Saturday, January 10, 2015

Grey Squirrel

Cute little darling or tree rat?

Depends on your attitude to introduced species or your fondness of our indigenous red squirrel Sciurus vulgaris. 

Eastern grey squirrels, Sciurus carolinensis, were introduced from the Eastern USA on several occasions from 1876 to 1929 (Oliver Rackham - The History of the Countryside). Up until that time the red squirrel was the only one you'd have come across. I would be confident to bet that fewer than 1% of people have seen a red squirrel in the wild in the last ten years.

They are in the same phylum and class as us (mammals) but a different order: Rodentia. The family is Sciuridae which contains about 250 species, and the name comes from the ancient greek meaning 'shadow tailed'.

Under English law, if a grey squirrel is trapped it may not be released but must be 'humanely destroyed'. The reasons for the extirpation of the red by the grey are still debated. The grey is more omnivorous than the red, which means it is less likely to suffer food shortages. It is also a carrier of a virus which makes the red squirrels very poorly. It is bigger than the red and could beat it in paw-to-paw combat. But there are anomalies in its spread that mean there must be other ecological mechanisms involved. 

The other interesting thing about squirrels is that they are masters of deception. They cache several thousand items of food each season, usually by burying in the ground. However, if they are being 'watched' by a rival (of the same species or another after the same foodstuff) they will pretend to bury it, whilst in fact hiding it in their mouths and burying it later out of sight of the rival. Or if the rival is unable to climb trees, they will hide it up in a tree. This behaviour begs questions about consciousness and the theory of mind. Discuss.

The large nests that they build in trees are called dreys.
Post a Comment