Woodland jumping mice, Napaeozapus insignis, are found throughout northeastern North America, from central Manitoba to northern Quebec and south into the lower Appalachian Mountains (northern Georgia). In Michigan, N. insignis occurs in the Upper Peninsula and in the northern three tiers of counties in the Lower Peninsula. (Baker, 1983; Brower and Cade, 1966; Burt, 1946; Whitaker and Wrigley, 1972)
Boreal habitats contain higher densities of N. insignis than non-boreal habitats. Furthermore, woodland jumping mice prefer forested areas with dense woody undergrowth. Throughout their range, woodland jumping mice are found in spruce-fir and hemlock-hardwoods. They are also found in forest edge habitats that are near water or have sufficient cover (shrubs, ferns, grasses, rocks). Woodland jumping mice occur at sea level in the St. Lawrence region and at elevations of up to 2013 m in the Appalachian highlands. Due a lack of appropriate habitat, in many areas populations of woodland jumping mice are restricted to mountain tops, relict forest patches, and cool, moist coves. (Baker, 1983; Brower and Cade, 1966; Whitaker and Wrigley, 1972; Wrigley, 1972)
Napaeozapus insignis is found in a wide variety of habitats in Michigan. These habitats include old growth dry and wet hardwoods, second growth hardwoods, mixed conifer swamp, tamarack and black spruce bog, second-growth fir and spruce, and in grassy areas with second-growth ash cover. (Baker, 1983)
Napaeozapus insignis is a medium sized rodent that weighs between 17 and 26 g in the spring and early summer, and as much as 35 g during pregnancy or just before hibernation. Females are slightly larger than males. Total body length, from nose to end of tail vertebrae, ranges from 205 to 256 mm. They have a tricolored fur pattern with white underparts, yellowish orange sides lightly streaked with black guard hairs, and a dark dorsal stripe from nose to tail. The tops of their feet are white. Most noticeably, they have a long bicolored tail that is sparsely haired, thin, tapered, scaly, and white-tipped. Tail length ranges from 115 to 160 mm (approximately 60 % of the total body length). The number and length of tail vertebrae is increased to make this length possible. They have four pairs of mammae (1 pectoral, 2 abdominal, 1 inguinal). Adaptations of N. insignis for a saltatorial lifestyle are long hind legs with elongated ankle bones and long toe bones. (Baker, 1983; Brower and Cade, 1966; Burt, 1946; Linzey and Brecht, 2002; Whitaker and Wrigley, 1972; Whitaker, 1963; Wrigley, 1972)
In the field, the only other rodent N. insignis could be confused with is Zapus hudsonius (meadow jumping mouse). Woodland jumping mice are rarely found in open areas, have a white-tipped tail, are larger, and are more brightly tricolored than are meadow jumping mice. (Baker, 1983)
The skull of N. insignis is small, high-crowned, and similar to the skull of Z. hudsonius. Napaeozapus insignis has large, oval infraorbital foramina, small auditory bullae, a short and broad palate, and narrow zygomatic arches. They have three molariform teeth (Z. hudsonius has four) and grooved incisors that are orange or yellow. Their molars are rooted and semi-hypsodont and they do not have premolars. Woodland jumping mice have 16 total teeth and a dental formula of 1/1, 0/0, 0/0, 3/3. (Baker, 1983; Costello and Rosenberger, 2003; Linzey and Brecht, 2002; Whitaker and Wrigley, 1972)
Northern populations average 12% larger in body size than southern populations. Northern and eastern populations tend to be more yellowish and southern populations are reddish orange. Northwestern populations have pale colored sides and dark backs. These distinctions in appearance and geographic differences helped Whitaker (1972) to identify five subspecies of woodland jumping mice. Napaeozapus insignis insignis is found in New Brunswick, Canada, N. i. abietorum in Ontario, and N. i. saquenayensis in Quebec. Napaeozapus insignis roanensis inhabits the Roan Mountains of North Carolina, and N. i. frutectanus is found in eastern Wisconsin and in Michigan. (Baker, 1983; Whitaker and Wrigley, 1972)
Woodland jumping mice have a basal metabolic rate of 1.8 ml O2/g hr. Brower and Cade (1966) found that N. insignis has precise thermoregulation when active, deep seasonal hibernation, a high lower critical temperature, and a poor ability to tolerate high ambient temperatures. These are likely adaptations to living in the cold. (Brower and Cade, 1966)
