FIELD GUIDE TO NORTH AMERICAN MAMMALS …users.tamuk.edu/kfjab02/Biology/Mammalogy/lab/Smithsonian NMNH... · FIELD GUIDE TO NORTH AMERICAN MAMMALS North American Porcupine (Erethizon

FIELD GUIDE TO NORTH AMERICAN MAMMALS North American Porcupine(Erethizon dorsatum)

ORDER: RodentiaFAMILY: Erethizodontidae

Conservation Status: Least Concern.

North American Porcupines are large, slow-moving, tree-climbing rodents,protected from predators by their formidable quills. In winter, they eat thebark, phloem, and cambium of trees, particularly conifers. In spring andsummer, they mostly forage on the ground, feeding on grasses, sedges,acorns, and flowers. They readily consume crops or gnaw on automobile tires,so are sometimes regarded as pests. Porcupine young are exceptionally welldeveloped at birth. Their eyes are open and they have teeth and even quills,which are soft at birth but harden within a few hours. Within a week, they canfeed on their own. Few predators even try to kill Porcupines with anyregularity, except one, the fisher. Fishers attack Porcupines from the front,grabbing them by the face, thus avoiding the quills. Porcupines do not throwtheir quills - which are modified hairs - but the quills pull loose from thePorcupine when they are stuck into an adversary, and they have barbed tips,so they are not easily removed.

Also known as: Porc-epic, Hedgehog, Quillpig, Quiller

Sexual Dimorphism: Males are heavier than females.

Length: Average: 772 mm Range: 600-1,300 mm

Weight: Range: 3.5-18 kg

Credit: painting by Todd Zalewski fromKays and Wilson's Mammals of NorthAmerica, © Princeton University Press(2002)

Data provided by NatureServe incollaboration with Bruce Patterson, WesSechrest, Marcelo Tognelli, GerardoCeballos, The Nature Conservancy —Migratory Bird Program, ConservationInternational — CABS, World WildlifeFund — US, and Environment Canada —WILDSPACE.

My North American Mammals Field Guide Page 1 of 1

FIELD GUIDE TO NORTH AMERICAN MAMMALS American Beaver(Castor canadensis)

ORDER: RodentiaFAMILY: Castoridae


The largest North American rodent and the only one with a broad, flat, scalytail, the Beaver is now common and widespread, even in areas it did notinhabit during pre-colonial times. The modifications it makes to theenvironment by felling trees and building dams result in changes to plant,animal, and microbial communities that are sometimes desirable andsometimes not. The Beaver itself is not easily seen, being nocturnal andsecretive, but it can be spotted in ponds, lakes, or large streams at twilight bya quiet observer. Its pelage is brown, with gray underfur, and is prized bytrappers. The webbing on its hind feet help it to swim; claws on the digits ofits forefeet give it dexterity in handling food; comblike claws on its hind feethelp it in careful grooming; and it can close its mouth behind its front teeth,so that it can carry woody material without taking in water. Beavers cacheand consume the inner bark of both deciduous and evergreen shrubs andtrees, as well as terrestrial and aquatic plants. Their young, called kits, leavethe colony at the age of six months.

Also known as: Canadian Beaver, North American Beaver

Sexual Dimorphism: None

Length: Range: 1,000-1,200 mm

Weight: Range: 16-30 kg




FIELD GUIDE TO NORTH AMERICAN MAMMALS Yellow-faced Pocket Gopher(Cratogeomys castanops)

ORDER: RodentiaFAMILY: Geomyidae


The Yellow-faced Pocket Gopher feeds on starchy, tuberous roots of desertshrubs and on the roots and leaves of low-growing forbs. Like other pocketgophers, this species is considered an agricultural pest, doing extensivedamage in orchards, gardens, potato patches, and other croplands. It digslong burrow systems, preferring deep sandy or silty soil. Burrow systemsseem to contain only one nesting chamber, and except when breeding orraising young, these animals live alone. Yellow-faced Pocket Gophers livefrom less than one year (males), to a little more than one year (females).Females may reproduce within the same season as their birth and can haveup to three litters in a season. Litter size averages 2-3, and ranges from 1-5.

