Leucistic House Finch
Jun 30, 2009 | by Adrian Binns
While the male House Finch (left) is perfectly normal, the female (right) on the other hand is leucistic or partially albino, since only some of her feathers are white. The white color is a result of genetic mutation.
Leucism is caused by a reduction in all types of skin pigments (basically they fail to develop properly), whereas albinism is a genetic mutation that prevents the production of melanin only.
There are two type of leucism – paleness, where a bird is evenly pale all over, and pied, in which there is an absence of skin pigments in some feathers causing a blotchy appearance. The female House Finch (below), falls into the last category, having lost the pigmentation around her neck and throat.
Though leucism is not uncommon, those individuals that have it may have a hard time attracting mates and be more vulnerable to predators. Consequently, this is not something that is often passed on to offspring.