Mammals of North America Read online

  Larger than other lowland western cottontails, relatively smaller ears than Desert Cottontail. Range extends into some western states, requiring especially careful scrutiny in Texas and New Mexico where it can easily be confused with the Manzano Mountain and Robust Cottontails, which are restricted to select mountain ranges. One additional cryptic rabbit from the mountains of southwestern New Mexico (Hidalgo, Luna, southern Grant counties), S. f. holzneri, is still considered a subspecies since its relationship to Mexican populations of Eastern Cottontails remain unclear. (See page 42 for map and more details on eastern cottontails.)

  MANZANO MOUNTAIN COTTONTAIL Sylvilagus cognatus 440-462mm, 55-75mm

  Restricted to the Manzano Mountains, New Mexico. A large rabbit with relatively dark and rich colored fur. This mountaintop endemic has recently been considered a full species, but is very similar to the Eastern Cottontail and difficult to distinguish. It has relatively small ears compared to adjacent Desert and Eastern Cottontails from the western plains. Uses upper montane and subalpine coniferous forest with Douglas fir, white fir, Engelmann spruce and corkbark fir. Also found in subalpine-montane grassland, and montane scrub on dry, steep western slopes.

  ROBUST COTTONTAIL Sylvilagus robustus 440-482mm, 50-80mm

  A large rabbit restricted to montane areas of the Trans-Pecos area of Texas and New Mexico. Compared with other cottontails it is more grizzled gray than brownish. it has longer ears (near 70mm) than the Eastern Cottontail (typically 55mm). Uses pinyon-oak-juniper woodlands of the Guadalupe, Davis, Chinati, and Chisos Mountains at elevations between 1400m and 2400m. May also occur in the Mogollon highlands. The populations in the Guadalupe and Davis mountains are particularly endangered and may now be extinct.

  PLATE 12

  PYGMY RABBITS AND

  SHORT-EARED COTTONTAILS

  BRUSH RABBIT Sylvilagus bachmani 303-369mm, 10-30mm, 511-917g

  Small rabbit with short legs and tail. Ears are slightly pointed and sparsely haired inside (not well haired like Pygmy Rabbit). Dark gray on back and sides; pale gray on belly and underside of tail. Whiskers are mostly black, some may have white tips. Will forage in groups. Thumps ground with hind foot when frightened; may climb low branches to escape. Grasses form most of the diet, although they also browse on shrubs. Can be seen sunning in mid-morning, but is secretive and wary most of the time. Californian subspecies (S. b. riparius) is Endangered. Lives in dense brush, from sea level up to about 2000m.

  PYGMY RABBIT Brachylagus idahoensis 252-285mm, 15-20mm, 373-435g; 320-305mm, 15-24mm, 415-458g

  Our smallest rabbit. Ears are very short, rounded, and densely haired inside and out. Inconspicuous tail is buff (not white) on underside. Autumn pelage is long and gray on the back; belly hairs are white tinged with buff. Mid-winter fur is worn and gray, becoming somewhat darker gray in spring and summer. Moves by scurrying, rather than hopping. Mostly crepuscular, but can be seen feeding any time during the day. Females have up to 3 litters of 6 young per year. Alarm call is a buzzing, one-to seven-syllable squeal. Specialist of big sagebrush habitat, on plains, hillsides, gullies, and also along roadsides.

  SWAMP RABBIT Sylvilagus aquaticus 452-552mm, 50-74mm, 1.6-2.7kg

  Our largest rabbit; ears are relatively small. Underside of tail is white. Head, back, and upper tail are rusty brown to black; throat and belly are white. Cinnamon eye rings. Feet are pale to reddish. Most active at dusk. Good swimmer. Territorial, unlike most cottontails. Males defend territories both vocally and by scent-marking using a chin gland. Animals can be found resting during the heat of the day on stumps and logs, low tree crotches, in honeysuckle tangles, cane patches, and even in grassy patches on the floodplain. Common in swampy areas.

  MARSH RABBIT Sylvilagus palustris 425-440mm, 33-39mm, 1.2-2.0kg

  Smaller than Swamp Rabbit, with a dingy underside of tail (rarely white). Dainty feet are red to buff in color. Back, rump, upper tail, and hind legs are chestnut brown to rusty red; back of neck is dark cinnamon; abdomen is white, rest of belly is buff to brown. Florida Keys subspecies (S. p. hefneri) Endangered. More active at night than in the daytime. Nests of soft grasses lined with rabbit fur are found among sedges at the water’S edge. Uses swamps, lake borders, and other wet areas, in lowlands below 150m elevation. More common in brackish water areas, especially marshes with hummocks of vegetation. Frequently found in cattail marshes.

