December 23, 2008
More anomalies at the feeder
There's still plenty of snow in Astoria and plenty of reason to stay indoors and watch the bird feeder. Today an interesting FOX SPARROW showed up at the feeder.
The vernacular for this condition is "pied". The technical term is more complicated and depends to a large degree on which textbook one picks up. It is a form of albinism in that affected feathers are lacking in pigment. Most sources differentiate between true albinism which is a genetic condition and partial-albinism which is often environmental. But some texts argue that only total lack of pigment (including eye pigment) can be called albinism, independent of cause, and leucism is the term for all other pigment deficiencies. Still other sources split the condition into complete, incomplete, imperfect and partial albinism. No matter what terms you choose, there will be someone out there who will try to correct you.
At the other end of the the scale are "over colored" birds. In my yard today, I also found an exceptionally dark FOX SPARROW which is probably partially melanistic. Note that it has almost no white in the throat or chin and even the properly brown parts are a bit darker than typical.
One of the positive things about being snowbound is that it gives us time to really study those species we often take for granted...
Posted by mbalame at December 23, 2008 2:15 PM