Perception Channels: tactile ; chemical
IUCN Red List of Threatened Species: least concern
The diet of R. fulvescens mainly consists of seeds, the green shoots of vegetation and some insect larvae. The fulvous harvest mouse seems to enjoy butterfly larvae (Grzimek 1972, Grzimek 1990).
Reithrodontomys fulvescens can be found in southeast Arizona, southwest and east Texas, east Oklahoma, southeast Kansas, southwest Missouri, west Arkansas, Louisiana, and west Mississippi (Whitaker, J.O. Jr. 1980, Davis and Schmidly 1994).
Biogeographic Regions: nearctic (Native )
This mouse occurs mostly in low grassy or weedy areas or along creek bottoms with tangled vines and bushes. In southern areas, R. fulvescens lives in "arid inland valleys where temperatures are high and the soil is sandy or rocky" (Hall and Kelson 1959).
Terrestrial Biomes: savanna or grassland
This mouse resembles the house mouse but differs in its hairier tail and grooved upper incisors (Nowak 1991). The length of the tail is greater than half of the total body length (Whitaker, Jr. 1980). Ears of R. fulvescens are large. The hair on the upper body is a mixture of reddish brown and black, creating a salt and pepper effect (Hall and Kelson 1959). R. fulvescens has a tail that is much longer than its body and its under parts are white to buff. The adult plumage is brighter than that of the juvenile and adults molt once a year. Females have six mammae. A typical harvest mouse weighs about 18 grams.
Average mass: 18 g.
Other Physical Features: endothermic ; bilateral symmetry
Peaks in reproduction for R. fulvescens occur in late spring and early autumn with a breeding season that extends from February all the way through to October. The gestation period is approximately twenty days with an average litter size of about three or four. Each newborn weighs about one gram. By the second week, the young are well-furred and by about nine to twelve days, the eyes are open (Davis and Schmidly 1994). At three weeks, the young leave the nest and by five weeks, they are at full size (Grzimek 1990).
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sexual
About 17 subspecies of R. fulvescens are recognised and they vary in both colouring and size. Their total length ranges from about 134 to 189 mm (5.3 to 7.4 in) with a tail between 73 and 116 mm (2.9 and 4.6 in). Their yellowish-buff or tawny fur is relatively coarse and has a streaked or speckled effect caused by the mixture of black guard hairs and the paler, banded hairs of the undercoat. Often, a dark stripe runs along the spine. The underparts are grayish-white, sometimes tinged with buff. This mouse can be distinguished from the rather larger hairy harvest mouse (Reithrodontomys hirsutus) by its pelage and skull characteristics, the pale underside of the tail and the whitish or buff color of the hind feet.
The fulvous harvest mouse has a widespread distribution with a range extending from Honduras, Guatemala and El Salvador northwards through Mexico to the southwestern United States, where it is present in Arizona, Texas, Oklahoma, Kansas, Missouri, Arkansas, and Mississippi. Its typical habitat is grassy areas containing some shrubs, especially in areas with mesquite or pine/grass ecozones.
The fulvous harvest mouse is nocturnal. In Arkansas, animals began to deposit fat in their tissues in November and this peaks in January and then the fat reserves are steadily used up by April. Other adaptations to winter include a lengthening of the animal's hair and a possible daily reduction of its body temperature during sleep in the daytime. The animal quickly recovers from hypothermia and resumes activity when it warms up. A nest is built in vegetation just off the ground and consists of a ball of grasses and sedges about 75 mm (3.0 in) in diameter. It is usually occupied by a pair of mice which may be a pair-bonded male and female. When the mice are inside, the entrance, or pair of entrances, is plugged. When the animals move about outside, much of their time is spent off the ground in low vegetation.
The diet of the fulvous harvest mouse varies seasonally, but in milder climates, consists primarily of insects and other invertebrates throughout the year, whereas in colder regions, invertebrates predominate in the spring, and seeds in the fall and winter. A small proportion of green leafy and other plant food is also eaten. Predators of this mouse include barn owls (Tyto alba) and red-tailed hawks (Buteo jamaicensis).
In Mexico, breeding seems to take place throughout the year, but in Texas, usually two breeding peaks occur, one in late spring and the second a few months later. The litter size is usually two to four offspring, but may be more. The young are blind, naked, and helpless at birth, their eyes open between the ninth and 12th days and weaning takes place between the 13th and 16th. Life expectancy is up to 15 months for males and up to 12 months for females.