Males come out of hibernation approximately 2 weeks before females and mating occurs immediately after both sexes emerge and again in mid to late summer (in the case of a second litter). Very few data exist about the mating system of N. insignis. In captivity, breeding females injure the ears and tails of males when pursued. However, captive woodland jumping mice are generally passive with each other (even while breeding). (Wrigley, 1972)
Female woodland jumping mice are reproductively receptive when they emerge from hibernation in early- to mid-May. Litters are possible from May through September, peaking in June and August. The earliest record of pregnancy is May 8, however most females do not reproduce until June. There are often 2 litters in one season, although this is more common in the southern part of the range. There are usually fewer young in second litters than in first litters. Many females have their second litters in August. The latest recorded pregnancy is September 1. Wrigley (1972) found that 70% of the individuals in a population of N. insignis collected in the fall were young from that year (based on the examination of 2,529 museum specimens collected throughout their range). Woodland jumping mice that do not reproduce tend to be mice that were born in second litters the previous year. Both females and males are reproductively mature when they emerge from hibernation the year after they are born. (Baker, 1983; Burt, 1946; Whitaker and Wrigley, 1972; Wrigley, 1972)
Compared to most other rodents, zapodids have a longer period of development. This could be due to extra time needed for growth and coordination of specialized limbs for jumping. Litters contain 1 to 7 young (average is 4.5) and the gestation period is from 23 to 29 days. Young are blind, naked, unpigmented, and weigh about 1 g at birth. By day 10, young woodland jumping mice have visible pigment spots beneath the skin all over the body. Their bodies are covered with fine hair by day 14. Young jumping mice are fully furred by 24 days and their eyes open by 26 days. By day 34, the young are weaned and they have the appearance of adults, except they are smaller and their sides are yellowish brown (adults have orange-brown sides). A molt to the adult pelage occurs between 63 and 80 days. Most adults go through their yearly molt in August. (Baker, 1983; Burt, 1946; Whitaker and Wrigley, 1972; Wrigley, 1972)
Little is known about the parental care of woodland jumping mice because they are extremely difficult to observe in the wild, and most captive females kill their young shortly after they are born. Females care for the young, have smaller home ranges than males, have been observed covering the nest entrance during the day, and have been found in nests with their young. Because of their long developmental period, these mice provide a longer period of parental care than do many other small northern mice. The role of males in parental care is unknown. (Baker, 1983; Wrigley, 1972)
Zapodids have relatively long life-spans. Brown (1970) estimated that Zapus princeps lives at least 4 years in the wild and Walter (1964) found that Sicista betulina can live 3.3 years in nature. Even though woodland jumping mice have a high turnover rate in the fall, they live longer in the wild than most other North American small mammals, up to 4 years of age. Their average lifespan is 3 years. This long lifespan is at least partly due to the ability of jumping mice to hibernate. Age is estimated by the attrition of molars and since N. insignis only uses its teeth for half of the year, determining age can be difficult. (Baker, 1983; Whitaker and Wrigley, 1972; Wrigley, 1972)
Napaeozapus insignis is primarily nocturnal, but may be active during the day, especially on cloudy or rainy days. Woodland jumping mice seek shelter in their own burrows (they are excellent diggers), in the burrows of other small mammals, or under shrubs. The entrance to a burrow is covered during the day. Burrows may be as long as 1.5 m. A globular nest is built in a small tunnel, in brush, or on the ground. Nests are made of grass and dead leaves, and have a diameter as large as 154 mm. (Baker, 1983; Burt, 1946; Linzey and Brecht, 2002; Whitaker and Wrigley, 1972; Wrigley, 1972)
When speed is needed, a quadrupedal hop is used, but the normal mode of locomotion is a quadrupedal walk. A single hop normally covers 0.6 to 0.9 m, and can be as long as 1.8 m and as high as 0.6 m. Jumping mice use trails created by other small mammals to travel, but not nearly as regularly as do meadow voles (Microtus pennsylvanicus). Woodland jumping mice can climb within bushes and on vines, but are not arboreal. Finally, these mice can swim underwater and on the surface for short distances. (Baker, 1983; Burt, 1946; Whitaker and Wrigley, 1972; Wrigley, 1972)
