Mammals of North America
Page 9
PLATE 42
MID-CALIFORNIA FIVE-TOED
KANGAROO RATS
HEERMANN’S KANGAROO RAT Dipodomys heermanni 250-313mm, 160-200mm, 70-80g
Medium-large kangaroo rat with relatively broad face and moderate-sized ears. Has five toes on the hind feet. Dorsal pelage varies from tawny-olive strongly overwashed with black to orangish yellow. Tail crest may be dark and only slightly crested, blackish and very scantily haired or white tipped. Ears are smaller (12-15mm) than those of the Narrow-faced Kangaroo Rat. Smaller than the Giant Kangaroo Rat and larger than the San Joaquin Valley Kangaroo Rat. The subspecies D. h. morroensis from the Morro Bay area is Endangered, and typically lacks a hip stripe. They excavate their own burrows and also use abandoned ground squirrel tunnels. Occurs in wide range of habitats from Lower Sonoran to Transition zone.
GIANT KANGAROO RAT Dipodomys ingens 312-348mm, 157-197mm, 93-195g
Largest of the kangaroo rats. Has a dusky-colored nose, whitish cheeks, and blackish eyelids. Lateral white stripes along the tail are only slightly narrower than the dorsal and ventral dark stripes. Has five toes on the hind feet. Tail tuft is dark in appearance because of a mix of pale and dark hairs. This Endangered species is restricted to southwestern San Joaquin Valley and adjacent arid areas of the Inner Coastal ranges of California. Primarily nocturnal, they sometimes forage in the daylight, especially at dusk. Burrows are frequently remodelled by changing entrances. Uses sandy loamy soil on level and gently sloping ground vegetated with annual grasses and forbs and widely scattered shrubs from 200-800m.
NARROW-FACED KANGAROO RAT Dipodomys venustus 293-336mm, 175-210mm, 68-97g
Large, dark-colored, five-toed kangaroo rat with black nose that merges into a black band at the base of the whiskers. Top of head and back are darker, sides and thigh patches are yellowish brown. Ears are large and nearly black, with pale spots at the base and at the top of the fold. The subspecies (D. v. elephantinus) in southern parts of the Gabilan Mountains, California, has lighter ears and less distinctive facial markings, and was previously considered a separate species. Darker than the Agile Kangaroo Rat, with bolder face markings, larger ears, longer tail, and longer rostrum. Darker than Heermann’S Kangaroo Rat, and with much larger ears. Small geographic range along the California coast up to 1770m in elevation. Uses slopes with chaparral, oaks, or digger pine on sandy soils.
PLATE 43
SOUTHERN CALIFORNIA FIVE-TOED KANGAROO RATS
DULZURA KANGAROO RAT Dipodomys simulans 273-302mm, 160-181mm, 55-70g
Intermediate in size, with long, bicolored tail that has a blackish crest and tuft. Has five toes on the hind feet. Upperparts vary from pale grayish brown to dark reddish brown, depending on geography. Smaller than the Agile Kangaroo Rat. Longer ears (15-20mm) than Stephens’S Kangaroo Rat. Extends from Baja California, Mexico, into southern California. Nocturnal, but active at both dusk and dawn as well as occasionally during the day. Good swimmers, they use their large hind feet to their advantage in the water. Uses coastal chaparral and grasslands on gravelly or sandy soil from sea level to 2300m.
STEPHENS’S KANGAROO RAT Dipodomys stephensi 277-300mm, 164-180mm, 45-73g
Medium-sized five-toed kangaroo rat with yellowish-brown upperparts overlain with black hairs. Narrow lateral white tail stripes are indistinctly demarcated from the dark stripes (not sharply demarcated broad lateral stripes as in the Agile Kangaroo Rat). Has smaller ears (12-14mm) and occupies more open habitats than the Agile and Dulzura kangaroo rats. Seriously Endangered by agricultural and urban development, now restricted to Riverside, San Bernardino, and San Diego counties, California. Found in sparse grasslands and coastal sage-scrub habitats from 85-850m.
AGILE KANGAROO RAT Dipodomys agilis 277-320mm, 170-195mm, 63-79g
Intermediate-sized five-toed kangaroo rat with large ears and dark reddish-brown upperparts. The belly is white, and the long, bicolored tail has a blackish crest and tuft, with broad, sharply demarcated white lateral stripes. Pelage of young animals is darker than adults, with hairs on tail not elongated into a crest. Larger than the Dulzura Kangaroo Rat, with longer ears (16-19mm) than Stephens’S Kangaroo Rat. Active mainly at night, and solitary except during the breeding season from March to July. Found primarily in areas of loose soil in open chaparral and coastal sage-scrub from 500-2300m.