Sexual Dimorphism: Males are larger than females.

Length: Range: 220-315 mm

Weight: Range: 385-410 g males; 225-290 g females

Cratogeomys castanops - yellowishvariation, left; reddish variation, right Credit: painting by Elizabeth McClellandfrom Kays and Wilson's Mammals of NorthAmerica, © Princeton University Press(2002)



FIELD GUIDE TO NORTH AMERICAN MAMMALS Texas Pocket Gopher(Geomys personatus)



Only soils with low percentages of silt, clay, and gravel will do for the TexasPocket Gopher, so many of its populations are isolated from one another. Thespecies occurs in southern Texas and extreme northeastern Mexico,burrowing in deep, sandy soils and only infrequently emerging aboveground.It forages on plant root systems, and is capable of pulling some plantsthrough the soil and into its burrow. While in the burrow, Texas PocketGophers keep any entrance to the surface plugged with soil; this closed-doorpolicy not only helps to keep out unwanted guests, it also helps to maintain asuitable subterranean environment. Variation in size is one notable trait ofthe species, probably a result of population isolation.

Also known as: South Texas Pocket Gopher, Carrizo Springs Pocket Gopher, Del Rio PocketGopher, Nueces Pocket Gopher, Padre Island Pocket Gopher, Rio GrandePocket Gopher, Seaside Pocket Gopher


Length: Average: 270 mm Range: 216-360 mm

Weight: Range: 165-400 g

Credit: painting by Elizabeth McClellandfrom Kays and Wilson's Mammals of NorthAmerica, © Princeton University Press(2002)



FIELD GUIDE TO NORTH AMERICAN MAMMALS Botta's Pocket Gopher(Thomomys bottae)



Pocket gophers dig with their front claws and with their teeth. A pocketgopher can close its mouth behind its front teeth, so it can dig without gettinga mouthful of dirt. Its "pockets" are fur-lined, external cheek pouches, one oneach side of its mouth, which it uses to transport food. Botta's Pocket Gopherhas an extremely broad geographic range, and individuals vary widely inappearance: they can be nearly white, gray, brown, or blackish-brown. Theyvary in size, too. Males are larger than females. Males grow throughout theirlives, whereas females stop growing after their first pregnancy, so older malescan be much larger than females. Pocket gophers live in small, localpopulations, spending almost their entire lives underground in their networkof burrows.

Also known as: Valley Pocket Gopher


Length: Range: 170-280 mm males; 150-240 mm females





FIELD GUIDE TO NORTH AMERICAN MAMMALS Gulf Coast Kangaroo Rat(Dipodomys compactus)

ORDER: RodentiaFAMILY: Heteromyidae


Gulf Coast Kangaroo Rats are confined to barrier islands of northeasternMexico and southern Texas and the nearby Texas mainland. No fossils of thisspecies have been found, but because of features of its teeth and skull,scientists think it is the most primitive living species of kangaroo rat. It hasfive toes on each hind foot, unlike most kangaroo rats, which have four.Seeds are its main food, although it also eats insects. Unlike Ord's KangarooRat, which shares part of its range, it can take advantage of areas that havebeen cleared for farming and ranching. It must have soft soil to dig itsburrows, however, whereas Ord's Kangaroo Rat usually lives where the soil ishard-packed and vegetation is thick.


Length: Average: 228.1 mm males; 227.6 mm females Range: 203-255 mm males; 210-266 mm females

Weight: Average: 53 g males; 45 g females Range: 46-60 g males; 44-46 g females




FIELD GUIDE TO NORTH AMERICAN MAMMALS Hispid Pocket Mouse(Chaetodipus hispidus)



"Hispid" refers to the coarseness of this pocket mouse's fur. Hispid PocketMice are larger and more robust than other pocket mice in their range, andlike the others, they are solitary except in the breeding season. The gestationperiod is not known, but females in the northern part of the range may havetwo litters of 4-7 young a year. In the southern part of the range, matingactivity has been seen year-round.







