Bronzed Cowbird
Molothrus aeneus
The male bronzed cowbird is 20 cm (7.9 in) long and weighs 68 g (2.4 oz), with green-bronze, gloss-black plumage. His eyes are red in breeding season and brown otherwise. The female is 18.5 cm (7.3 in) long and weighs 56 g (2.0 oz). She is a dull black with a brown underbelly, and has brown eyes. Young birds have coloring similar to the females, with the exception of grey feather fringes.
ID text from Wikipedia, CC BY-SA 4.0
Giant Cowbird
Molothrus oryzivorus
The male giant cowbird is 34 cm (13 in) long, weighs 174–242 g (6.1–8.5 oz) and is iridescent black, with a long tail, long bill, small head, and a neck ruff which is expanded in display. The female is smaller, averaging 29 cm (11 in) in length and weighing 144–167 g (5.1–5.9 oz). The female is less iridescent than the male, and the absence of the neck ruff makes her look less small-headed. Juvenile males are similar to the adult male, but browner, and with a pale, not black, bill.
ID text from Wikipedia, CC BY-SA 4.0

Where you might meet both
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Play today's Daily BirdPhotos and recordings are credited to their authors under the licence shown. Full profiles: Bronzed Cowbird and Giant Cowbird.