Total - a complete absence of melanin. The melanin is not only missing from the skin but also from the eyes and hair. This is the rarest form of albinism. Imperfect - melanin is present but only in small amounts. Partial - melanin is absent from only certain areas.
Partial albinism is the most common form.
It, however, is still quite rare. A study done in 1936 concluded that albinism in any form was present in only one-half of one percent of the avian population. A 1995 study noted that albinism had been recorded in 304 of the more than 700 species of North American birds. Since the browner pigments are generally the ones more affected by albinism, albinism is more common among darker species. Blackbirds, crows and robins are more susceptible than cardinals, goldfinches and other brightly colored birds.