Geographic Range
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.
Habitat
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
Physical Description
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.
- Other Physical Features
- endothermic
- homoiothermic
- bilateral symmetry
- Sexual Dimorphism
- sexes alike
Reproduction
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.
- Key Reproductive Features
- iteroparous
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- 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
-
provisioning
-
pre-weaning/fledging
-
provisioning
- female
-
protecting
- female
-
provisioning
Lifespan/Longevity
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.
Behavior
Northwestern deer mice are nocturnal and have a more loosely structured social hierarchy
than some of their sister taxa. A rapid growth rate, larger litter sizes, and simple
nests contribute to their social structure difference. Males exhibit severe aggression
when confronted by other males. Males show aggression towards other males in their
territory, submission when in a new territory, and are more prone to initiate grooming
when encountering new females. Females show no defensive behavior around their nest
unless they are pregnant. In some instances females will share their nest with their
younger, reproducing female offspring.
Home Range
Territoriality in northwestern deer mice is dependent on population density. In a
heavily populated area males will have relatively small territories, while in a low
density area they maintain larger territories. Females typically maintain smaller
territories that overlap with the territories of several males.
Communication and Perception
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.
- Perception Channels
- visual
- tactile
- acoustic
- ultrasound
- chemical
Food Habits
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
Predation
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.
- Anti-predator Adaptations
- cryptic
Ecosystem Roles
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
- fleas ( Opisodasys keeni )
- fleas ( Hystrichopsylla occidentalis )
- fleas ( Catallagia charlottensis )
- fleas ( Ceratophyllus ciliates protinus )
- fleas ( Megabothris abantis )
- fleas ( Malaraeus telchinus )
- ticks ( Ixodidae )
- bot flies ( Oestridae )
Economic Importance for Humans: Positive
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
Economic Importance for Humans: Negative
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
Conservation Status
Peromyscus keeni
is listed as “least concern” by the IUCN because of their widespread, stable populations
and adaptability to various habitats.
Other Comments
Peromyscus keeni
includes the previously recognized species
Peromyscus oreas
and
Peromyscus sitkensis
as well as some populations previously recognized as
Peromyscus maniculatus
(
P. m. algidus
,
P. m. hylaeus
,
P. m. keeni
,
P. m. macrorhinus
, and
P. m. prevostensis
). It is possible that 3 other
P. maniculatus
subspecies should be included in
P. keeni
:
P. m. carli
,
P. m. doylei
, and
P. m. triangularis
.
A health condition of the genus
Peromyscus
that is prevalent at a similar rate in humans is periodontal disease.
Peromyscus keeni
exhibited this disease at rates between 7 and 13.5%, with a significantly increased
rate in populations on isolated islands. This condition occurs rarely in any other
mammalian species, which may make
Peromyscus
a valuable research model.
Additional Links
Contributors
Tanya Dewey (editor), Animal Diversity Web.
Kimberly Dullen (author), University of Alaska Fairbanks, Hayley Lanier (editor, instructor), University of Alaska Fairbanks .
- Nearctic
-
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- temperate
-
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
- terrestrial
-
Living on the ground.
- forest
-
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
- rainforest
-
rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.
- coastal
-
the nearshore aquatic habitats near a coast, or shoreline.
- riparian
-
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
- endothermic
-
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- iteroparous
-
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
- seasonal breeding
-
breeding is confined to a particular season
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- viviparous
-
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
- altricial
-
young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.
- nocturnal
-
active during the night
- motile
-
having the capacity to move from one place to another.
- sedentary
-
remains in the same area
- solitary
-
lives alone
- territorial
-
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
- social
-
associates with others of its species; forms social groups.
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- ultrasound
-
uses sound above the range of human hearing for either navigation or communication or both
- chemical
-
uses smells or other chemicals to communicate
- carrion
-
flesh of dead animals.
- cryptic
-
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
- herbivore
-
An animal that eats mainly plants or parts of plants.
- granivore
-
an animal that mainly eats seeds
- omnivore
-
an animal that mainly eats all kinds of things, including plants and animals
References
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