A tough nut to crack

Virginie Millien, professor and curator of paleontology and zoology at the Redpath Museum, comments in The Gazette on why Montreal squirrels are grey while Toronto and Ottawa squirrels are black. Studies have shown animals with black hair lose 20-per-cent less body heat than lighter-coloured animals, but climate is probably not the only force at work, according to Millien. The genetic mutation could also be from squirrels evolving to adapt to a more urban environment.