Sonoma chipmunk

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Sonoma chipmunk
Sonoma chipmunk at Samuel P. Taylor State Park.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Sciuridae
Genus: Neotamias
Species:
N. sonomae
Binomial name
Neotamias sonomae
(Grinnell, 1915)
Tamias sonomae distribution map.png
Distribution of Neotamias sonomae
Synonyms
  • Tamias sonomae (Grinnell, 1915)
  • Eutamias sonomae Grinnell, 1915
Sonoma chipmunk, juvenile (left) and adult (right) Tamias sonomae at Samuel P. Taylor State Park.jpg
Sonoma chipmunk, juvenile (left) and adult (right)

The Sonoma chipmunk (Neotamias sonomae) is a species of rodent in the squirrel family Sciuridae. It is endemic to northwestern California in the United States. [1] Members of Neotamias are characterized by having two premolars. [2] N. sonomae has two subspecies: N. s. alleni and N. s. sonomae. [3]

Distribution

The Sonoma chipmunk is only found in California, north of the San Francisco Bay. Most of its range is within Sonoma and Marin counties. [3]

Habitat

Sonoma chipmunks are found in areas of forest or chaparral. They can be found in forests of sticky laurel, Ponderosa pine, Douglas fir, spruce, redwood, and black oak. They are more often than not associated with coniferous forests. The chaparral that Sonoma chipmunks inhabit is characterized by sagebrush plains. [2] Sonoma chipmunks are found in elevations from 0 to 1800 m. [3] These chipmunks typically live on the ground and make burrows in the ground, but they can climb and may make nests in trees. [2]

Physical characteristics

Body

The Sonoma chipmunk has a total body length (including tail) ranging 220–264 mm (8.7–10.4 in). Tail length ranges 100–126 mm (3.9–5.0 in), hind foot (pes) length is 34–39 mm (1.3–1.5 in), and ear flap (pinna) length is 15–19 mm (0.59–0.75 in). [3] The Sonoma chipmunk weighs 25–125 grams (0.88–4.41 oz), and thus is a small mammal in size.

Color

These chipmunks have five black/brown stripes running the length of their body with white stripes in between. [2] The rest of the dorsal and ventral parts of the body range from tawny to cinnamon to gray. The tail is edged in white. The belly is grayish white. Sonoma chipmunks have two molts per year, having a summer and winter pelage. The winter pelage is generally slightly darker and duller than the summer pelage. N. s. alleni is smaller and darker than N. s. sonomae. There is no distinct sexual dimorphism. [3]

Gender differences

Both males and females share similar external features, exhibiting no apparent sexual dimorphism. These chipmunks are characterized by five black longitudinal back stripes separated by four dull gray or brownish stripes. [4] Unique to the Sonoma chipmunk, these back stripes aren't clearly demarcated, which aids in its camouflage within the chaparral habitat. The upper parts of the chipmunk display a reddish-brown hue, except for a black patch behind each eye and whitish stripes beside them. The sides are rusty-colored, while the underside is creamy white. Their bushy tail mirrors the body's coloration. The fur is soft, dense, and becomes slightly woolly during winter. Seasonal changes lead to two molts each year, with the summer fur being brighter than the winter one.[ citation needed ]

Subspecies

There are many subspecies of the Sonoma chipmunk. T. s. alleni and T. s. sonomae are some , with the former being slightly smaller and darker in fur color. Structurally, the chipmunk's skull is long and narrow, with distinct features like a deep rostrum, separated nasals, and a long, inflated braincase. It has a total of 22 teeth, with specific characteristics in its upper incisors and cheek teeth. The baculum, or penile bone, has a thin shaft and features a low keel, with a specific angle and design at the tip.

