Grey Squirrels have been found to be one of the most prolific and adaptive species. These mammals are in fact native to eastern and midwestern parts of USA and also some parts south eastern provinces in Canada. These were deliberately released in UK at some point of the 20th century and they are giving one hell of a ride for the eco-system in UK.
Let us start with some basic stuffs. These are in the Least Concern level on the conservation chart, which means they are not threatened. Sciurus carolinensis is the scientific nomenclature for these grey squirrels and the typically are from grey to brown color.
In size, these squirrels grow to about 23 – 30 cm and the tail grows from 19 to 25 cm. The adults can weigh up to 600 g from 400 g. Grey squirrels are scatter hoarders and they have an awesome spatial memory which can lead them to their food hoards very accurately. These squirrels have almost taken over the whole of southern UK and Wales from the Red Squirrels, which have been pushed to the northern UK. If there were no Conifers on the northern UK, then the red squirrels would not stood a chance. The grey squirrels are not so good with conifers but they are good with immunity to a lot of diseases which are deadly to the Red squirrels like Parapoxvirus. Grey squirrels are also more fat than the Red squirrels which allow the grey ones to store more food in the form of fat to survive the winter. Surviving the winter with less amount of food is a big deal since these squirrels don’t hibernate. The trouble is not just with the effect on Red squirrels, but these grey squirrels have caused quite a mess for the trees and many other birds too by consuming their eggs and other means. But to me both are Kings of their own jungles.