  PLATE 13

  EASTERN COTTONTAILS

  EASTERN COTTONTAIL Sylvilagus floridanus 40-50cm, 2-6cm, 800-1500g

  Our most common cottontail; has relatively large ears. Different from Appalachian and New England Cottontails by: 1) often showing a white (never black) spot between ears; 2) lacking a black fringe on front edge of ears; 3) lacking a black penciled effect on back; 4) having a postorbital process that is broad, flat, and frequently touching the skull (not thin, tapering, and rarely touching skull); 5) having a suture between nasals and frontals that is smooth (not jagged or irregular). Upperparts are densely furred in brownish or grayish; belly and undertail are furred in white. Common in variety of habitats including overgrown fields, meadows, and brushy areas. (See also page 38 for western form.)

  NEW ENGLAND COTTONTAIL Sylvilagus transitionalis 40-44cm, 5-7cm, 995-1347g

  Restricted to New England. Virtually identical to the Appalachian Cottontail, distinguished only by range and genetics. Identification vs. Eastern Cottontail outlined above. Nests are in depressions, ca. 12cm deep by 10cm wide and lined with grass and fur. Eats grasses and clovers in summer and forbs and twigs in winter. Home ranges are less than a hectare, although males have slightly larger home ranges than females. Hard to see, as they are secretive and avoid open areas. Prefers forested habitats with understory of blueberry or mountain laurel and rarely ventures into the open.

  APPALACHIAN COTTONTAIL Sylvilagus obscurus 39-43cm, 2-6cm, 756-1038g

  Restricted to Appalachian highlands. Identification vs. Eastern Cottontail outlined above. Differentiated from New England Cottontail only by range and genetics. Upperparts are pinkish buff; belly is white or buff. Back is overlaid with a black wash, creating a penciled look. Cheeks are grizzled. Rounded ears are fringed with black hairs. Usually shows a distinct black (never white) spot between ears. Feeds on grasses, shrubs, ferns, forbs, and even pine needles, unique among cottontails. Quite prolific, with a single female averaging 24 young per year in several litters from March to September. Occurs in dense cover within high elevation boreal forests.

  EUROPEAN RABBIT Oryctolagus cuniculus 34-45cm, 4-8cm, 1.3-2.2kg

  A small, non-native species restricted to islands of Pacific coast. Upperparts generally grayish and interspersed with black, brown, and sometimes red hairs. Underparts are pale gray. Tail almost completely white, with some dark hairs on upperside. Relatively short ears lack black tips. Domestic breeds vary from black to white. Mainly crepuscular. Most common in drier areas with sandy or lighter soils near sea level.

  CAPE HARE Lepus capensis 64-70cm, 7-10cm, 3.0-5.6kg

  Non-native species with declining distribution. Different from native Lepus in having dorsal hairs white at base. Slender body with rusty-to yellow-brown upperparts in summer with black hairs interspersed; white below. Grayish upperparts in winter. Center of tail black above; tail all white below. Predominantly nocturnal. Populations are presently known from Ontario and the Hudson River Valley. Uses open, cultivated fields.

  PLATE 14

  NORTHERN HARES

  NORTHERN HARES - These snow-adapted species are generally brown in summer and white in winter. Their smaller ears distinguish them from jackrabbits. Skull characters are needed to distinguish some species in winter.

  SNOWSHOE HARE Lepus americanus 40-44cm, 2-5cm, 0.9-1.7kg; 42-52cm, 3-8cm, 0.9-2.2kg

  Smaller than other Lepus; base of winter hairs brown (not white). Summer pelage rusty brown above and grayish below; ears tipped in black; nostrils and tail white. Winter pelage white with black-tipped ears and yellowish underpaws. Some populations in Oregon an
d Washington are brown all year. Mostly nocturnal, but can be seen around dawn or dusk. Uses dense thickets in coniferous and mixed forests in the north, and deciduous forests in the south of its range. Active year-round, with breeding occurring from March-July. Litter size ranges from 1-8 and gestation is 34-40 days.

  ALASKAN HARE Lepus othus 56-59cm, 6-10cm, 3.9-7.2kg

  Restricted to coastal Alaska. Larger than Snowshoe Hare with longer ears (more than 73mm) and winter pelage that is completely white to the base, except black ear tips. Summer pelage is reddish brown or brownish gray with a white or gray tail. Distinguished from Arctic Hare by geographic range, by brownish (not grayish or white) summer pelage, and by having more strongly recurved incisors, a heavier rostrum, and a longer upper tooth row. Claws very stout to allow for digging through hard snow crust to reach plants beneath. Inhabits tundra and dense alder thickets, from sea level to 600m.

