Bushy-tailed woodrats are found in western North America, ranging from arctic Canada to northern New Mexico and Arizona. This species was thought to be restricted to higher elevations until very recently, when the first reports documenting Neotoma cinerea at elevations as low as 1200 m appeared. These findings lend support to molecular evidence which had earlier indicated that bushy-tailed woodrat populations were not isolated on mountain ranges throughout the Holocene. It is currently unclear whether these lowland populations are isolated by even lower valleys, or whether this species can exist in low, xeric areas as well. Bushy-tailed woodrats are currently found at elevations up to at least 3700 m. During the Pleistocene, N. cinerea is well-known at lower elevations, and its range extended south to southern Mexico. Up to thirteen subspecies are recognized. These subspecies are primarily defined based on geography and local ecology, and are not universally accepted.

(Escherich, 1981; Grayson and Livingston, 1989; Grayson et al., 1996; Mewaldt, 1982; Smith et al., 1995)

Biogeographic Regions: nearctic (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: Western North America, from southeastern Yukon and westernmost Northwest Territories southward through British Columbia and western Alberta to northern Arizona and New Mexico, east to the western Dakotas (Smith 1997). See Grayson and Livingston (1989) for a discussion of high-elevation records (3648 m and 4342 m).

Bushy-tailed woodrats are sexually dimorphic: adult males usually weigh 300-600 g with an average of 405 g, whereas adult females usually weigh only 250-350 g with an average of 270 g. These ranges are relatively large because this species occupies a large geographic range, and its body size is closely correlated with climate (conforms to Bergmann's rule). Neotoma cinerea is the largest and most cold-tolerant species of woodrat, and the largest and most sexually dimorphic individuals of this species are found in the northern parts of its range. In addition, body size of bushy-tailed woodrats (examined via fecal pellet size in middens) has been shown to correlate with known climatic fluctuations over the past 25,000 years. Woodrats are good climbers and have sharp claws. They have hypsodont molars with enamel ridges. The color of the pelage varies across the range, but is usually buff with white areas around the feet. The bushy tail characteristic of the species is used to warm the animal. Pictures of bushy-tailed woodrats are available in Vaughan (1990), Escherich (1981), and on the web at: . Escherich (1981) provides pictures of both sexes at various point throughout ontogeny, as well as pictures of skulls and skins.

(Egoscue, 1962; Escherich, 1981; Finley, 1990; Hickling et al., 1991; Martin, 1973; Smith, 1995; Smith et al., 1995; Vaughan, 1990)

Average mass: 335.5 g.

Average basal metabolic rate: 1.152 W.

Length: 47 cm

Weight: 444 grams

• Terrestrial

Bushy-tailed woodrats occupy a range of habitats from boreal woodlands to deserts. They are cliff-dwellers, and are often found on isolated, high-elevation bouldery exposures under a variety of temperature and moisture regimes. They require adequate shelter inside the rocks, though they are occasionally found inhabiting abandoned buildings as well.

(Frase and Sera, 1993; Grayson and Livingston, 1989; Topping and Millar, 1996; Vaughan, 1990)

Terrestrial Biomes: taiga ; desert or dune ; savanna or grassland ; chaparral ; forest ; mountains

Comments: Alpine to Sonoran life zones. Inhabits mountains, cliffs, talus slopes, caves, and rock outcrops, both in forests and open deserts; also in deserted buildings and mine shafts. Young are born in nest within den built of sticks among rocks or in old building or mine shaft.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Because this species occupies such a wide range of habitats, its diet is variable. However, N. cinerea may best be described as a generalist herbivore. Most authors have considered it entirely herbivorous, though Johnson and Hansen (1979) believed a small component of its diet consists of arthropods. Bushy-tailed woodrats eat lots of woody vegetation, and in drier habitats also concentrate on succulents. This species gets all of its water from its food and does not need to drink. Woodrats tend to eat plant materials which have high concentrations of defensive chemicals; they combat these defenses by eating only small amounts of each species. Neotoma cinerea also tends to eat low-energy food items and plants which are high in oxalates. This has implications for the building of middens, discussed below. Neotoma cinerea has an enlarged caecum, and engages in coprophagy. Johnson and Hansen (1979) provide a list of specific food items utilized by this species in a cool, dry environment in Idaho.

