Scientific Name: Molothrus ater
Pictures: (click for larger images)
Some male Black-headed Cowbirds in a tree. This was NOT in Westwood, but rather up at Lake Arrowhead in the nearby mountains, where UCLA has a conference facility. Since these birds are so rare in Westwood, I figured I'd probably never get a photo of them here, so a photo from somewhere else is better than none at all. 5-20-05 Black-headed Cowbird illustration
-Photo by Jason Finley
-Illustration by Robert C. Stebbins from "Birds of the Campus" (1947) by Dr. Loye Miller.
Description: Small. 7.5" in length (beak to tail), smaller than a pigeon. Looks similar to Brewer's Blackbird, but is smaller and males have noticeably brown head above black body. The males have dark eyes, unlike the Blackbirds' bright green eyes. Female is grayish brown.
Commonality/Seasonality: Rare, but probably year-round.
Location: Probably wherever Brewer's Blackbirds can be found. Bobby Walsh saw some on the grassy strips that line Le Conte on either side of Westwood on 4/8/05. They tend to be nomadic, so they're a real wild card.
Notes: Cowbirds are "brood parasites," meaning that they lay their eggs in the nests of other species. The young cowbird will often be raised by its unwitting foster parents, and will deprive the other young birds of food or even push them out of the nest. Sad, but that's nature, red in tooth and claw. You can't blame the cowbirds anymore than you can blame hawks for killing prey or Cedar Waxwings for eating berries; they are simply carrying out their evolved instincts. We humans are the only animals with the capability of overriding our instincts and choosing our behaviors, and thus we are the only animals with moral responsibility. Remember that.
Also, cowbirds are not monogamous. They used to follow bison herds around North America.
Historical: Dr. Loye Miller wrote about the "Dwarf Cowbird" as it was known back then:
In late April or early May these erratic birds generally appear about the Esplanade. Mixed groups of males and females wander here and there. Occasionally they drop down onto the lawn with their larger cousins, the Blackbirds, but the brown heads of the males and the smaller size will distinguish them at once. [Miller refers to "the Esplanade" several times, but I'm not sure where that really was/is]
-Miller, Loye. "Birds of the Campus, University of California, Los Angeles," from University of California Syllabus Series, No. 300. Text by Loye Miller, illustrations by Robert C. Stebbins. Los Angeles: University of California Press, 1947.