Massive southern invasions by northern birds linked to climate shifts

[PhysOrg]

With puzzling variability, vast numbers of birds from Canada's boreal forests migrate hundreds or thousands of miles south from their usual winter range. These so-called irruptions were first noticed by birdwatchers decades ago, but the driving factors have never been fully explained. Now scientists have pinpointed the climate pattern that likely sets the stage for irruptions - a discovery that could make it possible to predict the events more than a year in advance.

 

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