Monday, June 30, 2014

Common Yellowthroat

Common he may be in name, but the Common Yellowthroat deserves more respect. 

Yes, Common Yellowthroats are widespread and numerous, but also secretive. You might never see one without making an effort.  A brushy hiking trail near a marsh is a good place to start looking for a Common Yellowthroat…a favorite spot.

He’s a stocky little warbler of color, contrast and melodic voice.

This Common Yellowthroat flew to me as I watched from the dappled shade of the Forest Beach Migratory Preserve. 

He was unaware of me. 

I took his picture.

My camera flashes made him twitch, but he didn't fly away.  

He sang out in a sharp clear voice, a wichety-wichety-wichety song, to proclaim all this marshland was his.

The male Common Yellowthroat is largely dull
olive-green, but that contrasts nicely against a bright lemon-yellow throat. The female wraps herself in shades of light grey with just a hint of a yellow.

A black mask covers the male's face giving him a sinister look he really doesn’t deserve. 

A 1st year male is just now getting his distinctive black mask.

(Click any picture to enlarge)

Horicon Marsh, May 30. 2011

This somewhat confused Common Yellowthroat has been duped into raising a Brown-headed Cowbird’s chick.  

A female Brown-headed Cowbird surreptitiously laid an egg into the nest of this yellowthroat in hopes of getting the yellowthroat to hatch it. The ploy worked. The little yellowthroat struggles to find enough food to satisfy his huge freeloading foster child.

Parasitism is a bizarre approach to parenting, but it works. The cuckoo bird is even more famous for using this tactic.  

Brown-headed Cowbird egg, pierced and ejected

Normally, the Brown-headed Cowbird’s egg is larger and hatches faster. The more aggressive cowbird chick gets the most food and pushes out the yellowthroat chicks. 

Some songbirds recognize these attacks and eject or pierce the brown-speckled cowbird egg. If unable to remove the alien egg, they might rebuild a new nest right on top and start over.  

Strangely, some birds never recognize the odd egg. 

By failing to recognize the big alien chick, they spend valuable time raising a Brown-headed Cowbird chick at the expense of their own species' propagation.  

Interestingly, the cowbird chick, having never seen her real parents, nor taught the tactic, will grow up to carry on this parasitic trait as an adult.