Meadow jumping mice range in length from 180 to 240 mm, with the tail making up 108 to 165 mm of that length. The hind feet are 28 to 35 mm long.
Mass varies quite a bit with the season. Summer weights range between 11.15 and 24.8 grams, averaging between 16 and 19 g. Before hibernation, meadow jumping mice may reach weights up to, or greater than, 35 g. Females may sometimes be slightly larger and weigh more than males.
Meadow jumping mice are recognized for their extremely long tails and long hind feet. Small and slender, they differ from woodland jumping mice in that they do not have a white-tipped tail and are generally duller in color. Adults have a dark or olive brown band on their back, which is paler in juveniles. The sides are a pale yellowish-brown, with black hairs lining them, and the underparts are white or buffy-white. The tail has few hairs, is dark brown on top and yellow-white on the bottom, and is longer than the body. The coat is short, thick, and mostly coarse. These mice undergo a yearly molt that usually starts after mid-June for adults or in August for the juveniles and lasts for about three weeks. Meadow jumping mice have small and delicate forelimbs with four toes on each foot. The hind limbs are longer and have five toes. The bottoms of the feet are naked. The head is small and narrow, and the nose is short and pointed. Meadow jumping mice are the only mammal with eighteen teeth.
Meadow jumping mice may be found throughout northern North America. They are found from the Atlantic Coast to the Great Plains in the United States, northward throughout the north eastern and north central states to the arctic tree-line of Alaska and Canada, and as far south as Georgia, Alabama, Arizona, and New Mexico.
Meadow jumping mice may live in various habitats that have some low plant cover, but moist grassland is preferred and heavily wooded areas are avoided. Grassy fields and thick vegetated areas bordering streams, ponds, or marshes generally have greater numbers of meadow jumping mice. It is possible that these mice prefer habitats with high humidity.
No information is available on the mating system of meadow jumping mice.
The breeding season of meadow jumping mice occurs shortly after hibernation in late April or May. Males emerge from hibernation slightly before females and are ready to mate when the females emerge. Within two weeks after emergence, most females are pregnant. Pregnancy usually lasts about 18 days, but may be longer for females that are nursing young. A female may have 2 to 3 litters in a year. The average litter size is 5.3, though the number of young ranges between 2 and 9. In the north, most young are born and weaned between June and August. Small and weighing about 0.8 g, the newborns are naked, pink, blind, clawless and deaf, but squeak loudly at birth. In the first week, their ears unfold, fur begins to cover their backs, and their claws appear. They begin crawling between the first and second weeks, and by the third week they can hop, creep, and hear. Their front teeth have appeared, and they have tawny coats. By the end of the fourth week, the young have adult fur, and open eyes. Weaned, they leave their mother between the 28th to 33rd day. Those young females born during the spring may reproduce after two months.
Female meadow jumping mice provide all the care for their young, until they are weaned and independent.
Most meadow jumping mice in the wild die in their first year; about 9% of those who live longer make it into their third year. Maximum lifespan in captivity is five years. (Kurta, 1995)
Meadow jumping mice are solitary, but not aggressive toward others of their kind. They are generally active at night (although they occasionally come out during the day), and usually move in short hops of about 2.5 to 15 cm or by crawling along runways made by voles or in the grass. They are also great swimmers and diggers and can climb. These mice are known to wander, and may roam up to 1 km in search of moist habitat. Summer nests are made of grass and are generally placed in or under protective structures or underground. Hibernation nests are made of grass and leaves and usually lie in burrows 0.3 to 0.9 m below the ground. These animals begin to hibernate between late September and early October. Timing of hibernation is believed to depend upon the amount of fat reserves each mouse has. Juveniles usually start hibernating later than adults. While hibernating, body temperature may drop as low as 2 degrees celsius. These mice reemerge in mid to late spring.
Home ranges vary between 0.15 and 1.10 hectares and may overlap. Up to 10 or more meadow jumping mice may be found per acre, but 2 to 3 individuals per acre is typical in high quality habitat. There is some disagreement over how much the size of populations change in this species.
Meadow jumping mice make few sounds, except the squeaking of young. Adults may call in clucks, chatter their teeth, and drum the ground with their tails. They have a keen sense of smell and probably use scent to communicate as well.
Meadow jumping mice perceive their environment using their eyes, their ears, their nose, and their whiskers.
Meadow jumping mice mostly eat seeds, but also feed on berries, fruit, and insects. Grasses may be cut in sections to reach the seeds at the tips. These mice may leave these piles of grass debris scattered on the ground. In the spring, one half of the diet may be made up of animal foods after emergence from hibernation. Especially important are caterpillars and beetles. Later, seeds and underground fungi make up a greater part of the diet. Weight generally increases toward the beginning of the fall, especially two weeks before hibernation begins, so that the mice will have enough fat to survive the winter.
Predators of meadow jumping mice include great horned owls, screech owls, red-tailed hawks, weasels, and foxes. If startled, these mice leap up to 1 m high in the air and then either short hop or crouch, flattening their brighter belly against the ground. This stillness seems to be their best defense against predators.
Meadow jumping mice are an important food source for many predators, and may play a role in spreading the seeds of some of the plants they eat. They have few parasites.
Meadow jumping mice may eat grain, but numbers aren't generally high enough to have a large impact.
Meadow jumping mice are not currently threatened, although some populations may be affected by changes in land use and habitat destruction.
Allison Poor (editor), University of Michigan-Ann Arbor.
Jocelyn Smith (author), University of Michigan-Ann Arbor.
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