Red squirrels: Altruists or self-serving survivalists?

A University of Alberta researcher has discovered a rare practice by red squirrels that seems to have human-like dimensions of altruism

By Brian Murphy on June 2, 2010

(Edmonton) A University of Alberta researcher has discovered a rare practice by red squirrels that seems to have human-like dimensions of altruism, but at its heart is also a survival tactic.

U of A researcher Jamieson Gorrell was observing a red-squirrel population when he discovered a female had adopted a newborn squirrel abandoned by its biological mother.

�I climbed a tree to check out some newborns and when I reached in, I pulled out a baby red squirrel that shouldn�t have been there; I couldn�t believe it,� said Gorrell.

Gorrell, a PhD candidate in evolutionary biology, determined the baby squirrel had been taken from a nearby tree after it had been abandoned by its biological mother. �Somehow the adopting mother had determined that its neighbor had disappeared,� said Gorrell. �It went over to investigate and adopted the abandoned baby as its own.�

Gorrell says that, while some animals have been known to adopt foundlings, this case was very odd because squirrels are among the most solitary, antisocial species in the wild. �Social animals like chimpanzees will adopt, but squirrels are another matter,� said Gorrell. �Apart from mating, both male and female squirrels avoid all contact with one another. That�s why I decided to investigate this strange adoption case.�

U of A researchers have been studying this population of red squirrels in an area of Kulane National Park in the Yukon for close to two decades so Gorrell had a lot of historical data to search through.

Eventually Gorrell says his detective work paid off with a breakthrough discovery. �I found that four times in 20 years, female red squirrels have adopted abandoned babies.� But Gorrell says something even more startling stood out: �In every case the foundling was related genetically to its adoptive mother.�

Gorrell says that discovery prompted the research team to find out how the adoptive mother identified the genetic link with the foundling and if being related is a condition of adoption for squirrels.

�We�re not sure, but we think squirrels identify family connection between one another through their constant vocalizing or chattering,� said Gorrell. The researchers theorize that the chattering squirrels use to mark their territory and ward off intruders contain signals describing their genetic history.

�This may have enabled the adopting female to have identified the biological mother, before she disappeared, as a relative,� said Gorrell. �So when the adopting mother went to the neighbouring nest she recognized a genetic connection with the abandoned baby.�

The research by Gorrell and his colleagues at McGill University was published June 1, online by Nature Communications.