Wednesday, April 01, 2009

New Migrations

It was inevitable that new species of birds would start showing up at the feeders. I was very happy to see these female brown headed cowbirds (Molothrus ater ) yesterday, members of the blackbird family. They have a reputation for mating with any male and then laying eggs in other bird's nests for others to raise! (I think I know a few females of the human species who have the same view of raising a family.) But the biology is actually kinder and is about the bird migration pattern of following the herds of bison for insects and therefore having to leave behind their eggs in any nest found along the way. Her young are the first to hatch in the nest and are usually the larger of the hatchlings and so get most of the food.

And this from a backyard bird website: "An average female lays about 80 eggs, 40 per year for two years. About 3 percent of those 80 eggs end up as adults -- an average of 2.4 adults per female. Clearly, such numbers more than compensate for the excessive loss of eggs and young in the nests of inappropriate hosts. Each pair of cowbirds replaces itself with an average of 1.2 pairs which will double a cowbird population in eight years. "

I was hoping to get a photo of the male who is a deep purple black, but I was not so lucky on this day.


Mohammad Ali said...
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Mohammad Ali said...

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