Keys to the Mammals and Mammal Skulls of the Northern Coastal Plain of Virginia

This publication is designed to function as a tool for the identification of the mammal species that occur on the Coastal Plain of northern Virginia. We provide whole-body and skull keys to the 40 species that occur in this region. Baseline data for this work were collected during several studies conducted on Fort A. P. Hill, Caroline County. The intended audience includes interested naturalists, teachers, students, field biologists, and natural resource managers. INTRODUCTION These keys address all native land mammal species with geographic ranges that include Fort A. P. Hill (APH), Caroline County, Virginia, and nearby portions of the northern Coastal Plain. The species are representative of the mammal fauna of the northern Coastal Plain of Virginia. APH is centered approximately 77° 15' N and 38° 05' Wand is about 15 km east of the Fall Line-the boundary between the Piedmont and Coastal Plain physiographic regions. The current landscape consists of a mosaic of managed habitats that range from old field to mature hardwood forest (Mitchell and Roble, 1998; Bellows et al., 2001 c ). Baseline data for this work were collected as part of several studies conducted on APH ( e.g., Bellows et al., 1999; Bellows and Mitchell, 2000; Bellows et al., 2001 a, 2001 b ). Bellows et al. (2001 c) provide descriptions of the biologies, ecologies, and distributions of the 40 indigenous species we address herein, as well as descriptions of watershed drainages, climate, and habitats of the region. The presence of 38 mammal species on APH has been verified through direct observation or voucher specimens. One bat species, Myotis austroriparius, was identified by examination (ASB) and by photograph (David Webster, University of North Carolina at Wilmington). Mustelafrenata has not been captured or observed; however, APH is well within its geographic range (Hall, 1981) and its presence on the post is likely. The range of another species included in the keys, Blarina carolinensis, does not include APH, but it is found nearby to the north and east in the Northern Nec·k (Tate et al., 1980; Pagels and French, 1987). Native species Sigmodon hispidus and Ochrotomys nuttalli with range limits nearby the project area, as well as the known introduced species Rattus rattus, R. norvegicus, and Mus musculus, are not included herein. These species are described in Bellows et al. (2001c). Corresponding author: (Phone) 804-828-0076, jpagels@mail l .vcu.edu 4 VIRGINIA JOURNAL OF SCIENCE MAMMALS DESCRIBED IN THE FOLLOWING KEYS Notations on abundance are based on various studies at APH unless otherwise noted. Vernacular names follow Jones et al. (1997). Didelphis virginiana, Virginia opossum ( common) Sorex hoyi, pygmy shrew (common) Sorex longirostris, southeastern shrew (common) Blarina brevicauda, northern short-tailed shrew (abundant) Blarina carolinensis, southern short-tailed shrew (see text above) Cryptotis parva, least shrew ( common) Sea/opus aquaticus, eastern mole (probably common, but rarely captured) Condylura cristata, star-nosed mole (uncommon, rarely captured) Myotis austroriparius, southeastern myotis (rare) Myotis septentrionalis, northern myotis ( common) Myotis lucifugus, little brown myotis (common) Lasiurus borealis, eastern red bat (migratory [Shump and Shump, 1982], abundant) Lasiurus cinereus, hoary bat (migratory [Zinn and Baker, 1979], uncommon, rarely captured) Lasionycteris noctivagans, silver-haired bat (migratory [Handley and Patton, 1947], uncommon) Pipistrellus subjlavus, eastern pipistrelle (common) Eptesicusfuscus, big brown bat (abundant) Nycticeius humeralis, evening bat (uncommon) Sylvilagus jloridanus, eastern cottontail (abundant) Tamias striatus, eastern chipmunk (uncommon) Marmota monax, woodchuck (abundant) Sciurus carolinensis, eastern gray squirrel (abundant) Glaucomys volans, southern flying squirrel ( common) Castor canadensis, American beaver (abundant) Oryzomys palustris, marsh rice rat (uncommon, rarely captured) Reithrodontomys humulis, eastern harvest mouse (uncommon) Peromyscus leucopus, white-footed mouse (abundant) Microtus pennsylvanicus, meadow vole ( common) Microtus pinetorum, woodland (pine) vole (probably common, rarely captured) Ondatra zibethicus, common muskrat (common) Zapus hudsonius, meadow jumping mouse (common) Canis latrans, coyote (uncommon) Vulpes vulpes, red fox (uncommon) Urocyon cinereoargenteus, common gray fox (common) Procyon lotor, common raccoon ( common) Mustela frenata, long-tailed weasel (not observed but likely present [Hall, 1981]) Mustela nivalis, least weasel (rare) Mustela vison, American mink (uncommon) Lontra canadensis, northern river otter (uncommon) Mephitis mephitis, striped skunk (common) Lynx rufus, bobcat (rare) Odocoileus virginianus, white-tailed deer (abundant) ANNOTATED KEY TO THE MAMMALS This key relies heavily on external features, particularly selected measurements (Fig. 1), coloration, and certain easily viewed features of the skull. All morphological KEYS TO VIRGINIA COAST) characteristics are evident or can be measured o fication may be required in some instances ( e Unless the term "total" is used, numbers of teet one-half of the jaw. For example, when desc Virginia opossum, 5/4 means five upper inciso1 on one side ( or a total of 10 upper incisors an characteristics are described in the key or on tht KEY TO THE ORDERS< la. Hind foot with thumb-like first toe, opposat males; incisors 5/4 . . . . . . . . . . . . . lb. Hind foot first toe not thumb-like or opposa females; incisors never more than 3/3 . . . 