By Susan Milius
Warming temperatures in parts of Europe may be knocking the local cuckoos out of sync with some of their usual targets for illicit egg laying.
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Cuckoos swoop in to the nests of other bird species and lay eggs. After hatching, a cuckoo chick kills its foster siblings and hogs the food for itself. In parts of Europe that have warmed since 1990, the common cuckoo, Cuculus canorus, appears to be shifting its targets away from bird species that either don’t migrate or that travel only a relatively short distance each year, says Anders Pape Møller, a researcher for the French national research organization CNRS who is based at the University of Paris South in Orsay. In these zones, an increasing proportion of cuckoo eggs end up in nests of long-distance migrants, Møller and his colleagues report in a paper posted online the week of September 13 in Proceedings of the Royal Society B.
What’s driving the shift, Møller says, is that climate change affects migration patterns differently depending on their scope. Cuckoos themselves migrate all the way from Europe to sub-Saharan Africa for the winter. By the time they return in spring, early warming has already pushed the year-round residents and short-distance migrants too far along in their nesting to be good cuckoo targets.