Question

We rarely find a white crow.
Find the functions.

Answer 1

Answer:

American Crows, Corvus brachyrhynchos, frequently show problems with pigment deposition. Approximately 1% of nestlings that I band in New York show some white in their feathers, and four times that many have spots of white on their toes, bill, or other part of the body. I find young like this every year, and the occurrence is about what I would predict based on seeing abnormal crows in large foraging flocks.

This nestling from my study in 1993 showed rather extreme amounts of white relative to what I usually see. (It was found dead on the Cornell Campus soon after fledging.)

Although I have had several young crows with white in the wings in a single nest , I have not found white to occur in the wings of young of the same adults over successive years (but it could happen). I have a few families that have had multiple broods of young with white spots on their toes, but the numbers are small enough that I cannot distinguish them from random occurrences at this point