Weekly Chirp: Is THAT a Cowbird?

The Cowbird has acquired its name due to the habit of feeding in close proximity to cattle and other grazers.  It is not a particularly handsome bird, but it has an interesting method of ensuring breeding success of the species.   

  The Brown Headed Cowbird is found throughout the United States.  In our area, we also have the Bronzed Cowbird.  As I mentioned in a previous article, these birds survive due to nest parasitism.  Both species have added to the declination of many smaller species, such as the Black Capped Vireo and the Golden Cheeked Warbler.  The larger, more aggressive Cowbird will push eggs of a smaller unsuspecting bird right out of the nest and lay its own larger eggs in that nest.  (Cowbirds never build their own nests!)  Once the eggs have hatched, the larger sibling, the Cowbird, will dominate the distribution of food from the parents.

  But here is the mystery that has puzzled Ornithologists:  After being raised by the foster species, how does the Cowbird know it is not a Vireo or Warbler or any other bird that has raised it from birth?  Studies have created a variety of theories.  One is that the parent will keep an eye on the foster nest and reunite with its offspring once they have fledged.  Another is that they are innately drawn to the sound of an unrelated female Cowbird call, not necessarily its true parent.  How do these young Cowbirds know who they are?  How do they find their real identity and join their flock?  They cannot mate with a Vireo or Warbler, so how do they survive?  They must learn who they are, what they are supposed to do and how to continue the survival of their species!

  If you have a theory of what continues to puzzle the professionals, we’d like to hear it.  We will publish the most likely or interesting theory sent to us by 5pm on Monday, July 21st! Please send to editor@kinneycountypost.com