The Mulot, or Guernsey Vole: ours are biggest
From The Zoologist, May 15th 1906, in the Library.
Field-Vole (Microtus agrestis). I would like to draw attention to the great variability in the size of the Field-Vole. According to my own experience those in the South of England are, on the whole, smaller than those of the midland and nothern counties. Specimens I have examined, collected in Surrey, Hampshire, and Middlesex, were quite typical; whilst some collected in Warwickshire and Yorkshire were very large indeed, quite above the average. Whilst I was in Guernsey I was shown some Field-Voles that were very nearly as large as half-grown rats. I very much regret now I did not obtain some of these, as they might have proved to be an undescribed species or form. It is worth noting that - in the case of Voles, at least - those found on islands are larger than those of the mainland. Thus we have the Orkney Vole considerably larger than its near ally, the Field-Vole; and the Skomer Island Vole, which may be compared to a large Bank-Vole; and, lastly, the Guernsey Voles I have alluded to above. [From 'Field Notes on some of the smaller British mammalia', by Gordon Dalgliesh, pp. 168 ff.]
In 1909, an article was published in the Report and Transactions of the Guernsey Society of Natural Science and Local Research (now the Société Guernesiaise), pp. 34 ff., entitled 'The Guernsey Vole'. The Guernsey vole had been identified as a new species by Professor G. S. Miller, and named by him Microtus sarnius. R H Bunting of the Natural History Museum had been over to the island studying the voles:
Like the common Field Vole, it is gregarious, but unlike that animal, which lives in rough, uncultivated grass-land, the Guernsey Vole inhabits the the eath banks of hedges dividing fields under cultivation, preferably those which are not near a roadway or houses. The runs used by the voles are well marked, not only by the earth being well trodden, but also by the over-arching of such grasses and plants as grow in front of them. That the voles have themselves made these runs seems probable, since they are often too small to have been previously made by rats, and generally too high in the hedge and too old to be old mole tracks. Such vole holes as I examined penetrated a good way into the bank, and became too complicated for me to examine further without incurring the displeasure of the farmer who works the land.
It is probable that young are produced all through the warmer months of the year. Traps visited at dusk as well as in the early morning sometimes contained voles, which consequently must be diurnal as well as nocturnal in their habits of feeding. They appeared fairly common in certain hedges at St Martin's (the only parish in which I was able to trap) and seemed to be well known (as mulots)¹ by the neighbouring farmers.
For a modern account of local wildlife, see Daly, S., Wildlife of the Channel Islands, 2004.
¹ A general term for a field-mouse.