Mammals of North America

by Roland W Kays

  PLATE 87

  MEPHITIS

  STRIPED SKUNK Mephitis mephitis 57–80cm, 18–39 cm, 1.2–6.3kg

  Unmistakeable and well known due to unique color pattern, and distinctive odor. Dorsal stripes converge to a V at the nape. A pair of dorsal stripes typically mark the back, but these may be so variable in size and shape that skunks look all white, all black, or spotted. The amount of white in the tail is similarly variable. Fur is coarse. Females are 15% smaller than males. Typically raises tail and stomps front feet before spraying. They can shoot the spray accurately to 4m several times in quick succession. The noxious odor is reflected in the scientific name “Mephitis,” which means bad odor. Holding the animal off the ground by the tail to prevent it spraying is an old wives tale, disproven by generations of daring young naturalists. Summer dens are in rock piles or hollow logs, and winter dens are more substantial underground burrows, often originally excavated by woodchucks or badgers. Winter dens may be occupied by multiple animals. Breeding season is Februrary–March, typically resulting in a seasonal peak of activity that can be seen and smelled by people. Litters of 1–10 are born 59–77 days later. Young can emit musk as young as 8 days. They are weaned at 2 months, and overwinter mortality of yearlings is high. Nocturnal hunter of insects, rabbits, birds and eggs, carrion, fruit, and small vertebrates in all habitat types except most arid, and favors woodlands, fields, agricultural areas, and human neighborhoods.

  HOODED SKUNK Mephitis macroura 56–79cm, 27–43cm, 800–900g; 65cm, 37cm, 400–700g

  Has soft fur, with a hood of long white hair on the nape. Head has one thin white stripe; back has either one wide white stripe, or two separated thin white stripes. Fur is much longer and softer than in other skunks. Tail is longer than that of the Striped Skunk. More secretive than most skunks, rarely dens in man-made structures. Diet consists primarily of insects, small vertebrates, bird eggs, and fruit if available. They break chicken eggs by throwing them between their hind legs, football style. Small vertebrates are taken opportunistically as they make their nightly rounds. Forages among leaves and litter, pouncing on beetles and other insects as they scatter. Active year-round, but almost completely nocturnal and spends daylight hours sleeping in the den. Anal glands provide powerful defense mechanism, and they can spray many times in succession in a short period of time. Pre-spray behavior similar to that of M. mephitis, with foot stomping preceding full-scale spraying. Nightly foraging begins after dusk with routes following rock walls, streambeds, and other protected areas. Solitary except when females are with young, but several may come together at carrion sites. Unlike Striped Skunks, females normally do not den communally during the winter. Breeding season is February–March, and litter size ranges from 3 to 8. Lactation lasts through August. Prefers arid lowlands below 2500m, but also occurs in deciduous and coniferous forests, forest edges, pastures, rocky canyons, and riparian habitats.

  PLATE 88

  OTARIID SEALS

  OTARIIDS-THE EARED SEALS-These Pacific seals have small, but distinct ears. Their hind flippers can rotate under their body, increasing their mobility on land.

  CALIFORNIA SEA LION Zalophus californianus 2.0–2.5m, 350–400kg; 1.6–1.8m, 90–120kg

  Unique with doglike face and brown color. Males are larger, darker, and have a thick neck and an enlarged, pale forehead. Pups are born dark, but quickly molt into a lighter blond pelage like females. First toe on hind flipper is largest. This is the most familiar and commonly kept pinneped in zoos and aquaria, as well as circuses. Males wander north in the winter as far as Vancouver. Often unwary near cities. Feeds on small fish and squid at sea; returns to shore for pupping and mating, where annual aggregations on rocky or sandy beaches are full of noise and activity.

  NORTHERN FUR SEAL Callorhinus ursinus 1.9–2.1m, 175–275kg; 1.2–1.5m, 30–50kg

  Head is short and nose is very sharply pointed. Also distinguished from Guadalupe Fur Seal by having fur that forms a straight line at the base of the foreflipper, rather than extending to a point. Females are brown; males grow darker as they age, some appear black, especially when wet. Pups are born black, molt to a silvery color in late summer, and become golden brown over winter. Toes on hind flippers are all similar in size. Congregate on the shores of the Pribilof, Aleutian, and Channel Islands to breed and pup, then scatter to feed at sea. Seals tagged as pups do not return to their natal rookery to breed, unlike sea lions.

