Brown Headed Cowbird

Description:

The second and third images show the courtship behavior of the male of the brown headed cowbird species, the female acted indifferent to the display and just kept eating. "The Brown-headed Cowbird is typical for an icterid in general shape but is distinguished by a finch-like head and beak and is smaller than most icterids. The adult male is iridescent black in color with a brown head. The adult female is slightly smaller and is dull grey with a pale throat and very fine streaking on the underparts. The total length is 16–22 cm (6.3–8.7 in) and the average wingspan is 36 cm (14 in).[2] Body mass can range from 30–60 g (1.1–2.1 oz), with females averaging 38.8 g (1.37 oz) against the males' average of 49 g (1.7 oz).[3]" Wiki: http://en.wikipedia.org/wiki/Brown-heade...

Notes:

This is some really GREAT information about these parasitic egg layers. "Reproduction Eastern Phoebe nest with one Brown-headed Cowbird egg Adult female This bird is a brood parasite: it lays its eggs in the nests of other small passerines (perching birds), particularly those that build cup-like nests. The Brown-headed Cowbird eggs have been documented in nests of at least 220 host species, including hummingbirds and raptors.[4][5] The young cowbird is fed by the host parents at the expense of their own young. Brown-headed Cowbird females can lay 36 eggs in a season. More than 140 different species of birds are known to have raised young cowbirds.[6] Unlike the Common Cuckoo, it has no gentes whose eggs imitate those of a particular host. Some species, such as the House Finch feed their young a vegetarian diet. This is unsuitable for young Brown-headed Cowbirds, meaning almost none survive to fledge.[7] [edit]Host response The acceptance of a cowbird egg and rearing of a cowbird can be costly to a host species. In the American Redstart, nests parasitized by cowbirds were found to have a higher rate of predation, likely due in part to the loud begging calls by the cowbird nestling, but also partly explained by the fact that nests likely to be parasitized are also more likely to be predated.[8] Host birds sometimes notice the cowbird egg, to which different host species react in different ways. Rejection manifests in three forms: nest desertion (e.g., Blue-gray Gnatcatcher), burying of the egg under nest material (e.g., Yellow Warbler),[9] and physical ejection of the egg from the nest (e.g., Brown Thrasher).[5] Brown-headed cowbird nestlings are also sometimes expelled from the nest. The Gray catbird rejects cowbird eggs over 95% of the time; experimentation has suggested that in this species, the cost of accepting an egg is much higher (0.79 catbird fleglings) than the cost of rejecting an egg(0.0022 catbird fledglings).[10] Nestlings of host species can also alter their behavior in response to the presence of a cowbird nestling. Song sparrow nestlings in parasitized nests alter their vocalizations in frequency and amplitude so that they resemble the cowbird nestling, and these nestlings tend to be fed equally often as nestlings in unparasitized nests.[11] [edit]Parasite response It seems that Brown-headed Cowbirds periodically check on their eggs and young after they have deposited them. Removal of the parasitic egg may trigger a retaliatory reaction termed "mafia behavior". According to a study by the Florida Museum of Natural History published in 1983, the cowbird returned to ransack the nests of a range of host species 56% of the time when their egg was removed. In addition, the cowbird also destroyed nests in a type of "farming behavior" to force the hosts to build new ones. The cowbirds then laid their eggs in the new nests 85% of the time.[12] [edit]Human intervention Humans sometimes engage in cowbird control programs, with the intention of protecting species negatively impacted by the cowbirds' brood parasitism. A study of nests of Bell's Vireo highlighted a potential limitation of these control programs, demonstrating that removal of cowbirds from a site may create an unintended consequence of increasing cowbird productivity on that site, because with fewer cowbirds, fewer parasitized nests are deserted, resulting in greater nest success for cowbirds.[13]" Wiki: http://en.wikipedia.org/wiki/Brown-heade...