What we’ve covered so far: Didelphimorphia Didelphidae – opossums (1 B.C. species) Soricomorpha Soricidae – shrews (9 B.C. species) Talpidae – moles (3 B.C. species) What’s next: Rodentia Sciuridae – squirrels (16) Muridae – mice, rats, lemmings, voles (16) Aplodontidae – mountain beaver (1) Castoridae – beaver (1) Dipodidae – jumping mice (2) Erethizontidae – N. American porcupines (1) Geomyidae – pocket gophers (1) Heteromyidae – kangaroo rats, pocket mice (1) Rodent diversity Order Rodentia • Dentition highly specialized for gnawing • Incisors: o single pair of upper, single pair of lower o grow continuously (rootless) o enamel on anterior surface, not posterior surface Order Rodentia • Dentition highly specialized for gnawing • Incisors • Diastema • No canines Family Sciuridae Family Sciuridae • Postorbital process well-developed • Rostrum short, arched • Infraorbital canal reduced relative to many other rodents • 1/1 0/0 1-2/1 3/3, anterior premolar sometimes small and peg-like Glaucomys sabrinus—northern flying squirrel • Can glide 5-25 meters • Strictly nocturnal • Share nests, reduce activity in winter because of cold Glaucomys sabrinus—northern flying squirrel • Conspicuous notch anterior to postorbital process • 5 upper cheekteeth Marmota spp. – marmots and woodchuck Marmota spp. – marmots and woodchuck • Rows of cheek teeth parallel, or nearly so • Postorbital processes protrude at 90° Marmota spp. – marmots and woodchuck • M. monax • M. caligata • M. vancouverensis • M. flaviventris Marmota monax - woodchuck • Posterior border of nasals forms a “V” • Maxillary row < 21 mm Marmota vancouverensis – Vancouver Island marmot • Posterior border of nasals forms a “V” • Maxillary row > 21 mm Marmota caligata – hoary marmot • Posterior border of nasals forms an arch • Maxillary row > 21 mm Marmota flaviventris – yellow-bellied marmot • Posterior border of nasals forms an arch • Maxillary row < 21 mm Sciurus carolinensis – eastern gray squirrel • Dorsal pelage variable (often gray, but can be light-colored or even black) • Long bushy tail (>50% body length) Sciurus carolinensis – eastern gray squirrel • 5 upper cheekteeth; P1 small and peg-like • Infraorbital foramen a canal on the side of the rostrum • 2 transbullar septae Spermophilus spp. – ground squirrels, rock squirrels • 5 cheekteeth per side – no peg-like cheekteeth • Flattened zygomatic plate Spermophilus spp. – ground squirrels, rock squirrels Maxillary toothrow > 10 mm • S. columbianus • S. parryii Maxillary toothrow < 10 mm • S. lateralis • S. saturatus Spermophilus columbianus – Columbian ground squirrel • Range: southern BC interior east of Rockies • Concerns about poisoning by ranchers worried about competition with livestock • Side of neck grayish Spermophilus parryii – Arctic ground squirrel • Range: northwest BC • Highly colonial, with hundreds of animals per colony and a few dominant males • Eat carcasses of animals • Side of neck reddish • Ventral side of tail reddish with black tip Spermophilus lateralis – golden-mantled ground squirrel • Range: Rocky Mountains • Prominent black stripes bordering light stripes on back and mantle • Unlike chipmunks, no stripes on face Spermophilus saturatus – Cascade mantled ground squirrel • Range: southern Cascades (limited range could pose conservation risk) • Black stripes on back; mantle inconspicuous • Unlike chipmunks, no stripes on face Tamias spp. - chipmunks Tamias spp. - chipmunks • 5 upper cheekteeth; P1 small and peg-like • Infraorbital canal pierces zygomatic plate Tamias townsendii – Townsend’s chipmunk • Skull length > 37 mm • Maxillary toothrow length > 6 mm • Pale, indistinct stripes on back and head Tamias minimus – least chipmunk • Skull length < 33 mm, toothrow < 6 mm • Total length < 195 mm • Distinct stripes on back and head • Range: northern half of BC Tamias amoenus – yellow-pine chipmunk • Skull length 33-37 mm, toothrow < 6 mm • Total length > 195 mm • Distinct stripes on back and head • Range: southern half of BC Tamias ruficaudus – red-tailed chipmunk • Skull length 33-37 mm, toothrow < 6 mm • Total length > 195 mm • Distinct stripes on back and head • Range: extreme southeastern BC Tamiasciurus spp. – American red squirrels • 4 upper cheekteeth • Zygomatic arches parallel or nearly so • 3 transbullar septae Tamiasciurus douglasii – Douglas’ squirrel • Ventral pelage yellow or orange • Range: southwestern BC Tamiasciurus hudsonicus – North American red squirrel • Ventral pelage white or gray • Range: most of BC including Vancouver Island Red squirrel midden.