Field Key to the Small Terrestrial Mammals (Orders Insectivora and Rodentia) of the Santa Fe Watershed

FIELD KEY TO THE SMALL TERRESTRIAL MAMMALS (ORDERS INSECTIVORA AND RODENTIA) OF THE SANTA FE WATERSHED

JENNIFER K. FREY

DEPARTMENT OF FISHERY AND WILDLIFE SCIENCES P.O. BOX 30003, CAMPUS BOX 4901 NEW MEXICO STATE UNIVERSITY LAS CRUCES, NEW MEXICO 88003-0003

Note: Keys are for adult specimens. Juvenile rodents are typically a dull gray color; hind feet often measure equivalent to adults in all but the youngest of some species. Use a thin, stiff ruler for measurements; ruler should be cut to start at 0 mm mark. Tail should be measured with ruler placed along the dorsal surface of the tail (0 at the junction between tail and rump) and with the tail perpendicular to the body; measure to the end of the last vertebrae (not the hair). Hindfoot should be measured with ruler placed along the bottom of the foot (0 at the heel) with the foot bent perpendicular to the leg; measure to the end of the longest claw (not to the end of the toe). Ear should be measured with the ruler placed into the notch at the base of ear (0 at notch); measure the longest distance to the end of the external ear.

KEY TO THE SMALL TERRESTRIAL MAMMALS

1a Long pointed flexible nose extends well beyond mouth, small eyes, small external ears…………..(Order Insectivora) 2 1b Not as above; single pair of upper and lower incisors separated from other teeth by a large gap……………………………….…………………………………..…………………………………………...(Order Rodentia) 6

ORDER INSECTIVORA (INSECTIVORES) FAMILY SORICIDAE (SHREWS)

2a Tail < ½ body; external ear extend beyond fur………………………………………….….Notiosorex crawfordi [NOCR] Desert shrew - possible in woodland. 2b Tail > ½ body, external ears hidden in fur………………………………………………………………….………….………….3

3a Size large; distinctly bicolored body-black dorsal, white ventral; hindfeet fringed with stiff hairs…………………………………………………………………………………………..….…..Sorex palustris [SOPA] Water shrew - occurs in wet habitats. 3b Not as above………………………………………………………………………………………….………………………………4

4a Hindfoot < 11.5; brownish…………………………………………………………………………..…….Sorex nanus [SONA] Dwarf shrew - occurs primarily in forested habitats; requires specimen to confirm identification. 4b Hindfoot > 11.5……………………………………………………………………………………………………………………….5

5a Brownish; underparts tan or gray; relatively large body..……………………………..….……..Sorex monticolus [SOMO] Montane shrew - occurs primarily in mesic forest, meadow and riparian habitats; requires specimen to confirm identification. 5b Brownish; underparts and feet brownish or buffy…………………………….…….…..………..…..Sorex cinereus [SOCI] Cinereus shrew - occurs primarily in wet areas in coniferous forest or montane meadows; requires specimen to confirm identification. Sorex preblei is very similar and is possible in relatively arid habitats. 5c Grayish; underparts and feet whitish………………………………………………………………....Sorex merriami [SOME] Merriam’s shrew - occurs primarily in woodland, scrub or arid forested habitat; requires specimen to confirm identification.

ORDER RODENTIA (RODENTS)

6a External cheek pouches present…………………..………..……………………….(Families Geomyidae, Heteromyidae) 7 6b External cheek pouches absent……….………………..………………………(Families Sciuridae, Muridae, Dipodidae) 13

7a External ears reduced, barely visible above fur; tail < 60% body; fusiform body shape; long front claws…………………………………………………………………………………….……………………(Family Geomyidae) 8 7b External ears extend beyond fur; tail > 60% body……………….…………………..……………...(Family Heteromyidae) 9

FAMILY GEOMYIDAE (POCKET GOPHERS)

8a Richly colored with small black patches behind ears………………………..…………………..Thomomys bottae [THBO] Botta’s pocket gopher - occurs in the lower elevations of the Sangre de Cristo Mountains and are occasionally caught in Sherman traps. Requires specimen to confirm identification. 8b Less richly colored with larger black patches behind ears…………………………………..Thomomys talpoides [THTA] Northern pocket gopher - occurs in the higher elevations of the Sangre de Cristo Mountains and are occasionally caught in Sherman traps. Requires specimen to confirm identification.

