Of the seven unique species of mice in Alberta, the western deer mouse is one of the most economically important.[1]https://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex594/$file/683.pdf?OpenElement Formerly confused with the eastern deer mouse, both species were grouped under P. Maniculatus as the North American deer mouse. However, a 2019 study found significant genetic divergence within the species and split it into two, with maniculatus representing the eastern group and sonoriensis representing the western group.[2]https://www.researchgate.net/publication/336616821_TAXONOMY_AND_PHYLOGENETICS_OF_THE_PEROMYSCUS_MANICULATUS_SPECIES_GROUP Western deer mice are populous in the western mountains and live in wooded areas and areas that were previously wooded.[3]https://academic.oup.com/jmammal/article-abstract/33/1/50/834886?redirectedFrom=fulltext&login=false The western deer mouse is widespread throughout the western half of North America, mainly in areas west of the Mississippi. They can be found throughout Alberta and are common in both Calgary and Edmonton. In a survey of small mammals on 29 sites in subalpine forests in Colorado and Wyoming, the deer mouse had the highest frequency of occurrence; however, it was not always the most abundant small mammal.[4]https://en.wikipedia.org/wiki/Western_deer_mouse


The western deer mouse has white feet, white or light-coloured undersides, and brownish upper surfaces. The tail is distinctly bi-coloured; the upper portions brown or gray, the underside white, with a well-defined line where the two colours meet. White-footed mice are about the same size as, or slightly larger than house mice and, at a distance, may be confused with house mice. The bi-coloured tail differentiates one from the other. In comparison to house mice, white-footed mice have larger eyes and ears. They are considered by most people to be more “attractive” than house mice, and they do not have the characteristic mousy or musky odour of house mice. The western deer mouse measures 50 to 90mm in length with an additional 50 to 88mm tail and weighs up to 90g.[5]https://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex594/$file/683.pdf?OpenElement


All types of mice pose 2 main risk factors for homeowners and their inhabitants: health risks and structural damage risks. Mice can spread deadly diseases to humans and pets by contaminating the homes they enter, while also chewing electrical wires, getting into vehicles, and causing fires. Your home insurance policy most likely will not cover damage caused by mice or any other vermin. This is a standard exclusion found in virtually any home insurance policy available in Canada. [/fn]https://www.squareone.ca/resource-centres/insurance-basics/mice-damage[/fn]

Signs of Infestation

Deer mice damage upholstered furniture, mattresses, clothing, paper, or other materials they find suitable for constructing their nests. Nests, droppings, and other signs left by deer mice are similar to those of house mice. However, deer mice have a much greater tendency to cache food supplies such as acorns, seeds, or nuts than do house mice. This may help in the identification of the species of mouse responsible for the observed damage.[6]http://ipm.ucanr.edu/PMG/PESTNOTES/pn74161.html For a complete list of signs of infestation, see our information on house mice.


When a deer mouse population has become quite high, toxic bait (rodenticides) can serve as a valuable component of a pest management program for controlling population levels. The overwhelming majority of over-the-counter poison solutions are not labelled for deer mice and therefore cannot be used for the control of them. Most baits are labelled for house mice and rats only. If the infestation is small, deer mice can be controlled through the sealing of entry points and manually trapping them, however once the populations begin breeding they can become very difficult to control with traps alone. For this reason, we recommend a professional rodent control program in order to eliminate deer mice quickly and effectively.


When it comes to preventing deer mice, we recommend sealing off entry points, controlling vegetation around the home, securing garbage in containers, and practicing good sanitation in food handling areas. There is a more detailed list available on our house mouse information page. One important note about deer mice is that commercially sold ultrasonic devices and other frightening devices aren’t effective at repelling deer mice. Chemical repellents, also commercially available for outdoor use, aren’t sufficiently effective to justify their expense.[7]http://ipm.ucanr.edu/PMG/PESTNOTES/pn74161.html


Deer mice live in many different habitats throughout their range. They can be found in alpine habitats, northern boreal forest, desert, grassland, brushland, agricultural fields, southern montane woodland, and dry upper tropical habitats. Their most common habitats are prairies, bushy areas, and woodlands.[8]http://www.biokids.umich.edu/critters/Peromyscus_maniculatus/ 


Deer mice are predominantly granivorous, feeding on a range of seeds. However, they will also consume fruits, invertebrates, fundi, and to a lesser extent green vegetation. Deer mice are often known to cache their food and store some of their food near their nests, especially in autumn when foods such as tree seeds and nuts are most plentiful.[9]http://ipm.ucanr.edu/PMG/PESTNOTES/pn74161.html

Lifecycle & Reproduction

Mice will generally bear a litter of five to six young, following a 21 to 23-day gestation period. Deer mice may have more than one litter per year. Lifespan is usually short, ranging from four to 20 months. Mice do not hibernate, but deer mice may become completely inactive for a few days when winter weather is severe.[10]https://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex594/$file/683.pdf?OpenElement