The red squirrel's range spans northern Europe to Asia, but it is considered endangered in the United Kingdom. The main problem is that the Eastern gray squirrel, introduced from North America, has spread across most of the United Kingdom. Gray squirrels normally outcompete the reds, and they carry a deadly virus called squirrelpox, which quickly kills red squirrels. Yet the tide may be turning. The Isle of Anglesey is now free of grays, thanks to an eradication project that took 18 years. Some advocates hope that the recovery of the pine marten, a relative of weasels and badgers that preys on gray squirrels, might provide long-term relief for the reds. Scientists caution that much about the pine marten's resurgence and ecological impact remains unknown. The plight of the United Kingdom's red squirrels is a cautionary tale: The gray squirrel has colonized part of northwest Italy and may be poised to invade neighboring countries.
- ↵* in Bangor, U.K.