Birds in California are laying eggs earlier in the spring to cope with climate change.
Species can respond to climate change either by shifting their geographical range or by changing the timing of life events. To determine how birds are reacting to a warming world, Jacob Socolar at the University of Connecticut in Storrs and his colleagues analysed historical data on bird sightings that correlate with both breeding and nesting. The team found that the state’s birds have moved their breeding window up by an average of about one week over the past century. The shift in timing reduced the average temperature during nesting by about 1 °C — roughly the same amount that temperatures rose over the study period.
By breeding earlier, birds can continue to nest at an ideal temperature range without having to relocate.