So how do the greys manage to replace reds so easily? To start with, size does matter. The greys are nearly twice the size of the reds, so of course where greys move in the reds become stressed at this oversized competition.
Both species are tree squirrels that are also classed as rodents because their teeth grow throughout their life. A commonly asked question is whether the 2 species can breed together but as they are too genetically different no, actually they can't. For the record, the white squirrels—and the black ones—you hear about are the American grey species. A greys coat has 3 colours in it, black, white and a reddish brown. In the black or white animals the other 2 colours are missing due to their genetic makeup. Food and good nest building sites are limited and the larger greys outcompete our smaller native red squirrels for essential resources. Grey squirrels live at a higher density—sometimes up to 10 or more per hectare whereas the reds live at around 1 per hectare. And this means other woodland animals—and the trees, which the greys ring bark are put under a lot of pressure. Both greys and reds eat a wide range of foods but the greys can digest chemicals -called tannins - in acorns, which the reds can't do effectively, although they do forage for acorns and eat a few. This gives a huge advantage to the American greys, who get fat on acorns and put on 20% of their bodyweight for the winter The most devastating and cruel twist of fate is that around 70% of grey squirrels carry a disease called squirrelpox virus, which they do not contract themselves but they pass it on to any reds they come into contact with. The disease can virtually wipe out a population of red squirrels very quickly. However, red numbers can start to rise once the disease burnt itself out - after killing 90% of the population. Once the greys are taken out and the disease has gone, then the red squirrel numbers do begin to rise. This scenario has been playing in other parts of the UK for many years.
The Isle of Wight is 'grey free' and we want it to remain that way! As an important stronghold for our nationally endangered native red squirrel we must be especially vigilant to keep the American off the Island. The greys are appealing in their own way but unfortunately they carry a horrific disease, called squirrelpox virus, which they don't contract but the reds do and die horribly from. Greys also live at much higher densities and take resources from red squirrels, birds and other small mammals. They also damage trees. Wight Squirrel Project monitors squirrels using various non-intrusive methods and if a grey is reported it is logged and the area monitored more intensively. There are contingency plans for dealing with any greys found on the Island. There is a problem with identification however as red squirrels can have grey coats!! Tricky! Light levels and the distance away the 'grey' is seen can also change perception. Here are a few ways to 'spot the difference'. Firstly, size matters! An adult grey is nearly twice the size of an adult red and an altogether chunkier animal. A young grey squirrel could be the size of an adult red of course. In the winter, reds have the iconic long eartufts, greys never have long eartufts. Reds lose their eartufts in the summer. A grey coloured red squirrel doesn't usually have a brindled coat as a grey does. If you can get a close look at a greys coat, it has 3 colours in it, white, black and a brownish red. To make matters worse, when a grey moults, it can look red for a short time! Looking at the tail is a good way to identify between species. A grey squirrel's tail has the 3 colours in it. The bulk of the tail is red/brown with a band of black around it and then a halo of white. A red squirrel's tail – even those with a grey coat – does not have this distinctive banding.
If you think you have seen a grey squirrel on the Isle of Wight, please ring Helen on 01983 611003. Usually a chat and few questions can determine if the animal is a grey squirrel – or hopefully not.
For more information on red squirrels and projects on the island, visit the IOW Red Squirrel Trust website.
You can easily and effectively help red squirrels by becoming a Friend of the Red Squirrel. Become our Friend.
Have you seen a Red Squirrel on the Isle of Wight?. Please let us know.