  GUADALUPE FUR SEAL Arctocephalus townsendi 1.9–2.4m, 150–220kg; 1.4–1.9m, 40–55kg

  Males have a large head with a long pointed snout. Females are like Northern Fur Seals, but have larger flippers, with fur on the foreflipper. Toes on hind flippers are all similar in size. Males do not have enlarged head crest found in other fur seals. Dry fur is brown or dusky black and has a thick, grizzled appearance compared with coarser hair of sea lions. Now breeds and pups only at Guadalupe and Islas San Benito in Baja California, Mexico. A threatened species, rookeries on Southern California islands were hunted to local extinction at the turn of the nineteenth century. Uses precipitous rocky coasts and caves. Hunts fish and squid in the open sea.

  STELLER’S SEA LION Eumetopias jubatus 2.7–3.2m, 500–1120kg; 1.9–2.9m, 263–365kg

  Bearlike head with a short straight snout. Larger and paler than California Sea Lion. Males have long, coarse hair on massive chest, neck and shoulders. Pups are born with a dark brown fur that molts to a lighter color after three months. First toe on hind flipper is largest. Skull unique with conspicuous space between upper fourth and fifth post-canine teeth. An endangered species that is declining in numbers. Hauls out all along our west coast for pupping and breeding in traditional rookeries, most common in Alaska. These are easily detected by the cacophony produced by the seals’ vocalizations. Swims far from shore to fish.

  PLATE 89

  PHOCID SEALS

  PHOCID SEALS-These earless seals are awkward on land and cannot stand on their hind flippers. They are exceptional swimmers, very specialized for deep and lengthy underwater dives.

  HARP SEAL Pagophilus groenlandica 1.7–1.9m, 115–140kg

  A white seal with a black lyre-shaped marking on back. Face is black. Males are slightly larger. Pups are white and turn silver-gray with black blotches as juveniles. Some females retain silver coat for up to 8 years. Some males develop a dark “sooty” coat. Swim in large herds throughout the North Atlantic. Thousands haul out together on the pack ice to pup and nurse young. Hunting of these seal pups for fur has recently sparked controversy. After pupping, animals make an annual migration that covers some 5000km of their Arctic territory.

  RINGED SEAL Pusa hispida 1.0–1.5m, 45–107kg

  A dark gray-colored seal with light rings on the body. Males are slightly larger. Pups are white; juveniles are silvery in color without rings. Much smaller than the Harbor Seal, with almost no neck and a short face. Strong nails on front flipper used to carve ice lair under snow drifts where they hide from predators and the weather. Females give birth in these lairs; males maintain their own lairs. Some populations are vulnerable to overhunting, but these seals are generally abundant on and around pack and fast ice, and are the most common seals in the Arctic.

  RIBBON SEAL Histriophoca fasciata 1.5–1.6m, 70–80kg

  A brown seal with whitish ribbons around their head and flippers. Male is dark brown; female is lighter. The pup’s white coat is shed at 5 weeks for a gray coat that is bluish above and silvery below. More slender than other seals, with a long neck and flippers. Mates, pups, and molts on heavy pack ice in late winter and spring, and moves to the open sea in late spring and summer when the northern seas become ice-free. They are almost never seen on land. Most common in the Bering Sea, but occasionally seen in Chukchi and Beaufort seas.

  HOODED SEAL Cystophora cristata 2.3–2.8m, 200–435kg; 2.0–2.3m, 150–350kg

  Silvery-gray seals with black splotches and conspicuous ornaments in the males. Female is distinguished from splotchy Gray Seal by having a shorte
r snout. Male is larger, and has a dark hood on the top of its head that can be inflated. Additionally, it can inflate its nasal septum like a red balloon. Both tricks probably attract females and intimidate rival males. Pups are silvery blue above and white below. Has the shortest lactation period of any mammal at 4 days, during which the pups gain an average of 7kg per day on extremely fat-rich milk produced by the females. Comes to pack ice around Labrador and Davis Strait to give birth later in spring than most seals, then migrates to areas around Greenland.

