grounds of Myrtle Warbler discovered

Using isotope fingerprints in feathers, researchers have pinpointed the northern breeding grounds of Myrtle Warblers.

Myrtle Warblers breed across much of Canada and the eastern United States, but winter in two distinct groups—one along the Atlantic and Gulf coasts, another along the US Pacific Coast. They are also one of the few breeds of eastern warbler that have been able to extend their range into the far northwest of the continent.

"The Pacific Coast warblers migrate through the Vancouver area, but it's been a bit of a mystery exactly where they breed over the summer," says David Toews, who began the research while a graduate student at the University of British Columbia (UBC).

So Toews, UBC undergraduate student Julian Heavyside, and UBC professor Darren Irwin used isotope signatures to pinpoint where the Myrtle Warblers breed.

'We were able to match stable hydrogen isotopes in feathers collected in Vancouver to latitudinal isotope records in rainwater, to determine where the feathers were actually grown," says Toews, who conducted the analysis as a postdoctoral researcher at Cornell University.

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