  ARCTIC HARE Lepus arcticus 56-63cm, 4-10cm, 2.5-3.8kg

  Restricted to northeastern Canada. Larger than Snowshoe Hare with winter pelage that is completely white to the base, except black ear tips. Summer pelage gray in southern subspecies; remains white in northern subspecies. Distinguished from Alaskan Hare by range, summer color, and skull characters described above. Moves quickly in a series of hops, each of which may cover 1.2m, and can run up to 64km per hour, as well as swim. Normally solitary, but can form huge groups of up to 300 animals. Lives in tundra. May retreat below timberline in winter, found from sea level to 900m in summer.

  WHITE-TAILED JACKRABBIT Lepus townsendii 56-62cm, 7-10cm, 2.6-4.3kg; 58-65cm, 7-10cm, 2.5-4.3kg

  White phase White-tailed Jackrabbits are distinguished from Snowshoe Hares by larger body size, longer ears, and hair that is dark at the base. White winter pelage may be tinged with buff on ears, face, back, and feet. Ear tips are black. Tail is white, sometimes with a buff dorsal stripe. Southern populations remain brown in winter. (See page 47 for summer pelage.) Primarily nocturnal and solitary except during the breeding season, which may begin as early as February in southern part of range. Young are born fully haired, with incisors erupted and eyes open. Widest elevational range of any hare, from sea level up to 4000m.

  PLATE 15

  JACKRABBITS

  JACKRABBITS - The enormous ears of these hares help them keep cool in their hot, arid habitats.

  ANTELOPE JACKRABBIT Lepus alleni 55-67cm, 5-8cm, 2.7-5.9kg

  Large ears tipped in white. Only found in Mexico and southern Arizona. Back is yellowish brown darkened with black hairs; sharply demarcated sides are gray; underparts are white. Throat patch is orangish yellow. Large ears nearly naked except long white hair fringing the edge. Nocturnal and crepuscular, rarely vocalizes. Does not drink water. Stands on hind feet and reaches high to forage on leaves, buds, and bark. Rests under bushes during the day. Favors desert plains with grasses, mesquites, and Acacia but can persist in areas with little vegetation from sea level to 1500m.

  WHITE-TAILED JACKRABBIT Lepus townsendii 56-62cm, 7-10cm, 2.6-4.3kg; 58-65cm, 7-10cm, 2.5-4.3kg

  Tail is white, sometimes showing a buff dorsal stripe. Ear tips are black. Summer upperparts are yellowish brown (campanius subspecies east of continental divide) or grayish brown (townsendii subspecies west of divide); underparts are white or pale gray with a darker throat. Northern populations molt to white in winter (see previous plate). Larger than Black-tailed Jackrabbit, and females slightly larger than males. Nocturnal. Feeds primarily on succulent forbs and grasses in summer, and uses wider variety of shrubs in winter. Introduced to Wisconsin. Uses open grassland, sagebrush, and meadows, especially on mountain slopes and ridges.

  BLACK-TAILED JACKRABBIT Lepus californicus 46-63cm, 5-11cm, 1.3-3.3kg

  Black upper tail and ear tips. Upperparts and sides are brown to dark gray, underparts pale gray. Tail gray below and black above; black color may extend as a line up lower back. Long legs allow leaps of up to 2m vertically and 6m horizontally during escape maneuvers. Mostly nocturnal. Will feed in groups in open pastures and rangeland. Introduced to many eastern states. Uses agricultural and range lands, especially areas with cacti and low shrubs, although complete elevation range is sea level to almost 4000m.

  WHITE-SIDED JACKRABBIT Lepus callotis 52-53cm, 5-9cm, 1.5-2.2kg; 54-57cm, 5-9cm, 2.5-3.2kg

  Only found in Mexico and Hidalgo County, New Mexico. White sides unique. Back is pale brownish red; sides, rump, thighs, and underparts are white. Black hairs are mixed throughout upperparts. Tail is white below and black above; some black tail hairs are tipped in white. White-tipped ears are sparsely haired with a dusky spot along posterior border. Pair-bonding occurs during breeding season from April-August. Litter size is small, 1-4 with an average of 2. Like many hares, constructs daytime resting places called shelter forms, usually surrounded by clumps of grass. Nocturnal. Prefers level desert grasslands with little shrub cover.