PLATE 44
OTHER FIVE-TOED KANGAROO RATS
CHISEL-TOOTHED KANGAROO RAT Dipodomys microps 245-295mm, 135-175mm, 40-70g
Medium-sized, narrow-faced, small-eared, kangaroo rat with incisors that are flattened anteriorly and not strongly incurved. Has five toes on the hind feet. Metallic gray pelage, darker tail stripes, and a more prominent face mask distinguish it from Ord’S Kangaroo Rat. Long whiskers maintain contact with the ground even when the animal is in midair. Hind feet and tail are shorter than those of Panamint Kangaroo Rat. Eats more leaves than other kangaroo rats, and is one of few mammals adapted to feed on Atriplex saltbush. Occupies desert valleys dominated by saltbush in the Great Basin.
PANAMINT KANGAROO RAT Dipodomys panamintinus 285-334mm, 156-202mm, 57-95g
Medium-sized five-toed kangaroo rat with pale, clay-colored upperparts tinged with pale ocher. Thigh patches are large and colored like the back. Facial crescents and end of nose are broadly blackish, but are not continuous (or just barely continuous) over the sides of the nose. Inner sides of legs are dusky pale brownish and underparts are white. Tail has a ventral stripe that may extend to the end of the tail vertebrae. Has a longer tail than the Gulf Coast Kangaroo Rat and longer feet (42-48mm) than Ord’S Kangaroo Rat. Lower incisors are rounded and curved like most other kangaroo rats, but unlike the Chisel-toothed Kangaroo Rat. Uses coarse sand and gravelly desert flats with scattered desert scrub vegetation.
ORD’S KANGAROO RAT Dipodomys ordii 208-365mm, 100-163mm, 50-96g
Medium-sized, relatively short-tailed five-toed kangaroo rat. Color of back may be brownish, reddish, or blackish, depending on the subspecies. The belly is white. Has shorter hind feet (39-44mm) than the Panamint Kangaroo Rat. The Chisel-toothed Kangaroo Rat has chisel-shaped lower incisors; the Gulf Coast Kangaroo Rat has an orange cast to the pelage and a shorter, less-crested tail. Nocturnal and active year-round, Ord’S Kangaroo Rat is more often seen on cloudy nights and rarely on cold or snowy nights. Occupies variety of habitats associated with fine-textured, sandy soils including semiarid grasslands, mixed grasslands, and scrublands.
GULF COAST KANGAROO RAT Dipodomys compactus 205-266mm, 104-135mm, 44-60g
Medium-sized kangaroo rat with a short tail. Found only in southern Texas. Coastal island forms are orangish yellow or grayish cream on the back; mainland animals are reddish yellow on the back. This color covers the entire back and is purest on the sides and flanks. Upperparts are lightly washed with black. Ears, underside of feet, and dorsal and ventral tail stripes are similar to the dorsal color. Cheeks are white. Tail is shorter and less hairy than Ord’S Kangaroo Rat. Has five toes on the hind feet. Uses sparsely vegetated areas with sandy soil, such as open mesquite savanna. In areas where their range overlaps with Ord’S Kangaroo Rat, Gulf Coast Kangaroo Rats are more likely to be in softer soil areas where the vegetation is lower and the landscape generally more open.
PLATE 45
JUMPING MICE
JUMPING MICE - Superficially look like the unrelated kangaroo rats with their long tails and large feet. These nocturnal mice have grooved upper incisors and a tricolored pelage with distinct colors on the back, sides, and belly. Sexes are similar. Not seen in winter because all species hibernate for most of the cold months.
WOODLAND JUMPING MOUSE Napaeozapus insignis 210-255mm, 125-160mm, 15-30g
Redder than the Meadow Jumping Mouse with a white tail tip. Pelage is smooth (not grizzled) and the color becomes more orangish toward southern portion of range. No whitish border on ears. Only three cheek teeth on each side of upper jaw. True to their name, these nocturnal mice are able to jump up to 4m. The long tail acts as
a balance during jumping, and the large hind feet provide the power. They do not make runways, although they will use those of other species. Feeds on fungi, insect larvae, and fruit. Found only in or along wooded areas; rarely in open habitats.
