Wood Mouse

THE WOOD MOUSE

Habitat

Occurrence: All over Europe, from Northern Africa to southern Scandinavia, Britain and Iceland. For Central and Northern Europe, the wood mouse in rural areas is the natural occurring mouse species, more common than the house mouse. In and on buildings both kinds, house mice and wood mice, can be found alongside each other.

Despite their name, they are not restricted to forests. Contrary, they don’t like closed needleleaf forests. Wood mice are regarded as pioneer species are highly adaptive and inhabit almost any kind of environment. They prefer hedge rows, grassland, cultivated land, riverbanks, trenches, gardens, parks, edges of deciduous and mixed wood. They settle in garden sheds, barns, shacks, grain stores and stables, also under piles of brick or wood. In autumn, wood mice enter human buildings to find shelter for wintertime.

Inside of buildings they populate the same areas as house mice.

Attics
Garages
Garden sheds
Basements
Ceiling, floor and wall voids, often near corners and heat sources
Corners in cluttered areas
Beneath cabinets
Furniture voids - couches, chairs, dressers
Bases of kitchen furniture and appliances
Cluttered, neglected drawers
Storage boxes

Lifestyle / behaviour

Mainly nocturnal activity to avoid predation. Wood mice are excellent climbers jumpers and swimmers. They can jump vertically up to 45cm.

Wood mice live mostly in burrows. The burrow is about 50cm underground and usually has several entrances, a nesting chamber and several storage chambers. The nesting chamber is slightly larger than the animal and cladded with soft materials like moss, leaves and fibres. Indoors, nests are padded with soft materials like shredded paper, textiles, hair etc. Sometimes, nests are found in nesting boxes for birds or dormice. They also like to use mole or vole tunnels. Often nests are built under the roots of trees or bushes to be safe from wild boars. When they have babies, females close the entries with stones, leaves and twigs before leaving the burrow. Good and safe burrows are used over generations. In winter, nests are populated by several individuals, but when breeding season starts each animal occupies its own territory. Nest Location: Less than 20m from food source. Wood mice are known for their mobility. They can travel up to 1200m in one night.

The territory of a male ranges over several female territories. A male territory can be up to 3000sqm, a female territory 100-200sqm.

Wood mice like to gnaw in different places and often. Small amounts of food are ingested in different places. Not only food but also other materials are gnawed (building materials, Styrofoam, wood, paper, cables). They collect food and carry it to safe hiding places to eat under cover. Food is stored inside the burrow and in the surroundings. Forgotten or lost food stores play a major role in the expanding of crop trees and other food plants.

As many rodents, wood mice have reduced ability to recognize colours, but have excellent night view. They can see infrared light, such as coming from trail cameras for instance.

Wood mice do have a magnetic sense and can find the most direct way back to their nests, even over long distances. Important point when you trap wood mice alive. Release them not closer than 5km from your home. Wood mice do long migrations according seasons between summer territories (hedges, grassland) and winter territories (woodland or houses). In the dark, they orientate by whiskers and body hair along walls and other vertical surfaces and follow their urine scented traces and smear marks. Outdoors, wood mice also place twigs and leaves on their runways as landmarks for better orientation.

Dark and smelly smear marks on strongly frequented mouse runway across wall and cable.

Outdoors, population density is related to abundance of tree crops and may vary from 1-100 individuals per hectare.

Wood mice are an important food source for many predators: owls, raptor birds, martens, foxes, cats, weasel, stoats, snakes etc. When caught by the tail by a predator, the skin rips off easily and the mouse may escape (tail autonomy). This trick works only once, the skin does not recover, instead the skinned part dries out and falls off. But normally, the tail is used for climbing, balancing and when standing on the hind legs.

They do not hibernate and are active in winter. But when conditions are very bad, they can fall into a torpor (all vital functions reduced to minimum).

Wood mice have excellent hearing and are sensitive to ultrasonic sound. During courtship, males sing ultrasonic songs for the female. Baby mice calls are also in the ultrasonic range.

