Tamias merriami
Merriam's chipmunk

Merriam's chipmunks (Tamias merriami) are distributed throughout central and southern California. In particular, they occurs below 2700 m in the South Coast, Transverse, Peninsular, and Southern Sierra Nevada ranges. (Harvey and Polite, 1999)

Merriam's chipmunks occur in habitats that have trees, shrubs, logs, stumps, snags, rocks, and litter. An important factor is understory brush that they use for foraging. These animals inhabit chaparral, oak and pine forests, thickets by streams, and are often found around rock outcroppings. They also inhibit a wide variety of habitats if there are no competing species, such as black bears, mule deer, wild pigs, deer mice, kangaroo rats, and woodrats. (Best and Granai, 1994)

Merriam's chipmunks are grayish-brown, with dark stripes of equal width on the dorsal area. The stripes are typically gray or brown, rarely black. The belly and cheeks are white. The tail is long and bushy, and is usually edged with dull white. The average length of the head and body is 134.6 mm. Length of tail is 109.5 mm. The average mass is 71.8 g from males and 77.8 g for females. Hind foot length averages 35.8 mm. The length of the rostrum is 14.1 mm. Braincase length is 24.2 mm. The length of the maxillary tooth-row is 5.9 mm. The length of nasals is 12.1 mm for males and 12.6 mm for females. Width of nasals is 2.5 mm. The depth of the cranium is 14.7 mm. The dental formula for Merriam's chipmunks is i 1/1, c 0/0, p 2/1, m 3/3 = 22. (Best and Granai, 1994)

Merriam's chipmunk seems to follow Gloger's rule. The darker populations occur in the humid coastal areas of the redwood forests from San Francisco Bay southward. The palest populations are in single-leaf pinyon forests in Walker Pass in the semi-arid Kern Basin and on the eastern slope of the Sierra Nevada. (Best and Granai, 1994)

Merriam's chipmunks can live up to 5 years in the wild. (Best and Granai, 1994)

Merriams's chipmunks are diurnal and most do not hibernate. At high elevations, some may hibernate to avoid the snow and cold. During the fall, they collect and cache food, choose a shelter spot, and feed to increase thier mass. During the winter, males form groups and display for precourtsip. Mating continues through spring. In the summer, adults molt and gain weight. (Best and Granai, 1994)

Merriam's chipmunks use woodpecker cavities, natural cavities, and burrows from pocket gophers for night shelter. Most night shelters face east. They usually do not forage more than 300 meters from their night shelter. Merriam's chipmunks travel along tree branches and logs. The trails are communal and are used generation after generation. (Best and Granai, 1994)

Home Range

Most members of this species forage within an range of 300 meters of their night shelter. (Best and Granai, 1994)

Merriam's chipmunks use four main calls. The "chuck" has a narrow frequency range and causes others to be quiet and to hide. The "chip" has a wide frequency range and can be located without difficulty. It is usually made by a chipmunk by its den and incites others to call. The "trill" is usually intertwined with the chip and is used for alarm. Lastly, the "chipper" is a series of disorderly notes made from an individual who has been scared and is going for cover. (Best and Granai, 1994)

Scent communication is also important. These animals have functional scent glands by the age of 4 weeks. The vulva emits an odor important for reproduction. Scent marking is common. (Best and Granai, 1994)

In addition, there is tactile communication during mating and between a mother and her offspring. Because the species is diurnal and social, it is likely that visual signals, such as body postures, are also used.

Evidence has shown that Merriam's chipmunks consume more than seventy species of plants. Acorns are a major food source throughout the year. These animals will also consume insects, lizards, muscle tissue of sparrows, seeds found in the feces of goldfinches, and embyronic membrane from eff shells of California quail. (Best and Granai, 1994)

They have two daily forages and a resting period during midday. The first foraging period is in the morning and lasts about three and half hours of constant activity. The second foraging is more relaxed and ends when they goes into their shelter for the night. Searching for food to store in caches takes up most of its active time. Foraging areas are jointly used and there is seldom conflict over food. These animals search for food in forest understory and in trees.

Using their cheekpouches they carry food to another site where they remove the husk and then eat the seeds. If they cache an acorn, they do not remove the husk. They make a pit about 3.8 cm deep and deposit a single acorn. They cover the hole with leaf litter and soil. Merriam's chipmunks also store food in dead logs, between limbs, and branches of trees. When storing food, females generally cache acorns further apart than males. (Best and Granai, 1994)

Merriam's chipmunks are prey to several species. These include long-tailed weasels (Mustela frenata), bobcats (Lynx rufus), coyotes (Canis latrans), gray foxes (Urocyon cinereoargenteus), sharp-shinned hawks (Accipiter striatus), badgers (Taxeda taxus), Coopers's hawk (Accipiter cooperii), great horned owls (Bubo virginiana), Pacific rattlesnakes (Crotalus viridis), garter snakes (Thamnophis), gopher snakes (Pituophis melanoleucus), and domestic cats (Felis domesticus). (Best and Granai, 1994; Harvey and Polite, 1999)

Merriam's chipmunks are prey items for a wide variety of carnivores. They also cache acorns, which may help disperse oak trees. (Best and Granai, 1994)

This species has no reported negative economic impact on humans.

There is no specific information available on this topic. However, these animals are cute and can be entertaining to people who view them scurrying about. Also, they serve as food for predators which people also enjoy watching. Although this does not exactly make Merriam's chipmunks a source of ecotourism, it should be noted that even without substanitial economic impact on humans, there is some human benefit from this species.

Merriam's chipmunks are not listed by CITES or IUCN. (Best and Granai, 1994; Harvey and Polite, 1999)