Eastern Chipmunk Tamias Striatus

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MAMMALS OF MISSISSIPPI 6:1-6

JEAN E. CHERVENAK

Department of Wildlife and Fisheries, Mississippi State University, Mississippi State, Mississippi, 39762, USA

Abstract—Tamias striatus (Linnaeus, 1758) is a sciurid commonly called the eastern chipmunk. Tamias striatus is solitary, diurnal, omnivorous, and undergoes winter torpor. Individuals establish solitary home ranges centered around extensive burrows. Diseases and parasites that affect T. striatus include West Nile Virus, Cuterebrid bot ﬂ ies, and Baylisascaris procyonis. Tamias striatus is abundant throughout its range in eastern North America, inhabiting hardwood forests. It is 1 of 25 species within the genus Tamias, and the only member of subgenus Tamias. The species is considered non-threatened, and is commonly seen throughout its range.

Published 5 December 2008 by the Department of Wildlife and Fisheries, Mississippi State University

Eastern chipmunk DISTRIBUTION Tamias striatus (Linnaeus, 1758) Tamias striatus is widely distributed throughout its range in eastern North America (Rowe et CONTEXT AND CONTENT al. 2006). The northern extent of their range is Order Rodentia, suborder Sciuromorpha, family the southern tip of James Bay Canada, and the Sciuridae, subfamily Xerinae, tribe Marmotini. southern limit is the Gulf of Mexico (Fig.2; Elliot Tamias is not monotypic. 1978).

GENERAL CHARACTERS FORM AND FUNCTION Tamias striatus is a small rodent, weighing The skull of T. striatus is superiorly fl attened between 73 and 136 g. Total body length is with a shallow brain case (Fig. 3). The 205 to 299 mm. Tail length is 69 to 115 mm. upper incisors are slightly recurved and Dorsal pelage is reddish brown, with fi ve dark short, molars are low crowned with wide stripes alternated with two light buff stripes. Stripes are also found on the sides of the head. The tail is somewhat fl attened and fully furred. Ventral pelage is whitish; sometimes buff (Fig. 1; Sealander 1979). Tamias striatus is not sexually dimorphic (Elliot 1978).

Fig. 1. An adult Tamias striatus from northern New Fig. 2. Geographic Distribution of Tamias striatus Jersey. Used with permission of photographer . (Wilson and Ruff 1999). Females disperse approximately 85 m and may overlap home ranges with their mothers (Burke da Silva et al. 2002). Potential lifespan of T. striatus may be as long as eight years; however, longevity in the wild is generally 2 to 3 years (Sealander 1979).

Space use.—Tamias striatus is adapted to mature deciduous forests with sparse understory vegetation. Forest fragmentation is not a large concern to the chipmunk, especially if there are forested travel corridors. Individuals have been documented crossing open ﬁ elds >220 m wide (Reunanen and Grubb 2005).

The eastern chipmunk establishes a solitary home range of approximately 0.5 to 1 acre, with a central home burrow maintained from season to season. Home ranges may overlap slightly, but only in the less used outer regions. Fig. 3–Geographic distribution of Canis latrans. Adapted Individuals do not usually travel more than 45 from Jackson (1951), Hill et al. (1987), and Thornton et m from their burrows. During breeding season al. (2004). Created using ArcGIS. males will occasionally move from 60 to 90 m from their burrows in search of females in spaced cusps, and there may be subsidiary estrus. A single female’s home range may be cusplets between primary cusps (Howell 1938). visited by up to 12 different males while she is Dental formula is i 1/1, c 0/0, p 1/1, m 3/3, total in estrus (Elliot 1978). 20 (Sealander 1979). Tamias striatus creates a burrow with a single ONTOGENY AND REPRODUCTION entrance; secondary entrances are plugged Tamias striatus reproduces in spring and with leaves and soil. Tunnels within the burrow summer, though individual females may only form a complex network around a nesting have one litter per year. Estrus lasts one cavity, with food hoards scattered throughout. day, and most females within an area will go Burrows also contain a drainage system of into estrus within a few days of each other. deep, tapered tunnels extending below the level Both sexes mate multiple times with multiple of the living tunnels. Because these burrows partners, copulating in cavities. Gestation are so complex, they are reused from season to length is approximately 30 days (Elliot 1978). season (Elliot 1978). Litter size ranges from 1 to 8, averaging 4 to

