H.J. Ruiz – Avian101

Brood Parasitism

This post is to explain a bit about brood parasitism that happen in places where birds like in this case brown-headed cowbirds invade other species bird’s nests in order to lay an egg to be hopefully hatched by the host! Read more…

“Brood parasitism relieves the parasitic parents from the investment of rearing young or building nests for the young, enabling them to spend more time on other activities such as foraging and producing further offspring. Bird parasite species mitigate the risk of egg loss by distributing eggs amongst a number of different hosts.^[1] As this behaviour damages the host, it often results in an evolutionary arms race between parasite and host.”

Family Icteridae

• Genus Molothrus
  • Shiny cowbird Molothrus bonariensis
  • Brown-headed cowbird Molothurs ater
  • Screaming cowbird Molothrus rufoaxillaris
  • Giant cowbird Molothrus oryzivorus
  • Bronzed cowbird Molothrus aeneus

“Most avian brood parasites are specialists which parasitize only a single host species or a small group of closely related host species, but four out of the five parasitic cowbirds are generalists,(with the exception of the screaming cowbird) which parasitize a wide variety of hosts; the brown-headed cowbird has 221 known hosts. They usually lay only one egg per nest, although in some cases, particularly the cowbirds, several females may use the same host nest.”

Important note:

Today July 11th I will be traveling with my wife Lucy and son Tyler to Florida for vacation. I’m not going to publish any posts on July 12th, July 13th, July 14th and July 15th. I’ll resume posting on Saturday July 16th.

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