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Neotoma lepida intermedia

(Desert Woodrat)

Interesting Facts

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Common Names

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Common Names in English:

Desert Woodrat, San Diego Desert Woodrat

Description

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Habitat

Desert woodrats are found in a variety of shrub and desert habitats , primarily associated with rock outcroppings, boulders , cacti, or areas of dense undergrowth (Bleich 1973; Bleich and Schwartz 1975; Brown et al. 1972; Cameron and Rainy 1972; Thompson 1982). Bleich and Schwartz (1975) recorded 81% of captures of woodrats in rocky areas on the Naval Weapons Station , Fallbrook Annex in northern San Diego County, substantiating other work on habitat selection by this species (Cameron and Rainey 1972; Thompson 1982). Desert woodrats are noted for their flexibility or plasticity in utilizing various materials , such as twigs and other debris (sticks , rocks, dung), to build elaborate dens or “middens,” which typically include several chambers for nesting and food, as well as several entrances. Middens may be used by several generations of woodrats (Cameron and Rainey 1972). Woodrats often are associated with cholla cactus which they use for water and dens or boulders and boulder piles (Thompson 1982). Thus, their distribution is a consequence of habitat structure and heterogeneity (i.e. , patchiness). Thompson (1982) found that woodrats at Joshua Tree in the Mojave Desert actively avoid open areas. They also inhabit pinyon-juniper hillsides at lower elevations and juniper woodland (MWD and RCHCA 1995). The desert woodrat often is associated with large cactus patches (S. Montgomery, pers. comm. 1998), and within coastal sage scrub communities, it almost is invariably associated with prickly pear (Opuntia occidentalis). It also is found in rocky outcroppings and boulder-covered hillsides in chaparral or oak woodlands (MWD and RCHCA 1995). In chaparral, rock dens usually are located near primary food sources to minimize travel time and exposure to predators . In the Mojave Desert, dens comprised of cholla were preferentially inhabited compared to yucca, and were occupied for longer periods (4.1 months versus 2.5 months, respectively) (Smith 1995). Smith (1995) suggests that cholla provides better protection from predators than yucca.

Typically found at an altitude of 0 to 2,147 meters (0 to 7,044 feet).[1]

Ecology:
List of Habitats : 8.1 Desert - Hot

Biology

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Diet

Desert woodrats primarily are herbivorous, and their diet may include leaves, seeds, berries , parts of flowers, and yucca shoots (Cameron and Rainey 1972). Woodrat foraging behavior entails venturing from a sheltered area or den to a plant, usually within 3 meters of the den, clipping the vegetation, and then returning to the sheltered area or den to consume the food morsel (Thompson 1982). Although many parts of plants may be collected and brought back to the den, only certain parts of the plant may be consumed. For example, in the Mojave Desert, Thompson (1982) observed that woodrats consumed only the stems and twigs of creosote (Larrea tridentata) and left the leaves and flowers in piles. According to Thompson, little time is spent feeding at the site of the plant and feeding usually occurs in areas sheltered on three sides with good protection from aerial predators (e.g. , owls). Den sites in cacti would provide similar protection from predators (e.g., Smith 1995). There was no evidence of hoarding food in the Thompson (1982) study, but others have noted vegetative caches in dens (e.g., Cameron and Rainey 1972).

Reproduction

Desert woodrat litter sizes typically are 2-3 pups (Bleich 1973; Bleich and Schwartz 1975). Gestation period is 30-36 days and females can bear up to four litters per year. Bleich (1973) found pregnant desert woodrats on the Naval Weapons Station , Fallbrook Annex in February, March, April, and December. Juveniles 3-4 weeks of age were trapped in December, indicating breeding in late October or early November (Schwartz and Bleich 1975). Lactating females were collected in March and July and a scrotal male was collected in July (Bleich 1973). Bleich (1973) concluded that desert woodrats breed year-round at Fallbrook, but that the peak breeding season appears to be November to April. On the other hand, Smith (1995) documented reproductive failure in the desert woodrat during a severe drought in the eastern Mojave Desert. Age of sexual maturity was not noted in these studies.

Dispersal : The only information on dispersal by desert woodrats reviewed was the study discussed above by Smith (1995) where males apparently dispersed more than females.

