Pet mouse behaviour and body language explained

What noises do mice make?

Mice make most of their calls in ultrasound that people cannot hear, so a happy mouse cage usually sounds quiet. RSPCA Australia lists the sounds people can hear as gentle chirps or clucks, grinding, squeaks and hissing. The RSPCA says mice hear a very wide range of frequencies, which is why they are so sensitive to high-pitched and sudden noise.

RSPCA Australia also notes that mice rarely make sounds we can hear, so a new sound, or the same sound over and over, is worth a closer look.

Grinding splits our sources. RSPCA Australia lists it among the normal sounds you can hear, while the RSPCA lists grating teeth as a reason to see a vet. We read it by context: quiet grinding in a mouse that is eating, moving and grooming normally is fine, and grating in a hunched, still mouse is not.

What does it mean when a mouse squeaks?

A squeak usually means a mouse is surprised, protesting or scared. Among cage mates it often means "back off": over food, the best nest spot or who is in charge. The PDSA says squeaking, sniffing and chasing during introductions are normal dominance behaviour, and to separate mice straight away only if blood is drawn.

A mouse that squeaks every time you pick it up is usually still nervous. Go back a step with hand-feeding, as our guide to taming a pet mouse explains. A mouse that has always been calm and suddenly squeals when touched may be hurting, and needs a vet.

Mouse body language: what each sign means

Mice say more with their bodies than their voices. Watch posture, fur, tail and ears together, not one sign alone.

Normal pet mouse behaviour

Normal mouse behaviour is busy, curious and very social. Mice are most active at dusk, dawn and through the night, says the RSPCA, and Wood Green notes pet mice often have broken-up sleep patterns, so they may be awake when you are home. Day to day, expect to see:

• Running along walls and bars rather than across open floor. The RSPCA says mice like contact with upright surfaces and find open spaces stressful.
• Digging and tunnelling in deep bedding.
• Carrying nesting about and rebuilding the nest, sometimes every night.
• Gnawing on cardboard, wood and chews; their front teeth never stop growing.
• Eating some of their own droppings, which the RSPCA says gives them vitamins.
• Choosing one corner as a toilet, and marking objects with scent.
• Sleeping in a heap, though The Crittery says one mouse sometimes sleeps alone.
• Investigating a new toy, avoiding it, then coming back to it; RSPCA Australia says mice are wary of new things at first.

Most of this needs space and things to do. Our guide to pet mouse enrichment shows how to give mice room for it.

Are my mice fighting or playing?

Chasing, pinning, short squabbles and even same-sex mounting are normal, say The Crittery and RSPCA Australia. A fight is different: raised fur, hissing, rolling balls of mice, one mouse being chased nonstop, and wounds. Separate them if blood is drawn.

Males are more likely to fight. The MSD Veterinary Manual says fight wounds are common in males, and the RSPCA warns males can be aggressive towards mice they do not know, and fight more if they can smell females. The RSPCA also says adding or removing even one mouse can set off intense fighting across a group. Our guide to male or female mice covers safe groups and introductions.

Abnormal mouse behaviour: signs something is wrong

Abnormal behaviour in mice usually points to pain, illness or a home that does not meet their needs. The RSPCA says any change from a mouse's normal behaviour could mean something is wrong. Watch for:

• Repetitive movements done over and over in the same spot. The RSPCA links these to barren homes, stress and boredom.
• Barbering, where one mouse chews another's fur or whiskers into bare patches. The MSD Veterinary Manual links it to dominance, stress, boredom or inheritance.
• Self-gnawing or over-grooming to the point of sores. The RSPCA says to see a vet.
• Hiding all the time, or a mouse sitting hunched and alone.
• Sudden aggression in a mouse that used to be gentle, which can be pain.
• Head tilt, circling or wobbling, often an ear or breathing infection.

Rule out illness with a mouse-savvy vet first, then look at space, hides and enrichment, as RSPCA Australia advises. The signs and what vets do about them are in our pet mouse health guide.

Noises mice make in a house: wild mice

If you hear scratching, scurrying or gnawing in walls, lofts or under floors at night, it is usually wild mice moving about. The RSPCA says rodents are naturally nocturnal and good climbers. The squeaks you hear are rare, because most of their calls are ultrasound.

The RSPCA lists the wild mice of Britain as the house mouse, the wood mouse, the yellow-necked mouse and the harvest mouse. House mice are most often found in homes and gardens and can come in at any time of year. Wood mice, among the most common wild rodents in the UK, usually only come into buildings in winter. The Wildlife Trusts say house mice are now found far less often in houses than in sheds, garages and farm buildings, thanks to better building.

For wild mice, the RSPCA asks people to use humane deterrents, starting with removing food such as spilled bird seed, which mice love. Please never use ultrasonic repellers in a home with pet mice: they are designed to bother rodents, and your mice will hear them all day.

Pet fancy mice are the house mouse species, tamed over a very long time. Our pages on pet mouse facts and pet mouse breeds and colours explain more, and the full care picture is in our pet mouse care guide.