"The native red squirrel Sciurus vulgaris was formerly distributed throughout Great Britain , but, since the early 20 th century, has been undergoing a long-term replacement by the introduced grey squirrel Sciurus carolinensis . This is though to be through a combination of competitive exclusion and epidemic disease. In England and Wales , replacement of the red by the grey is at an advanced stage; in Scotland there are still large areas with red squirrels.
The UK Red Squirrel Group has recognised that the removal of the grey squirrel, to reverse the decline of the red, is neither realistic nor achievable and that preventing the spread of greys into areas of broadleaved woodland is extremely difficult. Instead, it has proposed a conservation strategy based on defending red squirrel populations in areas where they appear to be at least competitive disadvantage to grey squirrels. For England , this would retain red squirrels only on some islands and in large areas of coniferous forest in the north. The England Squirrel Group has identified and agreed a series of priority areas that meet these criteria. Here, the intention is to maintain the red squirrel through a combination of habitat manipulation and detection and removal of grey squirrels.
A consequence of this strategy is that areas outside the priority areas that currently have red squirrels can be expected to lose them over the next decades. This means that the area occupied by reds will decline until it is approximately equal to the area of defended priority areas. Although it may seem unusual to have a BAP target that accepts a decline in range and population, to do otherwise is considered unrealistic and out of step with the UK strategy
Predicting the rate at which red squirrels may continue to be lost is difficult as it depends, to some extent, on unpredictable factors such as outbreaks of squirrel pox virus disease and the extent to which reds will persist in the presence of greys.
Targets may be set either in terms of range or populations. However, knowledge of red squirrel population size is poor and there are currently no field methods available that could be used on a sufficiently wide scale to generate meaningful population estimates, or even estimates of population change. We propose, therefore, to set only a range target.
There are now 172 10km squares fully or partly in England with red squirrel records and 82 10km squares fully or partly in England that intersect with the priority areas that will be actively defended. Our preliminary estimate of the rate at which reds may be lost is shown in the table below"