FIELD GUIDE TO NORTH AMERICAN MAMMALS Mexican Spiny Pocket Mouse(Liomys irroratus)



The Mexican Spiny Pocket Mouse occurs in central and northeastern Mexicoand the extreme south of Texas. It inhabits a variety of semi-arid brushy orrocky habitats, and is common where it lives. The "pockets" of the pocketMouse are fur-lined cheek pouches, where seeds are carried from the foragingarea to the burrow. Mexican Spiny Pocket Mice are grayish-brown, with whiteunderparts. On the back, a mixture of stiff spiny hairs and soft ones gives theanimal a somewhat coarse appearance. These Mice are nocturnal and areactive year-round.


Length: Average: 238 mm males; 226 mm females Range: 216-262 mm males; 207-251 mm females





FIELD GUIDE TO NORTH AMERICAN MAMMALS Merriam's Pocket Mouse(Perognathus merriami)



Merriam's Pocket Mice are found in short-grass prairie, desert scrub, andopen, arid brushland. They are most common where the vegetation is denseenough to provide them with seeds and some protection from predators, butnot so dense that it inhibits their movements. Grazed pastures suit theirneeds well. Their silky fur is yellowish-orange with a slight blackish tinge onthe back, and their bellies are white to pale buff. A dark stripe runs justbehind the nose, and a pale ring encircles each eye. They are very similar inappearance to Silky Pocket Mice and Plains Pocket Mice. They are docile,readily tamed, and easily kept in captivity.



Weight: Average: 8 g Range: 5-9 g

Perognathus merriami - indistinguishablevisually from P. flavus; differentiated byterritory Credit: painting by Elizabeth McClellandfrom Kays and Wilson's Mammals of NorthAmerica, © Princeton University Press(2002)



FIELD GUIDE TO NORTH AMERICAN MAMMALS Northern Pygmy Mouse(Baiomys taylori)

ORDER: RodentiaFAMILY: Cricetidae


Northern Pygmy Mice are the smallest rodents in North America. They livein a variety of habitats where there is dense ground cover, and eat grass seedsand leaves, prickly pear cactus fruit and stems, mesquite beans, and granjenoberries (granjeno is an evergreen shrub). They will also eat snakes, snails, andinsects if presented with them. They cope with desert heat by entering torpor.Males help care for the young, grooming them and returning them to thenest. Nests have been found under fallen logs or in thick clumps of grass.Young Mice reach sexual maturity quickly, females at about 60 days andmales at about 70-80 days. The median life span is only 23 weeks, althoughcaptives, in laboratories, have been known to live as long as 170 weeks.Snakes and owls prey on them.



Weight: Range: 6-9.5 g

Credit: painting by Wendy Smith fromKays and Wilson's Mammals of NorthAmerica, © Princeton University Press(2002)



FIELD GUIDE TO NORTH AMERICAN MAMMALS Southern Plains Woodrat(Neotoma micropus)



Southern Plains Woodrats are found in places where grasses, creosotebush,mesquite, and cactus grow. Local populations can reach high levels and thencrash. Crashes can be associated with changes in habitat—for example, anunusually rainy year may kill cactus the Woodrats rely on for food. Like manyrodents, these woodrats are active between dusk and midnight. Whendisturbed, individuals thump or drum their hindfeet, possibly tocommunicate territorial ownership. They live in association with many othermammals, including armadillos, cotton rats, kangaroo rats, grasshoppermice, jackrabbits, and cottontails.

Also known as: Hoary Woodrat, Baird Woodrat, Black Woodrat, Plains Woodrat, GrayWoodrat, Rata de Campo




Credit: painting by Ron Klinger from Kaysand Wilson's Mammals of North America,© Princeton University Press (2002)



FIELD GUIDE TO NORTH AMERICAN MAMMALS Northern Grasshopper Mouse(Onychomys leucogaster)



Northern Grasshopper Mice are highly predatory, and their skulls and teethresemble those of flesh-eating carnivores such as cats and dogs. Theirforelimbs, equipped with elongated fingers and claws, have developed greatdexterity, so they are able to manipulate captured prey. These Mice have acomplex social system, using howling vocalizations to broadcast informationon sex, identity, body size, and location. Grasshopper Mice prey primarily ongrasshoppers, crickets, and beetles, yet they incorporate some seeds intotheir diet, presumably a dietary preference retained from a seed-eatingancestry.




