Search results
Results from the WOW.Com Content Network
The brown-headed cowbird (Molothrus ater) is a small, obligate brood parasitic icterid native to temperate and subtropical North America. It is a permanent resident in the southern parts of its range; northern birds migrate to the southern United States and Mexico in winter, returning to their summer habitat around March or April.
The brown-headed cowbird produces very rapid clusters of notes that alternate in frequency, with the right syrinx producing the high frequency notes and the left syrinx producing low frequency notes. The entire cluster is sung during a single respiratory expiration, called "pulsatile expiration", in which no inflow of air occurs between notes.
Although most birds acquire song learning within the first year, brown-headed cowbirds have a delayed sensitive period, occurring approximately one year after hatching. [35] This may be an adaptation to prevent the young birds from learning the songs from the foreign bird species.
The eastern phoebe's call is a sharp chip, and the song, from which it gets its name, is fee-bee. The eastern wood pewee ( Contopus virens ) is extremely similar in appearance. It lacks the buff hue usually present on the lighter parts of the eastern phoebe's plumage, and thus has always clearly defined and contrasting wing-bars.
Kirtland's warbler is highly susceptible to nest parasitism by this cowbird. [30] Brown-headed cowbirds feed mostly on seeds from grasses and weeds, with some crop grains. Insects such as grasshoppers and beetles, often caught as cows and horses stir them into movement, make up about a quarter of a cowbird's diet.
Song sparrows' nests are parasitized by the brown-headed cowbird. The cowbirds' eggs closely resemble song sparrows' eggs, although the cowbirds' eggs are slightly larger. Song sparrows recognize cowbirds as a threat and attack the cowbirds when they are near the nest. There is some evidence that this behavior is learned rather than instinctual ...
They are in general medium to large birds, typically with gray or brown plumage, often with white markings on the wings. They have longish bills with hooked tips and webbed feet with sharp claws. They look like large dark gulls, but have a fleshy cere above the upper mandible. They are strong, acrobatic fliers. Great skua, Stercorarius skua (R)
Different host species show different responses to their nests being parasitised, with behaviours ranging from accepting and caring for the cowbird eggs, to rejecting the eggs from the nest. [2] As the shiny cowbird is an effective generalist brood parasite, it can be considered the South American counterpart to the brown-headed cowbird. [6]