Tender Hearted Squirrels

By Robert J. Korpella

First posted on 06-04-2010

They chatter, chase, compete for food and sometimes even get pretty aggressive with rivals, but researchers are discovering that squirrels have a soft heart when it comes to orphaned relatives.

Professor Andrew McAdam of the University of Guelph in Canada worked alongside other researchers from the University of Alberta and McGill University in a recent study of red squirrels. Their discovery that this species adopts pups that have lost their mothers is surprising because this type of behavior is uncommon among asocial animals, like squirrels.

“Social animals, including lions and chimpanzees, are often surrounded by relatives, so it’s not surprising that a female would adopt an orphaned family member because they have already spent a lot of time together,” said McAdam, an evolutionary biologist. “But red squirrels live in complete isolation and are very territorial. The only time they will allow another squirrel on their territory is the one day a year when the females are ready to mate or when they are nursing their pups.”

But squirrels do draw some lines on adoption. They only adopt orphans they are related to, and even then, only on rare occasions. The team only observed 5 adoptions in a 20 year span of time.

Adoptions are only possible if the mother dies and a related squirrel is nearby and is also nursing. In all 5 cases documented by the research team, all the pups were nieces, nephews, siblings or grandchildren to the adoptive mother.

The team found it remarkable that squirrels were able to determine which pups they were related to. Calls play an important role in the process and, should squirrels not hear a relative’s voice for a few days, they are liable to go out and investigate.

“We suspect that, if they find pups on the territory, they remember that their neighbor was a relative and carry the pups back to their nest. This would be quite intelligent behavior for a squirrel.”