Peromyscus keeni

"Keen's Deermouse is the most common deermouse in the Pacific Northwest. It inhabits rainy, mild climate zones at higher elevations than the closely-related Deermouse (Peromyscus maniculatus), and prefers areas where the forest canopy is somewhat open. Observers report that it is very good at climbing and jumping. It is often a pest in rural areas, especially in winter, because it readily moves into buildings."

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Mammal Species of the World

This species occurs from Washington north to southern Alaska in the United States and Canada, and west of the Coastal and Cascade mountain ranges, including the Queen Charlotte Islands and islands along the coast of British Columbia and the Alexander Archipelago. Peromyscus keeni also occurs in Yukon Territory and occurs farther inland in British Columbia than previously documented (not mapped here) (Lucid and Cook 2004).

Included are the ranges of the following nominal Peromyscus maniculatus and P. sitkensis taxa of Hall (1981): oreas, interdictus, isolatus, sitkensis, oceanicus, algidus, hylaeus, keeni, macrorhinus, and prevostensis (carli, doylei, and triangularis probably also should be included) (Hogan et al. 1993).

Peromyscus keeni is found in western British Columbia, western Washington, and southeastern Alaska, including the Haida Gwaii (Queen Charlotte) islands, the Alexander Archipelago, and other coastal islands.

Biogeographic Regions: nearctic (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (250-20,000 square km (about 100-8000 square miles)) "Washington north to southern Alaska, and west of the Coastal and Cascade mountain ranges, including the Queen Charlotte Islands and islands along the coast of British Columbia and the Alexander Archipelago. Occurs sympatrically with Peromyscus maniculatus austerus in the southern portion of this distribution as well as Balaclava, Malcolm, and Vancouver islands, British Columbia" (Hogan et al. 1993). Peromyscus keeni also occurs in Yukon Territory and occurs farther inland in British Columbia than previously documented (Lucid and Cook 2004).

Included are the ranges of the following nominal Peromyscus maniculatus and P. sitkensis taxa of Hall (1981): oreas, interdictus, isolatus, sitkensis, oceanicus, algidus, hylaeus, keeni, macrorhinus, and prevostensis (carli, doylei, and triangularis probably also should be included) (Hogan et al. 1993).

Former species "P. sitkensis" occurs only on several smaller outer islands of the Alexander Archipelago off southern coast of Alaska; Peromyscus populations on the Queen Charlotte Islands of British Columbia were identified as P. sitkensis by Thomas (1973), as P. oreas by Gunn and Greenbaum (1986).

Former species "P. oreas" occurs in western Washington and southwestern British Columbia (see Allard et al. [1987] for localities); exact range is uncertain due to current difficulties in allocating certain island populations to a particular species (Carleton 1989).

Peromyscus keeni is sympatric with Peromyscus maniculatus throughout the Olympic Peninsula and the Puget Sound region and along the Pacific coast west of the Coast and Cascade ranges (subspecies oreas); also occurs on northern and western Vancouver Island (subspecies interdictus) and small islands in the Queen Charlotte Strait (subspecies isolatus) (identified as P. sitkensis by Thomas 1973).

Northwestern deer mice are medium sized cricetids. Juveniles are a grayish color, while adults are tri-colored. They are brown dorsally and light grey ventrally with tails that are brown dorsally and white ventrally. Northwestern deer mice have long tails (more than 100 mm) and large, naked ears. The tail is slender with short hair and is distinctly bi-colored. Peromyscus keeni is distinguishable from P. maniculatus because of its darker fur color and longer tail (tail length in P. maniculatus is less than 100 mm). Body size in northwestern deer mice is significantly correlated with elevation, with body size peaking at intermediate elevations.

Range mass: 10 to 30 g.

Range length: 181 to 236 mm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: sexes alike

Length: 23 cm

Weight: 45 grams

Length:
Average: 210 mm
Range: 181-236 mm

Weight:
Range: 10-30 g

Differs from P. MANICULATUS in being significantly larger, with tail length typically greater than 100 mm; chromosome FN (85-92) exceeds that of sympatric populations of low-FN (74-78) P. M. AUSTERUS (Hogan et al. 1993).

