Mammals of North America

by Roland W Kays

  Small bat most closely resembling the Little Brown Myotis. Differs from that species in having sparser and shorter hairs on the toes, shorter hind feet, a slight keel on the calcar, a pinkish nose and duller pelage. Forearm 31–40mm. Hibernates in cold caves and mines with high humidity, where it sometimes forms large colonies. They cluster together tightly in the hibernaculum, with up 450 individuals per square foot of cave ceiling. This Endangered species is sensitive to disturbance in the hibernacula. Summer nursery roosts are under tree bark, especially in hickory trees. Found in a variety of habitats in eastern deciduous forests.

  PLATE 73

  OTHER EASTERN BATS

  WESTERN PIPISTRELLE Pipistrellus hesperus 60–86mm, 25–36mm, 2–6g

  Tiny bat with blunt, slightly curved tragus, and small hind foot less than half as long as the tibia. The black face mask contrasts strongly with yellowish, gray-brown body color. Active in the early twilight, this species has slow erratic flight that looks almost like a butterfly. Forearm 26–33mm. Roosts in crevices and mine tunnels in rocky outcrops near water sources. With expanding human populations, the bats have taken to roosting in stucco cracks near swimming pools as a logical substitute. Found from sea level to 3000m, favors canyons and cliff faces, but occurs in a wide variety of desert scrub and arid grassland habitats as well.

  EASTERN PIPISTRELLE Perimyotis subflavus 75–90mm, 33–45mm, 6–10g

  Small bat with yellowish-to grayish-brown pelage, and a somewhat paler belly. Dorsal hairs are tricolored, and membranes are dark brown. In winter, hibernating individuals sometimes collect droplets of moisture on them, given them a sparkling appearance. Forearm 31–35mm. Summer roosts are in and on buildings, under shutters, and in attics and lofts of barns. Hangs with a hunched posture while sleeping. Individuals swarm in late summer and early autumn, seeking mates before entering hibernating caves. Uses a variety of habitats, especially open pasture.

  BIG BROWN BAT Eptesicus fuscus 87–138mm, 34–56mm, 11–23g

  As the name suggests, this is a large brown bat with naked, dark membranes. The tail is enclosed in interfemoral membrane. It has short ears, a keeled calcar, and a forearm length of 39–54mm. Males are solitary in spring and summer, but females gather in small maternity colonies of 20–75 individuals and their young. They use hollow trees, but are equally common in buildings, including barns and churches. Although hibernacula in caves are common, this species also sometimes hibernates in cold buildings. Widely distributed throughout North America, this species occurs in a wide variety of habitats, and frequently roosts in man-made structures.

  LITTLE BROWN MYOTIS Myotis lucifugus

  Obviously browner than the pipistrelles, smaller than the Big Brown Bat, and not white on the belly like the Evening Bat. (See page 158 for more details.)

  EVENING BAT Nycticeius humeralis 83–96mm, 35–40mm, 9–14g

  Similar to the Big Brown Bat, but smaller, with reddish to dark brown fur above and somewhat paler below. The ears are blunt and rounded, with a tragus that is short and curves forward. Forearm 34–37mm. One of the few bats that does not use caves, the Evening Bat apparently migrates southward to overwinter, rather than hibernating. Males remain in the southern part of the range, with only the females moving north to form maternity colonies of 30 to several hundred individuals and their young. They forage over water at dusk and into the early evening. Common in buildings and other man-made structures.

  PLATE 76

  TEMPERATE CATS

  BOBCAT Lynx rufus 48–125cm, 11–20cm, 7.2–31.0kg; 61–122cm, 9–17cm, 4–24kg

  North America’s most abundant spotted cat, with a tail tip that is black above and white below. Spots may be inconspicuous. Tail is relatively longer than in the Canadian Lynx. Coat color varies from yellowish to reddish brown and is marked with dark brown or black streaks and spots. Underparts are white and spotted. Ears have short (less than 2.5cm) black tufts and a white spot on the back. Primarily a nocturnal hunter of rabbits, and other small prey, Bobcats may be active at any time of day, and are capable of taking a wide range of prey from mice to deer. Territories are marked with exposed feces, urine deposits, and scrapes made with the hind feet. Litters average 3, born after a gestation period of 62 days. Dens are located on rocky outcrops, in brush piles, hollow logs, caves, fallen trees, and dense bushes. Occurs in almost every habitat within range.