Onychomys leucogaster - gray (left) andcinnamon (right) variations Credit: painting by Ron Klinger from Kaysand Wilson's Mammals of North America,© Princeton University Press (2002)



FIELD GUIDE TO NORTH AMERICAN MAMMALS Coues's Rice Rat(Oryzomys couesi)



Coues’s rice rats prefer cattail-bulrush marshes for habitat. Like the closelyrelated Marsh rice rat, Coues’s is thought to be highly aquatic, active at night,and carnivorous. They are excellent climbers, and nest above the ground.Their nests are built either in cattails or in small trees. When they nest incattails Coues’s rats only use the cattail leaf to build their nests. In trees, therats use a mix of plant materials for the nest. They tend to breed during thenon-winter months, and may breed throughout the year when winter is mild.They usually have litters of five, after a gestation of about 25 days. Thedistribution of Coues’s rice rat in the United States - limited to southernTexas - along with their restricted habitat preference makes this species oneof the rarest rodents in the United States.

Also known as: Reasca Rice Rat




Credit: painting by Ron Klinger from Kaysand Wilson's Mammals of North America,© Princeton University Press (2002)



FIELD GUIDE TO NORTH AMERICAN MAMMALS Marsh Rice Rat(Oryzomys palustris)



Marsh rice rats are among the most common mammals inhabiting tidalmarshes of the Gulf and Atlantic coasts. Being good swimmers, diving to 10m and crossing 300 m stretches of water, and able climbers, these rice ratsare suitably equipped for life in an environment where water levels fluctuate.They and Coues's rice rats are carnivores: they prey on crabs, clams, snails,fish, insects, baby turtles, and birds. As opportunistic feeders, they will alsoeat carrion and even some plant material. In some places, they breedthroughout the year, and in other places, they breed from March to October.A litter of five, after a gestation of about 25 days, is typical. In a little over aweek, the newborn rats' eyes open and they are beginning to nibble solidfood. They are weaned before they are three weeks old. As with manynocturnal rodents, owls are the main predator.

Also known as: Rice Rat



Weight: Average: 56 g males; 48 g females Range: 46-80 g males; 40-60 g females

Orysomys palustris - lower image issilvery subspecies O. p. argentatus ofFlorida Keys Credit: painting by Ron Klinger from Kaysand Wilson's Mammals of North America,© Princeton University Press (2002)



FIELD GUIDE TO NORTH AMERICAN MAMMALS White-footed Deermouse(Peromyscus leucopus)



The White-footed Deermouse has a very wide distribution. It is the mostabundant rodent in mixed deciduous and coniferous forests in the easternUnited States, and is probably equally abundant near farms. Its habitatpreferences are very different in southern Mexico, however, as it prospers insemi-desert vegetation. White-footed Deermice are excellent swimmers, andso are able to colonize islands in lakes with relative ease. They are notagricultural pests, and they are important ecologically because owls, weasels,snakes, and many other predators eat them. Individuals may live severalyears in captivity, but an almost complete turnover occurs annually in wildpopulations. In some places they carry the tick that transmits Lyme disease.

Also known as: Wood Mouse, Deermouse, White-footed Mouse






FIELD GUIDE TO NORTH AMERICAN MAMMALS Fulvous Harvest Mouse(Reithrodontomys fulvescens)



The fulvous Harvest Mouse is a nocturnal species that lives in grassy fieldswhere there are shrubs. These Mice are good climbers, and buildbaseball-sized nests up off the ground, in vegetation. Winter nests aresturdier than summer nests. When a nest is occupied—often by twoMice—the one or two entrances are plugged. Fulvous Harvest Mice eatinvertebrates when they are available, during the spring and summer, andswitch to seeds in fall and winter. Along the Texas coast, where invertebratesare available year-round, they are the dominant item in the diet. Males andfemales seem to travel together, which suggests they may pair-bond inmonogamous relationships, a rarity for mammals. These Mice live for about ayear, and seldom longer than 14 months.



