The remaining population of red squirrels in the UK is thought to be 120,000 of which roughly 75% of these are located in Scotland. Grey squirrels currently out number reds by around 66 to 1 in England. Red squirrels live for an average of three years in the wild but have been known to live for up to 10 years in a protected environment.
For a variety of reasons the British red squirrel is one of the UK’s most threatened species and is still in need of urgent protection and intervention. Over the years several factors have had a very negative impact on red squirrel numbers. Perhaps the most serious was the mass deforestation of Britain that has taken place at various times in this country’s history. In fairness, this had a devastating impact on all woodland creatures. Just as bad was the attitude of some estate owners. For many years red squirrels were also seen as a threat and a pest. Gamekeepers often had instructions to kill them. Fortunately, this practice stopped in 1920. Currently, the main threats to red squirrels are:
1. LONG TERM CLIMATE CHANGE
Warmer average temperatures favour deciduous / broadleaf trees and conifer forests have been retreating north for thousands of years. These conifers are the safest habitat for red squirrels and without them they are far more vulnerable to predators and competition.
2. HABITAT DESTRUCTION / FRAGMENTATION
Clearing indigenous forests for agriculture and settlement resulted in massive habitat destruction for the red squirrel. This process started hundreds of years ago and occasionally still continues today. It can also result in the isolation of red squirrel populations from both each other and their sources of food. This threat can also increase the risk of predation from wild and domestic animals if red squirrels have to cross open areas.
In addition, where broadleaf trees have been replanted – often for commercial purposes – the new tree species is not ideal for red squirrels. Reds favour particular species within conifer forests such as Scots Pine, Norway Spruce and Lodgepole Pine.
3. GREY SQUIRREL DOMINANCE
The introduction of the grey squirrel to Britain in 1876 had a profoundly negative impact. The main reason is that the larger and more adaptable grey generally out-performs its red cousins in terms of habitat usage, food tolerance and immunity to disease. As a result the population of grey squirrels has rapidly expanded while red squirrels have slowly but surely been pushed out due to attrition of numbers. Greys store body fat faster than reds and are often better suited to the types of woodlands now common in England.
4. SQUIRREL POX (SQUIRREL PARAPOXVIRUS)
The grey is a carrier of squirrel pox and although this is relatively harmless to greys, it is deadly to reds. This means that when grey squirrels come into contact with reds it is not uncommon for there to be a significant outbreak of the disease and a rapid decline in red squirrel numbers. It is for this reason that every effort needs to be made to keep the two populations apart.
5. OTHER DISEASES
Red squirrels are vulnerable to other diseases as well as squirrel pox.
The adenovirus is a relatively recently identified threat and as such its impact on wild populations is still not well understood. The infected squirrels show little or no outward signs of illness until death.
6. ROAD KILLS
Road traffic is responsible for many red squirrel deaths each year.
The main predators of the red squirrel are birds of prey (raptors) such as the golden eagle (Aquila chrysaetos), buzzard (Buteo buteo) and the northern goshawk (Accipiter gentilis). Ground-based predators include the pine marten, red fox and wildcat. Domestic cats will also prey on red squirrels if the two species come into contact.