Behavior

Daily Activity: Thompson’s (1982) radiotelemetry study of desert woodrats in Joshua Tree in the Mojave Desert indicated that woodrats spent about 70% of the day in their diurnal den site, 21% at feeding sites, and less than 10% traveling or exploring. Woodrats tend to be relatively sedentary and do not venture far from their diurnal dens.

Survival: The only study of survival reviewed was Smith (1995), who monitored desert woodrat den use and survival during a severe drought in the eastern Mojave Desert (the UC Granite Mountains Reserve) east of Barstow, California. She found that the mean survival for animals trapped at least two times was 5.4 months, and only 3.3 months considering all trapped animals. Although not analyzed statistically, more females were trapped in subsequent trapping intervals than males (67% versus 30%), suggesting greater natal dispersal by males. It is assumed that under less severe environmental conditions , that survivorship is somewhat greater than observed by Smith.

Socio-Spatial Behavior: Thompson (1982) found that woodrats forage in distinct and predictable spatial patterns confined to a few spatial loci. He concluded that patterns of movement and spatial activity by this sedentary species primarily are determined by habitat structure. Different areas of their home range are used differentially. Den sites tended to be on the periphery of the home range, as did other distinct loci of use. Woodrats moved between loci along distinct routes. As expected with a sedentary species, home ranges of woodrats are relatively small. A live-trapping study or rodents, including the desert woodrat, by Bleich and Schwartz (1975) on the Naval Weapons Annex, Fallbrook concluded that male and female home ranges were 371 sq meter (0.037 hectare [ha]) and 433 sq meter (0.0433 ha), respectively. Average moves by males and females were 13.2 meters and 14.5 meters. There was some male-male and female-female home range overlap, but mostly male-female overlap.

Taxonomy

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Similar Species

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Members of the genus Neotoma

ZipcodeZoo has pages for 40 species and subspecies in this genus:

N. albigula (White-Throated Woodrat) · N. albigula albigula (White-Throated Woodrat) · N. albigula venusta (Colorado Valley Woodrat) · N. angustapalata (Tamaulipan Woodrat) · N. anthonyi (Anthony's Woodrat) · N. bryanti (Bryant's Woodrat) · N. bunkeri (Bunkers Woodrat) · N. chrysomelas (Nicaraguan Woodrat) · N. cinerea (Bushy-Talied Woodrat) · N. cinerea cinerea (Bushy-Tailed Woodrat) · N. devia (Arizona Woodrat) · N. floridana (Key Largo Woodrat) · N. floridana baileyi (Bailey's Eastern Woodrat) · N. floridana floridana (Eastern Woodrat) · N. floridana haematoreia (Southern Appalachian Eastern Woodrat) · N. floridana illinoensis (Eastern Woodrat) · N. floridana smalli (Eastern Woodrat) · N. fuscipes (San Joaquin Valley Woodrat) · N. fuscipes annectens (San Francisco Dusky-Footed Woodrat) · N. fuscipes fuscipes (Dusky-Footed Woodrat) · N. fuscipes luciana (Monterey Dusky-Footed Woodrat) · N. fuscipes riparia (San Joaquin Valley Wood Rat) · N. goldmani (Goldman's Woodrat) · N. lepida (Desert Woodrat) · N. lepida intermedia (Desert Woodrat) · N. lepida lepida (Desert Woodrat) · N. leucodon (White-Toothed Woodrat) · N. macrotis (Big-Eared Woodrat) · N. magister (Allegheny Woodrat) · N. martinensis (San Martin Island Woodrat) · N. mexicana (Mexican Woodrat) · N. mexicana mexicana (Mexican Woodrat) · N. micropus (Southern Plains Woodrat) · N. micropus leucophaea (Southern Plains Woodrat) · N. micropus micropus (Southern Plains Woodrat) · N. nelsoni (Nelson's Woodrat) · N. palatina (Bolano's Woodrat) · N. phenax (Sonoran Woodrat) · N. stephensi (Stephens's Woodrat) · N. varia (Turner Island Woodrat)

More Info

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Further Reading

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Notes

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Contributors

Identifiers

Footnotes

  1. Mean = 361.800 meters (1,187.008 feet), Standard Deviation = 455.930 based on 333 observations. Altitude information for each observation from British Oceanographic Data Centre. [back]
Last Revised: 7/14/2012