(Escherich, 1981; Frase and Sera, 1993; Haufler and Nagy, 1984; Johnson and Hansen, 1979; Vaughan, 1990)

Comments: Feeds on a variety of vegetation; twigs, shoots, leaves, needles, fruit, and seeds. May store food.

Most individuals occupy separate dens. Male may exclude other males from small rock outcrop inhabited by multiple females (Escherich 1981). Home range size in Alberta averaged 6.1 ha for males, 3.6 ha for females, much larger than for other woodrat species; females moved up to 470 m from the nest (Topping and Millar 1996). Average population density is about 1 per 20 acres (Banfield 1974).

Comments: Active throughout the year. Primarily nocturnal but may be seen during the day.

Some aspects of the reproductive cycle of bushy-tailed woodrats are still under debate. These animals have been considered polygamous, polygynous, and/or promiscuous by various authors. Often these conclusions have been based not on actual observed matings, but on the size and relative overlap of male and female ranges. Breeding chiefly occurs in spring and summer (May through August). Females have small litters (up to six young at a time, though litter sizes over four tend to suffer losses since the female has only four mammary glands) but may have up to three litters per year. Modal litter size is three. Females have been observed breeding as soon as twelve hours after giving birth, and be may pregnant with one litter while nursing another. Males fight for access to mates, both through scent marking and actual physical contact. Fights consist largely of biting and scratching and may result in serious injury. Gestation period in captivity is 27-32 days. Newborns weigh approximately 15 g. Eyes open at around 15 days old, and weaning occurs at 26-30 days.

Males are heavier than females from early in development on. By weaning, males weigh 120-150 g, and females weigh 85-135 g. Females do not alter their foraging movements between pregnancy, lactation, and the post-reproductive period -- even though nutrient demands are higher at certain stages. Heavier females tend to have significantly more males in their litters than lighter females. Males are larger and require more energy to raise, though after weaning female offspring tend to reap more rewards from their mothers via philopatry (see "Behavior" section below). Females breed for the first time when they are yearlings.

(Egoscue, 1962; Escherich, 1981; Finley, 1990; Hickling et al., 1991; Moses and Millar, 1992; Moses et al., 1995; Topping and Millar 1996a; 1996b)

Average birth mass: 13.5 g.

Average gestation period: 30 days.

Average number of offspring: 3.68.

Average age at sexual or reproductive maturity (female)

Sex: female: 353 days.

Breeding peaks in spring. Gestation lasts about five weeks. Up to 2-3 litters/year. Litter size is about 3-4. Births occur April-August in California. Young males disperse by 2.5 months, many females breed in natal area. Commonly 1 adult male with 1-3 adult females (Escherich 1981).

Neotoma cinerea is not in any danger, and I did not find any literature discussing the problems of conservation of this species.

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Bushy-tailed woodrats are attracted to shiny items and often steal them from campsites or buildings. They can be a pest species throughout their range as they find a way into buildings and establish den sites.

Bushy-tailed woodrats are important to humans for several reasons. They are important to paleontologists and paleoclimatologists not only because their middens preserve easily-dated plant macrofossils, but also because this species incorporates lots of bones into its middens as well. Packrat middens are a major source of information about Pleistocene paleoclimates and paleoecology in the western United States.

Neotoma cinerea is also important as a prey species. For instance, the bushy-tailed woodrat is one of the major food items for northern spotted owls, a species which is in jeopardy because of range reductions due to logging. The carrying capacity of owls in a particular habitat is largely dependent upon the density of their prey. Interestingly, however, Neotoma cinerea is least frequent in old-growth forests, and found more frequently in more recently cut and open habitats.

(Frase and Sera, 1993; Rosenberg et al., 1994; Vaughan, 1990)