Woodland jumping mice hibernate for at least six months of the year. They hibernate from September or October to May in a subterranean burrow. Young do not enter hibernation until late October, about one month after adults begin hibernation. Body fat is quickly accumulated several weeks before entering hibernation. An adult that weighs 20 g in the summer may gain up to 10 g to in preparation to hibernate. While hibernating, woodland jumping mice curl up in a ball in their underground nests and enter a torpor where their normal body temperature of 37 C drops considerably. Finally, up to 35% of body weight is lost during hibernation. (Baker, 1983; Whitaker and Wrigley, 1972; Wrigley, 1972)
In captivity, tail drumming and sporadic jumping are signs of excitability or nervousness. After approximately one month in captivity, woodland jumping mice calm considerably and can be easily handled. Woodland jumping mice do not typically display aggressive behavior towards each other or defensive behavior over food. When given the choice, they prefer to sleep in the same nest box as other woodland jumping mice. (Baker, 1983; Wrigley, 1972)
Territory sizes of small rodents are hard to determine because direct observations in the wild are difficult and it is even harder to observe defensive behavior in nature. Therefore, little is known about the territory size and territorial behavior of N. insignis. Individuals are seldom caught enough times to estimate home range size accurately, and these mice frequently move to new areas. Nevertheless, it has often been estimated that males have home ranges between 0.4 and 3.6 hectares and that ranges of females are between 0.4 and 2.6 hectares. Ranges of females and males overlap. Woodland jumping mice are highly mobile, a characteristic which helps them find food. Temporary food sources, such as ripened berries, attract relatively high numbers of woodland jumping mice. Apparent evidence of colonialism in N. insignis may actually be temporary congregations around a food source. The average population density, in favorable habitat, is 7.5 per ha. However, population density estimates range from 0.64 to 59 per ha. (Baker, 1983; Hanney, 1975; Whitaker and Wrigley, 1972; Wrigley, 1972)
Not much is known about the communication in woodland jumping mice. In captivity, individuals are very tolerant of each other and show few signs of aggression. Individuals are normally silent; however young mice are constantly squeaking and making suckling sounds shortly after being born. Adults utter a soft clucking sound while sleeping or just before hibernation.
Although not specifically reported for this species, there is undoubtedly tactile communication between mates, as well as between mother and offspring. It is also likely that, as in other small rodents, chemical signals pass between individuals helping to identify individuals, sexes, and the reproductive condition of any particular mouse. (Baker, 1983; Whitaker and Wrigley, 1972; Wrigley, 1972)
Woodland jumping mice are omnivorous generalists. Primary food sources are fruits, seeds, fungi, and insects. Napaeozapus insignis is dependent on the fungus Endogone for food. Endogone was the most abundant food found in the stomachs of specimens from North Carolina, Tennessee, New York, and New Hampshire. Linzey (1973) found that Endogone was in the stomachs of 78% of the mice examined, adding up to 40% of the total food volume. This large percentage of consumed Endogone is not found in any other small mammal. Other plant materials found in the stomach of N. insignis were raspberries, may apples, blueberries, ferns, leaves, and nuts. Connor (1966) found that insects made up 22% of the stomach contents he examined. The insect species found were larval Lepidoptera, adult Coleoptera, and larval Diptera. Linzey (1973) found that Lepidoptera larvae made up over half of the animal foods consumed by his study animals. They do not cache food. (Connor, 1966; Connor, 1966; Linzey and Brecht, 2002; Linzey and Linzey, 1973; Whitaker and Wrigley, 1972)