Habitat and Ecology

Systems

• Terrestrial

Northwestern deer mice are adapted to many habitats, but appear to thrive in upland and new-growth forests. They also commonly inhabit old-growth forests and floodplains, although those are less favorable because they lack the spatial and temporal complexity that promotes survivorship. They are found in rainy areas with mild climates and semi-open canopies. They are found at higher elevations than Peromyscus maniculatus in the same region. On small islands, northwestern deer mice are found along the edges of cedar-spruce forest and on beaches where logs, rocks, and debris provide sufficient cover.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: forest ; rainforest

Aquatic Biomes: coastal

Other Habitat Features: riparian

Comments: "SITKENSIS" inhabits the edge of dense Sitka spruce-western cedar forests of outer coastal islands; found at forest edge and on beaches in cover of logs, stumps and rock crevices (Banfield 1974).

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Northwestern deer mice are mainly granivorous ground foragers. In an intake preference study done on foods from southeastern Alaska seeds from trees, shrubs and fruits were compared as well as fruits for palatability. It was found that salmonberry, stink currants, devil's club seeds, and Sitka spruce seeds were preferred. When diet composition in different ecological habitats was compared, stomach contents did not vary significantly. All diets were composed mostly of fruits and seeds of understory plants, followed by tree seeds and leaf material, with small amounts of arthropods and traces of fungi. Tree seeds become a more important part of their diets during winter and early spring because these mice do not cache food or store seasonal fat. In some areas they eat the eggs of nesting birds, including marbled murrelets (Brachyramphus marmoratus) and rhinoceros auklets (Cerorhinca monocerata).

Animal Foods: birds; fish; eggs; carrion ; insects; terrestrial non-insect arthropods

Plant Foods: leaves; seeds, grains, and nuts; fruit

Other Foods: fungus

Primary Diet: herbivore (Granivore ); omnivore

Comments: Diet includes various seeds, fruits, and small invertebrates.

Northwestern deer mice influence seabird populations in coastal areas by preying on their eggs and nestlings. Marbled murrelet (Brachyramphus marmoratus) and rhinoceros auklet (Cerorhinca monocerata) are preyed on by these mice. In one study area, 34% of rhinoceros auklet eggs had been preyed on by northwestern deer mice. Predation occurs mostly during the early post-laying period when adults are foraging and occurs minimally in later incubation and hatchling periods. If food sources for the rhinoceros auklets become limited their foraging time increases, which puts their eggs at an even greater risk for predation.

Seed dispersal mutualism has been suggested between Peromyscus maniculatus and limber pine (Pinus flexilis). Other Peromyscus species may drive seed defense evolution through their secondary dispersal effects, causing the method of seed dispersal which plants rely on to change in the presence of ground scavengers.

Peromyscus keeni can be a host to several invertebrate parasites such as lice, ticks, bots and fleas. The flea species that are known to use P. keeni as a host are: Hystrichopsylla occidentalis, Catallagia charlottensis, Ceratophyllus ciliates protinus, Megabothris abantis, Opisodasys keeni, and Malaraeus telchinus.

Ecosystem Impact: disperses seeds

Commensal/Parasitic Species:

• fleas (Opisodasys keeni)
• fleas (Hystrichopsylla occidentalis)
• fleas (Catallagia charlottensis)
• fleas (Ceratophyllus ciliates protinus)
• fleas (Megabothris abantis)
• fleas (Malaraeus telchinus)
• ticks (Ixodidae)
• bot flies (Oestridae)

Primary predators are American martens (Martes americana), owls (Strigidae), red foxes (Vulpes vulpes). Other terrestrial predators are likely to take northwestern deer mice and their young, including large snakes, other raptors, and weasels (Mustela). Northwestern deer mice are cryptically colored and secretive to avoid predation.

Known Predators:

• American martens (Martes americana)
• owls (Strigidae)
• red foxes (Vulpes vulpes)
• large snakes (Serpentes)
• weasels (Mustela)

Anti-predator Adaptations: cryptic

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 81 to >300

Comments: Many local populations.

10,000 to >1,000,000 individuals

Comments: "SITKENSIS" reportedly is rare and local.

Distribution of "SITKENSIS" on smaller outer islands indicates it is probably less competitive than MANICULATUS, which occupies larger islands (Banfield 1974). "SITKENSIS" probably originally reached many islands on natural rafts.

