The temperature difference between summer and winter plays a significant role in the egg clutch size of birds - Publication in PLoS Biology

09.12.2008

The world is home to about 9,700 bird species. Some of them lay ten eggs in their nest, while others lay only one. Scientists from the Johannes Gutenberg University Mainz, the University of California at San Diego and Stanford University have used a novel approach to investigate which factors are decisive for clutch size, thus presenting the first global analysis of the clutch sizes of birds. "We have found a clear north/south divide," reported Professor Dr. Katrin Böhning-Gaese of the Institute for Zoology at Mainz University. "In northern latitudes, the birds lay more eggs, while in the tropics they lay fewer eggs." The decisive reason for the different clutch sizes, according to the scientists, is the difference in temperature between summer and winter and the associated consequences for the life of the birds.