Old bones revisited.

These fragmentary skulls were excavated from a Neolithic burial site on the Orcadian island of Rousay in the early 1930s. They belong to a species of grazing rodent widely known as the Orkney vole Microtus arvalis but locally called a cuttick, cutoo, or volo.

Microtus arvalis is widely distributed on continental Europe but in the British Isles it is only found on the Channel Island of Guernsey and on 8 of the Orkney islands lying to the north of mainland Scotland; Mainland Orkney, Eday, Westray, Sanday, Burray, Hunda, South Ronaldsay and Rousay. The species has never occurred on mainland Britain.

This strange distribution deserves some explanation! Guernsey voles may have been introduced but it is more likely that they are a relict population from the end of the Pleistocene when sea levels were much lower than at present and the island was connected to continental Europe. 

The Orkneys have never been attached to Europe by dry land and it is unlikely in the extreme that voles swam to them. The first Orkney voles almost certainly arrived as stowaways on the boats of Neolithic settlers around 5500 years ago. Genetic studies of the voles suggests that their ancestors originated in France or Spain.

Since arriving in Orkney the voles have increased considerably in size; at 40-70g they are getting on for twice the weight of their continental cousins. Island life obviously suites them!