Botta's pocket gopher

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Botta's pocket gopher
Botta's Pocket Gopher (Thomomys bottae).jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Geomyidae
Genus: Thomomys
Species:
T. bottae
Binomial name
Thomomys bottae
(Eydoux & Gervais, 1836)
Thomomys bottae distribution map.svg
Botta's pocket gopher range

Botta's pocket gopher (Thomomys bottae) is a pocket gopher native to western North America. It is also known in some areas as valley pocket gopher, particularly in California. Both the specific and common names of this species honor Paul-Émile Botta, a naturalist and archaeologist who collected mammals in California in 1827 and 1828.

Description

Botta's pocket gopher skull and teeth from Elliot 1901 Thomomys bottae skull from Elliot 1901.jpg
Botta's pocket gopher skull and teeth from Elliot 1901

Botta's pocket gopher is a medium-sized gopher, with adults reaching a length of 18 to 27 cm (7.1 to 10.6 in), including a tail of 5 to 6 cm (2.0 to 2.4 in). The overall dental formula is 10131013. [2] Males are larger, with a weight of 160–250 g (5.6–8.8 oz), compared with 120–200 g (4.2–7.1 oz) in the females. [3] Male pocket gophers are widely believed to continue growing throughout their life. However, size variation would indicate that some males are predisposed to be larger than others, and the largest male may not be the oldest. [4] Coloration is highly variable, and has been used to help distinguish some of the many subspecies; it may also change over the course of a year as the animals molt. [5] Both albino and melanistic individuals have also been reported. However, Botta's gopher generally lacks the black stripe down the middle of the back found in the closely related southern pocket gopher, a feature that may be used to tell the two species apart where they live in the same area. [2]

Distribution

Botta's pocket gophers are found from California east to Texas, and from Utah and southern Colorado south to Mexico. Within this geographical area, they inhabit a range of habitats, including woodlands, chaparral, scrubland, and agricultural land, being limited only by rocky terrain, barren deserts, and major rivers. [2] They are found at elevations up to at least 4,200 metres (13,800 ft). [6] Skeletal remains of Botta's pocket gophers, dating back 31,000 years, have been identified from Oklahoma. [7]

Around 195 subspecies have been described, mostly on the basis of geographical distribution. Some of these have previously been described as distinct species in their own right. The distribution of the type localities of these subspecies is as follows: [2]

Ecology

Botta's pocket gopher is strictly herbivorous, feeding on a variety of plant matter. Shoots and grasses are particularly important, supplemented by roots, tubers, and bulbs during the winter. [2] An individual often pulls plants into the ground by the roots to consume them in the safety of its burrow, where it spends 90% of its life.

The metabolic rate, consumption rate and amount of energy assimilated for non-reproductive adult gophers is consistent through winter, spring, summer and fall. [8] The average adult Botta's pocket gopher has a body temperature of 36 °C (97 °F). Burrowing can be extremely energetically demanding requiring between 360 and 3,400 times as much energy as moving across the surface, depending on soil density. Due to the high cost of burrowing, Botta's pocket gopher is good at conserving energy by having a low basal metabolic rate and thermal conductance. [9]

The main predators of this species include American badgers, coyotes, long-tailed weasels, and snakes, but other predators include skunks, owls, bobcats, and hawks. This species is considered a pest in urban and agricultural areas due to its burrowing habit and its predilection for alfalfa; however, it is also considered beneficial as its burrows are a key source of aeration for soils in the region.

Digging by Botta's pocket gophers is estimated to aerate the soil to a depth of about 20 cm (7.9 in), [2] and to be responsible for the creation of Mima mounds up to 2 m (6 ft 7 in) in height. Populations of the species have been estimated to mine as much as 28 t (28 long tons; 31 short tons) of soil per hectare per year, much of which is moved below ground, rather than being pushed up into the mounds. [10] The species also has been associated with the deaths of aspen in Arizona [11] and creates patches of bare ground that may limit the establishment of new seedlings. [12]

Behavior

An individual emerging from a burrow in southern California ThomomysBottae 9788.JPG
An individual emerging from a burrow in southern California

Botta's pocket gopher is highly adaptable, burrowing into a very diverse array of soils from loose sands to tightly packed clays, and from arid deserts to high altitude meadows. They are able to tolerate such a wide range of soils in part because they dig primarily with their teeth, which are larger and with a thicker layer of enamel than in claw-digging gophers. In comparison, gophers digging with their claws are generally only able to dig in softer soils, because their claws wear down more quickly than teeth do in harder materials. [13]

Botta's pocket gophers are active for a total of about nine hours each day, spending most of their time feeding in their burrows, but are not restricted to either daylight or night time. [14] They make little sound, although they do communicate by making clicking noises, soft hisses, and squeaks. [2]

Their burrows include multiple deep chambers for nesting, food storage, and defecation, that can be as much as 1.6 m (5 ft 3 in) below ground. A series of tunnels close to the surface is used for feeding on plant roots, with shorter side tunnels for disposal of excavated soil. On the surface, the burrows are marked by fan-shaped mounds of excavated soil, with the actual entrance usually kept filled in for protection. [2] Population densities between 10 and 62 per acre have been reported. [2]

Aboveground traces of these burrows are sometimes called "gopher eskers".[ citation needed ]

