Long-eared chipmunks, Tamias quadrimaculatus, are abundant and widespread throughout the northern Sierra Nevada of California from Plumas County south to Madera County and in Nevada in the Lake Tahoe area. (Clawson, et al., 1994)
Tamias quadrimaculatus is typically found in mixed chaparral, ponderosa pine, mixed conifers, brush fields, and Douglas fir. Its habitat preference includes brush patches, fallen logs, stumps, rocks, and ground litter. Nests are located in trees and in underground burrows. It is often found in dense shrubs with low to moderate canopy and along forest edges at low to mid elevations of 960 to 2,250 m. (Clawson, et al., 1994)
Long-eared chipmunks were first described by Gray (1867). Ears are long and slender. Pelage is reddish in color with a white-edged tail. The back is marked by five dark and four pale stripes, and there is a noticeable white patch behind each ear.
Males are smaller than females with a total length of 233 mm on average for males and 239 mm for females. The length of head and body for males and females is 138 mm and 141 mm, respectively. Females weigh between 81 and 105 g, whereas males weigh between 74 and 89 g.
A major distinction of this species is the increased width of the zygomatic process compared to other members of the Tamias. The baculum differs from other chipmunks in this group by having a longer shaft, a proportionally shorter tip, and a wider angle between the tip and shaft. (Broadbooks, 1999; Gray, 1867; Johnson, 1943; Levenson, 1990; White, 1953)
Like other hibernating chipmunks, T. quadrimaculatus is both homoiothermic and heterothermic. Although the body temperature is maintained at a set point, the set temperature is higher when the animal is active than when it is torpid. Chipmunks are endothermic. (Nowak, 1999)
Males have cuts on their faces and bodies during breeding season. Females lack these injuries, indicating that there may be some aggression between males, possibly from competiton for mates. If they follow the pattern of other members of their genus, it is likely that mating in this species is polygynous. (Broadbooks, 1999; Nowak, 1999; Storer, 1944)
Reproduction takes place from April to mid-July, with mating taking place typically in April and early May. The gestation period of 31 days ensures that the young are born by June. Lactation is thought to last about one month, and the young emerge in July and August. By September the young are almost fully-grown. They nest in trees, logs, stumps, and burrows. If like other chipmunks, these animals are capable of breeding by the mating season following their birth. (Broadbooks, 1999; Harris, 2005; Ross, 1930; Storer, 1944)
Details on the parental investment of this species are scant. However, if like other chipmunks, males play no significant role in parental care. Females give birth to their young in underground burrows, but later move their family to a nest in a tree stump or in a tree (Broadbooks, 1999). The female provides her young with protection and with nourishment until the young are weaned. The age of independence is not known with certainty, but young probably leave their mother's nest before hibernation. (Broadbooks, 1999; Nowak, 1999)
Longevity has not been reported for T. quadrimaculatus. However, most chipmunks do not live more than a few years, and it is likely that this holds for this species as well. Tamias ruficaudus is reported to have lived 8 years in the wild, although less than 10 percent of individuals in this species lived longer than 5 years. (Nowak, 1999)
Tamias quadrimaculatus is diurnal and hibernates from the end of October until March. It may be active at any time if conditions are favorable. Members of this species store fat and use food from underground caches as principal energy source during the winter months. Males tend to emerge from hibernation earlier than females. After reproduction, their coats molt into bright summer pelage, then in autumn molt again into winter pelage.
Dens may be made either in the ground or in trees. Hibernation probably occurs in burrows, but females have been found with their offspring in tree nests. Since births generally occur underground, it is likely that the female moves her family into the trees sometime after birth.
Tamias quadrimaculatus is most active on the forest floor. When alarmed, this species hides in dense brush or hollow logs rather than in trees.
During breeding season, most males have cuts on their faces and bodies, indicating that there may be competition between males for mates. Females usually maintain a separate home range territory, most likely by force. (Broadbooks, 1999; Johnson, 1943; Nowak, 1999; Storer, 1944; Tevis, 1955)
The size of home ranges in this species has not been reported. However, in other members of the genus Tamias, home ranes are generally no greater than 1 hectare. This species is probably similar. (Nowak, 1999)
Data on the communication patterns of this species were not available. However, most chipmunks use a variety of signals in their communication, and it is likely that T. quadrimaculatus is similar to other members of the genus.
