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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.
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 ...
Brown-headed cowbirds (Molothrus ater) parasitize eastern towhee nests. In a South Carolina old field, 5 of 19 eastern towhee nests were parasitized. [51] Each parasitized nest contained 1 Brown-headed Cowbird egg. The desertion rate for parasitized nests was 20%, which was similar to nests that had not been parasitized (21%).
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 genus was introduced by English naturalist William Swainson in 1832 with the brown-headed cowbird (Molothrus ater) as the type species. [2] [3] The genus name combines the Ancient Greek mōlos, meaning "struggle" or "battle", with thrōskō, meaning "to sire" or "to impregnate". [4]
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.
Shiny cowbird: Molothrus bonariensis (Gmelin, JF, 1789) At least 102 species [7] Brown-headed cowbird: Molothrus ater (Boddaert, 1783) At least 174 species [7] Screaming cowbird: Molothrus rufoaxillaris Cassin, 1866: Most commonly Agelaioides badius, occasionally four other species [d] [8] Giant cowbird: Molothrus oryzivorus (Gmelin, JF, 1788)