About Molothrus aeneus (Wagler, 1829)
Description: Male bronzed cowbirds measure 20 cm (7.9 in) in length and weigh 68 g (2.4 oz), with glossy green-bronze black plumage. Their eyes turn red during the breeding season, and are brown at other times of year. Females are 18.5 cm (7.3 in) long and weigh 56 g (2.0 oz), with dull black plumage, a brown underbelly, and brown eyes. Juvenile birds have similar coloration to females, but differ by having grey fringes on their feathers.
Distribution and habitat: Their breeding range extends from the U.S. states of California, Arizona, New Mexico, Texas, and Louisiana south through Central America to Panama. They are most commonly found in farmland, brush, and feedlots. Outside of the breeding season, they occupy very open habitats and roost in thick woodland. They forage in open areas, often near cattle in pastures. Their diet is made up mostly of seeds and insects; during breeding season they also eat snails to obtain calcium.
Ecology: Like all cowbirds, the bronzed cowbird is an obligate brood parasite. It lays its eggs in the nests of other bird species, and host parents feed the young cowbird at the cost of their own offspring. Documented host species include Prevost's ground-sparrows and white-naped brush finches. Bronzed cowbird chicks develop rapidly and leave the host nest 10 to 12 days after hatching.
