Threats to Red Squirrels

Protecting red squirrels is at the heart of our work

The Grey Squirrel

The introduction of grey squirrels from America between 1876 and 1929 and their rapid spread had a devastating impact on red squirrel populations in the British Isles. In contrast to the red squirrel which has evolved in Britain over millennia, the heavier grey squirrel lives in denser populations than British woodland can sustain.

Squirrel eating acorn on tree


The higher population density of the larger grey squirrel results in a higher daily food requirement from its habitat.  It can eat a greater variety of plant foods at an earlier stage of maturity. For example, red squirrels find unpalatable the tannin in acorns, a plentiful and high energy food source favoured by greys which will also eat all the other foods eaten by reds. The outcome is inevitable: the red squirrels are literally starved out.


Grey squirrels are carriers of squirrel-pox virus and often remain asymptomatic. The disease is devastating for red squirrels and an outbreak can wipe out the majority or all of a local population. Infected individuals can take up to two weeks to die, often starving to death as they are unable to feed themselves.

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