Additionally, the yellow-pine chipmunk and the Townsend's chipmunk are also recognized as subspecies. The yellow-pine chipmunk will be smaller and less reddish than N. onomae and will lack a white-edged tail. N. sonomae can be distinguished from the Townsend's chipmunk by having longer ears, tail, and legs, being paler, and having a bushier tail. [3]

Structure

The skulls of Sonoma chipmunks have the distinct post orbital process that is found in all sciurids. [2] The skull has a deep rostrum, a long braincase, and small incisive foramina. [3] The incisors are curved and pincer-like, and the molars are simple and cuspidate. The dental formula for N. sonomae is 1.0.2.31.0.1.3 × 2 = 22. [2]

Diet and behavior

Sonoma chipmunks typically forage on the ground or climb along small branches in brush. [3] They eat seeds, fruits, herbs, buds of woody plants, as well as insects and bird eggs, and primarily consume the reproductive products of shrubs. [5] Food is collected in their cheek pouches and stored in their burrows. [2] These chipmunks will find elevated places to eat and rest so they can watch the surrounding area for predators. Sonoma chipmunks have high-pitched, bird-like alarm calls that are distinct from other chipmunks and are emitted in response to potential threats. Females are usually the ones to make alarm calls. These alarm calls likely evolved due to kin selection, as the chipmunks nearby that hear the alarm calls are typically related to the individual making the alarm call. When an alarm call is heard, the chipmunk will quickly move along a direct path to a covered, protected area and become still. [3] These chipmunks undergo torpor in winter but arise periodically to eat from their food cache, since they do not accumulate fat stores. [2] Sonoma Chipmunks many also hibernate in winter, and they don't have migratory patterns. They are also diurnal animals, meaning they are active during the day time and inactive or have periods of rest during the night time.[ citation needed ]

Predator/competition

Sonoma chipmunks may be preyed upon by long-tailed weasels, bobcats, badgers, gray foxes, and various hawks and owls. They may also compete for resources and food against T. amoenus, T. ochrogenys, and T. senex chipmunks, and mule deer, black bears, wild pigs, turkeys, California quail, and various other rodents, birds, and insects.[ citation needed ]

Diseases

Sonoma Chipmunks from the northern coastal region of California are more susceptible to pathogen infection than those from the Sierra Nevada, as indicated in earlier regional studies on vector-borne zoonotic diseases in California chipmunks. Sonoma chipmunks are often exposed to agents of Lyme disease and anaplasmosis in regions where humans also have recorded infections. Chipmunks were also identified as hosts of various Rickettsia spp. and plague, with certain variations observed based on geographical regions and chipmunk species. One particular scientific journal noted that between 2005 and 2015, 709 chipmunks across nine species in California were tested for various vector-borne zoonotic pathogens; the results revealed varying levels of exposure to and infection by pathogens like Borrelia spp., Anaplasma phagocytophilum, and SFG Rickettsia spp. [6] across different regions and species, suggesting certain chipmunk populations and areas are more susceptible to certain diseases. This emphasizes the ecological significance of chipmunks in the maintenance and transmission of various diseases in California and highlights the need for further research to elucidate the specific roles of different chipmunk species in disease ecology.

Reproduction

Sonoma chipmunks breed once per year, anywhere from February to July, but most often in April to May. There is occasionally a second breeding season for females if their first litter is lost. Gestation lasts for 28–36 days. [2] 3–5 young are produced per litter, but it is usually 4.

The babies are weaned after approximately 3 weeks, and the mother stops associating with them after they are weaned. The juveniles stay together for a few more weeks after their mother leaves. After this, the juveniles disperse. [3] Males disperse in a larger range than females. Juveniles reach sexual maturity within one year, and the lifespan of these chipmunks is around 64 months. [2] Females have higher survivorship and live longer than males.

There is a 1:1 ratio of males to females when the juveniles disperse in spring. By the end of the year, this ratio favors females due to the higher risk of mortality in the wider ranging males. However, the ratio again becomes 1:1 by the fall of their second year of life, as first-year adult females have a high risk of mortality during their first breeding attempt. Over time, the ratio will once again favor females. [3]

Typically, females raise a litter by themselves. Through their offspring's early age, the females stay with their young and suckle them for at least 3 weeks after they emerge. Especially during the night, females protect their litters from predators and traps. In addition, depicted by an experiment and extrapolated to real life scenarios, adult female chipmunks gave alarms (emergency warnings) significantly more often than adult males, which speaks to their protective and more alerted nature. Another statistics show that lactating first year females gave alarms less often than did older lactating females, meaning that as female Sonoma chipmunks age, they become more alert due to their protectiveness over their offsprings. [7]