2a. Forelimbs modified as wings, for flight; sku 20 mm or less; a large U-shaped opening in or two incisors . . . . . . . . . . . . . . . 2b. Forelimbs not modified as wings; skull ve~ size; upper jaw complete without U-shaped 3a. Feet with hooves; upper incisors absent . 3b. Feet with claws; upper incisors present . 4a. Canines absent, toothrows with a conspicuc mens with and without a diastema; size frm rabbits and the beaver . . . . . . . . . . . 4b. Canines present, toothrows with no conspic length ranges from very small, approx. 70 r 1200 mm (coyote) . . . . . . . . . . . . . 5a. Incisors 2/1, second upper incisor a small p longer than tail . . . . . . . . . . . . . . 5b. Incisors 1/1; ears much shorter than tail .. 6a. Canines nearly equal in size to adjacent tee small(< 100 g) ............. . 6b. Canines noticeably larger than adjacent tet from <65 g (least weasel) to 40-200 kg (bl, KEY TO THE GENERA AND S I. Order Didelphimorphia (Marsupialia). J placed in the single Order Marsupialia, severa 1992). The Virginia opossum is the only nati Mexico (Gardner, 1982). . . . . . . . . . . . . . . . . . . . . . ' iI. Order Insectivora. The Order Insectivo sentatives found throughout much of the worli KEYS TO VIRGINIA COASTAL PLAIN MAMMALS 5 characteristics are evident or can be measured on whole or partial specimens. Magnification may be required in some instances (e.g., examination of shrew dentition). Unless the term "total" is used, numbers of teeth refer to the upper and lower teeth in one-half of the jaw. For example, when describing the number of incisors in the Virginia opossum, 5/4 means five upper incisors on one side and four lower incisors on one side ( or a total of IO upper incisors and eight lower incisors). Other useful characteristics are described in the key or on the figures when first used. KEY TO THE ORDERS OF MAMMALS la. Hind foot with thumb-like first toe, opposable; marsupium present in females; incisors 5/4 ................ (Marsupialia) Didelphimorphia lb. Hind foot first toe not thumb-like or opposable; marsupium not present in females; incisors never more than 3/3 . . . . . . . . . . . . . . . . . . . . . . 2 2a. Forelimbs modified as wings, for flight; skull small, greatest length about 20 mm or less; a large U-shaped opening in rostrum (snout) between one or two incisors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Chiroptera 2b. Forelimbs not modified as wings; skull very small, < 10 mm to large, deer size; upper jaw complete without U-shaped opening in rostrum . . . . . . 3 3a. Feet with hooves; upper incisors absent 3b. Feet with claws; upper incisors present Arti odacty la ... 4 4a. Canines absent, toothrows with a conspicuous diastema (Fig. 2A), specimens with and without a diastema; size from very small mice and voles to rabbits and the beaver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4b. Canines present, toothrows with no conspicuous diastema (Fig. 2B); total length ranges from very small, approx. 70 mm (pygmy shrew) to nearly 1200 mm (coyote) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5a. Incisors 2/1, second upper incisor a small peg behind first; ears much longer than tail . . . . . . . . . . . . . . Lagomorpha 5b. Incisors 1/1; ears much shorter than tail . . . . . . . . . . . . . . . . . Rodentia 6a. Canines nearly equal in size to adjacent teeth; incisors not 3/3; body size small ( < 100 g) . . . . . . . . . . . . . . . . . . . . . . . . . . . . Insectivora 6b. Canines noticeably larger than adjacent teeth; incisors 3/3; range in size from <65 g (least weasel) to 40-200 kg (black bear) . . . . . . . . . Camivora KEY TO THE GENERA AND SPECIES OF MAMMALS I. Order Didelphimorphia (Marsupialia). Although marsupials traditionally were placed in the single Order Marsupialia, several orders are now recognized (Gardner, 1992). The Virginia opossum is the only native North American didelphid north of Mexico (Gardner, 1982). . . . . . . . . . . . . . . . . . . . . . Virginia opossum, Didelphis virginiana ii. Order Insectivora. The Order Insectivora is a large, diverse order with representatives found throughout much of the world. Virginia representatives of this order 6 VIRGINIA JOURNAL OF SCIENCE are moles and shr~ws. Mol:s are e~sily recognized by their extremely enlarged forefeet, an adaptat10n for thetr fossonal or burrowing mode of locomotion. Shrews are well