FAMILY HETEROMYIDAE (KANGAROO RATS)

9a Hindfoot sole densely furred along length…………………………………………………..….……………(Kangaroo rats) 10 9b Hindfoot sole partially furred or naked………………………………………………………….………………(Pocket mice) 11

10a Size large; hindfoot > 44; tail tip white…….…………………………………...….…………Dipodomys spectabilis [DISP] Banner-tailed kangaroo rat - unlikely in level open juniper woodland. 10b Size small; hindfoot < 43; tail tip dark……………………..………………….……...……………...Dipodomys ordii [DIOR] Ord’s kangaroo rat - possible in the woodland zone.

11a Tail > 60; hindfoot 18-20, usually 19; light patch behind ear present but not conspicuous……………………………………………………..………………….Perognathus flavescens apache [PEAP] Apache pocket mouse - unlikely in very sandy areas in woodland zone. 11b Tail < 61; hindfoot 15-19, usually 17; light patch behind ear conspicuous….………………Perognathus flavus [PEFL] Silky pocket mouse - possible in woodland zone.

12a Pelage color pattern with stripes, spots or mottling………………………….………………(Family Sciuridae, squirrels) 13 12b Pelage color pattern without stripes, spots or mottling……………………....…(Family Muridae, rats, mice and voles) 18

FAMILY SCIURIDAE (SQUIRRELS)

13a Black and white stripes on sides of head……………..……………………………………..……….(Tamias, chipmunks) 18 13b No stripes on face………………………………………………………………………………..…………………..………..… 19

14a Hindfoot < 32; blackish lateral stripes; buffy upper lip; brighter coloration; small……...…..….Tamias minimus [TAMI] Least chipmunk - occurs primarily in spruce-fir forest but may occur in other habitats at lower elevations. 14b Hindfoot > 33; brownish lateral stripes; whitish upper lip; duller coloration………..…...Tamias quadrivittatus [TAQU] Colorado chipmunk - occurs primarily in ponderosa pine and mixed conifer forest.

15a Stripes on back or sides………………………………………………………………………..…………………………………16 15b No stripes on back or sides………………………………………………………………..……………………………………..17

16a Superficially resembles chipmunk due to lateral stripes; no facial stripes………..……..Spermophilus lateralis [SPLA] Golden-mantled ground squirrel – occurs in conifer forest. 16b Dorsal pattern of stripes alternating with rows of spots…………………..…….Spermophilus tridecemlineatus [SPTR] Thirteen-lined ground squirrel – unlikely in large grasslands. 16c Reddish dorsal color separated from white belly by black stripe……………....…….Tamiasciurus hudsonicus [TAHU] Red squirrel – occurs primarily in mixed conifer and spruce-fir forest but occasionally found in other forest types; occasionally caught in Sherman traps.

17a Overall grayish or brownish pelage with mottled appearance; mottling may appear like white spots; tail bushy; adults large (tail >150; hindfoot > 48)……………………………………………..….….Spermophilus variegatus [SPVA] Rock squirrel - occurs primarily below the forest zone but may occupy relatively open rocky habitats at higher elevations. Juveniles occasionally caught in Sherman traps; adults too large. 17b Overall tannish or reddish pelage with light spots on back; tail well-furred but not bushy; adults medium (tail < 90; hindfoot 29-35)………………………………………………..Spermophilus spilosoma [SPSP] Spotted ground squirrel – possible in woodland. Families Muridae (Rats, Mice and Voles) and Dipodidae (Jumping Mice)

18a Tail < 60% body…………………………………………………………………………………………………………………….19 18b Tail > 60% body ….………………………………………………………………….……………………………………………..22

19a Soles of feet furred; tail white-tipped; ears conspicuous; distinctive odor………….…Onychomys leucogaster [ONLE] Northern grasshopper mouse – possible in woodland. 19b Soles of feet naked or slightly haired; no white tip on tail; ears not conspicuous……………………...……….…(voles) 20

Voles

20a Tail > 1/3 total; tail > 50; may have reddish dorsal color………………………………...….Microtus longicaudus [MILO] Long-tailed vole - occurs primarily in mesic forest and riparian shrub habitat 20b Tail < 1/3 total length; tail < 50……………………………………………………………………………………………………21

21a Dorsal color brown; tail 39-50; hindfoot > 20……………………………………………..Microtus pennsylvanicus [MIPE] Meadow vole – occurs in wet meadows and marsh with saturated soil 21b Dorsal color reddish, face and flanks gray, belly whitish; tail < 21; hindfoot < 20.….…Clethrionomys gapperi [CLGA] Southern red-backed vole – occurs in mesic sites in mixed conifer and spruce-fir forest 21c Dorsal color grayish brown; tail 30-39; hindfoot < 20…………………….………….….Phenacomys intermedius [PHIN] Heather vole – rare occupant of the higher elevations of the Sangre de Cristo Mountains but little is known about its habitat affinities; requires specimen for verification.

