One of the pleasures of my job is that I get to see lots of photos of unusually colored animals that Missourians submit to us for an explanation. They include individuals with no pigments (true albinos), melanistic (all or mostly dark-colored due to excess pigment) and a variety of piebald patterns where some of the normal pigments are missing, leaving white feathers or fur.
Biologists use the term leucistic to describe animals whose normal pigments are present but are distributed to the body in unusual patterns. A leucistic animal can have pale colors overall or can have normal colors next to pure white areas. The presence and distribution of pigments is genetically controlled, and abnormal deposition of pigments is very rare. One study of birds at feeders recorded fewer than 1,000 leucistic birds in 38 million observations.
The leucistic American robin pictured here was observed in a neighborhood in O’Fallon, Mo., this month. It behaves like others of its species, spending much of its time in the spring hunting for earthworms in residential lawns. It makes me wonder how the other robins regard this bird that doesn’t look like them. Is it prized as a wondrous variation, like the Native Americans treated the rare albino bison? The other robins don’t seem to treat it any differently. Leucistic birds are reportedly less likely to attract mates and more likely to fall victim to predators. Those factors certainly must contribute to their rarity.
Photos by D. Baldwin of O'Fallon, Mo.