Related to the hypothesis that albinism may occur more commonly in
species or populations that suffer less predation, is the abundance
of polymorphisms in predators themselves. Predators are by definition
less likely to be prey items than other animals, so they have low rates
of predation. Could this be why so many hawks, owls, and large cats
come in several colour types. Of course the predators may also gain a
benefit by being unique in their appearance since this may make it more
difficult for the prey animals to identify them as predators.
Other large birds that may be largely free from predation also show
polymorphisms, like herons and egrets, strengthening the general argument.
We could try and make a list of animals that show polymorphisms and see
if we can find any pattern.

BTW, I once saw a completely albino American Robin in Ontario with strikingly
pink eyes.

Al Jaramillo
jaramill at sfu.ca
Vancouver, B.C.