Q: I was interested in your article on white squirrels (Cottage Q&A, Winter ’23). We had a white chipmunk at our cottage. At first it appeared to have some white fur around its nose. Over the summer, the white area progressed until the animal was white on the front third of its body, but it had regular chipmunk colours at the back. The following summer, the chipmunk was entirely white. What caused this gradual colour change?—Carolyn Odecki, Trout Lake, Ont.
A: Huh. This question had our experts, well, not entirely stumped, but let’s say half-stumped. We know for sure that this chipmunk was not an albino—you didn’t describe any pink eyes. It also doesn’t sound like a piebald (that is, an animal born with irregular patches of two colours). David Hackett, a small mammals expert with Nipissing University in North Bay, Ont., believes your chippie was most likely leucistic—it had a recessive gene that caused a partial loss of pigment. The strange part? This doesn’t explain why the chipmunk got lighter with age. No one we asked had ever heard of a leucistic mammal gradually changing from dark-coated to light-coated.
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“The best explanation I can come up with is something termed ‘progressive greying,’ ” says Vernon C. Bleich, a professor with the University of Nevada, Reno, who has studied abnormal colouration in squirrels. “But it’s most frequently reported in birds.” In these cases, the bird’s plumage becomes lighter and lighter as the animal ages and moults. Eventually, the plumage can turn white. “Progressive greying has seldom been described in mammals,” says Bleich. (Grey hair in humans doesn’t count; research suggests that progressive greying is a different process.)
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Maybe the chipmunk’s fur got lighter each season because of the sun, or maybe it just looked lighter under different light conditions. Or heck, maybe you were seeing multiple chipmunks. “Or maybe it was the same chipmunk, but it was observed at different moult stages within a summer,” says Hackett. His best theory is that multiple factors played a role in your observations over the years. “I suspect we are dealing with one light-coloured, leucistic chipmunk that the cottager noticed more and more over time. In late summer, the chipmunk would certainly stand out with more contrast in a dark forest compared to a better-lit spring forest, which could add to the ‘progressive’ effect,” he says. “As a white-haired human with many years of real-world biological experience, I have found that single clean-cut hypotheses often fall short in dealing with real-world situations.” Yeah, same. Except the white-haired part.
Got a question for Cottage Q&A? Send it to answers@cottagelife.com.
This article was originally published in the Early Summer 2026 issue of Cottage Life.
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