  CANADIAN LYNX Lynx canadensis 82–95cm, 9–12cm, 7–18kg

  This northern species has a tail that is all black at the tip. Upperparts are grizzled grayish brown with a varying degree of spotting. Winter fur is long and thick. Ears have long (4–5cm) black tufts of hairs and a central white spot on the back. Tail is relatively shorter than in the Bobcat; ear tufts and feet are larger. Females are slightly smaller than males. Threatened because of sensitivity to human disturbance. Specialist hunter of Snowshoe Hares; also hunts other small mammals, beaver, and deer. Larger food items may be cached under snow or brush and visited later. Solitary, except for females with young. Peaks of activity occur at dawn and dusk, but may be active anytime. Breeding season is March–April, with an average of 3 kittens born after 60–70 days. Dens are in hollow logs, stumps, timber clumps, or root tangles. Young remain with mother until next breeding season. Denizen of boreal forests.

  COUGAR Puma concolor 1.7–2.5m, 68–96cm, 36–120kg; 1.2–1.6m, 27–37cm, 29–64kg

  An unmistakable large cat with uniform color and long black-tipped tail. Monotone pelage varies geographically and seasonally from gray to reddish brown. Cubs have a soft, spotted coat. Hunts deer and other large and medium-sized mammals. Commonly called Mountain Lion or Puma. Subspecies in Florida(P. c. coryi) is Endangered. Subspecies from northeastern United States(P. c. couguar) is apparently extinct; modern sightings in this area are from escaped captive animals. Population densities low, as each animal needs 100–500km2 of home range. Crepuscular and nocturnal, they may cover about 1Gkm per night when hunting. Large prey is cached under brush and leaves, and retuned to on subsequent nights. Ungulates are the main food, but Cougars also take rabbits, beavers, porcupines, opossums, coyotes, bobcats, raccoons, skunks, and occasionally domestic livestock. Uses most habitats in range that offer cover and prey; avoids shrubless deserts and agricultural areas.

  PLATE 77

  TROPICAL CATS

  TROPICAL CATS-These four felines range widely in tropical America, but are only found near the borderlands of the United States. Because of their secretive nature they are rarely seen.

  MARGAY Leopardus wiedii 86–130cm, 33–51cm, 3–7kg; 80–103cm, 32–44cm, 3–5kg

  Smallest North American spotted cat, with large eyes and a long tail. Smaller than the Ocelot, with a longer tail, relatively larger eyes, and a more delicate facial structure. Spots may coalesce to a greater or lesser extent. A hunter of small prey on the ground and in the trees. Very agile and acrobatic, and more arboreal than most cats. Ankle joints can turn 180°, allowing mobility on tree trunks and along branches. Margays can jump vertically 2.5m and horizontally 4m, changing direction in mid-air if necessary. Probably never common in Texas, the last record was from 1852. Uses most tropical forest types from sea level to 3000m.

  OCELOT Leopardus pardalis 95–137cm, 28–40cm, 7–14kg; 92–121cm, 27–37cm, 7–11kg

  A solidly built spotted cat, with a short tail that barely touches the ground. Larger than the Margay, with a shorter tail and a more robust skull structure. Rare and Endangered in Texas. This nocturnal hunter feeds on a variety of small prey, especially rodents. May travel 6km per night when hunting. Sleeps in dense thickets during the day. Solitary except when mating, which can occur in any month of the year; 1–3 kittens are born after gestation of 70–80 days. Uses a wide range of tropical habitats with vegetative cover.

  JAGUARUNDI Puma yagouaroundi 88–137cm, 32–61cm, 4–9kg

  Only small wildcat with a unicolored coat. Two color morphs occur together: reddish brown and dark gray. Young animals may have white markings around their mouth. Tail
and neck are relatively long, legs are relatively short. Our most diurnal cat; hunts a variety of small, terrestrial prey. Endangered in North America because of small range. Breeds year-round, and 2–4 kittens are born after gestation period of 60–70 days in dens under root tangles, hollow logs, or in rock crevices. They produce a whistle-like vocalization that sounds like a bird call. Uses thick cover in mesquite or pine-oak woodlands of Arizona and Texas.

  JAGUAR Panthera onca 1.7–2.4m, 52–67cm, 79–158kg; 1.6–2.2m, 43–60cm, 31–85kg

  The largest cat in the New World, Jaguars are unmistakable, powerfully built, spotted cats. Coat is tawny-colored with large black rosettes. Rosettes are also visible in the rare black morph. Active any time of day. The US population was hunted to extinction in the 1800s, but recent sightings in Arizona suggest the possibility of reestablishment. They are active both day and night. Solitary hunters of large and medium-sized prey in warm forests and desert scrub, they prefer streamside and wetter habitats.