  PLATE 90

  GRAYISH SEALS

  SPOTTED SEAL Phoca largha 1.4–1.7m, 81–109kg

  A grayish seal with dark splotches, typically found on ice around Alaska. Overlaps little with the very similar Harbor Seal. Distinguished from Harbor Seal by range, having white (not dark) pups and a smaller, more delicate skull. Breeds in isolated pairs on pack ice in winter and spring and hauls out on ice to give birth to a single pup. One of the few seals that is seasonally monogamous, and family units of male, female, and young can be seen together during the breeding season. Gestation period is 10.5 months, including delayed implantation, and lactation lasts 3–4 weeks, during which time the young more than doubles its birth weight. Eats fish, shrimp, cephalopods, and crustaceans along coastal waters.

  HARBOR SEAL Phoca vitulina 1.4–1.9m, 75–150kg; 1.2–1.7m, 60–110kg

  A wide-ranging grayish seal usually found hauled out on rocks. Color pattern may be dark with irregular pale rings or pale with dark splotches. Pups typically molt in utero and are born with a dark pelage. Often has banana-shaped profile when on rocks. Typically shy when hauled out, but sometimes habituate to humans. Most populations are recovering with recent protection from hunting. Although capable of traveling long distances, most do not migrate, and are year-round residents. Capable of diving to 450m and staying underwater for 30 minutes. Feeds on wide variety of fish, cephalopods, and crustaceans. Common on undisturbed beaches, ledges, and rocks.

  GRAY SEAL Halichoerus grypus 2.0–2.7m, 240–320kg; 1.6–2.2m, 150–260kg

  A large gray seal with an exaggerated snout. Larger than the Harbor Seal, with a less doglike face. When viewed head-on the nostrils are curved resembling the letter W (not heart shaped like in the Harbor Seal). The color of males varies from black to gray-green, and can be solid or mottled. Females are typically silvery with dark patches, rarely solid black or cream-colored. Males are larger, with longer, broader snouts and more massive necks that are often scarred from fighting. Pups are born with white fur that molts to adult color at two to four weeks. Largest breeding area is on Sable Island, off the coast of Nova Scotia, where 15,000 young are born each year. Breeds and molts on land or ice, feeds on fish in the open sea.

  CARIBBEAN MONK SEAL Monachus tropicalis 2.1–2.4m, 70–140kg

  An extinct brownish seal from the Caribbean. Adults were pale brown on the back and lighter on the belly. This was the only seal from the Gulf of Mexico, and was recorded off the Florida and Texas coast. It preferred to haul out on sandy beaches, where they had little fear of humans, who hunted them to extinction. The last confirmed sighting was 1952. Its two sister species, the Hawaiian and Mediterranean Monk Seals, are both seriously Endangered. Juvenile Hooded Seals sometimes wander south into the Caribbean, and can be distinguished by having a much shorter face and by being smaller.

  PLATE 91

  BIG SEALS AND MANATEE

  WEST INDIAN MANATEE Trichechus manatus 2.7–3.5m, 500–1650kg

  Unmistakable slow-moving mammal with a blunt nose and a broad spatulate tail. Gray skin is often green from algae growing on back. Young nurse from a nipple under the flipper. Endangered and vulnerable to collisions with speed boats. Manatees are the only mammalian marine herbivores, and feed on marine plants in shallow Florida waters. Become tame in protected areas, and accept human contact from divers. Occasionally wander as far north as the Chesapeake Bay in summer, and aggregate at warm water sources in winter. Favored habitats include large rivers, lagoons, and estuaries in coastal areas.

  WALRUS Odobenus rosmarus 2.5–3.5m, 590–1656kg; 2.3–3.1m, 400–1250kg

  A large pinkish seal with tusks, which are greatly enlarged canine teeth. Broad snout is covered with short whiskers. The color of an individual can vary from white to pink to reddish brown as blood flow to the skin changes for temperature control. Atlantic Walrus is smaller, with smoother skin and more rounded snouts than Pacific Walrus. Male is larger, with larger tusks and thick skin on the neck and shoulders. Tusks are used in displays to intimidate other males, and often break in fights between males. A clumsy walker on ice and rocks, it is an adept diver to forage on prey dwelling on the ocean bottom, including crabs, anemones, sea cucumbers, shrimp, clams, worms, snails, octopuses, tunicates, fish, and occasionally other seals.

