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Bronzed Cowbird Molothrus aeneus


The Bronzed Cowbird is a brood parasite that ranges from the U.S.-Mexico border southward to northern Colombia and occurring in all Central American countries in between. Bronzed Cowbirds are slightly larger than the better known and related Brown-headed Cowbird (Molothrus ater); the "average" host of the Bronze Cowbird is larger than the "average" host of the Brown-headed Cowbird as well. Many aspects of the Bronzed Cowbird's breeding biology have been assumed to be similar to that of the Brown-headed Cowbird, although the former may be more specialized in its host selection.
Human settlement of the New World has led to habitat changes favorable for Molothrus cowbirds and range expansion northward by Bronzed Cowbirds in the US has been recorded.  Changes in distribution and abundance patterns in its neotropical distribution is less well known.  Too little is known about interactions between Bronzed Cowbirds and their hosts to make more than general descriptive statements.
Such neglect is unfortunate because, compared to other parasitic cowbirds, the Bronzed Cowbird seems intermediate in many aspects of its behavior and breeding biology. A better understanding of this species would help to advance our understanding of the evolution of brood parasitism.

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© Matthew D. Medler

  • Year-round
  • Migration
  • Breeding
  • Non-Breeding

Recommended Citation

Bronzed Cowbird (Molothrus aeneus), In Neotropical Birds Online (T. S. Schulenberg, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. retrieved from Neotropical Birds Online: