April 27, 2013

Wild populations of great tits and earlier springs




One of the many changes that results from global warming is a shift to earlier springs - something that has led many biologists to worry what will happen to populations that have adapted to specific events with precise timing when that timing shifts.

Bernt-Erik Sæther, an NTNU biologist and director of the university's Centre for Biodiversity Dynamics, was a co-author on a paper published Friday, 26 April in Science magazine that explores this problem.

Earlier springs have caused caterpillars to hatch and grow earlier than they used to. But great tits, which catch caterpillars to feed their young, have not been able to advance their timing of egg-laying to keep pace with the caterpillars.  This has caused an increasing mismatch between the peak availability of caterpillars and the hatching of baby great tits, which has caused early offspring survival in great tits to decline.