New World Blackbirds and Orioles: Icteridae

Blackbirds build their bowl-shaped nests in shrubs, trees, and reeds, with the exception of a few species that live in vegetation-free areas that build nests in rock crevices. Orioles build orb-shaped nests constructed of grasses that hang down from a tree branch. One species of Icteridae, the baybird, takes over abandoned nests of other birds. Others are parasitic, meaning that they lay their eggs in another bird's nests for the nest-owner to hatch and fledge, when the young bird is ready to fly on its own.

Depending on the species, male blackbirds have anywhere from one to up to fifteen female mates. Often those male birds that are polygynous (puh-LIJ-uh-nus; have more than one mate) live with a bird population that is mostly female.