Rodents rely heavily on their sense of olfaction to interact within their social hierarchies. Dominance can be conveyed to other members of the community solely by odor. A recent topic of interest for research is rodent ultrasound. Ultrasonic vocalizations have been observed in research mice as well as in wild populations of P. californicus and P. boylii. Based on literature on other mammal and bird ultrasound, it is likely that this method of communication is used by all Peromyscus species to communicate with offspring, maintain territory boundaries, and to communicate with as well as attract mates. It is unlikely that ultrasonic vocalizations are used as a alarm calls as this behavior is only known from diurnal animals.

Communication Channels: acoustic ; chemical

Perception Channels: visual ; acoustic ; ultrasound

Comments: Active throughout the year.

Little research has been conducted on the lifespan of northwestern deer mice. Related species (P. maniculatus, P. californicus, and P. leucopus) have expected lifespans in the wild of 342.2 days for males and 280.9 days for breeding females. Some individuals survive to reproduce for a second breeding season.

Range lifespan
Status: wild: 3 (high) years.

Average lifespan
Status: wild: 1 years.

There is no available information on mating systems in northwestern deer mice. Mating systems in Peromyscus are variable, and include monogamous, roving, or polygynous mating behaviors. At high female densities, males become more territorial and defend a small number of females or maintain a monogamous relationship with one female. In areas with low female densities, females become solitary and males develop a less territorial, roving strategy where they mate with multiple females. Females generally maintain small, solitary home areas in all mating systems.

During the breeding season, northwestern deer mice females with mates have short breeding intervals and exhibit postpartum estrus. Breeding intervals are increased among females that do not have established mates. In wild populations, many adults only live long enough to reproduce during one breeding season. Adult males enter breeding condition prior to adult females and all females average 2 to 3 litters per breeding season. Females give birth to 2 to 5 young after a gestation period of 23 to 25 days. Gestation periods are shorting when females are nursing a previous litter. Litter size is positively correlated with relative litter mass: larger litter sizes result in smaller body sizes of young in that litter. Young are weaned and independent at 3 to 4 weeks old and may be able to breed as early as 5 to 6 weeks old. Males have a lifetime reproductive success that is twice that of females.

Breeding interval: Female northwestern deer mice breed two to three times per breeding season.

Breeding season: Breeding occurs from February to October.

Range number of offspring: 2 to 5.

Average number of offspring: 4.3.

Range gestation period: 23 to 25 days.

Range weaning age: 3 to 4 weeks.

Range time to independence: 3 to 4 weeks.

Range age at sexual or reproductive maturity (female): 5 to 6 weeks.

Range age at sexual or reproductive maturity (male): 5 to 6 weeks.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous ; post-partum estrous

Parental investment in northwestern deer mice has not been well-studied. Like all mammals, females invest substantially in young through gestation and lactation.

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)

Multiple litters of about 3-5 young probably are produced each year. Gestation lasts about 23 days (nonlactating) or 25 days (lactating) (Kirkland and Layne 1989). Probably capable of breeding at about 5-6 weeks. In southern British Columbia, "OREAS" was reported as breeding from March through July; 21 litters averaged 6.1 young (see Kirkland and Layne 1989).

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 3
Species With Barcodes: 1

Year Assessed

Assessor/s

Reviewer/s

Justification

Peromyscus keeni is listed as “least concern” by the IUCN because of their widespread, stable populations and adaptability to various habitats.

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Reasons: Widespread on coastal islands and western mainland of the Pacific Northwest from Washington to southern Alaska; precise distribution is not clearly known; taxonomy of PEROMYSCUS has been unstable in this region.

Population

Population Trend

Global Short Term Trend: Unknown

Major Threats

Conservation Actions

Peromyscus maniculatus is a natural reservoir for  Lyme disease and hantavirus. Peromyscus keeni may also transmit these pathogens and negatively affect human health. Northwestern deer mice may also enter homes and become a nuisance.

Negative Impacts: injures humans (carries human disease); household pest

Species in the genus Peromyscus are useful for the research of genomic imprinting. Peromyscus has been an important model for showing an X-linked locus in hybrid dysgenesis when crossing different species. They have also been used for researching reproductive isolation in mammals. Peromyscus have a much longer lifespan than typical lab mice, making them useful for many forms of research. The longevity of Peromyscus has been analyzed as baseline research for comparative aging research. Their physiological characteristics may help us understand and treat age-related diseases such as cancer.

Positive Impacts: research and education