  PLATE 78

  CANIS

  CANIS-All North American species in this genus are capable of interbreeding in the wild. Furthermore, their distribution is constantly changing with a dramatic series of extirpations, reintroductions, and natural expansions. This causes confusion for both identification and taxonomy. The major forms are described here, although their taxonomic status and nomenclature may change in the future. Domestic dogs may sometimes go feral, but rarely show characteristic ears and face of wild canids. Coydogs (coyote x dog hybrids) only occur with very low coyote density and are rare now that coyotes have populated most of the continent. Packs of feral domestic dogs persist, especially in the south and in some cities.

  WOLF Canis lupus 1.0–1.3m, 35–52cm, 30–80kg; 0.9–1.2m, 35–52cm, 23–55kg

  Largest wild canid. Fur usually grizzled gray but ranges from pure white to black to reddish brown. Commonly called the Gray Wolf. Bushy tail often tipped in black. Distinguished from Coyote and domestic dogs by larger body size, large nose pad (>25mm), relatively shorter ears, and tail usually held horizontally (not down) when running. Canids between the Wolf and Coyote in size (typically 14–39kg) remain a taxonomic problem. Some taxonomists argue that all intermediates are recent hybrids between Wolves and Coyotes and therefore do not merit species’ status. Others argue they are not hybrids, or that they are ancient hybrids, and that they deserve full status as one or two distinct mid-size Canis species: the Eastern Wolf(C. lycaon) from the north and/or the Red Wolf(C. rufus) from the southeast. Red Wolves now only occur in and around active reintroduction programs in coastal North Carolina. Packs usually consist of 5–10 family members. Their pack hunting is adapted to kill large prey, including moose, bison, and deer. Wolves can also survive on medium-sized mammals such as Beaver and muskrat, and will also hunt mice. When hunting large prey, pack members take turns pursuing the target, chasing it until its too tired to defend itself. Howling can be heard for great distances. Common where not persecuted; lives in all habitats within its range except deserts and high mountain tops.

  COYOTE Canis latrans 1.0–1.3m, 30–39cm, 7–20kg

  Smaller than wolves, with a smaller nose pad (less than 25mm) but relatively larger ears. Upperparts are variable in color, but typically brownish, often with redish highlights on legs. Belly and throat are pale. Tail usually held down when running. Coyotes expanded their range in all directions in the mid–1900s following extirpation of Wolves. To the south they have reached the Panama Canal. To the east they have now colonized all natural habitats and are increasingly common in suburban areas. Western Coyotes are typically 12–14kg while eastern coyotes average 16–18kg, and may grow up to 23kg. Eastern Coyotes are also more variable in color, with a variety of blond and reddish forms common, as well as occasional black animals. Where hunted intensively Coyotes form smaller packs, but breed at an earlier age. Coyotes feed on a wide variety of small and medium-sized prey, as well as fruit in season. Eastern Coyotes also hunt deer. Higher-pitched howling than Wolves, with more yips. Common in all natural habitats, including suburban forests.

  PLATE 79

  SMALLER FOXES

  FOXES-These diminutive canids typically hunt small and medium-sized prey such as birds, rabbits, and mice. All den in ground holes or brush piles.

  SWIFT FOX Vulpes velox 74–82cm, 17–33cm, 2.2–2.9kg; 68–75cm, 23–30cm, 1.8–2.3kg

  Smallest North American canid, with a long, bushy, black-tipped tail. Similar to the Kit Fox but with a shorter tail and smaller ears. Buff-gray above with brownish sides, legs and lower surface of tail. Undersides are lighter. Shorter summer fur is more reddish gray. Large triangular ears. Often lumped with the Kit Fox into one species(V. velox). Nocturnal hunter of lagomorphs, rodents, and other small prey, such as birds, lizards, and insects, they are active throughout the night. During the day, they stay in the den, or sometimes sun themselves near the entrance. The gestation period is 49–55 days, and litters of 3–6 pups are produced in February–April. Extremely rare, or possibly extirpated in the northern part of its range, but reintroduced in Canada’s prairie provinces. The two species also differ in habitat preference, with the Swift Fox preferring short and mixed grass prairies.

