Evolution of clutch size in birds: Adaptive variation in relation to territory quality

Abstract

Reproductive output from enlarged or reduced magpie broods showed that each female generally lays a clutch of optimal size. This size varies considerably between females. Approximately 85 percent of the within-years variation in clutch size was associated with differences between territories. Colonial bird species, lacking individual foraging territories, have a smaller clutch size variation than territorial species. Copyright © 1980 AAAS.