Weight: Range: 6.5-25 g




FIELD GUIDE TO NORTH AMERICAN MAMMALS Hispid Cotton Rat(Sigmodon hispidus)



The Hispid Cotton Rat's fur is sprinkled or streaked with blackish or darkbrownish and grayish hairs. The Rats molt, losing and getting a new coat,three times in three months as they move through juvenile and subadultstages and into adulthood. Hispid Cotton Rats inhabit tall, dense grasses thatprotect them from birds of prey. Their range has recently expandednorthward into central Virginia, Kentucky, northern Missouri, southernNebraska, and northern New Mexico, and westward into western Coloradoand the Imperial Valley of California. Where their range and the ranges ofPrairie Voles and Pygmy Mice now overlap, the Hispid Cotton Rat appears tobe competitively excluding these species.




Sigmodon hispidus - upper right (with S.ochrognathus) Credit: painting by Todd Zalewski fromKays and Wilson's Mammals of NorthAmerica, © Princeton University Press(2002)



FIELD GUIDE TO NORTH AMERICAN MAMMALS Common Muskrat(Ondatra zibethicus)



Common Muskrats, so-called for their odor, which is especially evidentduring the breeding season, are highly successful semi-aquatic rodents. Theyoccur in both brackish and freshwater lakes, ponds, streams, rivers, andmarshes throughout much of North America, except in parts of the Southwhere tidal fluctuation, periodic flooding, or drought limit their distribution.Common Muskrats have a variety of aquatic adaptations, including arudder-like tail that is flattened side-to-side, partially webbed hind feet, andfur that traps air for insulation and buoyancy. Because their fur hascommercial importance, they were taken to Japan, South America,Scandinavia, and Russia, and there are now feral populations in some placeswhere they were introduced.

Also known as: Mudcat, Muskbeaver, Musquash, Muskrat


Weight: Range: 680-1,800 g




FIELD GUIDE TO NORTH AMERICAN MAMMALS Texas Antelope Squirrel(Ammospermophilus interpres)

ORDER: RodentiaFAMILY: Sciuridae


Notable for its running speed, the Texas Antelope Squirrel has the longesthindlimbs and tail of any antelope squirrel. In the field, the squirrels arenoticeable because of the way they carry the tail arched forward over theback. This common inhabitant of the Chihuahua Plateau occurs in rockyhabitats in desert mountain ranges, nesting in burrows or in between rocksand crevices, and eating various seeds, berries, and insects. Antelopesquirrels do not hibernate--they are active year round.

Also known as: Trader Spermophile







FIELD GUIDE TO NORTH AMERICAN MAMMALS Black-tailed Prairie Dog(Cynomys ludovicianus)


Conservation Status: Least Concern. Although there are still largepopulations of this species, some have disappeared as a result of humanactivity.

Black-tailed prairie dogs exhibit the most complex social behavior of allprairie dogs. Social groups called "coteries" live together in very largecolonies called "towns." The largest town ever recorded stretched for 65,000square km (25,000 square miles) under Texas prairie. An estimated 400million prairie dogs lived there. Topographical or vegetational features serveto subdivide the towns into clusters of coteries. The members of each coteriecooperate to defend their territory against others. Black-tailed prairie dogsare active all year, although they may spend extended periods of timeunderground in winter. They breed in February or March and usually have 3or 4 young, who are first seen aboveground in May or June.


Length: Average: 387.8 mm males; 371.2 mm females Range: 358-429 mm males; 340-400 mm females

Weight: Average: 907g males; 863 g females Range: 575-1,490 g males; 765-1,030 g females




FIELD GUIDE TO NORTH AMERICAN MAMMALS Southern Flying Squirrel(Glaucomys volans)



Most of the Southern Flying Squirrel's range is east of the Mississippi River,but it occurs west of the river in central Texas, and as far south as Honduras,in Central America. Like the Northern Flying Squirrel, it has a glidingmembrane (patagium) and a flattened tail. Flying squirrels are nocturnal andare much smaller than most tree squirrels, which are diurnal. Althoughprimarily associated with hardwoods, especially oaks and hickories, SouthernFlying Squirrels inhabit forests of diverse types, and even live in cities andsuburbs. A natural cavity or old woodpecker hole in a live or dead tree is thetypical nest site. Where the ranges of the two species of flying squirrelsoverlap, it appears the Southern Flying Squirrel may out-compete its largerrelative.