Deviation from other chipmunks

Sonoma chipmunks's reproduction rate is slightly higher compared to other similar chipmunks like yellow-pine chipmunks. [8] Sonoma chipmunks tend to produce 3–5 per litter while yellow-pine chipmunks produce 2 litters per year. Consequently, the population structure is more consistently distributed across the age groups for Sonoma chipmunks, whereas for yellow-pine chipmunks, adults form the majority of the population.[ citation needed ]

Related Research Articles

<span class="mw-page-title-main">Chipmunk</span> Tribe of mammals (rodent (marmot))

Chipmunks are small, striped rodents of Sciuridae, the squirrel family; specifically, they are ground squirrels (Marmotini). Chipmunks are found in North America, with the exception of the Siberian chipmunk which is found primarily in Asia.

<span class="mw-page-title-main">Least chipmunk</span> Species of rodent

The least chipmunk is the smallest species of chipmunk and the most widespread in North America.

<span class="mw-page-title-main">Siberian chipmunk</span> Species of mammal

The Siberian chipmunk, also called common chipmunk, is native to northern Asia from central Russia to China, Korea, and Hokkaidō in northern Japan. It was imported from South Korea and introduced in Europe as a pet in the 1960s.

<span class="mw-page-title-main">Hopi chipmunk</span> Species of rodent

The Hopi chipmunk, Neotamias rufus, is a small chipmunk found in Colorado, Utah and Arizona in the southwestern United States. It was previously grouped with the Colorado chipmunk, T. quadrivittatus. This species is listed as "Least Concern" on the IUCN Red List as it is common, widespread, and without any major threats. It was last evaluated in 2016.

<span class="mw-page-title-main">Cliff chipmunk</span> Species of rodent

The cliff chipmunk is a small, bushy-tailed squirrel that typically lives along cliff walls or boulder fields bordering Pinyon-juniper woodlands in the Western United States and Mexico. Cliff chipmunks are very agile, and can often be seen scaling steep cliff walls. Cliff chipmunks do not amass body fat as the more common ground squirrel does. They create caches of food which they frequent during the cold winter months.

<span class="mw-page-title-main">Alpine chipmunk</span> Species of rodent

The alpine chipmunk is a species of chipmunk native to the high elevations of the Sierra Nevada of California.

<span class="mw-page-title-main">Yellow-pine chipmunk</span> Species of rodent

The yellow-pine chipmunk is a species of order Rodentia in the family Sciuridae. It is found in parts of Canada and the United States.

<span class="mw-page-title-main">Gray-footed chipmunk</span> Species of rodent in the family Sciuridae

The gray-footed chipmunk is a terrestrial and forest-dwelling species of chipmunk and rodent in the family Sciuridae. It is endemic to New Mexico and in the Sierra Diablo and Guadalupe Mountains in the Trans-Pecos region of Texas in the United States. Its natural habitat are coniferous forests. First discovered in 1902, they are distinguished by the unique gray dorsal colouring on the hind feet, hence the common name. They demonstrate sexual dimorphism, and the female is larger than the male.

<span class="mw-page-title-main">Gray-collared chipmunk</span> Species of rodent

The gray-collared chipmunk is a species of rodent in the family Sciuridae. It is endemic to Arizona and New Mexico in the United States.

<span class="mw-page-title-main">Yellow-cheeked chipmunk</span> Species of rodent

The yellow-cheeked chipmunk, also known as the redwood chipmunk, is a species of rodent in the squirrel family, Sciuridae. It is endemic to areas near the coast of northern California in the United States where it inhabits coastal coniferous forest.

<span class="mw-page-title-main">Palmer's chipmunk</span> Species of rodent

Palmer's chipmunk is a species of rodent in the family Sciuridae, endemic to Nevada. Its natural habitat is temperate forests. It is threatened by habitat loss. It is named after Theodore Sherman Palmer, an American botanist and zoologist.

<span class="mw-page-title-main">Colorado chipmunk</span> Species of rodent

The Colorado chipmunk is a species of chipmunk in the squirrel family Sciuridae. It is endemic to Colorado, Utah, Arizona and New Mexico in the United States.

