For several days I had noticed a pair of House Finches flying to and from a holly near my front porch. Typically, just standing next to the bush for longer than a few seconds would cause a bird to bolt from deep within the leaves near the top.
I suspected the finches had constructed a nest, and I retrieved a step ladder in order to have a better look. I was surprised by what I found
The House Finches were indeed nesting in the bush off my front porch, and when I examined the nest more carefully I made an interesting discovery. The nest contained three light blue House Finch eggs, but unexpectedly, it also held a fourth and different kind of egg. This one was white with brown speckles and slightly larger than the others.
Clearly this fourth egg did not belong with the other three, and a little research revealed that this egg belonged to a different species of bird altogether, the Brown-headed Cowbird.
The cowbird is a what is known as a parasitic species. It lays its eggs in the nest of other, smaller birds. The host species (in this case the House Finch) then incubates the cowbirds eggs along with its own, and when the eggs hatch, the larger cowbird juvenile is frequently able to out-compete the host bird’s young for parental care, due to its larger size.
|Date||–||May 11, 2008 – Jun 3, 2008|
|Time of Day||–||Various|
|Type of Behavior||–||Care of Young, Nesting|
|Main Article||–||House Finch||Observation Location|