Nutrition

Food: Wood mice feed on many different foods, depending on the seasonal availability: all kinds of seeds, especially tree seeds like acorn, beechnuts, nuts, cherry stones, buds, berries, fruits, moss fruit bodies, fungi, green plants and roots. Especially in spring and summertime 20% of the food can be insects, spiders, worms, snails and other small animals. Food is stored in food chambers inside the burrow or in safe feeding places. Recent research showed that mice do not only destroy Styrofoam or candle wax, but also can digest it at a certain extent thanks to special gut bacteria.

Daily Amount: 3-6g

Reproduction

Wood mice do reproduce at a lower rate than house mice or common voles. Calamities with huge numbers of wood mice have not been observed. Mating usually starts between three and six months. Breeding Season: in central Europe March to October, Southern Europe during the hole year.

Most of the time, a dominant male mates with several female. Only at times of high population density, regular social structures and territories collapse and female mate with many male to reduce social stress and avoid infanticide by frustrated male.

Litter Size: 2-8, mostly 5-6 pups
No. of Litters: 2 (spring and autumn)
Sexual Maturity: 3 months
Gestation Period: 25-30 days
Polyandry: female wood mice do mate with several males.

Facts

Scientific Name: Apodemus silvaticus
Other Names: Long tailed field mouse, common field mouse
Colour: the top side is grey, brown or beige, darker along the spine, underside is grey white, legs white
Weight: Adults 18 - 36g
Body Length with tail: 15-22cm
Tail Length: 7-10,5 cm, bit shorter than body, covered with fur, top dark underside white.
Ears: larger than house mouse
Eyes: larger than house mouse, protruding
Hind legs: longer than house mouse and well developed. Covered with white fur
Lifespan: 6-18 months
Droppings: bkack 3-6mm

Manifestations & Damages

Overview

Mice can be detected by sounds, droppings, gnaw marks, and urine odours. Wood mice are not shy. Often, when a human observer remains quiet and still wood mice will emerge.

Even though the wood mouse feed on plants, real damage in their natural habitats is low. They can damage seedlings or young trees and thus cause reductions in reforestation. In their natural habitat they are regarded as beneficial species. More trouble occurs inside of human buildings.

In winter, wood mice invade human housings. In warmer countries they also come in summer to human buildings to find shelter from heat.

As other rodents, wood mice destroy food and feed by direct consumption as well as by contamination with saliva, urine, droppings and hair.

Additional, damage is produced by gnawing materials like paper, cardboard, insulation material, packaging, textiles, cables, pipes and wood, be it for opening food containers, gaining nesting material, making slip throughs wider or simply to grind of the teeth.

Wood mice can be harmful to health. They harbour pathogens and parasites and carry them into human housings. Wood mice bear fleas, ticks, mites, and tapeworms. They transmit Toxoplasmosis and gut viruses. Transmission of pathogens occurs by contact with faeces, urine, saliva, blood or hair of the rodents.

Faeces

Most common evidence for mouse activity is the droppings. Wood mouse poop is usually dark-coloured, 5 - 6mm in length. The droppings look almost like house mouse poop with slightly brighter colour. An adult mouse typically produces 50 to 75 droppings per day and even a small mouse infestation can produce literally thousands of droppings in a short time.

Wood mouse droppings: often pointed at one end

Mouse droppings and urine along skirting board

Heavy infestation, many droppings

Gnaw Marks

Wood mice love to gnaw various material. The gnaw marks and shredded materials are an additional evidence for the presence of mice. The width of the teeth marks can distinguish wood mice from rats: a mouse’s tooth is 0.5mm wide and a rat’s tooth 2-3mm.

Besides chewing wires, mice gnaw plastic items, wood, corners of cereal boxes and bags. Additionally, they shred paper, cardboard and textiles to gain nesting material.

Mouse damage holes are typically small, clean-cut holes about 2 cm in diameter.

Mice broke into a storage box in an attic and shredded the content.

Wood Mouse gnaw marks_urine and droppings

Gnawed water pipe

Mice damaged roof foils (vapour barrier).

By consequence condensing water may long-term damage the construction wood

Inside buildings, mice use cable ducts and pipe penetrations to expand.

Mouse poop and urine stains in the left corner.

