The Wonderful Wood Mouse

This article was originally published in The Northumbrian Magazine and is republished with permission. Author John Steele previously worked as a long serving Northumberland National Park Ranger.

A hilarious disaster film over Christmas featured in the starring role a most resourceful mouse who literally brought down a multi-million dollar property in his efforts to defend himself.

“It’s the Omen with whiskers” was the description used by its pursuers, but I suspect there are many people who share similar feelings towards this most humble of creatures.

Since humans first began to inhabit dwellings the mouse must have shared the space with them gaining shelter, warmth and food. But when did it start running the gauntlet of anxious humans?  I suspect as soon as it began to compete with us by eating or spoiling hard won, stored winter food stuffs and seed corn for the following year.

The house mouse originates from south western Asia and probably travelled to Britain as a hitch-hiker with migrant humans long ago. It’s known that they were present at the beginning of the Iron Age over 2,500 years ago, but they probably arrived here much earlier. The other common mouse in our area is the native wood mouse, variously called the field or long- tailed mouse over the years.

a small wood mouse being held

Both these species are to be found indoors at times, mainly in autumn and winter. The house mouse is the main occupier of our dwellings, with the wood mouse turning up in outbuildings and garden sheds.

The two species are superficially similar at first glance.  They take a little sorting out, but by looking at the fur colour differences can be seen. The wood mouse is a rich orange brown with a clear break in the colour on the lower flank to its white belly, whereas the house mouse is a grey brown with no break to the paler belly colour. The wood mouse also has larger eyes and ears than its rodent cousin and usually has a small yellowish mark between its front legs.  It is known that in the English population around one in 50 has a white tip to the tail.

You can also tell the two apart by examining the teeth – a very useful tool to a naturalist sorting through the undigested remains of owl pellets to see what they have eaten. Even telling the sexes apart is possible when looking at the different-shaped pelvic bones.

Outside the house mice can be a real pest to the gardener. They have a sweet tooth for newly planted pea seeds, digging them up in turn and scampering off to store them under the garden shed or in a burrow system. I’m sure every experienced gardener has his or her own deterrent, but I read with interest an old strategy of soaking the peas in paraffin or rolling them in red lead before planting!

This hoarding habit is very strong in the wood mouse. In its woodland habitat hundreds of hazelnuts have been found stored in a pantry near the mouse’s nest within its burrow system. Hazelnuts eaten by the species have a characteristic roughened edge to the hole in the shell. Such activity probably accounts for the discovery by a farmer of a field drain packed with acorns from a near-by oak. The advantage to the woodland is that tree seeds get spread about, and because not all the seeds get eaten the trees regenerate.

Cat and Mouse illustration by John Steele

Normally a woodland walk reveals little sign of the nocturnal wood mouse unless you are searching under logs for eaten seeds, but every now and then your luck is in.

Over last Christmas it snowed, and conditions allowed me to get an idea how many mice are actually using the woods around Rothbury. Spotting their trail was not difficult, as every now and again my track was criss-crossed by series of marks looking as if toffee apples had been dropped at regular intervals. You see, in deepish snow a mouse jumps like a kangaroo, leaving the impression of its tail with every leap; I kid you not.

It always amazes me to think how the little devils get into houses, but every house will have chinks in its defences. Small finger-tip sized holes in walls or under doors are perhaps the more obvious entry points. Less obvious are holes at roof level. Both species are expert climbers, and any rough brick and rendered wall will provide access to the eaves.

I remember watching a young wood mouse quickly climb up a six feet of pebble-dash wall on my house before I apprehended it. I have also found old birds’ nests at the top of bushes containing the chewed remains of hawthorn berries, so you might as well forget all hope of being mouse-proof – especially if you have stairways to heaven like ivy or clematis clinging to the walls.

A smooth plastic or painted band six to eight inches wide, like a close- fitting fascia, will solve the problem, but please remember that the ‘mouse’ droppings in the loft may turn out to be left by bats. If in doubt, advice is always to hand on the bat advice line telephone (0345 1300 228).

Before the invention of tins and fridges in which food is now stored, protection of food from being spoiled by mice was a real problem. Apart from foodstuffs, mice seem to nibble at almost anything. Paper, stored clothing or fabrics make ideal nesting materials, while electrical cables, candles, soap and old lead pipes seem ideal for sharpening teeth on and not much else.

In the kitchen drawer of a holiday cottage I once came across a wooden spatula that had its fat-stained head bitten off. So much for taste!

When a wood mouse comes across a large item of food, it will hide it by covering it up with all sorts of debris pinched locally. Scraps of shredded paper, leaves, twigs, small stones and even bits of plaster are used. While I’ve never seen this myself, I can only imagine that after the banquet is over it looks rather odd, as though The Borrowers have been about!

Usually a house mouse can produce between five to ten litters a year, each consisting of five to six young. The young themselves are able to breed after only six weeks, so the potential population derived from one female in a year is……enormouse.