MEADOW JUMPING MOUSE Zapus hudsonius 180-235mm, 100-135mm, 12-30g
Yellowish mouse with a bicolored tail that lacks a white tip. Four cheek teeth. Yellow fur is less grizzled than in the Western Jumping Mouse, with a more distinctly bicolored tail and no white fringe on the ear. Slightly smaller than other Zapus. Primarily nocturnal, and escapes by making short leaps; shorter than those of the Woodland Jumping Mouse. Colorado and Wyoming subspecies (Z. h. preblei) is threatened. Found in grassy or weedy fields and occasionally along the edge of woods.
WESTERN JUMPING MOUSE Zapus princeps 215-245mm, 130-150mm, 18-25g
Pelage grizzled dorsally, with pale yellowish-buff lateral line. Ears have a slight whitish border; tail less distinctly bicolored. Due to the short active season, they have only a single litter of 2-8 young after an 18-day gestation period. After nursing for 30 days, the young must put on enough fat to hibernate in the next 45 days. They manage this by feeding on grass seeds and forbs, although early in the active period they feed on invertebrates and fungi as well. Found in high mountain meadows and in wetter streamside habitats.
PACIFIC JUMPING MOUSE Zapus trinotatus 210-250mm, 110-155mm, 20-30g
Brightly contrasting colors on back with a brownish (not white) border to the ears. Pelage tricolored, back dark brown, sides yellowish orange, and belly whitish. Distinct area of buff hair forms a lateral line. Fall pelage paler and less contrasting. Tail sparsely haired. Their erratic and evasive locomotion has led to their description as nervous or high-strung. Feeds mainly on grass seeds, and leaves characteristic piles of stem cuttings. Found in wet meadow habitats of the Pacific Northwest.
PLATE 46
EASTERN AND CENTRAL WOODRATS
WOODRATS - Also known as packrats, these soft-furred, nocturnal rats have long tails and relatively large ears. Characters of the tail or throat often distinguish species.
EASTERN WOODRAT Neotoma floridana 305-450mm, 130-180mm, 220-385g; 300-400mm, 130-170mm, 175-260g
A medium-sized woodrat, grayish-brown dorsally and white ventrally. Differs from Allegheny Woodrat primarily in having a skull with a maxillovomerine notch, and by geographic range. Worn summer pelage may appear cinnamon-orange. Head becomes grizzled in older animals. Larger than Mexican Woodrat, with throat and breast hair that is white to base. Paler in color than Southern Plains Woodrat. Dens constructed of sticks, often around large rock or log. Key Largo subspecies, N. f. smalli, is Endangered. Found primarily in wooded areas, but also in hedgerows and rocky outcrops in grasslands.
ALLEGHENY WOODRAT Neotoma magister 370-465mm, 145-215mm, 230-485g; 350-445mm, 140-210mm, 230-455g
Only woodrat in range. Slightly larger, and with slightly hairier tail than Eastern Woodrat; skull needed for certain identification. A large woodrat, cinnamon brown with gray dorsally and gray or white ventrally. Juveniles are grayer; summer animals are darker. Does not build complex stick dens, but makes grass and bark nests in crevices and abandoned buildings, and nearby latrine sites with large accumulations of feces are a sure sign of their presence. Rare and declining, apparently because of a disease transmitted from large Raccoon populations. Found along cliffs, caves, and talus slopes of the Appalachian Mountains.
MEXICAN WOODRAT Neotoma mexicana 290-415mm, 105-205mm, 150-255g
Smallish woodrat with sparsely haired tail and throat hairs gray at base. Back may be grayish brown or rufous brown; white below with a bicolored tail. Color is less gray than Southern Plains Woodrat. A dusky line usually borders the mouth. May build stick dens; more typically uses crevices, tree cavities, or buildings for nests. Mexican Woodrats have the weakest instinct for collecting items, the behavior that led to the name packrat. Food includes berries, seeds, and green vegetation. Found on rocky outcrops or cliffs and rocky slopes in mountainous areas and woodlands.
SOUTHERN PLAINS WOODRAT Neotoma micropus 335-410mm, 130-175mm, 210-315g; 310-380mm, 130-165mm, 180-275g
Steel-gray back with throat hairs white to base. Bicolored tail is relatively short and sparsely haired. Fur soft, dense, darker than in the Eastern Woodrat, and less colorful than the Mexican Woodrat. Belly is pale gray; throat and chest are white. Feet are white. Dens are built from sticks, manure, and cactus joints around desert vegetation. Breeding occurs in spring and fall and a litter of 2 or 3 is born after a gestation period of 30-39 days. Young are weaned at 30 days, disperse in 6 months, attain adult size at 9 months, and live up to 27 months. Found on rocky hillsides and grassy lowlands with desert scrub vegetation.