  KIT FOX Vulpes macrotis 73–84cm, 26–32cm, 1.4–2.7kg

  Similar to the Swift Fox but with a longer tail and larger ears. The Kit Fox is distinguished by its longer tail (62% head and body length vs. 52%), larger ears (more than 75mm) set close to the midline of the skull, a head that is broader between the eyes but narrower at the snout, and more slitlike, less-rounded eyes. The pelage is generally gray, but mixed with rusty overtones, and the tail has a black tip. Primarily nocturnal, but occasionally active at all hours, it feeds predominantly on rodents and lagomorphs, but also takes small birds, fish, and insects. Males and females bond in the fall and breed in winter, but pairs may not persist from year to year. Litters of 3–14 cubs are born in March–April. Constructs elaborate den systems connected by tunnels, with multiple dens having many separate entrances. Prefers shrub-steppe and desert habitats.

  ARCTIC FOX Vulpes lagopus 83–110cm, 28–42cm, 3.2–9.4kg; 71–85cm, 26–32cm, 1.4–3.3kg

  Unique northern fox well adapted for living in harsh Arctic climate with distinctive color and short legs, snout, and ears. Unique among canids in having fur color that varies geographically and seasonally. Coastal populations are typically bluish gray in winter and dark bluish gray or chocolate-brown in summer. Continental foxes are usually white in winter and grayish brown in summer. Eyes have golden irises; soles of feet are furred. Thick, luxurious pelage insulates animals down to −70°C. Often bold in the presence of humans. Nocturnal except in Arctic summer. Hunts seabirds and small mammals alone, may scavenge in pairs or small groups. Introduced on several coastal islands, where they are farmed and harvested for the valuable fur. Populations cycle in concert with expanding prey populations, such as lemmings and voles. Inhabits Arctic tundra.

  PLATE 80

  LARGER FOXES

  RED FOX Vulpes vulpes 74–82cm, 27–33cm; 68–75cm, 23–30cm, 3–6kg

  Uniquely-colored fox with a bushy, white-tipped tail. Most animals are red-colored with black feet and black-tipped, triangular ears. Other morphs include a black phase, a silver phase (black hair tipped with silver), and a cross phase (reddish brown with dark on shoulders). Opportunistic foragers and scavengers, they prey heavily on voles and rabbits, as well as other small mammals, birds, invertebrates, and even fruit when available. Breeding occurs from December–March and litters of 4–7 pups are born after a gestation period of 51–53 days. They dig dens, or modify badger or woodchuck burrows for rearing the young, which are weaned after a lactation period of about 2 months. The world’s most widely distributed mammal, they are declining in the east due to Coyote expansion. Prefers landscapes with a mixture of both open fields and brushy or forested areas.

  GRAY FOX Urocyon cinereoargenteus 80–113cm, 27–43cm, 3–7kg

  A gray fox with a black-tipped tail. Back
is grizzled gray; sides are cinnamon-colored; belly is tan. A dark stripe runs down center of back and onto black-tipped tail. Often climbs trees, a trait facilitated by forelegs that rotate more than those of other canids. Dens are located in dense clumps of brush, abandoned buildings, rock outcroppings, hollow logs, or burrows. Family units consist of breeding pair and their offspring. Breeding season is January–March, and typically 4 pups are born about 2 months later. Pups begin foraging at about 4 months, and some may disperse as early as 7 months of age. Our most omnivorous canid, eats fruit and prey the size of rabbits or smaller. Active mostly at dawn and dusk, and seldom seen in daylight when they rest in dense vegetation. May range across 5km2 when foraging. Uses hardwood forests and brushy riparian habitats.

  ISLAND GRAY FOX Urocyon littoralis 62–79cm, 14–29cm, 1.6–2.5kg; 59–79cm, 11–29cm, 1.5–2.3kg

  Only found on six Channel Islands off California coast. Like Gray Fox, but smaller (one half to two thirds in size). Active day and night. Remarkably docile. Feeds on fruit, insects, and small mammals. A conservation risk because of small range; feral pigs and goats on the islands may attract avian predators (Golden Eagles) to which this isolated carnivore has no defense. Unlike their mainland relatives, island foxes are active both night and day. They forage extensively on seasonally available fruits and berries as well as deermice, birds, lizards, and insects. Breeding season is January–March, and the young are born in April or May. Unlike many other canids, they do not excavate their own dens, but use natural shelters such as brush piles, rock outcrops, bushes, or abandoned buildings. Lives in all habitats on islands at densities up to 14 per km2, with each fox occupying a home range of 20–40 hectares.