Mice

22a Tail long, scaly, with few hairs……………………………………………………………………………………………………23 26b Tail furred……..………………………….…………………………………………………………………………………………24

23a Tail > 120; pelage tricolored-white belly, orangish flanks, broad brownish mid-dorsal stripe………………………………………………………………………………………….Zapus princeps [ZAPR] Western jumping mouse – occurs primarily in riparian shrub (willow) habitat. It is remotely possible for the meadow jumping mouse (Z. hudsonicus) to occur in the watershed. This species is slightly smaller, has a more distinct bicolor tail and less well defined mid-dorsal stripe; it would likely inhabit marsh or wet meadow habitat; requires specimen for verification. 23b Tail < 100; uniformly gray-belly not obviously lighter than back…………………………………...Mus musculus [MUMU] House mouse - possible near human dwellings.

24a Mouse-like; hindfoot < 26………..……..……………………………………………….…………...(deer and harvest mice) 25 24b Rat-like; hindfoot > 27……………………..…………………………………………….………….…..(Neotoma, wood rats) 30

25a Tail not tufted-all hairs of about equal length; tail < 80………………………………………………………………………..26 25b Tail tufted with at least some terminal hairs longer in length; tail > 80….………………………………….….……………28

26a Ear 11-17; eyes appear set close together and nearer the nose; upper incisor with a longitudinal groove in surface (total 117-156, tail 50-83, hindfoot 15-21, ear 11-17)………...………………….…Reithrodontomys megalotis [REME] Western harvest mouse – occurs in grassland, meadow and marsh habitat. 26b Ear 16-20; eyes set wider apart and further from nose; upper incisor without longitudinal groove……………………………………………………..…………………………………………………………..33

27a Hindfoot 18 - 21; tail < 75 distinctly bicolored; pelage richly colored………..…….…Peromyscus maniculatus [PEMA] Deer mouse – occurs primarily in conifer forest, riparian, grassland, meadow and marsh habitat; may occasionally be found in all other habitats. 27b Hindfoot > 21; tail > 75 not distinctly bicolored; pelage dull colored……………….……..Peromyscus leucopus [PELE] White-footed mouse – possible in lower elevation warm riparian habitat.

28a Ear usually < 20; tail > body; dark dorsal color extends over ankles………………….……...Peromyscus boylii [PEBO] Brush mouse – occurs in relatively arid, shrubby locations typically in association with oak 28b Ear > 20; ankles without dark color……………………………………………………………………...……………………….31

29a Ear > 23; ear > hindfoot; tail< body; pelage brownish………………………..………………..…Peromyscus truei [PETR] Pinyon mouse – occurs primarily in juniper and pinyon-juniper woodland but may occasionally be found in adjacent grassland, oak shrub and ponderosa pine forest 29b Ear < 23; hindfoot > ear; hindfoot generally > 23; tail > body; pelage grayish………..….Peromyscus nasutus [PENA] Northern rock mouse – occurs primarily in rocky situations, especially in arid shrub and woodland WOOD RATS

30a Sole of hindfoot completely furred; tail very bushy; size very large; hindfoot > 40………………………………………………………..………………..…………..……..Neotoma cinerea [NECI] Bushy-tailed wood rat - occurs in conifer forest particularly where vertical rock crevices are available for middens. 30b. Sole of hindfoot naked or only partially furred; tail not bushy; hindfoot < 40…………………….…………….……….…..31

31a. Throat hair all white; white around mouth……………………………………….………………...Neotoma albigula [NEAL] White-throated wood rat – occurs below the forest zone and possibly in other relatively warm arid non-forested sites. 31b. Throat hair gray at base; may be dark around mouth………………………………………….Neotoma mexicana [NEME] Mexican wood rat – occurs in conifer forest and woodland.

Note: Other species on the watershed may on rare occasions be caught in Sherman traps. These include ermine (Mustela erminea), long-tailed weasel (Mustela frenata), juvenile cottontails (Sylvilagus nuttallii, possibly S. audubonii; requires specimen to verify) and potentially other juvenile mammals.