Sex ratio and egg size manipulation

Abstract

Abstract In this chapter we will look at the ability of harriers and other raptors to manipulate the number of sons and daughters they produce (sex ratio manipulation) and determine whether harriers can adaptively change the size of the eggs they lay. Both are relatively controversial topics because there is presently no known mechanism for females to alter the sex ratio of their eggs-but growing evidence that they can do so—and little experimental evidence that birds can adaptively change the size of the eggs they produce in relation to changing environmental conditions.