Birds of Maryland, Delaware, and the District of Columbia (9781421427348) by Beehler Bruce M.; Evans Middleton (PHT); Robbins Chandler S. (FRW)

Author:Beehler, Bruce M.; Evans, Middleton (PHT); Robbins, Chandler S. (FRW)
Language: eng
Format: epub
Publisher: Johns Hopkins Univ Pr
Published: 2019-11-15T00:00:00+00:00

Dense Cattails make for an ideal nest site for Red-winged Blackbirds; here mom has just delivered a meal to those insatiable mouths.

The Rusty Blackbird is an uncommon passage migrant and wintering wanderer in our Region. This declining species breeds in spruce bogs of Canada and Alaska and winters in much of the eastern United States south to the Gulf. Most often seen in small flocks in wooded swamps where it searches for food by flipping over leaves. Usually this species does not mix with other blackbirds, though small numbers and singletons can be found among large winter flocks of Red-winged Blackbirds. 1,200 were counted at Pocomoke City, MD, on 5 October 1995. Its western counterpart, the very similar Brewer’s Blackbird, breeds from Michigan to British Columbia and south to New Mexico, wintering to Mexico and the Deep South. It is an increasingly rare visitor to our Region, typically between late autumn and early spring. 223 were recorded on the Bombay Hook, DE, Christmas Bird Count on 22 December 1956. 125 were reported from nearby Leipsic, DE, on 27 December 1992. The Brown-headed Cowbird is a commonplace flocking blackbird, found in the Region year-round in large numbers but highly mobile in the nonbreeding season. The female is an infamous brood parasite who makes no nest of her own but instead lays her eggs in the nests of other species of birds, who are then left to raise the cowbird(s) as well as their own offspring. Since the cowbird nestling is much larger than the host nestlings, these usually end up severely malnourished, often perishing in the nest or pushed out by the aggressive cowbird nestling. Individual female cowbirds tend to parasitize just a single host species (especially Indigo Bunting, Yellow Warbler, and Song Sparrow), and yet cowbirds eggs have been found in the nests of more than 200 different host species. In earlier centuries, cowbirds inhabited the interior prairies and followed herds of American Bison, hence their colloquial name of “Buffalo Bird.” The species invaded the East when the forests were cut and open land created for agriculture. Cowbirds join mixed blackbird flocks in winter. 200,000 were recorded in Cecil County, MD, on 27 December 1952. 150,000 were recorded from Wicomico County, MD, on 15 December 1995. 50,000 were recorded at Dragon Run SP, DE, on 24 November 1974.

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