Grey Squirrels Drive Red Squirrels Towards Extinction in UK
Introduction of grey squirrels from North America in the 19th century has led to a drastic decline in the native red squirrel population, with conservationists exploring new control methods.
Endangered red squirrel populations in the UK have dramatically decreased, from an estimated 3.5 million to fewer than 300,000, largely due to the proliferation of invasive grey squirrels.
The situation is particularly critical in England, where red squirrel numbers are thought to be as low as 15,000 in some conservation areas. Conservation groups warn that the native red squirrels could vanish entirely within 25 years if current trends continue.
Grey squirrels were first introduced to the UK from North America in the 19th century. The earliest verified introduction is traced back to 1876, when a banker named Thomas V. Brocklehurst released a pair into Henbury Park, Cheshire, after acquiring them during a trip to the United States. Today, there are an estimated 2.5 million to 2.7 million grey squirrels across the UK.
Conservationists state that red and grey squirrels cannot coexist. Jackie Foott of the British Red Squirrel group explained that grey squirrels outcompete reds for food and habitat, and, crucially, carry the squirrel pox virus. While the virus does not affect greys, it is fatal to red squirrels, causing them to develop ulcers and blindness.
"The grey squirrel is a pest, non-native, invasive species," Foott stated, highlighting the significant damage they inflict on trees, crops, and properties, causing an estimated £40 million in damage to forests and forestry services annually.
Effective control methods for grey squirrels are limited. Fertility control is not currently viable as it can affect other species, and gene therapy is likely a decade away. For now, the primary methods involve lethal control through shooting or trapping.
However, conservationists are exploring new potential solutions. Graham Paskett from the Red Squirrel Survival Trust is involved in a joint field trial with the government's Animal and Plant Health Agency to test an oral contraceptive delivered via a specialized feeder. This feeder is designed so that only the heavier grey squirrels can access the contraceptives, leaving the lighter red squirrels unharmed.
If trials prove successful, landowners and forest rangers may be able to implement this new method. In the meantime, the reintroduction of native pine martens is also being considered as a potential aid. While pine martens do prey on red squirrels, the native reds have evolved to evade them. Grey squirrels, being less familiar with this native predator, are more vulnerable, offering a natural means of population control.