black squirrels

wijsman at wijsman at
Wed Jan 4 00:31:01 EST 1995

> Each Christmas we travel to my wife's parents' house in San Jose, CA. 
> There are a lot of old trees in that neighborhood, and many many squirrels.
> I vaguely recall my in-laws mentioning several years ago that there was a
> black squirrel about, two years ago I saw one, and this year they appeared
> to make up about half of the squirrel population.  The "normal" squirrels
> are grey, but the black ones are a very dark coal-black color.  In
> addition, and this is based on just watching them - no measurements, the
> black ones are slightly smaller, and their tails are slightly less bushy. 
> Do any zoologists out there know if this coat color allele is common in
> squirrels?  I've never seen a black one anywhere else, but judging from
> their increasing abundance, it looks like it provides a selective advantage
> in that suburban niche. 
> Regards,
> David Mathog
> mathog at
> Manager, sequence analysis facility, biology division, Caltech 

When I first moved to the Bay area (Palo Alto) about 14 years ago, one
of the first think I noticed was the apparent black/gray polymorphism
among the squirrels.  There were a few squirrels who were intermediate
- sort of a very dark gray, but mostly they came in definite
(beautiful!) black or definite ordinary gray. Menlo Park seemed to be
more gray than black, but the part of Palo Alto near old Palo Alto
seemed to be predominantly black.  South Palo Alto again ran towards
more gray, if I remember correctly.  I no longer live down there, so
can't comment on the current distribution.  Current residents of the
area - what do you see?

Ellen Wijsman
Research Associate Professor
Div of Medical Genetics, RG-25
and Dept of Biostatistics
University of Washington
Seattle, WA   98195
wijsman at

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