Of mice and men – the rodent that can cause havoc

The mouse’s bad habit of inviting itself into our homes has made it few friends among humans, but being hunted by us seems preferable to the owls, foxes and raptors waiting to pounce outside.

They say you can tell a great deal about a person by the state of their car. We had been driving around for a fortnight before we became aware that we were not alone.

It began with a minor dispute about the mess in my beloved’s vehicle. I had grumbled about the ripped-up sweet papers all over the front passenger foot well, and Iomhair, as he frequently does, had denied all responsibility and brushed my accusations aside.

As no one but us had used the car, I just raised my eyebrows and gave a cheeky response. But he stuck to his story.

Not long after, I was helping myself to a bar of chocolate in the door pocket when I noticed more papers on the floor ripped into tiny little pieces, plus some rather ominous slivers of plastic wire coverings. I looked more closely at the chocolate: it was already open at one corner.

And then I noticed the teeth marks. Iomhair has big teeth, and these marks were tiny. A mouse! We worked out that a fortnight earlier during a car clean-up operation, Iomhair had left a rucksack in the shed overnight before putting it back into the car. He had then driven to Glasgow, and we had both been to Perth on several occasions, as well as buzzing about locally daily.

Having sneaked into the bag, the backpacking mouse must have revelled in the warmth of the car while fuelled with a feast of crisp and chocolate crumbs. Its penchant for car wiring was of graver concern.

We set a couple of traps and caught the culprit within hours. It was then fed to my owls, while I had to eat humble pie.

At the moment, Edinburgh has a higher rate of pest control call-outs due to mice than any other Scottish city. For such diminutive creatures, the amount of damage they inflict is astonishing. Responsible for floods when plastic piping is chewed through, and fires when they cause wires to short out, mice can also be the ruination of crops and gardens, as well as destroying personal items.

They are the bane of insurance companies; indeed, many won’t pay up for ‘mouse damage’. (It’s crucial to scrutinise the small print before you sign up.)

Like their close relative the rat, their propagation rates are alarming. Their rampant sex lives and the fact that they can breed at less than two months of age (and all year round) are only part of the issue. Males are said to sing squeaky love songs to their mates. Their gestation period is a mere three weeks and just one healthy female produces at least 120 mice annually; when all the female offspring do the same thing, it is easy to see how things get out of control.

A mouse’s life is usually only a year to two years long, and they are heavily predated, but that still leaves plenty of time for mischief.

The word ‘mouse’ has ancient connections with various languages including Latin and Greek, and is thought, appropriately enough, to have meant ‘thief ’. Mice are good swimmers and superb climbers, and are happy to take huge aerial leaps to avoid trouble. Their frenetic disposition dictates that they must feed about 15 to 20 times a day; with such a catholic diet, they tend to be everywhere, all the time, and usually move into buildings in the late autumn.

The expression ‘as quiet as a mouse’ is inaccurate: the mice in our attic sound as if they are wearing clogs and have regular nightly ceilidhs until we set traps again. As we lie in bed we can hear their Highland flings across the boards above followed by a sharp snap, and then silence as another short life terminates.

Once widely viewed as Shamanic symbols of wisdom, discovery and organisation, they were also thought to be valuable in curing many common ailments such as bed-wetting and rheumatics. Three roast mice was said to cure whooping cough.

We have three types of outdoor mice in Britain: the wood mouse, also called the long-tailed field mouse; the yellow-necked mouse, which is far less common; and the harvest mouse, which is almost never found in Scotland. And then there is the ubiquitous house mouse.

Most of the mice in Scotland are wood mice, although these too can come indoors. House mice, however, really thrive best inside and in the presence of humans and our mess. Their strong, distinctive smell is enough to warn of a serious problem. We wage an eternal war but they have become immune to many types of poison, and the knock-on effects of secondary poisoning on some of the species dependent on them is of major concern.

On the island of St Kilda, two endemic subspecies of mouse were officially recognised. Only one now remains, the St Kilda field mouse, which is thought to have arrived with the Vikings.

Research has been done to find out why this mouse is almost twice the size of its mainland relations. It appears that it is because it has few predators and has evolved to be bigger to help it cope with the severity of the Atlantic climate.

When the islanders were evacuated in 1930, the house mouse soon disappeared, and there have been no signs since.

Naturalist and writer Frank Fraser Darling spent some time on Lunga, one of the Treshnish Isles, in 1937 and found that unlike the house mice on St Kilda, those on Lunga had adapted well to al fresco living even though the people had left 80 years before. They soon invaded his camp, but if these rodents were still there why had St Kilda’s own house mice died out within two years of the islanders’ departure?

Voles too can cause mayhem. They support a whole host of species such as owls, raptors and foxes, and their numbers tend to have four-to-five-yearly cyclical peaks and troughs, as do the creatures dependent on them. The short-tailed field vole is well known to foresters and farmers.

Like St Kilda’s field mouse, Orkney has its own endemic vole, and it too is considerably larger.

Its DNA suggests its origins were in Belgium some 5,000 years ago, and it must have arrived in the islands with Neolithic settlers.

Island mice are indeed unique. Foula, Shetland’s most westerly and isolated island, has its own endemic field mouse reputed to have particularly large feet. When I asked a Shetlander about this she replied: ‘It’s so as the puir beastie can haud onto the grund during the hurricane-force gales they get out there.’

  • This feature was originally published in May 2014.