<trp-post-container data-trp-post-id='359845'>Bronzed Cowbird

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Migratrice
  • Scientific Name: Molothrus aeneus
  • Spanish Name: Tordo bronceado
  • Family: Icteridae
  • Known Nicknames: Red-eyed Cowbird, Bronze Cowbird
  • Average Length: 18–22 cm / 7–8.7 in
  • Average Weight: 45–70 g / 1.6–2.5 oz
  • Wingspan: 30–36 cm / 12–14 in
  • Key Feature: Male has iridescent bronze-black plumage and bright red eyes
  • Primary Diet: Primarily Granivore and Insectivore
  • Range: Southern United States (Texas) through Mexico and Central America to Panama
  • Habitat: Open woodlands, scrub, agricultural areas, and forest edges
  • Social Structure: Highly Social, often in flocks
  • Nesting/Breeding: Brood parasite; lays eggs in nests of other bird species
  • Statut de conservation : Préoccupation mineure (LC)
  • Évolution démographique : Stable

The Bronzed Cowbird (*Molothrus aeneus*) is a sleek, iridescent brood parasite of the American tropics, distinguished by its glossy, metallic bronze-black plumage that shimmers with hints of green and purple in sunlight. Males are larger than females, with striking red eyes and a thick, conical bill, while females are a duller brownish-gray with a faint eye ring. Its most unique characteristic is its reproductive strategy: like other cowbirds, it lays its eggs in the nests of other bird species—often orioles or flycatchers—leaving the unwitting hosts to raise its young. A special feature is the male’s elaborate, low-pitched courtship song, a gurgling series of notes accompanied by a dramatic wing-flutter display, making it a subtle but captivating presence in open woodlands and agricultural areas from the southwestern U.S. to Panama.

Faits amusants

The Bronzed Cowbird is a master of "brood parasitism," laying its eggs in the nests of other birds—often orioles or mockingbirds—and leaving the unsuspecting foster parents to raise its oversized, fast-growing chicks. Unlike the Brown-headed Cowbird, the male Bronzed Cowbird has a bizarre courtship display where he puffs out his neck feathers into a spiky ruff, points his bill skyward, and emits a low, gurgling "glug" sound that resembles a liquid bubble popping. They are also surprisingly social, gathering in large, noisy flocks that sometimes follow cattle to snatch insects flushed from the grass, but they’ve been observed using a unique trick: perching on the backs of cows to pick ticks directly off the hide. Their iridescent, bronze-green plumage can look almost black in shade but flashes metallic purple and green in direct sunlight, making them one of the most visually deceptive members of the blackbird family.

Habitats et répartition

The Bronzed Cowbird inhabits open and semi-open environments, including scrublands, savannas, pastures, agricultural fields, riparian woodlands, and forest edges. It is commonly found near water sources and often associates with livestock, as it forages on the ground for seeds and insects among grazing animals. Its distribution spans from the southern United States through Mexico and Central America into northern South America, including Colombia and Venezuela. In the U.S., it is primarily resident in southern Texas and has expanded into parts of Arizona, New Mexico, and Louisiana, favoring lowland areas up to moderate elevations.

Comportements & Reproduction

The bronzed cowbird is a brood parasite, meaning it lays its eggs in the nests of other bird species, such as orioles and mockingbirds, to offload all parental care. Its social structure is loose and often nomadic, with males establishing temporary display areas called "arenas" where they perform elaborate bowing and wing-spreading rituals to attract females. Mating is promiscuous; a single male may mate with multiple females, and females often visit several male arenas before laying. A unique reproductive strategy involves the female cowbird monitoring potential host nests closely, sometimes removing or puncturing a host egg before depositing her own. This ensures her chick, which hatches quickly and grows aggressively, outcompetes the host’s offspring for food, often ejecting them from the nest. The cowbird’s parasitic behavior is so specialized that females can lay up to 40 eggs per breeding season, each in a different host nest.

Alimentation

The Bronzed Cowbird is primarily a granivore, with seeds—especially those of grasses and crops like sorghum and corn—making up the bulk of its diet. However, it is highly opportunistic and will readily consume insects, such as beetles, grasshoppers, and caterpillars, particularly during breeding season when protein is essential for egg production and chick growth. A fascinating aspect of its feeding behavior is its strong association with livestock: it frequently forages on the ground near cattle, horses, and other large mammals, catching insects flushed by their movement and even picking ticks and other parasites directly from the animals’ hides. Additionally, Bronzed Cowbirds are known to raid bird feeders for sunflower seeds and cracked corn, and they occasionally eat small fruits and berries, showcasing their adaptability to both natural and human-altered environments.

Couleurs

The male Bronzed Cowbird has glossy, iridescent black plumage with a bronze-green sheen on the wings, back, and tail, while the female is a uniform dull gray-brown with a paler throat and faint streaking on the underparts. Both sexes have a stout, conical bill and red eyes, with males showing a slight neck ruff during breeding. No camouflage adaptations are present; the male’s metallic sheen is a display trait, while the female’s drab color provides basic concealment in open habitats.

Distribution Map

Places linked to this species. A sighting is never guaranteed.