Good neighbours help squirrels survive, research suggests
A squirrel’s chances of survival and successful breeding are improved if it lives next to familiar neighbours, researchers say.
A study measured year-to-year survival of North American red squirrels – and found keeping the same neighbours was so beneficial that it outweighed the negative effects of growing a year older.
However, researchers found that living near genetic neighbours did not improve survival rates.
Lead author Dr Erin Siracusa, of the Centre for Research in Animal Behaviour at the University of Exeter, said: “These squirrels are solitary – each defending a territory with a ‘midden’ (food stash) at the centre – so we might assume they don’t co-operate.”
“However, our findings suggest that – far from breeding contempt – familiarity with neighbours is mutually beneficial.
“Defending a territory is costly – it uses both energy and time that could be spent gathering food or raising pups.
“It may be that, after a certain time living next to one another, squirrels reach a sort of agreement on boundaries, reducing the need for aggression.
“Competition is the rule in nature, but the benefits identified here might explain the evolution of co-operation even among adversarial neighbours.”
The research – part of the Kluane Red Squirrel Project – used 22 years of data on squirrels in Yukon, Canada, within the traditional territory of the Champagne and Aishihik First Nations.
The study looked at the area 130 metres of a central territory, examining both kinship (how closely related the squirrels were) and familiarity (how long individual squirrels occupied adjacent territories).
Researchers also studied survival rates and breeding success – for males this was measured by number of pups sired, and for females it meant pups surviving their first winter.
The team were surprised to find the benefits of familiar neighbours outweighed the effects of ageing.
Ageing alone reduced annual survival rates from 68% (age four) to 59% (age five), according to the study published in the journal Current Biology.
Dr Siracusa said the lack of evidence in the study for kinship being beneficial does not necessarily mean related individuals do not co-operate.
“Genetic relatedness in the neighbourhoods we studied was relatively low, and it’s possible that kin might be important at a smaller scale than the 130m radius we used,” she said.