PLATE 47
FURRY-TAILED WOODRATS
WHITE-THROATED WOODRAT Neotoma albigula 280-400mm, 75-185mm, 135-285g
Throat hairs are white to base. This medium-sized woodrat has a brown back and a bicolored tail. Tail has long hairs, but is not bushy. The soft short pelage often has blackish hairs interspersed with the brown. Ears are relatively long and feet are white. Large stick dens are constructed of cactus and the woody stems of mesquite, juniper, and other shrubs. Breeds year-round, with a gestation period of 38 days and litter sizes of 2 or 3. The young weigh about 10g at birth, and lactation lasts about 20-25 days. Found in a wide variety of habitats ranging from low desert to rocky slopes on mountainsides from sea level to 2500m (red area on map).
WHITE-TOOTHED WOODRAT Neotoma leucodon 335-410mm, 130-175mm, 210-315g; 310-380mm, 130-165mm, 180-275g
Identical in appearance to the White-throated Woodrat, but found only east of the Rio Grande in Texas, New Mexico, and Mexico. Recently described from genetic data; no morphological, ecological, or behavioral differences have been reported. Nocturnal and terrestrial, but capable of climbing in shrubs and cacti. Builds conspicuous stick nests at the base of shrubs or trees, or between boulders. Some nests are huge, up to 4m in diameter and 1m high. Occurs in arid woodlands and pastures, juniper woodlands, oak forests, and cactus shrublands (yellow area on map of White-throated Woodrat).
STEPHENS’S WOODRAT Neotoma stephensi 275-310mm, 115-150mm, 115-180g
Small woodrat with dusky-gray pelage and a semi-bushy tail. Western animals are darker, with throat hair dark to base and a nearly black tail; eastern animals are lighter in color with throat hairs that are white at the base and a tail with fewer black hairs. Belly is creamy in color. Dusky dorsal color extends to just below ankle, feet are white. Tail is bushier than in all woodrats except the Bushy-tailed Woodrat. This woodrat is one of the few mammals specialized to feed on conifer needles, specializing in juniper twigs. Dens are almost always found at the base of junipers. Also occurs in ponderosa pine, agave, and cactus habitats.
BUSHY-TAILED WOODRAT Neotoma cinerea 310-470mm, 130-225mm, 180-585g; 275-410mm, 120-195mm, 165-370g
Large woodrat with bushy, squirrel-like tail. Ears are large, thinly haired, and almost translucent. Back varies from pale gray to blackish brown and belly is buff to whitish; animals in cooler climates have darker coloration. Fur is long and dense. Whiskers are long. Some subspecies have white hair along mid-ventral line, others have white throats. Nocturnal and active year-round, these are classic packrats, carrying a wide variety of items back to the nest. Dens are haphazard accumulations of sticks, bones, and other material, often dropped in cracks and crevices. Urination spots often conspicuous. Found in wooded, mountainous habitats in the Northwest.
PLATE 48
WOODRATS AND RATTUS
DUSKY-FOOTED WOODRAT Neotoma fuscipes 335-470mm, 160-240mm, 205-360g
Has sooty-colored hairs on the top of hind feet. Medium-sized woodrat with brownish-gray back, pale to white belly, and a faintly bicolored tail. Pelage darker near coast. Constructs fairly elaborate stick nests on the ground, in the vegetation, and on rocky slopes. Found mainly in scrub and woodland communities (see red area on map).
BIG-EARED WOODRAT Neotoma macrotis 335-470mm
, 160-240mm, 205-360g
Externally in appearance like Dusky-footed Woodrat. This species was only recently split from N. fuscipes, the two differ mostly in genetic and obscure morphological characters; Big-eared Woodrat has a larger vomer, narrow presphenoid relative to the basisphenoid, and a flower-like glans penis. Behavior and ecology like Dusky-footed Woodrat (see yellow area on map of Dusky-footed Woodrat).
ARIZONA WOODRAT Neotoma devia 255-325mm, 110-160mm, 72-144g
Has very large petal-like ears and dark gray throat fur. Small body size with pale coloration. Belly is white. Range restricted to Arizona and northwest Sonora. Smaller and paler in color than the Desert Woodrat. Builds dens at the base of cliffs and on rocky outcroppings, and covers them with cactus. Found in both low deserts and mountain areas south of Grand Canyon and east of Colorado River.