5 young. The neonates are altricial and are Diet.—Although T. striatus is omnivorous, the reared in a nest chamber within the burrow species feeds primarily on seeds, buds, and (Sealander 1979). Juveniles emerge from berries (Reunanen and Grubb 2005). Other the burrow at about 40 days of age and components of the eastern chipmunk’s diet disperse about 1 to 2 weeks later (Elliot 1978). include songbird eggs (Schmidt et al. 2001) and Females begin reproducing at one year of age invertebrates (Mahan and Yahner 1998). (Sealander 1979). Tamias striatus relies on food stores cached ECOLOGY in the fall to survive winter torpor. These food Population characteristics.—Dispersal of stores consist primarily of acorns, beechnuts, juveniles varies between sexes, with males and sugar maple seeds (Humphries et al. dispersing up to 345 m from the natal burrow. 2003). Red oak acorns are the preferred food neighboring males will journey to her home for winter larders because of their higher lipid range in order to mate. Both males and content (Wood 2005). females mate multiple times with multiple partners. There is no pair bonding between Diseases and parasites.—The eastern males and females. Tamias striatus is chipmunk is parasitized by Cuterebrid botﬂ ies diestrous, with breeding seasons in spring (also called warbles–Jaffe 2005). Bot ﬂ ies (February through April) and summer (June lay their eggs at the entrance to burrows; the through August). Juveniles stay in the burrow hatched larvae enter the host’s eyes, nose, or for approximately 40 days, emerging in late mouth. The larvae then move beneath the skin spring (April through June) or early fall (August to the inguinal region where they mature and through October) depending on the breeding burst through the skin of the host. Infection season. Juveniles disperse between 1 to 2 of the lesion after the larvae leaves its host weeks later (Elliot 1978). can cause death if the infected individual was heavily parasitized (Elliot 1978). Communication.—Tamias striatus uses three distinctive alarm calls to alert other chipmunks West Nile Virus is prevalent in T. striatus, and to the presence of predators: a chuck, a chip, is contracted from mosquitoes. The disease and a trill. A chuck is used when an individual can be passed both from mosquitoes to T. spots an aerial predator, a chip for terrestrial striatus and vice versa. West Nile Virus causes predators, and trills when a predator is pursuing brain, kidney, and liver lesions; neurological an individual. Individual response to these symptoms such as head tilting, lethargy, and alarm calls varies depending on call rate and lack of coordination; and death in T. striatus number of individuals calling (Weary and (Platt et al. 2007). Kramer 1995).

Tamias striatus is also parasitized by Foraging.—Tamias striatus creates hoards Baylisascaris procyonis, a lower-intestine to store food. Scatter hoarding is much less dwelling nematode. Individuals are infected prevalent than larder hoarding since individuals when foraging in raccoon feces. The larval use their burrow hoards during winter torpor. cycle includes migration within the body, often In the autumn, chipmunks use their expansive into the central nervous system. Baylisascaris cheek pouches to carry seeds and acorns procyonis causes fatal or severe neurological gathered both on the ground and in the crowns disease in over 50 species of mammals and of trees. (Elliot 1978). birds (Page et al. 2001). During winter months, T. striatus uses burrow BEHAVIOR hoards gathered in the fall as the primary Grouping behavior.—Tamias striatus is source of energy. Individuals create several solitary, aggressive, and intolerant of other hoards within their burrows, storing surplus individuals. No long-term social bonding food to last the entire winter. When T. striatus occurs. Social interactions between adults emerges from hibernation in the spring, outside of the breeding season consist primarily overwintered seeds and acorns are the primary of aggressive chases, usually when one source of food (Elliot 1978). individual ventures too close to the center of another’s home range. The greatest extent Tamias striatus raids songbird nests for eggs of social cooperation in T. striatus is the use (Schmidt et al. 2001). T. striatus also forages of alarm calls to alert other individuals to the for undigested berry seeds and corn in raccoon presence of predators. (Elliot 1978). feces (Page et al. 2001).

