Shiny Cowbird

Overview

The shiny cowbird, Molothrus bonariensis, is a passerine bird in the New World family Icteridae. It is an obligate brood parasite that acts as an effective generalist, often considered the South American counterpart to the brown-headed cowbird.

Identification

• Males are all black with a purple-blue iridescence, while females are smaller with dull brown plumage that may be paler on the underparts.
• Females can be distinguished from the female brown-headed cowbird by their longer, finer bills and flatter heads.
• Sizes range from 18 cm to 22 cm in length, with mass varying between 31 g and 65 g depending on the subspecies.

Habitat

It resides in open habitats across most of South America, avoiding dense forests and high-altitude areas such as mountains. The species prefers disturbed land, including cultivated fields and areas affected by deforestation. Its range has shifted northward in the last century, reaching the Caribbean islands and southern Florida.

Diet

The diet consists mainly of insects, other arthropods, and seeds. They have been recorded foraging for grains in cattle troughs.

Did you know?

The species has spread significantly due to human activity, reaching mainland Puerto Rico in 1955, the Dominican Republic in 1973, and Cuba in 1982. It is implicated in the population decline of the critically endangered pale-headed brush finch by parasitising its nests.