0 the shiny cowbird , molothrus bonariensis , is a passerine bird in the new world family icteridae .
1  it breeds in most of south america apart from the most dense jungles , mountains and deserts (although spreading into these habitats as they are modified by humans), the coldest southernmost regions (e .
2 g .
3  tierra del fuego), and on trinidad and tobago .
4  it has relatively recently colonised chile and many caribbean islands , and has reached the usa , where it is probably breeding in southern florida .
5  northern and southernmost populations are partially migratory .
6 it is a bird associated with open woodland and cultivation .
7  the males song is a purr and whistle , purr purr purrte-tseeeee .
8  the males call is a sharp whistled tsee-tsee , but the female makes a harsh rattle .
9 like most other cowbirds , it is a brood parasite , laying its eggs in the nests of many other bird species , such as (in brazil) the rufous-collared sparrow and the masked water-tyrant .
10  the eggs are of two types , either whitish and unspotted , or pale blue or green with dark spots and blotches .
11  the hosts eggs are sometimes removed , and if food is short their chicks may starve , but larger host species are less affected .
12  the incubation period of 1112 days is shorter than that of most hosts .
13  extermination of the shiny cowbird within the tiny range of the pale-headed brush-finch has resulted in a population increase in this critically endangered species .
14 the male shiny cowbird is all black with an iridescent purple-blue gloss .
15  the smaller female is dark brown in plumage , paler on the underparts .
16  she can be distinguished from the female brown-headed cowbird by her longer , finer bill , pale supercilium and stronger face pattern .
17  there is an all-black plumage variation , and the northern subspecies m .
18  b .
19  cabanisii of panama and northern colombia is paler than the nominate m .
20  b .
21  bonariensis .
22  juveniles are like the female but more streaked below .
23  there is some variation in size across the range , with the race of m .
24  b .
25  minimus from northern south america and the west indies being the smallest at 31 to 40 g (1.1 to 1.4 oz) and 18 cm (7.1 in) in length and m .
26  b .
27  cabanisii being the largest at 55 to 65 g (1.9 to 2.3 oz) and 22 cm (8.7 in) on average .
28 this abundant and gregarious bird feeds mainly on insects and some seeds , including rice , and forages on the ground or perches on cattle .
