The western harvest mouse (Reithrodontomys megalotis ) is a small neotomine mouse native to most of the western United States. Many authorities consider the endangered salt marsh harvest mouse to be a subspecies, but the two are now usually treated separately.
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NocturnalNocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal",...
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GranivoreSeed predation, often referred to as granivory, is a type of plant-animal interaction in which granivores (seed predators) feed on the seeds of pla...
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HerbivoreA herbivore is an animal anatomically and physiologically adapted to eating plant material, for example, foliage, for the main component of its die...
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ZoochoryZoochory animals are those that can disperse plant seeds in several ways. Seeds can be transported on the outside of vertebrate animals (mostly mam...
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
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TerritorialA territory is a sociographical area that which an animal consistently defends against the conspecific competition (or, occasionally, against anima...
Among animals, viviparity is the development of the embryo inside the body of the parent. The term 'viviparity' and its adjective form 'viviparous'...
A burrow is a hole or tunnel excavated into the ground by an animal to create a space suitable for habitation, temporary refuge, or as a byproduct ...
Torpor is a state of decreased physiological activity in an animal, usually marked by a reduced body temperature and metabolic rate. Torpor enables...
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PolygynyPolygyny is a mating system in which one male lives and mates with multiple females but each female only mates with a single male.
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PolygamyPolygamy is the practice of breeding with multiple partners. When a male breeds with more than one female at the same time – it is called polygyny....
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Not a migrantAnimals that do not make seasonal movements and stay in their native home ranges all year round are called not migrants or residents.
Hibernation is a state of minimal activity and metabolic depression undergone by some animal species. Hibernation is a seasonal heterothermy charac...
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The mouse is nocturnal, with particularly intense activity on very dark nights. This mouse is particularly resourceful, making use of the ground runways of other rodents. It is also a very agile climber. Once temperatures reach a certain degree, the western harvest mouse goes into torpor, but scientists have yet to determine if it goes into true hibernation. This mouse builds spherical nests that are about 125mm in diameter. These nests can be found on the ground or under trees, logs, or plants that aid in protection from predators. Nests can also be found above ground or in burrows. There are usually one or more access points at the base of the nest.
The western harvest mouse is an herbivore with a diet consisting of mainly seeds and grains from various plants. These plants include: fruits, vetch, blue grass, fescue, oats, and brome grass. In preparation for autumn and winter, the western harvest mouse stores its food along runways created throughout fields that it occupies and in underground vaults. Although its primary food source is seeds, springtime dining is augmented with new plant growth. In June, July and August the mouse is known to consume certain insects, especially grasshoppers and caterpillars.
Breeding nests are spherical constructions woven from grass or other plant material. A nest is approximately 13 centimeters in diameter and lined with a more downy material of fibrous plants. A nest may have one or more entrances near its base. Most commonly, the nest is built on the ground in a protected area such as within a shrub or beside a fallen tree. However, the mouse will occasionally place the nest aboveground within a shrub.
It breeds from early spring to late autumn, with reduced activity at midsummer. The gestation period is 23 to 24 days. Repeated fertilization often occurs immediately after giving birth. It is not uncommon for a female to have ten to fourteen litters per annum, with a typical litter size of two to six individuals. However, litters of up to nine offspring can occur. Thus an annual production of forty to sixty young per female is normal. Newborn mice weigh approximately 1.0 to 1.5 grams.
Domestic and feral cats are a threat to the western harvest mouse. On the IUCN Red List it is listed as "Least Concern" (LC). Its many predators include the fox, weasel, coyote, hawk, snake and owl species. Other predators include shrikes, squirrels, raptors, short-tailed shrews, cats, and scorpions.