Other chipmunks have vocalizations of various types. They use body postures and tail movements in their communication. Tactile communication may occur between rivals, mates, and mothers and their offspring. The role of chemicals in communication has not been described. (Nowak, 1999)
Tamias quadrimaculatus is an omnivore that feeds mainly on fungi, seeds, berries and other fruits, conifer cones, and insects. Individuals feeding on fungi were shown to be fatter than those that did not have access to fungi. Long-eared chipmunks forage on the ground, in shrubs, logs, stumps, snags, and trees, and store seeds that they gather in underground caches for eating during winter hibernation. (Harris, 2005; Harris, 2005; Harris, 2005; Nowak, 1999)
Tamias quadrimaculatus plays an important role in seedling establishment. Seeds stored in caches are often forgotten and will later sprout, thus aiding reforestation. Interestingly, T. quadrimaculatus may also play a role in preventing the reseeding of forests. After fires, these chipmunks may prevent reetablishment of trees through their foraging behaviors.
Tamias quadrimaculatus plays a role in maintaining symbiotic mycorrhizal associations with trees. By consuming fungi, they help in the dispersal of spores of the subterranean sporocarps. (Clawson, et al., 1994)
These chipmunks have a very limited distribution, and are unlikely to have extensive contact with humans. However, there may be some indirect benefit from these animals through their role in helping disperse seeds and thereby reestablish forests.
There are no reported negative effects of these animals on humans.
These animals are not listed as endangered. However, because they have such a limited range, it is important to protect their habitat to ensure that this species continues into the future.
Crystal Neligh (author), California State Polytechnic University, Pomona, Matthew Johnson (author), California State University, Sacramento, John Demboski (editor, instructor), California State Polytechnic University, Pomona.
Nancy Shefferly (editor), Animal Diversity Web.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
uses sound to communicate
Referring to an animal that lives in trees; tree-climbing.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.
uses smells or other chemicals to communicate
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
union of egg and spermatozoan
forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
an animal that mainly eats all kinds of things, including plants and animals
scrub forests develop in areas that experience dry seasons.
breeding is confined to a particular season
remains in the same area
reproduction that includes combining the genetic contribution of two individuals, a male and a female
places a food item in a special place to be eaten later. Also called "hoarding"
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
Living on the ground.
defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement
uses sight to communicate
reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.
Black, C. 1972. Holaretic evolution and dispersal of squirrels. Evolution Biology, 6: 305-322.
Broadbooks, H. 1999. Long-eared chipmunk| Tamias quadrimaculatus . Pp. 375-376 in D Wilson, S Ruff, eds. The Smithsonian Book of North American Mammals. Washington and London: The Smithsonian Institution Press in Association with the American Society of Mammalogists.
Clawson, R., J. Clawson, T. Best. 1994. Tamias quadrimaculatus. Mammalian Species, 469: 1-6.
Gray, J. 1867. Synopsis of the species of burrowing squirrels in the British Museum. Annals and Magazine of Natural History, 20: 434-436.
Harris, J. 2005. "California Wildlife Habitat Relationship System" (On-line). Accessed November 13, 2005 at http://www.dfg.ca.gov/whdab/html/cwhr.html.
Johnson, D. 1943. Systematic review of the chipmunks of California. Univiersity of California Publication in Zoology, 48: 63-147.
Levenson, H. 1990. Sexual size dimorphism in chipmunks. Journal of Mammology, 71: 161-170.
Nowak, R. 1999. Walker's Mammals of the World, Sixth Edition. Baltimore and London: The Johns Hopkins University Press.
Ross, R. 1930. California Sciuridae in captivity. Journal of Mammology, 11: 76-78.
Storer, E. 1944. Some rodent populations in the Sierra Nevada of California. Ecological Monographs, 14: 165-192.
Tevis, L. 1955. Observations on chipmunks and mantled squirrels in northeastern California. The American Midland Naturalist, 5: 612-631.
White, J. 1953. The baculum in the chipmunks of western North America. University of Kansas Publications, 5: 612-631.