Also known as: Eastern Flying Squirrel



Glaucomys volans - left (with G.sabrinus); G. volans' belly hairs are whiteat base and tip Credit: painting by Todd Zalewski fromKays and Wilson's Mammals of NorthAmerica, © Princeton University Press(2002)



FIELD GUIDE TO NORTH AMERICAN MAMMALS Eastern Gray Squirrel(Sciurus carolinensis)



The adaptable, omnivorous, diurnal Eastern Gray Squirrel is the nativeAmerican mammal people most frequently see east of the Mississippi River.It prefers to den inside trees, but will construct large nests of leaves in thecanopy if tree cavities are not available. An average of two to three blind,hairless young make up a litter. Litters are produced once or twice a year, inFebruary and March and again in July through September. The young areweaned at eight or nine weeks, when their previously protective motherabandons them. In September, yearlings and some adults strike out toestablish their own home ranges in a process called the "fall reshuffle." Thesehome ranges are rarely more than one or two hectares in size. Successful asthey are, Eastern Gray Squirrels live only 11-12 months on average, but someindividuals have survived more than ten years in the wild. Factors affectingsurvival include the severity of winter, abundance of food, and parasites. Oneparasite, the mange mite, may cause enough hair loss to threaten survivalthrough winter.

Also known as: Cat Squirrel, Migratory Squirrel




Sciurus carolinensis - typical gray, left;black variant, right Credit: painting by Todd Zalewski fromKays and Wilson's Mammals of NorthAmerica, © Princeton University Press(2002)



FIELD GUIDE TO NORTH AMERICAN MAMMALS Eastern Fox Squirrel(Sciurus niger)



Eastern Fox Squirrels have long, foxtail-like tails, which they flick when theyare excited. They and Eastern Gray Squirrels are alike in many ways. Theybreed at the same time of year, nest in the same kind of places, and eat thesame foods. However, Fox Squirrels prefer more open habitat, whereas Graysprefer good tree cover. Fox Squirrels spend more time foraging and runningabout on the ground than do the grays, and may be encountered in fieldsquite far from any trees, where gray squirrel would not stray. Both speciesfeed on acorns, which are rich in tannins. Tannins are poisonous to manyanimals, including worms, and keep the squirrels free of roundworms andtapeworms. Fox Squirrels accumulate another chemical compound,porphyrin, in their bones and teeth, which makes their bones and teeth pinkand bright red under ultraviolet light. Here's a mystery: Gray Squirrels eatthe same foods and this does not happen to them—nor to any other healthymammal.

Also known as: Fox Squirrel, Cat Squirrel, Stump-eared Squirrel



Weight: Average: 800 g Range: 696-1,233 g

Sciurus niger - typical color, right;southeastern variation, top left; blackvariation, center top; black-headedvariation, lower center Credit: painting by Todd Zalewski fromKays and Wilson's Mammals of NorthAmerica, © Princeton University Press(2002)



FIELD GUIDE TO NORTH AMERICAN MAMMALS Mexican Ground Squirrel(Ictidomys mexicanus)



Mexican Ground Squirrels have adapted well to human activity and arecommon inhabitants of roadsides, cemeteries, and golf courses. They areomnivores, feeding on the seeds of a variety of grasses and forbs, green plantmaterial, and larval and adult insects. This burrow-dwelling species can befound in small, social colonies. Alarm calls alert members of the colony to thepresence of danger, and an erect posture is used to watch for potentialpredators. The species may be confused with the closely-relatedthirteen-lined Ground Squirrel, because both are marked by rows of whitespots on the back. However, the Mexican Ground Squirrel has a palercoloration and larger body size.

Also known as: Gopher, Picket Pen

Sexual Dimorphism: Males are slightly larger than females.