  NORTHERN ELEPHANT SEAL Mirounga angustirostris 3.6–4.2m, 1500–2300kg; 2.2–3.0m, 400–800kg

  Third largest of all seals, with a uniform brownish back and yellowish belly. Male is unmistakable with its enormous size, elephantine nose, and thickened neck. Canines of males are often exposed, and used to scar the necks of their male competitors. Newborns are black, and molt to a silvery color after weaning. Populations are recovering from historic overhunting. Males compete for females with visual and vocal displays, and occasionally violent physical combat. They may fast for up to 3 months while ashore competing for access to females. Hauls out on beaches to breed and molt from December–February, then migrates into the open ocean to feed on fish and squid.

  BEARDED SEAL Erignathus barbatus 2.0–2.6m, 225–360kg

  A large seal with a small head and prominent whiskers. Foreflippers are square-shaped. Whiskers are straight when wet and curved when dry. Female may be slightly longer than male. Adults are gray or brownish in color, sometimes with red on the face or flippers. Newborns are dark-colored with white patches on head and back. Juveniles often have irregular splotches of color on their heads and bodies. Feeds on crustaceans, mollusks, and fish caught at the sea bottom. Females begin breeding at 5–6 years of age, and produce a single young annually thereafter. Lives alone or in small groups at low densities on moving ice and in open water.

  PLATE 92

  ANTELOPES AND PIGS

  PRONGHORN Antilocapra americana 1.3–1.4m, 10–15cm, 42–59kg; 1.3–1.5m, 10–13cm, 41–50kg

  North America’s only native antelope has unique coloration and horns. Has a stocky build on long legs, and short black horns. Cinnamon-colored body, with a white rump, belly, and facial markings. Male horns have a forward pointing “prong,” while female horns are smaller, usually lacking prongs. The horn sheaths are shed in November and quickly regrown each year. Some females do not grow the sheaths. Male is larger and has a black line on the lower jaw. Hairs on the rump and back of the neck can be erected. Speeds of up to 72km per hour have been recorded. Eyes are large and project sideways, yielding excellent peripheral vision in their open habitats. Heavy eyelashes serve as sun shades. Feeds on a variety of plants, especially forbs and shrubs, and grasses during spring greenup. Relies on good vision and speed to escape predators in open, grassland habitats from sea level to over 3000m, but most common between 1200 and 1800m.

  BLACKBUCK Antilope cervicapra 1.2–2.1m, 10–17 cm, 20–57kg; 20–33kg

  An exotic, bicolored antelope introduced in Texas. Adult males have long, V-shaped, spiraling horns and are black above. Females and young males are tan above and usually do not have horns. Males lighten in color after the spring molt. Coloration is accentuated by white eye rings, chin patch, chest, belly, and inner legs. Native to India and Pakistan. Does not survive long periods of freezing temperatures. Grazes on short to mid-length grasses and some brush. Introduced widely in Texas, with more than 7000 animals counted in 51 counties in 1974, mostly on the Edward Plateau.

  COLLARED PECCARY Pecari tajacu 85–102cm, 3–5cm, 15–25kg

  A native piglike animal with grizzled dark coat and a whitish collar. The hairs on the head and back can be erected int
o a mane. Small, inconspicuous tail. This neotropical animal is restricted in the north by cold. Nocturnal in summer, but diurnal in winter. Produces a variety of grunts, snorts, and clicks, which serve to communicate with other herd members. They also mark and rub with facial glands, which probably helps to identify herd members. Groups are territorial, and dominance heirarchies dictate reproductive success of males. Territories are marked with dung piles, and with secretions from rump glands. Breeding season is November-January, and females produce a single young or twins. Diet includes fruits, seeds, roots, and tubers, as well as large amounts of cacti. Herds of 15–20 animals root and browse in grasslands, desert scrub, and arid woodlands.

  WILD BOAR Sus scrofa 1.3–1.8m, 15–30 cm, 35–200kg

  Basically a domestic pig gone wild, typically covered with thin, coarse grizzled black and gray hair. Hybrids may be variable in color, including spotted, black and tan. A mane of long bristles may develop down the back. The upper teeth (tusks) curve upward and are often conspicuous. Old World pig species widely introduced in North America. Feral populations are known from at least 18 states, especially in the humid south. Prolonged winter frost appears to restrict its winter foraging and, therefore, prevent its spread northward. Its rooting can be quite damaging to native vegetation. Shy and intelligent, difficult to see in their forest haunts.