Reproductive behavior.—Females stay Winter Torpor.—Tamias striatus is a food- within their home range during estrus. Many storing hibernator. Rather than storing fat, T. striatus creates a larder of various tree seeds in ACKNOWLEDGMENTS its burrow. Individuals are solitary, and remain I wish to thank my professor Dr. J. Belant for in their burrows for 4 to 7 months (Humphries his assistance and support throughout this et al. 2003). During bouts of torpor, individuals endeavor, as well as my fellow classmates rouse every 3 to 4 days to eat from their hoards who served as editors. I also thank the staff of (Elliot 1978). the Mitchell Memorial Library and the College of Forest Resources at Mississippi State CONSERVATION University for assistance in gaining access to Tamias striatus is not endangered, and is valuable information and materials. considered a species of least concern by the International Union for Conservation of Nature and Natural Resources Red List (IUCN 2007). LITERATURE CITED Burke Da Silva, K., C. Mahan, and J. Da Platt, K. B., B. J. Tucker, P. G. Halbur, S. Silva. 2002. The Trill of the Chase: Tiawsirisup, B. J. Blitvich, F. G. Fabiosa, eastern chipmunks call to warn kin. L. C. Bartholomay, and W. A. Rowley. Journal of Mammalogy 83:546–552. 2007. West Nile Virus Viremia in Elliot, L. 1978. Social Behavior and Foraging Eastern Chipmunks (Tamias striatus) Ecology of the Eastern Chipmunk Suffi cient for Infecting Different (Tamias striatus) in the Adirondack Mosquitoes. Emerging Infectious Mountains. Smithsonian Contributions Diseases 13:831–837. to Zoology. Reunanen, P., and T. C.Grubb Jr. 2005. Howell, A. H. 1938. Revision of the North Densities of Eastern Chipmunks (Tamias American Ground Squirrels. North striatus) in Farmland Woodlots Decline American Fauna. with Increasing Area and Isolation. Humphries, M. M., D. L. Kramer, and D. W. American Midland Naturalist 154:433– Thomas. 2003. The Role of Energy 441. Availability in Hibernation: an Rowe, K. C., E. J. Heske, and K. N. Paige. experimental test in free-ranging eastern 2006. Comparative Phylogeography of chipmunks. Physiological and Eastern Chipmunks and White-Footed Biomechanical Zoology 76:180-186. Mice in Relation to the Individualistic [IUCN] International Union for Conservation Nature of Species. Molecular Ecology of Nature and Natural Resources. 2007. 15:4003–4020. 2007 IUCN Red list of threatened Schmidt, K. A., J. R. Goheen, R. Naumann, R. species. www.iucnredlist.org, accessed S. Ostfeld, E. M, Schauber, and A, 23 September 2008. Berkowitz. 2001. Experimental Jaffe, G., Zegers, D. A., M. A. Steele, and J. Removal of Strong and Weak Predators: F. Merritt. 2005. Long-Term Patterns of Mice and Chipmunks Preying on Botfl y Parasitism in Peromyscus Songbird Nests. Ecology 82:2927– Maniculatus, P. Leucopus, and Tamias 2936. Striatus. Journal of Mammalogy 86:39– Sealander, J. A. 1979. A Guide to Arkansas 45. Mammals. River Road Press, Conway, Linzey, D. W. 1998. The Mammals of Arkansas. Virginia. McDonald and Woodward Weary, D. M., and D. L Kramer. 1995. Publishing Company, Granville, Ohio. Response of Eastern Chipmunks to Mahan, C. G., and R. H. Yahner. 1998. Lack Conspecifi c Alarm Calls. Animal of Population Response by Eastern Behavior 49:81–93. Chipmunks (Tamias striatus) to Forest Wilson, D. E. and S. Ruff. 1999. The Fragmentation. American Midland Smithsonian Book of North American Naturalist 140:382–386. Mammals. University of British Page, L. K., R. K. Swihart, and K. R. Columbia Press, Westmall, Vancouver, Kazacos. 2001. Seed Preferences and BritishColumbia, Canada. Foraging by Granivores at Raccoon Wood, M. D. 2005. Tannin and Lipid Latrines in the Transition Dynamics Content of Scatterhoards and of the Raccoon Roundworm Larderhoards. Northeastern Naturalist (Baylisascaris procyonis). Canadian 12:463–472. Journal of Zoology 79:616–622.

Contributing editor of this account was Clinton Smith.