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Introduction to small mammals of the North East

The small mammals section is an amalgamation of the orders of lagomorphs, rodents and
insectivores. The most obvious unifying characteristic of the extant British members of these
orders is that they are indeed all relatively small in size. However many of them do have other
similarities such as a breed fast, die young life history. They also include the species most
readily encountered by people. Some of these disparate groups are even surveyed by the same
methods; for example, small mammal traps which catch examples of both the smaller rodents
and insectivores. Similarly, an analysis of owl pellets from most places in the region would likely
reveal up to three insectivore and five rodent species.

Most of the species in this section are widespread in England and Wales, almost ubiquitous in
some cases. Consequently there is not a great deal that can be said about their regional status,
which is presumed to be similar to that nationally, and this is reflected in the shorter accounts
for the shrews and certain rodents. For other small mammal species their regional status is
also notable nationally; the Dormice Muscardinus avellarius in Allendale have long been an
incongruous population that is isolated from Dormouse populations much further south, while
for Harvest Mice Micromys minutus the Tees Valley is the most northerly place in Britain where
the species is widespread. For some time the south of our region was the northernmost limit
of the Grey Squirrel Sciurus carolinensis in England. Its regional conquest now seems to be
complete though its corollary, the loss of the Red Squirrel Scuirus vulgaris, would appear to be
still some way off, at least in Northumberland.

For many people, it is the species in this section that they are most familiar with: the squirrel or
hedgehog in their garden or the rabbits and moles in the road verges. Consequently this section
includes the best recorded mammals in the North East. Surely no species is easier to survey for
than the Mole Talpa europea, or at least its most obvious sign of mole hills. This is reflected by
the fact that records to date show it as being recorded in every 10 km square in our region barring
two partial squares on the coast. Conversely this section also includes the most under-recorded
species. Most people’s reaction to a mouse is to report it to the local pest control office rather
than the local Environmental Records Information Centre. If someone were lucky enough to
glimpse a shrew, even if they were a mammal enthusiast, how often could they confidently tell
whether it was Common or Pygmy without being able to fold its tail over its head to judge its
relative proportions? Consequently House Mouse Mus domesticus and Pygmy Shrew could, in
different ways, both claim to be the most under-recorded mammal species in our region.

That the distribution maps in this book reflect recording effort rather than the current distribution
of a species is particularly highlighted in this section. Where research projects have concentrated
on surveying a particular species they have in some cases, such as Water Shrew Neomys fodiens
and Harvest Mouse, caused a re-evaluation of that species’ status regionally. However this focus
of attention could, if not put into context, give an exaggeratedly positive impression of a species’
status. For example, the dots on the distribution maps for Red Squirrel show a much wider
coverage post-2000 than pre-2000, the opposite of what was actually happening to the Red
Squirrel itself in both numbers and distribution. A number of small mammals projects in the
region have shown what can be achieved in evaluating a species’ status and it will only be by
expanding that recording effort that we will be able to improve on our current understanding.

Written by Ian Bond (last updated Nov 12)