Spermophilus mexicanus - upper right(shown with S. spilomosa (center) and S.washingtoni (lower left)) Credit: painting by Todd Zalewski fromKays and Wilson's Mammals of NorthAmerica, © Princeton University Press(2002)



FIELD GUIDE TO NORTH AMERICAN MAMMALS Thirteen-lined Ground Squirrel(Ictidomys tridecemlineatus)



Thirteen-lined Ground Squirrels are often seen standing on their hind legson roadsides or other places where grass is mowed, such as lawns, golfcourses, or cemeteries. The squirrels probably once lived in short-grassprairie, and some human habitats suit them well. They dig a variety ofburrows, from short ones used for escape to deeper, longer ones with nestingchambers. Like most ground squirrels, they hibernate. In hibernation, theirheartbeat slows from more than 200 beats per minute to no more than five.How long they spend in hibernation annually depends on where they live,and at what elevation. Day length seems to determine when they enterhibernation in the fall, and some sort of internal clock prompts them toemerge in the spring. The Thirteen-lined Ground Squirrel's coat pattern isunique, with 13 dark and pale stripes running the length of the back; the darkstripes are patterned with small white spots.

Also known as: Gopher, Striped Ground Squirrel, Striped Gopher, Thirteen-lined Gopher,Striped Spermophile







FIELD GUIDE TO NORTH AMERICAN MAMMALS Spotted Ground Squirrel(Xerospermophilus spilosoma)



Spotted Ground Squirrels are among the smallest ground squirrels in NorthAmerica. They inhabit arid and semi-arid regions of Mexico and theSouthwest, and are found in scrubland and grassland as far north asWyoming and Nebraska. They feed primarily on green grasses, forbs, andseeds, but also eat insect larvae, insects, and even small vertebrates such aslizards and kangaroo rats. Their principal predators include snakes andhawks. In the northern part of their range, they hibernate for long periods. Itis not known whether this also occurs in the most southern reaches of therange.

Also known as: Gopher



Spermophilus spilomosa - center (with S.mexicanus (upper right) and S.washingtoni (lower left)) Credit: painting by Todd Zalewski fromKays and Wilson's Mammals of NorthAmerica, © Princeton University Press(2002)



FIELD GUIDE TO NORTH AMERICAN MAMMALS Rock Squirrel(Otospermophilus variegatus)



Rock squirrels, with their long, bushy tails, look very much like treesquirrels, but seldom climb trees. They are most commonly found in rockyhabitats—canyons, cliffs, and hillsides. Occasionally a nest is found in a tree,but they usually dig burrows, choosing a place that offers a near-by lookoutwhere they can watch for danger. Other mammals and even burrowing owlsare known to use their dens if the squirrels abandon them. The rock squirrel'sgeographic range is large, and it is found at elevations from sea level to 2,900m. Females produce one litter a year in places or at elevations where winterweather lasts longer, and two in warmer parts of their range.




Image shows variable amounts of blackcoloration in species Credit: painting by Todd Zalewski fromKays and Wilson's Mammals of NorthAmerica, © Princeton University Press(2002)



FIELD GUIDE TO NORTH AMERICAN MAMMALS Gray-footed Chipmunk(Tamias canipes)



Gray-footed chipmunks are shy and more often heard than seen. They makelight "chipper" or low "chuck-chuck-chuck" calls, and when they sensedanger, they scurry into deep brush, or underground, or up a tree. They areagile climbers, easily navigating rocks, cliffs, and trees. Acorns are probablytheir most important food during late summer and fall. They do not gettremendously fat in the fall, as do most animals that hibernate, so theyprobably feed on stored food.

Sexual Dimorphism: Males are slightly larger than females.



Credit: painting by Nancy Halliday fromKays and Wilson's Mammals of NorthAmerica, © Princeton University Press(2002)



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FIELD GUIDE TO NORTH AMERICAN MAMMALS …users.tamuk.edu/kfjab02/Biology/Mammalogy/lab/Smithsonian NMNH... · FIELD GUIDE TO NORTH AMERICAN MAMMALS North American Porcupine (Erethizon