The tricolored pattern of the pelage of N. insignis provides camouflage against dead vegetation. Napaeozapus insignis escapes from predators with a quick jump followed by a period of remaining motionless. Their coloration, escape behavior, and relative lack of odor are probably predator avoidance mechanisms. Woodland jumping mice are mostly safe from predators during hibernation. Timber rattlesnakes (Crotalus horridus), broad-banded copperheads (Agkistrodon contortrix), screech owls (Otus asio), bobcats (Lynx rufus), minks (Neovison vison), striped skunks (Mephitis mephitis), gray wolves (Canis lupus), and house cats (Felis silvestris) are all known predators of woodland jumping mice. (Baker, 1983; Linzey and Brecht, 2002; Whitaker and Wrigley, 1972; Wrigley, 1972)
Woodland jumping mice use fungi as a food source and therefore are responsible for the dispersal of mycorrhizal fungi (particularly Endogone). Mycorrhizal fungi provide trees with essential nutrients through their roots and break down detritus; both are essential roles in an ecosystem. Napaeozapus insignis is closely associated with other small mammals such as Peromyscus leucopus (white-footed mice). Also, N. insignis populations are complementary to populations of Myodes gapperi (southern red-backed voles). When one species exists, usually the other is not in that area. This may be due to aggression and not competition for resources. (Baker, 1983; Wrigley, 1972)
External parasites of N. insignis are fleas (Epitedia sp. and Ctenophthalmus sp.), many species of mites, chiggers, ticks, fleas, and botflies (Cuterebra sp.). A tiny mite, Demacarus newyorkensis, is the most common external parasite of N. insignis, these mites can number from 1 to several 100 per mouse. Red mites (Trombicula harperi) are also found on woodland jumping mice. Internal parasites of N. insignis are protozoans (Hexamita sp.), cestodes or tapeworms (Hymenolepis bennetti), and nematodes or roundworms (Citellinoides zapodis). (Baker, 1983; Linzey and Brecht, 2002; Whitaker and Wrigley, 1972; Whitaker, 1963; Wrigley, 1972)
Little is known about how woodland jumping mice benefit humans. The disperal of mycorrhizal fungi by these animals benefits many species of trees, some of which may be economically important.
There are no known adverse affects of woodland jumping mice on humans.
Woodland jumping mice have no special status on the IUCN Red List, US Federal List, or CITES.
The original classification of this species was Zapus insignis (Miller) in 1891. Differences found in the dental morphology, ear ossicles, and the bacula later led to the creation of the new genera of Napaeozapus and Euzapus. Currently, N. insignis is in the family Dipodidae with jerboas, jumping mice, and birch mice. However, some systematists place woodland jumping mice in their own family, Zapodidae. Dipodidae is divided into seven subfamilies; jumping mice are in the subfamily Zapodinae. (Whitaker and Wrigley, 1972; Wilson and Reeder, 1993)
Nancy Shefferly (editor), Animal Diversity Web.
Erin Harrington (author), University of Michigan-Ann Arbor, Phil Myers (editor, instructor), Museum of Zoology, University of Michigan-Ann Arbor.
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.
uses sound to communicate
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.
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.
a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.
uses smells or other chemicals to communicate
active at dawn and dusk
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.
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.
parental care is carried out by females
union of egg and spermatozoan
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.
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).
having the capacity to move from one place to another.
This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
an animal that mainly eats all kinds of things, including plants and animals
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
specialized for leaping or bounding locomotion; jumps or hops.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.
uses touch to communicate
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).
Living on the ground.
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
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Connor, P. 1966. The mammals of the Tug Hill Plateau, New York. New York State Museum and Science Service Bulletin, 406: 1-82.
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Whitaker, J. 1963. Food, habitat, and parasites of the woodland jumping mouse in central New York. Journal of Mammalogy, 44/2: 316-321.
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Wrigley, R. 1972. Systematics and Biology of the Woodland Jumping Mouse Napaeozapus insignis . Illinois University Biological Monographs, 47: 1-118.