Monday, May 27, 2013

A Study in Grosbeaks

Black-headed Grosbeaks are a common sight at everyone's feeders at this time of year.  Their striking contrast of colors always catches my attention and because of their unique plumage they are an easy species to identify. I always enjoy their brief visit each Spring when they arrive from their Winter homes in Mexico. I have recently become well enough acquainted with their song to identify them on a daily basis from their hidden perches high in the dense tree top foliage. Yesterday at the feeder my observations brought me to some new understanding and appreciation.  A quick glance at the above photo will probably tell you that you are looking at two male Black-headed Grosbeaks.  But a closer examination will reveal that only the bird on the right has a complete black head, whereas the bird on the left has an orange area back of the eye not filled in with black yet.  After consulting The Sibley Guide to Birds I have come to understand that the bird on the left has the non-breeding plumage of a first summer male.  A confirmation of that identification was an observation of their behavior at the feeder.  The mature male in the full back head of its breeding plumage was in control of the feeder.  The younger one, awkward at trying to hold his own on the feeder, had to wait his turn.  Once the older bird had had his fill the younger bird was allowed to take his place at the feeder. I find this fascinating in that despite that fact that the younger one has flown to Mexico and back under his own power there is still a protocol or pecking order to follow.

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