This species and the white-footed mouse (Peromyscus leucopus) are probably the most abundant of the park's mammals. The deer mouse prefers cool, moist forests and is found most abundantly at the higher altitudes, while the white-footed mouse tends to occur in greater numbers at the lower elevations. This altitudinal division has also been noted in areas surrounding the park.

Species Description:
- Adult Total Length: 155-220 mm (6-9 in.)
- Tail: 80-110 mm (3⅛-4⅜ in.)
- Hind Foot: 19-23 mm (?-⅞ in.)
- Weight: 13-23 g (?-4/5 oz.)

Physical Characteristics:
The dorsal coloration of the medium-sized deer mouse ranges from brownish-gray to reddish-brown. The belly is whitish, and the tail is sharply bicolored (dark above, white below). The eyes and ears are large.

Habitat:
The deer mouse is a forest dwelling rodent that prefers cool, moist forest. It may be found in mixed woods or conifers.

Reproduction:
Breeding extends from early spring to late fall with gestation periods ranging from 23-27 days. Average litters consist of two to four blind, naked, and helpless young. Females with embryos or placental scars have been recorded in the park during the following months: February (1), March (5), April (1), July (10), August (3), September (2), and December (7) (Komarek and Komarek, 1938; Linzey, 1995b). The average number of embryos per female (14 females) was 3.5 (2 - 4). A nursing female was recorded 14 March. Males examined during March (1), July (11), September (2), and December (6) were in breeding condition. Mice kept in captivity by Linzey have produced litters in every month, and it is probable that the wild population also reproduces throughout the year.

Longevity:
Wild deer mice rarely survive for more than 1.5 to 2 years, although captive deer mice have lived as long as 8 years (Linzey, 1998).

Terrestrial Ecology:
Deer mice are primarily nocturnal. They have good eyesight and keen senses of hearing, touch, and smell. Nests may be located in trees, stumps, wood piles, or buildings. Nests are constructed of leaves, grass, shredded bark, moss, paper, cloth, or any other available material.

Feeding Habits:
Examination of the stomachs of 105 Peromyscus maniculatus taken in various portions of the park during July (26), September (3), and December (76) revealed seeds, fruit, and vegetation as the principal food items by volume (Linzey and Linzey, 1973). Animal food (chiefly insects) constituted slightly less than 10% of the total food. A comparison of summer and winter food volumes from four localities showed that seeds apparently form a substantial portion of the diet regardless of the season or habitat, ranging from 57.5 to 67.5%. Insects form a larger portion of the diet in summer than in winter. Since the sample was dominated by winter specimens (76 to 29), the over-all figure of 10% volume of animal foods is probably lower than it would have been if the specimens had been taken at evenly distributed times throughout the year.

Home range size is generally between about 0.4 and 1.2 ha (Linzey, 1998). A definite homing ability for distances up to approximately 0.4 km is known for this species (Linzey, 1998).

Predators and Defense:
All instances of predation involving Peromyscus sp. are reported in this account of Peromyscus maniculatus, since remains of mice of this genus found in the stomachs of predators have not been identified to species. Three timber rattlesnakes (Crotalus horridus) taken near Laurel Creek, Trillium Gap, and Gregory Bald had eaten Peromyscus sp. (Stupka, 1945, 1947, 1954). Peromyscus were recorded in the stomachs of 21 of 44 timber rattlesnakes examined by Savage (1967). The stomachs of two screech owls (Otus asio) found at the Townsend Y and near park headquarters also contained remains of these mice (Stupka, 1938, 1949). A long-tailed weasel (Mustela frenata) seen on Mt. LeConte near LeConte Lodge was carrying a Peromyscus. A specimen was removed from the stomach of a bobcat (Lynx rufus) killed along the Newfound Gap Road in Tennessee (Stupka, 1952).

Parasites:
Tapeworm cysts of a species not determined and nematodes (Longistriata sp. and Oxyuris sp.) were found in the intestines and cecae of some specimens examined by the Komareks. Pfitzer (1950) removed a large number of fleas (Peromyscopsylla sp., Orchopeas sp., and Ctenophthalmus sp.) from the deer mouse. Linzey has recorded the following fleas: Stenoponia americana, Orchopeas maniculatus, Epitedia wenmanni testor, and Peromyscopsylla hesperomys (Linzey, 1995b).

The deer mouse ranges throughout much of Alaska and Canada, and is found throughout much of the United States, except for most of the southeastern states.

This species and the white-footed mouse (Peromyscus leucopus) are probably the most abundant of the park's mammals. The deer mouse prefers cool, moist forests and is found most abundantly at the higher altitudes, while the white-footed mouse tends to occur in greater numbers at the lower elevations although it has been recorded as high as 6,500 feet (Smith and Mouzon, 1985). These species come together in the park at about 3,000 feet (Komarek and Komarek, 1938). However, there is considerable overlap, and the two forms are frequently taken in adjacent traps. This altitudinal division has also been noted in areas surrounding the park. An indication of a seasonal difference in the distribution of these two species was recorded at Cosby in the 1960s (Linzey and Linzey, 1971). In March 1964, the deer mouse was recorded along Cosby Creek (1,720 feet). During the summers of 1963 and 1964, however, the area was occupied by white-footed mice, and no deer mice could be found.

References:

Handley, C.O., Jr. 1999. Deer mouse. Pages 575-577. In: D.E. Wilson, and S. Ruff (eds.). The Smithsonian Book of North American Mammals. Smithsonian Institution Press, Washington, D.C.

Linzey, D. W. 1995a. Mammals of Great Smoky Mountains National Park. The McDonald & Woodward Publishing Company, Inc., Blacksburg, Virginia.

Linzey, D. W. 1995b. Mammals of Great Smoky Mountains National Park-1995 Update. Journal of the Elisha Mitchell Scientific Society 111(1): 1-81.

Linzey, D. W. 1998. The Mammals of Virginia. The McDonald & Woodward Publishing Company, Inc., Blacksburg, Virginia.

Savage, T. 1967. The Diet of Rattlesnakes and Copperheads in the Great Smoky Mountains National Park. Copeia 1967 (1): 226-227.

Smith, T.R., and J.M. Mouzon. 1985. Small Mammal Survey in the Spruce-Fir Zone of Great Smoky Mountains National Park. Typewritten final research report. In library of Great Smoky Mountains National Park.

Stupka, A. 1935-63. Nature Journal, Great Smoky Mountains National Park. 28 volumes (years) each with index. (Typewritten copy in files of Great Smoky Mountains National Park library).

Linzey, D. W. and A.V. Linzey. 1973. Notes on Food of Small Mammals from Great Smoky Mountains National Park, Tennessee-North Carolina. Journal of the Elisha Mitchell Scientific Society 89 (1 and 2): 6-14.

Komarek, E. V. and R. Komarek. 1938. Mammals of the Great Smoky Mountains. Bulletin of the Chicago Academy of Sciences 5(6): 137-162.

Pfitzer, D.W. 1950. Report on mammals Collected or Observed, June-October, 1950. (Typewritten copy in files of Great Smoky Mountains National Park.)