Bronzed Cowbird

The bronzed cowbird, Molothrus aeneus, is a small member of the Icteridae family, known for its distinctive glossy plumage and brood parasitic behaviour. The male is particularly striking with his green-bronze, gloss-black feathers and, during the breeding season, his eyes turn a vivid red, reverting to brown at other times. The female is more subdued in coloration, presenting a dull black with a brown underbelly and maintaining brown eyes throughout the year. Juveniles resemble the female but can be distinguished by grey feather fringes.

Identification Tips

To identify the bronzed cowbird, look for the male's shimmering green-bronze plumage and red eyes during the breeding season. Females and young birds are less conspicuous but can be recognized by their duller black and brown colouring. The male measures about 20 cm in length and weighs 68 g, while the female is slightly smaller at 18.5 cm and 56 g.

Habitat

Bronzed cowbirds are typically found in farmland, brush, and feedlots. They adapt to very open habitats outside the breeding season and roost in dense woodland areas.

Distribution

These birds breed across a range that includes the U.S. states of California, Arizona, New Mexico, Texas, and Louisiana, extending south through Central America to Panama.

Breeding

The bronzed cowbird is an obligate brood parasite, laying its eggs in the nests of unsuspecting host species, such as Prevost's ground-sparrows and white-naped brush finches. The host parents then raise the cowbird chick, often at the expense of their own offspring.The cowbird chicks grow rapidly and typically leave the nest within 10 to 12 days.

Similar Species

The bronze-brown cowbird, found on the Caribbean coast of Colombia, was once considered an isolated population of the bronzed cowbird but is now recognized as a separate species.

Diet and Feeding

The diet of the bronzed cowbird primarily consists of seeds and insects. During the breeding season, they also consume snails as a source of calcium.

Conservation status

The bronzed cowbird is currently listed as Least Concern on the IUCN Red List, indicating that it is not at immediate risk of population decline or extinction.