Odd Couple. Song Sparrow with Cowbird Fledgling
It is not pretty, but there it is: Cowbirds are nest parasites. They lay their eggs in the nests of other species. The Cowbird egg hatches first. The Cowbird chick grows faster. The Cowbird chick tosses its legitimate nest-mates over the edge. Soon the Cowbird chick is the only chick in the nest, and gets all the food the parents bring back.
What you see here is a fledgling Cowbird still terrorizing its Song Sparrow host…begging for food in a voice that can not be denied. Does the Song Sparrow know, do you think, that it has raised a monster? Okay, that is a bit too anthropomorphic. The Cowbird is not a monster. It is just pursuing a survival style that has proven successful for untold thousands of years. And, if the season is good, the Song Sparrow may next again and raise a legitimate brood…and, further, there is always next year. There are lots of Song Sparrows.
Nest parasites are only a real problem for species that are already in trouble, where every nest and every fledgling counts. Still, I find it impossible to approve of the Cowbird’s lifestyle. As it happens, it does not need my approval, so there you have it.
Still…how can you not see the Song Sparrow in this next shot as long-suffering? I mean, look at that face! Resignation birdonified.
Canon SX40HS. Program with iContrast and –1/3EV exposure compensation. 1240mm equivalent field of view (840mm optical zoom plus 1.5x digital tel-converter function). f5.8 @ 1/200th @ ISO 160.
Processed in Lightroom for intensity, clarity, and sharpness.
Stephen, I’ve wanted to witness this brood parasitism for years and having had a female cowbird here this spring I was hoping this was going to be the year. But no such luck.
Did you know the Golden Eye duck also practices this form of reproduction?
I saw my first cowbird (fledgling nagging a song sparrow just like in the above pictures) three summers ago. Now they have become common here. (I live in NW Oregon.) Every single cowbird fledgling I have seen has had a song sparrow as foster parent. I wonder if they have a population explosion when they reach an area with cowbird-naive birds, and if the other birds learn from experience. I have read that cowbirds can destroy the nest of birds that get rid of cowbird eggs, but they can’t do that all the time. If female cowbirds lay 30 eggs a season, as i have read, most of them probably don’t survive. I got a photograph of a cowbird nestling in a song sparrow nest which I uploaded here: http://ibc.lynxeds.com/photo/brown-headed-cowbird-molothrus-ater/baby-cowbird-song-sparrow-nest
Yes! Yes! How remarkable! We have had a pair of cowbird fledglings with their foster parents, Mr. And Mrs. Sparrow, in our back yard all week! The sparrows are extremely attentive and dedicated!