The brown-headed cowbird is a widespread bird in North America, often seen in open habitats like fields and suburban areas. This article describes their key identifying features, highlights differences between sexes and ages, and discusses common look-alikes.
Key Identifying Features
Adult male brown-headed cowbirds are identifiable by their distinct coloration and compact body shape. These small blackbirds typically measure 6 to 8 inches (15-22 cm) in length, with a wingspan averaging around 14 inches (36 cm). They have a stocky build, characterized by a shorter tail and a thicker head compared to other blackbird species.
The adult male’s plumage is glossy black across the body, often with iridescent green or bluish highlights. Their rich, chocolate-brown head contrasts sharply, though it can appear entirely black from a distance or in poor light. Their bill is short, conical, and thick at the base, resembling a finch’s bill rather than the longer, more slender bills of many other blackbirds. Dark eyes and black legs complete their appearance.
Differences Between Sexes and Ages
Female brown-headed cowbirds appear notably different from males. They are slightly smaller, typically ranging from 6.3 to 7.9 inches (16-20 cm) in length. Their plumage is a plain, dull grayish-brown overall, lacking the glossy black body and distinct brown head of the male.
Females may show faint streaking on their belly and underparts, with a paler throat and sometimes a pale eyebrow. Juvenile cowbirds generally resemble adult females but are often lighter and more heavily streaked, particularly on the breast. Their plumage can appear mottled or scaly, especially on the back, and their beak may be paler than adults’. Young males gradually acquire their distinctive black and brown adult plumage through molting.
Common Look-Alikes
Several common backyard birds might be mistaken for brown-headed cowbirds due to similar size or coloration. Red-winged Blackbirds are often confused, but male Red-winged Blackbirds have prominent red and yellow shoulder patches, which cowbirds lack. Female Red-winged Blackbirds are more heavily streaked and possess a thinner bill compared to female cowbirds.
Common Grackles are another species that can cause confusion, but they are larger and lankier than cowbirds, measuring 11-13 inches (28-33 cm) with longer tails. Grackles also display iridescent purplish or bronzy hues across their entire body, and adults typically have yellowish eyes, unlike the dark eyes of cowbirds. European Starlings, while similar in size to cowbirds, have a shorter tail and a more pointed, straight bill. Starlings also exhibit iridescent black plumage that is often speckled with white, particularly outside the breeding season, a pattern not seen on cowbirds.