It might seem nuts . . but maths can save red squirrels

The plight of the red squirrel, at the paws of the larger American grey squirrel, might seem a million miles away from the cold, calculating world of number crunching.

But now mathematicians at Heriot-Watt University may hold the key to the species’ survival.

And if successful their work could be used in conservation efforts around the world.

The endangered red squirrel has seen its habitat steadily shrink as the more aggressive grey, originally imported from America in the 1930s, takes over.

When the native red population went into decline it was initially thought that the greys were simply more successful at survival. It was later discovered that they carry a disease, harmless to them but fatal to the red squirrel.

Grey squirrels also eat the same food as red squirrels, but can eat it at a more ripe stage, when it is unsuitable for reds.

All of this has led to a rapid decline of the red squirrel population, and most of the remaining animals, around 160,000, are holed up largely in coniferous areas of Scotland including parts of the Highlands and Borders as environmentalists work on a way to help the species survive.

Mathematicians at the university are also trying to work out an equation for the survival of the red squirrel.

Dr Andrew White, lecturer in mathematics, has been studying the plight of the rare animals and how to halt the steady encroachment of the invading imported greys.

With so few of the animals left, he knows environmentalists can’t afford to make any mistakes when implementing strategy in the wild.

And he believes that mathematical models created at the university could be used to help find the best way to save the squirrels.

"The environment is delicate and where animals are under threat, going out and trying out conservation strategies in the field could end up doing more harm than good," he said.

"That’s where mathematical models come in, as they are able to test a variety of conservation and management strategies theoretically and safely.

"There are too few red squirrels left in the wild to just try out a strategy and hope for the best, but a computerised mathematical model lets you experiment to establish what works best and what could actually be counter productive."

These mathematical models of conservation are already being put to use, with Professor Jonathan Sherratt trying to work out a model for why animal populations can expand and contract rapidly and seemingly without explanation.

He has been working with data gathered on the field vole population of the Kielder Forest in the Scottish Borders over the last twenty years.

Their population undergoes regular cyclical fluctuations, rising by up to a hundred-fold and then declining again over periods of about four years, yet nobody has been able to work out why.

Through mathematical simulations similar to those being used to work out conservation strategies for the red squirrel, Prof Sherratt has been able to demonstrate the key role played in the vole’s population by the large reservoir in the middle of the forest.

His mathematical model shows that if the reservoir is filled in, which could never be carried out in real life, the population throughout the forest disappears.

Doreen Graham, of the Scottish Society for the Prevention of Cruelty to Animals, said any move to help the survival of the red squirrel was to be welcomed.

"The current work on conservation of the red squirrel is more towards containing the spread of the grey squirrel and keeping them in certain areas," she said.

"If this model could test out conservation strategies it could lead to a more pro-active strategy to increase the population of the red squirrels, which everyone would welcome.

"The red squirrel is one of the most beautiful native animals we have and anyone who has seen them in the wild will not forget it. The more people working to help save them the better."