Researchers at the University of Illinois have shown through a multi-year study that cowbirds (Molothrus ater) conform to Bateman’s Principle, which holds that reproductive success is greater in males than in females when they have more mates. Cowbirds are distinct from 99% of other bird species in that they are brood parasites and lay their eggs in nests of birds of other species for them to raise. The researchers confirm a 70-year old theory that males in this species are more likely than females to have greater variation in the number of offspring they produce.
Click here for original story, Bateman’s cowbirds: A closer look at monogamy and polygamy in brood parasitic birds
Source: Phys.org