Winter nights can mean a mouse in the house or even a rat. But poisoning isn’t the only way to get rid of them – humane mouse traps and deterrents are both possibilities that cause far less unnecessary suffering.
You’re also more likely to see mice and rats in your garden during winter, but so long as they stay in the garden and don’t cause damage to your shed or anything else, they shouldn’t cause any problems out there.
Which rats and mice enter houses?
House mice (Mus musculus), wood mice (Apodemus sylvaticus), yellow-necked mice (A. flavicollis) and brown rats (Rattus norvegicus) are all common in houses. Of the three mice, the one you’re most likely to encounter at home is the wood mouse, as this species is even more common in houses than the house mouse.
House mice and brown rats are most frequent in houses close to city centres, wood mice in the suburbs, and yellow-necked mice in rural areas in the South-east and Welsh borders.
Rats and mice are most common in roof spaces, then cellars and cupboards. They can also live in wall spaces.
Other visiting small mammal may include voles and shrews.
What attracts mice and rats to your house?
There are two main things that can attract mice and rats to your house – food and shelter. If you don’t tidy up properly and there’s food waste on the floor or surfaces, rodents are going to love it!
Rats and mice also need shelter, particularly during winter to avoid the worst of the cold. The same is true when they’re trying to find a nice warm spot to raise their young. A heated home with lots of places to hide away is perfect, and an untidy home even more so.
Mice can squeeze through gaps less than 2cm in diameter, and rats only need slightly more space, so any small hole to the outside can serve as a rodent gateway straight into your home.
Signs of rats and mice in your house
Cloying ‘acetamide’ smell characteristic of house mice; other mice leave little odour.
Gnawing – rodents need to gnaw continuously to keep their incisors short.
Tooth marks – larger ones are made by rats, who can gnaw through soft metals, such as lead and aluminium.
Droppings – rat droppings are 12mm long and often tapered at one end; mouse droppings are roughly half the size and thinner.
Greasy fur marks – rats and house mice leave dirty black smears along well-travelled routes, particularly ‘loop smears’ where they squeeze under roof joints.
What problems can mice and rats cause?
Rodents generally cause minor problems in houses – of those with yellow-necked mice, 42 per cent suffer damage to furnishings and internal structures, 31 per cent to food, and 9 per cent to insulation and wiring; 18 per cent suffer no damage.
Chewing wiring is a particular problem as it can lead to fires and be expensive to repair.
How to get rid of rats and mice in your house
Snap traps are a kind of humane mouse trap that kills instantly.
Live traps (pictured above) may appeal, but ‘dumping’ the animal in the wild is likely to lead to its death. Also, if you don’t take the rat or mouse at least 2km away, it may well arrive back home before you do.
Indoor devices that use electromagnetic interference or ultrasound to drive rats and mice out of houses can work brilliantly. But don’t use them if there are bats in the house or roof.
Anti-coagulant mouse and rat poisons cause a slow, painful death. Problems also occur if the rodent is eaten before it dies – 40 per cent of barn owls, polecats, stoats and weasels carry rodenticides from eating poisoned prey.
Prevention is the best long-term way to get rid of rodents in your house: repair broken air bricks and holes in outside walls, floorboards or skirting boards; tidy up cupboards and remove nesting material.