All over the backyard, a persistent squawking and chirping alerts us to the presence of newly fledged young birds. In fact, the noise of these youngsters has entirely replaced the melodic singing of breeding adults. Weaning is a difficult process as any parent knows, because the youngsters understand that the best way to get something is to annoy the parent until they finally give in (sound familiar?). Some examples I have seen in the past couple of weeks:
Four fledgling House Finches bombarded their dad, urging him to find them some food. At one point they all sat on the fence directly above him, noisily chirping away. He looks unconcerned about it.
Dad led them over to the bird feeder, showing them, I suppose, that this is where you eat. But they wanted him to stick the seed in their mouths, by chirping continuously and fluttering their wings. Two young sat next to him, two others perched right above him.
They haven’t quite connected the appearance of seed with food — still too fixed on being fed instead. A female cowbird looks on; she didn’t have to worry about feeding her babies, because she left her eggs in someone else’s nest!
This is what happens to some of the local birds when cowbirds are in the area.
A Cowbird chick (left) begs incessantly as it follows its foster “parent”, a Chipping Sparrow around the yard. Note that the Cowbird is is almost twice the size of the sparrow, and probably developed at the expense of some of the sparrow’s own chicks. Chipping Sparrows apparently can’t tell the difference between their own eggs and one twice as large!
Brown-headed Cowbird egg in the nest of an Eastern Phoebe (By Frankie Rose [Public domain], via Wikimedia Commons).
Cowbirds are infamous as nest parasites, and lay their eggs in the nests of several different species of small birds. This isn’t as easy as it sounds because they have to find the nests of suitable species, determine the incubation stage of that nest, and deposit one egg, at will, while parents are off the nest. If they lay the egg too early, the parents might abandon the nest with a strange egg in it; if they lay the egg too late, their own egg might not get sufficient incubation time for full development. Having found an appropriate nest, then they have to quickly lay their egg in it. For comparison, it takes a hen more than 1/2 hour to get her egg out.
Why do they do it? Brown-headed Cowbirds once followed bison herds across the prairie, moving nomadically with the herds and feeding on the insects flushed by many hooves and the seed heads of prairie grasses. Nesting in one spot was thus impossible with such a nomadic lifestyle, and “egg-dumping” in other species’ nests became advantageous.
My question is…how does this little guy know who he is? A cowbird chick apparently avoids the problem the ugly duckling experienced when he got displaced from his swan parents’ nest.