For many people, rats and mice signify health hazard. Yet others can happily buy a pet rat or mouse at the petshop. A look at the local newpaper and the headline shouts out : "Tenant's agony over rat troubles at council house in Dumbarton". (D&VoLReporter 28/3/23). Are rats a problem or simply a symptom of other problems? Possibly both.
In the wild they are simply wildlife as with any other animal.
In built up areas they can be a problem. Perhaps it is the human species that attracts them through their discarded food or cosy corners. Rats communicate and mark their territory by urinating everywhere they go, representing a significant public health risk. They can carry many nasty diseases, which can spread to humans, normally through rats’ urine or body coming into contact with food preparation areas. If found in numbers they can really be quite a threat to us.
But out there in the natural environment, they face natural predators and their numbers are more controlled. And they even provide food for foxes and birds of prey.
Mice are less of an urban pest. They may nibble your insulation to make nests or get at your groceries, but many a cat has honed its skills at catching them. (Unfortunately, many a cat may also find it fun to catch one alive, bring it in, perhaps as a gift to you, and let it run around the house).
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.
There are 3 types of shrew in Scotland : common shrew, the pygmy shrew and the water shrew.
Shrews have a very high metabolic rate, so must eat 80 to 90% of their body weight every day – and nearly twice this when feeding their young. A shrew will die if deprived of food for more than a few hours.
Shrews benefit humans as they consume many leatherjackets (larvae of crane flies), caterpillars and other plant bugs. Each shrew eats hundreds of small invertebrates a day.
Due to their their scent glands located along their flanks which produce a distasteful musky odour shrews are rarely eaten by savengers. They were formerly subjected to persecution owing to the belief that if one was allowed to run round the feet or hands, the limbs would lose their power for ever afterwards. It was even thought that they could cause death to cattle. Such superstitions may have arisen from their distasteful properties.
BROWN RATS : Rattus norvegicus
The brown rat adapts itself to almost any environment. All it needs is shelter and food. They are omnivorous, eating pretty much anything, from fruit and seeds to human food waste, insects, birds' eggs or even small mammals. They are particularly common around towns and cities. Brown rats live in loose colonies and dig their own burrows. They are famously good breeders; a female brown rat can breed from around 3 months old, and has an average of five litters a year, each of up to 12 young.
A pair of brown rats on a dry stane dyke enjoying food put out for birds.
HOUSE MOUSE : Mus musculus
As its name suggests, the house mouse thrives wherever there are people, particularly in farm buildings, warehouses, sheds and garages, although it is no longer a common resident of our homes due to better construction. It eats grains, seeds, roots, fungi and insects. House mice construct a series of tunnels to live in. Females can have up to 10 litters a year of four to eight young.
WOOD MOUSE : Apodemus sylvaticus
The wood mouse is sometimes known as the long-tailed field mouse. It is most common in woodland, rough grassland, muirland and gardens. It is mostly nocturnal and an agile climber. They gather food stores of berries and seeds in the autumn, which they keep in underground burrows or sometimes in old birds' nests. Females have up to six litters a year of between four and eight young, and may even breed over winter if food is abundant. It is usually a golden-brown, with a pale underside, large ears and eyes, and a long tail. It is bigger than the harvest mouse, and browner in colour than the house mouse.
COMMON SHREW : Sorex araneus
The common shrew has tiny eyes, very small ears and a pointy face with a long nose. It is dark brown above, grey or silver below, and has chestnut-coloured sides. It is larger than the pygmy shrew, but its tail is only half the length of its body (pygmy shrew tails are two-thirds the length of their bodies).
PYGMY SHREW : Sorex minutus
When you find a very small shrew, this is probably what it is. Not a baby, but a pygmy shrew. It is very small, insectivorous mammal, the pygmy shrew has with tiny eyes and a large nose giving it a keen sense of smell. Shrews hectically snuffle through the undergrowth for their prey, which includes spiders and woodlice. They can be found in most habitats. Active by day and night, they are very territorial and aggressive for their size and can sometimes be heard fighting, their high-pitched squeaks particularly noticeable during the summer. Adults may only live for a year, just long enough to have one or two litters of around six young.
WATER SHREW : Neomys fodiens
This our largest shrew. It lives almost entirely in wetland habitats, such as streams, ponds, fens and reedbeds spending much of its time hunting for invertebrates and even swimming underwater to catch caddisfly and mayfly larvae. Although it doesn't have webbed feet, stiff hairs on its back feet and tail aid swimming. Water shrews live in small burrows in the banks of their watery habitats. They breed throughout summer, producing three to fifteen young per litter.
BRITISH PEST CONTROL ASSOCIATION : https://bpca.org.uk/a-z-of-pest-advice/rat-control-how-to-get-rid-of-and-prevent-rats-bpca-a-z-of-pests/188991
NATURESCOT website : https://www.nature.scot/plants-animals-and-fungi/mammals/land-mammals/other-small-mammals#:~:text=%20Mice%2C%20voles%20and%20shrews%20are%20the%20most,and%20nearly%20twice%20this%20when%20feeding%20their%20young.
SCOTTISH FIELD website : https://www.scottishfield.co.uk/outdoors/wildlifeandconservation/of-mice-and-men-the-rodent-that-can-cause-havoc/#:~:text=We%20have%20three%20types%20of%20outdoor%20mice%20in,wood%20mice%2C%20although%20these%20too%20can%20come%20indoors.