<span class="mw-page-title-main">Red-tailed chipmunk</span> Species of rodent

The red-tailed chipmunk is a species of rodent in the family Sciuridae. It is found in Alberta and British Columbia in Canada and Montana, Idaho and Washington in the United States.

<span class="mw-page-title-main">Allen's chipmunk</span> Species of rodent

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The Siskiyou chipmunk is a species of rodent in the family Sciuridae. It is endemic to northern California and central Oregon in the United States.

<span class="mw-page-title-main">Lodgepole chipmunk</span> Species of rodent

The Lodgepole chipmunk is a species of rodent in the family Sciuridae. It is found in the U.S. state of California at elevations from 1,500 to 3,000 metres. The Lodgepole chipmunk has a variety of common names including: Tahoe chipmunk, Sequoia chipmunk, Mt. Pinos chipmunk, and San Bernardino chipmunk.

<span class="mw-page-title-main">Uinta chipmunk</span> Species of rodent

The Uinta chipmunk or hidden forest chipmunk, is a species of chipmunk in the family Sciuridae. It is endemic to the United States. Formerly known as Tamias umbrinus, phylogenetic studies have shown it to be sufficiently distinct from the eastern chipmunk as to be placed in a separate genus, Neotamias. The same studies have also suggested that Palmer's chipmunk may actually be a subspecies of Uinta chipmunk, although the two are still generally regarded as separate species.

<i>Neotamias</i> Genus of rodents

Neotamias is a genus of chipmunks within the tribe Marmotini of the squirrel family. It contains 23 species, which mostly occur in western North America. Along with Eutamias, this genus is often considered a subgenus of Tamias.

<span class="mw-page-title-main">Ezo chipmunk</span> Subspecies of mammal

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References

  1. 1 2 Cassola, F. (2017) [errata version of 2016 assessment]. "Neotamias sonomae". IUCN Red List of Threatened Species . 2016: e.T42581A115191316. doi: 10.2305/IUCN.UK.2016-3.RLTS.T42581A22268516.en . Retrieved 11 November 2022.
  2. 1 2 3 4 5 6 7 8 9 10 Nowalk, R.M. (1991). Walker's Mammals of the World. Baltimore: Johns Hopkins University Press. pp. 1246–1250. ISBN   0801857899.
  3. 1 2 3 4 5 6 7 8 9 10 11 Best, Troy L. (1993-11-15). "Tamias sonomae". Mammalian Species (444): 1–5. doi:10.2307/3504266. ISSN   0076-3519. JSTOR   3504266.
  4. ↑ Best, Troy L. (1993-11-15). "Tamias sonomae". Mammalian Species (444): 1–5. doi:10.2307/3504266. ISSN   0076-3519. JSTOR   3504266.
  5. ↑ "Review for "Bibliometric analysis of the Doctor of Nursing Practice dissertations in the ProQuest Dissertations and Theses database"". 2021-05-21. doi:10.1111/jan.15006/v1/review3.{{cite journal}}: Cite journal requires |journal= (help)
  6. ↑ Straub, Mary H.; Roy, Austin N.; Martin, Amanda; Sholty, Kathleen E.; Stephenson, Nicole; Foley, Janet E. (2017-12-12). "Distribution and prevalence of vector-borne diseases in California chipmunks (Tamias spp.)". PLOS ONE. 12 (12): e0189352. Bibcode:2017PLoSO..1289352S. doi: 10.1371/journal.pone.0189352 . ISSN   1932-6203. PMC   5726628 . PMID   29232397.
  7. ↑ Smith, S. F. (1978-11-24). "Alarm Calls, Their Origin and Use in Eutamias sonomae". Journal of Mammalogy. 59 (4): 888–893. doi:10.2307/1380172. ISSN   1545-1542.
  8. ↑ Broadbooks, Harold E. (April 1970). "Populations of the Yellow-Pine Chipmunk, Eutamias amoenus". American Midland Naturalist. 83 (2): 472–488. doi:10.2307/2423957. JSTOR   2423957.
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