  PLATE 16

  PORCUPINE AND SEWELLEL

  NORTH AMERICAN PORCUPINE Erethizon dorsatum 60-130cm, 17-25cm, 3.5-18kg

  The only mammal in North America with quills. Males are larger, but females have longer tails. Slow and with poor eyesight, this large rodent is well protected from predators by its quill armor. Defends itself by erecting (not throwing) its quills, lowering its head, and backing up toward the intruder with its tail flailing. Dens in burrows, rocky crevices, and hollow trees. Eats a variety of plant material, but is especially fond of the cambium layer of coniferous trees, with hemlocks being a particular favorite. Will strip bark off trees and leave piles of feces beneath. Evidence of their feeding includes girdled trunks and branches contrasting markedly with uneaten parts of the trees. They also feed on a variety of smaller shrubs and canes. In spring, when new growth is available, porcupines feed more on the ground using succulent stems of wildflowers, sedges, and grasses. In summer they sometimes move into agricultural fields to feed on ripening crops, especially corn. In winter, when other food is scarce, they add acorns to their diet. Maximum lifespan is 10 years. Porcupines are solitary, although communal dens are known in the wintertime. Breeding may occur in almost any month, depending on location. The long gestation period is 204-215 days, and the single young weighs 400-500g at birth. Extirpated from many areas in the eastern and midwestern United States. Recently reintroduced in some areas. Rare to common in a variety of habitat types including forest, tundra, chaparral, and rangelands, from sea level to high mountains in the west.

  SEWELLEL Aplodontia rufa 24-47cm, 19-55cm, 0.8-1.2kg

  An odd, medium-sized burrowing rodent with small eyes and ears and long whiskers and claws. The fur is dark brown, and there is a pale spot below each ear. Somewhat resembles a giant pocket gopher. The tail is short and furred. Thought to be the most primitive rodent species and placed in its own family, the Sewellel has a distinctive triangular, flattened skull with high, conical cheek teeth. Although it rarely ventures far from its 15cm burrow entrance, it can climb trees in search of food. Strictly vegetarian, it is known for eating plants such as rhododendron and stinging nettle that other animals typically avoid. Extensive burrow systems include a toilet chamber. Typically remains underground in winter, eating cached foods. They are coprophagous, reingesting soft fecal pellets to maximize nutritional value from stored food items. The sole member of the rodent family Aplodontiidae. Also called mountain beavers, but they are neither montane nor aquatic. Nocturnal and secretive, and essentially solitary. After mating early in the year, a single litter of 2 or 3 is born in the spring after a gestation period of about a month. The young remain in the natal burrow throughout the summer, although lactation lasts only about 2 months. The young then disperse in the fall, and establish burrows of their own. Maximum lifespan is about 6 years. Endangered in California. Spends most of its life in underground burrows dug into the soil of moist forests with densely vegetated understories.

  PLATE 17

  LARGE AQUATIC RODENTS

  ROUND-TAILED MUSKRAT Neofiber alleni 16-23cm, 10-17cm, 200-300g

&nb
sp; A small muskrat with a round black tail. Pelage is glossy rich brown to black, with dense underfur that is gray to brown on the back, grading to grayish or buff on the belly. Smaller than the Common Muskrat, but much larger than any mice or voles. Builds dome-shaped grass houses 18-60cm in diameter at the surface of the water, with a pair of underwater entrances. Nocturnal feeders on aquatic grasses. Breeding is year-round and 2 or 3 young are born after a gestation period of 26-29 days. A single female can produce 4-6 litters per year. Lives in freshwater marshes in Florida and Georgia, where it prefers water depths of 30-45cm.

  COMMON MUSKRAT Ondatra zibethicus 41-62 cm, 18-30cm, 700-1800g

  A medium-sized, brown, aquatic rodent. Back is dark brown, underside is slightly paler. Black tail is vertically flattened. Long, coarse, glossy guard hairs cover the short, dense, silky underfur. Partially webbed hind feet are larger than the forefeet. Fringes of stiff hairs along the sides of the toes further enhance swimming ability. Larger-bodied in the north of their range. Clearly larger than the Round-tailed Muskrat and smaller than the Coypu or Beaver. Uses cut vegetation to build rounded houses about 2m in diameter and 1m high; also dens in holes dug into the shore. Crepuscular and nocturnal feeder on a variety of aquatic plants. Common in brackish and freshwater lakes, rivers, and swamps.