Black birds with a greenish sheen and brown heads sometimes visit my yard during spring migration. These are male brown-headed cowbirds, and they often arrive in mixed flocks of red-winged blackbirds ...
From may through July, 1993-1998 and 2001, effects of Brown-headed Cowbird (Molothrus ater) parasitism on 36 Warbling Vireo (Vireo gilvus) nests were documented in southwest Colorado. Overall ...
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