Mouse tunnels and nests in mineral wool

Mouse droppings and urine stains on ceiling boards

Sounds & Smells

When mice are active, they make noise by gnawing or by running around in empty spaces in ceilings or walls. Because of their nocturnal activity, these sounds can be especially annoying to the human inhabitants.

Mice continuously lose urine as they walk about. The smell helps them orientate themselves in the dark. With substantial or long-lasting infestation, a strong smell will be detected. Cat and dog owners may see their pets excitedly sniffing, probing and scratching places, where mice have been.

Management and control measures

Conservation status: House mice are not protected.

Prevention

Prevention - perfect climbing aid for rodents — Vegetation growing up to the roof, perfect climbing aid for rodents.

Prevention - Wooden wall cladding — Wooden wall cladding, seen from underneath. Aeration holes give access to the void and mice can climb up even to the roof without risc od predation.

Prevention - Aeration holes — Aeration holes for wall void, access points for rodents

Prevention - Typical access points open corners — Typical access points: open corners

Prevention -Mouse infestation inside of wall cladding — Mouse infestation inside of wall cladding.

Prevention -Access point is a cable outlet. — Access point is a cable outlet.

Prevent - Wood pile for shelter for mice — Wood piled up along a house wall. Perfect shelter and nesting place for mice.

Rodent population will increase in conditions that allow easy access to abundant food and good protective shelter. These should be avoided.

The best time to act against mice is in autumn, when crops have been harvested and the cold, wet weather sets in. The pests leave their summer quarters and look for dry and warm shelter in and on buildings. It is best to catch or drive the rodents away before they become ensconced in buildings.

It is always interesting to find out how the mice came into the building. Mice need an opening of only 6mm diameter to gain entry so there are often many access points aroundthe perimeter of a building. Mice penetrate mainly through open or poorly closing doors and gates, through basement windows, lighting shafts, air intake openings, pipe ducts, cable ducts, cooling and ventilation systems, outdoor lights, transformer stations, switch boxes and other apertures in outer walls. If possible, access points should be sealed to prevent future infestations. SWISSINNO Rodent Stop Steel Wool is a quick and easy fix to plug wall outlets, holes and cracks.

Wood mice are excellent climbers. Planted facades, wood cladding and insulation offer ideal climbing aids.

Eliminate nesting possibilities to discourage mice from colonising the site. Get rid of piles of wood stacked against house walls, and of bulky rubbish on the site, and of dense ground-covering vegetation to make the area unattractive for nesting.

Remove all food sources and avoid excessive bird feeding. Store foodstuffs, pet food and seeds in rodent-proof containers and not in bags or boxes.

Ultrasonic Repellents

Overview of SWISSINNO ultrasonic rodent repellers

Ultrasonic Rodent Repellents are an effective method of scaring mice away and preventing them from entering buildings. High-pitched frequency sound waves emit a non-repetitive pattern to prevent rodents from habituating to the sound.

It is important to note that ultrasonic frequencies do not travel through walls, so at least one repellermust be placed in each room.

Ultrasonic repellers are not completely effective on their own. For maximum control they should be incorporated into an integrated pest management strategy comprising mechanical traps with food deprivation, sanitation and the closure of access routes.

Trapping

Mousetraps are an effective method of non-toxic and humane mouse control. There are 3 types of mouse traps commonly used for rodent control: Snap Traps, Catch Alive Traps, and Electronic Traps.

The following table gives an overview of the different SWISSINNO mousetraps:

A SWISSINNO mousetrap provides a quick and easy solution to a rodent control problem and it can be used many times over. A big advantage of using a mousetrap is that it retains the animal’s carcass so that the ‘trapper’ can dispose of it safely. Death by poison is never instantaneous so the animal may leave the scene and die out of sight in an inaccessible place like behind the skirting boards or under the floor boards where it will decompose emitting noxious odours and attracting flies, maggots and other insects into the home.

Wood mice can get twice as big than house mice. Especially in Northern regions, huge specimen occur and overwhelm regular mouse traps. In this case consider using SWISSINNO rat traps instead.

