Expert: Julia Booth - 11/16/2008

Question
Julia~
Thanks for your quick reply to my other question.

Why do you suppose only SOME of the birds go through this process?
Thanks,
Bill

Answer
Why only some do it is a mystery to me as well, especially since it is usually necessary for both survival and procreation. Feathers get ruined and need to be replaced, just like hair, skin. Human skin cells repair and regenerate and although we don't molt, the mechanism is the same. Bird's behavior is controlled by external things like weather and temperature and internal things like hormones. Why some do it and others don't, or simply do it at different rates and times is beyond me.

Where I live, for instance, in southern California, there is no winter. So many of our birds and waterfowl do not change plumage as they would on the east coast. You will see gulls of the same age and species, with different plumages, at the same time -when they all should technically be changing together.

Try frequenting more of those bird blogs and forums like the one I sent you the link for. Some people have theories about these things and can be interesting.

Julia