Avian clutch size

One of the most consistent patterns in avian reproduction is the relationship between latitude and clutch size. Clutch size refers to the number of eggs laid in a single nesting. David Lack, an ornithologist and evolutionary biologist, was one of the first scientists to thoroughly investigate the effect of latitude on the number of eggs per nest. Since Lack’s first paper in the mid-1940s, an extensive amount of research has been performed in this area. Most avian species show the same pattern of clutch size in relation to latitude. This unique pattern is apparent among and within avian species. Typically, the avian clutch size geographic gradient is a robust pattern that depicts increased clutch sizes with increased latitude.