Mouse trapping: How to go about it:

Before setting out traps, clean up the area removing all tracks, faeces and urine. This will disturb and disorientate the mice and make them less suspicious of the traps. It also helps to see were latest rodent activities took place.
Remove all food and food sources. The hungrier the mice, the more readily they will accept the traps.
Mice learn quickly from trap failures. A bad trap often does not make a complete catch but injures the animal and causes it to suffer and to become trap-shy. Only high-quality traps like SWISSINNO mousetraps are effective and suitable for animal welfare.
Always check traps for proper function before use, especially for sensitive triggering and good spring tension. Don´t use traps that don’t set correctly or that fail to snap shut properly.
Wear gloves during trapping. That’s not because of the smell of humans. Rodents in and around buildings are not shy about humans´ smell. The use of gloves is recommended for hygienic reasons as rodents, dead or alive, can transmit serious diseases via contact with their fur or body fluids.
Good trap placement is the key to successful trapping. Set traps in areas of high rodent activity. Traps should be placed in the runways of the rodents. Mouse droppings and smear marks are good indicators. Traps are set best along walls or in corners and not in the middle of the room.

Optimal placement of the trap into a runway

Traps must sit firmly on the ground. Rodents shy off from traps that move or make sounds when touched. A secure position is also important for a clean strike and preventing failures.

Trap set on a board to give a good standing and fixed with a wire so it can't be dragged away.

It is better to set out more than a single trap, even if you think, that there is only one mouse present. If there are more mice, several traps should be set out anyways. The distance between traps should be no more than 5m.
If pets have access to the trapping sites, or when setting traps outdoors, the traps should be covered or placed in trap tunnels. This keeps non-targeted animals off the traps. The Mousetrap “No See-No-Touch” with its integrated tunnel is safe and does not need additional cover. The Mousetrap PRO SuperCat with patented trigger system is selective and helps avoid killing non targeted animals.

Traps set in a box to keep away non targeted animals and prevent trap loss.

Traps should be secured with a wire or cord to prevent loss. Caught mice can carry away the trap before they die. Outdoors predators often carry away caught rodents together with trap.

Set traps must be checked daily. Carcasses should be disposed of before they become a hygiene problem. In case of an incomplete catch foul catch (not lethal) the animal must be dispatched. Traps that have been ignored should be moved to a different pposition. If needed, traps should be rebaited respectively reset. Non-targeted animals should be released, provided that they are not injured.
If traps are found tripped but empty. (failed catches), it is recommended to switch to a different model of trap. The best trap for mice is the Mousetrap PRO SuperCat. With this model, no failures or imperfect catches occur.
Most SWISSINNO Mousetraps are baited with peanut butter. Replacement bait syringes are available separately. The range of attractive of this bait is not more than 2 meters and rodents will not be lured from further away or from the exterior of the building.
“Prebait”: If a trap is being ignored, placing a small amount of bait, no more than pea-size, in front of the trap may help.

Mouse trap with small portion of peanut butter as “prebait”

If the peanut butter baited traps do not work, try a chocolate spread like Nutella instead. Nutella is an excellent alternative.
The smell of a dead mouse from previous catch does not repel mice. In fact, used traps are more attractive to them. If traps need to be cleaned, use warm water only with a soft brush and not detergent.
Catch alive traps should be checked every 4 hours. Otherwise the stress can kill the captive rodent. Caught live mice must be released at least 2 km away, otherwise they will find their way back.
If there is evidence of the presence of species which are protected by law, it is recommended to contact local authorities before starting control measures. Already active measures would have to be stopped immediately until approved. Even the use of “catch alive” traps without authorisation represents an infringement.

Poison bait

It is better to fight mice with traps. SWISSINNO advises against the use of poison bait for several reasons:

Toxic baits endanger the environment, children, pets, domestic, farm and other non-target animals.
Poison baits cause slow and painful death of rodents. After consuming such bait, it takes several days for the animal to die.
When using poison bait indoors, the mice often die in inaccessible places and the dead bodies cannot be disposed of. They decompose and give off strong, unpleasant odours that last for weeks. Later the dried-up carcasses serve for years as food for other pests such as flies, moths, and beetles.