Scientists at Anglia Ruskin University (ARU) are attempting to comprehensively map the spread of the black squirrel population, a hundred years since the first was spotted in Britain.

Helen McRobie, Life Sciences lecturer at ARU, has set up a project to help track the geographical spread of the population by asking members of the public to submit sightings online of not only black, but also grey and the native red squirrels.

Black squirrels are the same species as the more common grey squirrel and as such are an intrusive species, introduced to the wild in Britain from the USA.

The only difference between grey and black squirrels is a genetically-caused pigment deficiency that causes the squirrel to only be able to produce black fur.

This darker pigmentation is thought to be advantageous to the black squirrel as it provides better camouflage in denser forests and helps absorb more heat from its environment.

Although best-suited to Canadian forests, the black squirrel is now currently outnumbering grey squirrels in areas such as Stevenage and Letchworth.

After the first black squirrel was spotted in Bedfordshire in 1912, their population has spread through Hertfordshire and Cambridgeshire including populations in Girton.

“As it stands,” Ms McRobie explains, “we know that the black squirrel gene has travelled approximately 50 miles in the last 100 years, which equates to half a mile a year.”

This project should not only help see how far black squirrel populations have spread but also help discover both why the black and grey squirrels have become such successful invasive species.