Quirks and Quarks

Late birds are missing the worm

Climate change is shifting songbirds' northerly flight times, but some of them are missing the window.
As climate change has shifted spring, certain bird species like the yellow-billed cuckoo, aren't able to adjust. (Andy Reago & Chrissy McClarren)

When songbirds return from their southern wintering grounds to North America, they're aiming for the "green-up," when flowers and leaves are blooming, and their insect food is at its most plentiful. Climate change, however, has been shifting the timing of spring green-up. 

In a study of 48 species of North American songbirds, Canadian biologist Stephen Mayor from the University of Florida combed through data gathered by ornithologist "citizen scientists" on when birds have been returning. What he found was that while some species are pretty good at moving their migration times to track the changing time of spring, nine of the species he studied were having a lot of trouble – missing it by nearly two weeks.

This could have important impacts on their nesting and reproductive success, and also the services they provide for humans, like spring insect control. 

Paper in Nature Scientific ReportsIncreasing phenological asynchrony between spring green-up and arrival of migratory birds

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These nine species of migratory birds are not adjusting to spring's shifting start date, possibly threatening their survival. (Elecia Crumpton, University of Florida)