Euphagus is a small genus of New World blackbirds. It contains two North American species, the Brewer's blackbird, Euphagus cyanocephalus, and the rusty blackbird E. carolinus. Both species are migratory, wintering in the southern United States and Mexico, although some Brewer's blackbirds are present all year in the western US. A prehistoric relative, Euphagus magnirostris, is known from Late Pleistocene fossils found in the famous tar seeps of Rancho La Brea, California. They build cup nests, and the female alone incubates the eggs. They are gregarious outside the breeding season.