The red squirrel population in the UK, long on the brink of complete destruction, has shown signs of resistance to a deadly poxvirus which has killed hundreds of thousands of them over the decades. A study in an area of Merseyside in the North West of England has shown that around 10 percent of the population there now carry squirrelpox antibodies in their bloodstream. The antibodies, which enable the squirrels and their descendants, to respond to the virus also indicate that a number of the animals have had the disease but have recovered.
This is the
first time that a red squirrel surviving exposure to the poxvirus has been recorded. The news has been welcomed by naturalists as an encouraging sign. So, what happened in Merseyside to make a difference?
Five years ago the squirrel poxvirus reached the small population of red squirrels in the Merseyside town of Formby, with a red squirrel population of around 1,000. The virus, which has ravaged the UK red squirrel population since 1945, swiftly decimated the animals, leaving only 150 of the original local population alive. It looked for a while that Formby might lose its red squirrels. Yet their numbers recovered and is now at 60 percent of its pre-pox levels, prompting scientists to look in to the reasons behind it.
A team from the University of Liverpool, led by Doctor Julian Chantrey, took blood samples from over a hundred of the surviving red squirrels. They captured a squirrel with ulcers around its face (a tell-tale sign of the poxvirus) and it inevitably tested positive for the disease. It was taken to a local RSPCA (
Royal Society for the Prevention of Cruelty to Animals) center and failed to expire. After two months it was tested again and found to be negative. Released back in to the wild, the red squirrel was captured on two further occasions and both times was found to be healthy. The squirrel soon became known as
Clark because of his never-seen-before superpowers.
Fewer than 10 percent of the Formby squirrels showed signs of antibodies but even such a small number is a sign that the red squirrel is beginning to form a resistance to the virus. It shows that there is a chance – however slim – of the antibodies spreading in to the red squirrel population and so helping the species avoid localised extinction in the British Isles. It also increases the chances that a successful vaccine might be developed. Yet how did the virus get there in the first place?
The answer lies in a somewhat unwelcome visitor from the United States. Grey squirrels were introduced to the UK in the late nineteenth century and by 1945 had spread throughout the country. It brought the squirrel pox, against which it had already developed a resistance, with it. As the species spread throughout England, Wales and the south of Scotland, it displaced the native (and arguably cuter) indigenous red squirrel. The numbers say it all: there are now close to three million greys in the UK, opposed to just 160,000 reds. Scientists have never been able to successfully work out just how the virus is passed from the grey to the red.
Although there are other reasons for the decline of the red, many studies have been undertaken over the decades. These showed that where the pox was present, reds were replaced by greys twenty times faster than otherwise. Greys quickly displaced the reds and became the squirrel du jour, not only in towns and cities but in the countryside too. The reds were pushed in to small enclaves of population on the mainland. They also retained populations on the islands of the United Kingdom, such as the Isle of Wight in England and Ynys Môn (known as Anglesey in English) in Wales.
Eradication of the disease is essential to the future of the red squirrel. Greys carry it and although it affects them too, most recover from the disease. Yet even if a cure was found, it is unlikely the two species could ever live together. Although they do not participate in paw-to-paw combat, the greys can digest food such as acorns easier than the red which gives it the upperhand. Add the fact that the red, being naturally a little highly strung, fails to breed as well when disturbed (and the bounding, bouncing and general nosing about of the greys qualify as this) and you do not have a recipe for successful squirrel integration.
Still, this news is added hope for the red squirrel. The Formby population has shown a remarkable resilience and ability to bounce back. Yet resistance is not full immunity. The poxvirus will, no doubt, strike it again – yet next time it is hoped that the mortality rate will not be as staggeringly high. When (it is not an if, unfortunately) it returns it could reveal whether or not the red squirrels of Formby have any long term immunity. Let’s keep our fingers crossed that one of the most popular British species of wildlife now has a better chance of long term survival.
First Image Credit Flickr USer Nico Kahkonen
Superman red squirrel modified courtesy of Flickr User Jenny Downing