Outside of the breeding season, each burrow is inhabited by a single adult, with any young leaving once they are weaned. Male burrows extend over a mean area of 474 m2 (5,100 sq ft), and those of females 286 m2 (3,080 sq ft), [15] but the gophers aggressively defend [16] a larger exclusive area, of 810 m2 (8,700 sq ft) for males and 390 m2 (4,200 sq ft) for females, around the burrow entrance. [2]

Reproduction

In areas with sufficient food, such as agricultural land, breeding can occur year-round, with up to four litters being born each year. In the north, and other, less hospitable, environments, it occurs only during the spring. The local habitat also affects the age at which females begin breeding, with nearly half doing so in their first year in agricultural land, but none at all in desert scrub. [2] Females can breed within the same season they are born, or within three months of their birth. Males tend not to breed until the season after they are born, or at least until they are 6–8 months old. [4]

Gestation lasts 18 days, and results in the birth of a litter of up to 12 pups, although three or four are more typical. The young are born hairless and blind, and measure about 5 cm (2.0 in) in length. [2] The first, silky coat of fur is replaced by a coarser coat of grey hair as the pups age, before the full adult coat develops. [5]

Botta's pocket gophers are capable of breeding with southern pocket gophers, and until the 1980s, were often considered to belong to the same species. However, male hybrids are sterile, and females have greatly reduced fertility, so rarely have offspring of their own. [17] Hybridization with Townsend's pocket gopher has also been reported, and it, too, appears not to extend much beyond the first generation. [18]

Related Research Articles

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<span class="mw-page-title-main">Northern pocket gopher</span> Species of mammal

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<span class="mw-page-title-main">Smooth-toothed pocket gopher</span> Genus of mammals

The smooth-toothed pocket gophers, genus Thomomys, are so called because they are among the only pocket gophers without grooves on their incisors. They are also called the western pocket gophers because they are distributed in western North America. They are considered distinct enough from other pocket gophers to be recognized as a separate subfamily or tribe.

<span class="mw-page-title-main">Ord's kangaroo rat</span> Species of rodent

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<span class="mw-page-title-main">Southeastern pocket gopher</span> Species of rodent

The southeastern pocket gopher is a species of pocket gopher that is native to the southeastern United States. It occurs in Alabama, Georgia, and Florida, where it is the only pocket gopher.

<span class="mw-page-title-main">California vole</span> Species of rodent

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<span class="mw-page-title-main">Heermann's kangaroo rat</span> Species of rodent

Heermann's kangaroo rat is a species of rodent in the family Heteromyidae. Their long smooth pelage resembles typical kangaroo rats, with their dorsal side showing a mixed range of olive, black and orange colors. There are 9 distinguished sub-species of Dipodomys heermanni: D.h. arenae, D.h. berkeleyensis, D.h. dixoni, D.h. goldmani, D.h. heermanni, D.h. jolonensis, D.h.morroensis, D.h. swarthi, and D.h. tularensis. The dental formula of Dipodomys heermanni is 1.0.1.31.0.1.3 × 2 = 20.

<span class="mw-page-title-main">Desert pocket gopher</span> Species of rodent

The desert pocket gopher is a species of rodent in the family Geomyidae. It is found in the state of Chihuahua in Mexico and in Texas and New Mexico in the United States.

<span class="mw-page-title-main">Plains pocket gopher</span> Species of rodent

The plains pocket gopher is one of 35 species of pocket gophers, so named in reference to their externally located, fur-lined cheek pouches. They are burrowing animals, found in grasslands and agricultural land across the Great Plains of North America, from Manitoba to Texas. Pocket gophers are the most highly fossorial rodents found in North America.

Buller's pocket gopher is a species of gopher that is endemic to Mexico.

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The Great Basin pocket mouse is a species of rodent in the family Heteromyidae. It is found in British Columbia in Canada and the western United States.

<span class="mw-page-title-main">Columbian ground squirrel</span> Species of rodent

The Columbian ground squirrel is a species of rodent common in certain regions of Canada and the northwestern United States. It is the second largest member of the genus Urocitellus, which is part of the tribe Marmotini, along with marmots, chipmunks, prairie dogs, and other holarctic ground squirrels. They are stout, with short dense fur, which is characteristically tawny across the bridge of the nose. Social encounters sometimes are initiated with kissing behavior and the most common activity above ground is standing at attention. Residing in mountainous terrain and high plains in northern latitudes, they hibernate for 8 to 9 months of the year in burrows, which may be used for many years. They are emaciated when emerging in the spring. The Columbian ground squirrel came to the attention of the scientific community through writings produced by Lewis and Clark, while 21st century molecular genetics has more finely illuminated its ties with other close relatives.

<span class="mw-page-title-main">Camas pocket gopher</span> Small species of burrowing rodent from Oregon

The camas pocket gopher, also known as the camas rat or Willamette Valley gopher, is a rodent, the largest member in the genus Thomomys, of the family Geomyidae. First described in 1829, it is endemic to the Willamette Valley of northwestern Oregon in the United States. The herbivorous gopher forages for vegetable and plant matter, which it collects in large, fur-lined, external cheek pouches. Surplus food is hoarded in an extensive system of tunnels. The dull-brown-to-lead-gray coat changes color and texture over the year. The mammal's characteristically large, protuberant incisors are well adapted for use in tunnel construction, particularly in the hard clay soils of the Willamette Valley. The gophers make chattering sounds with their teeth; males and females make purring sounds when they are together, and the young make twittering sounds. Born toothless, blind and hairless, the young grow rapidly before being weaned at about six weeks of age.

<span class="mw-page-title-main">Wyoming pocket gopher</span> Species of mammal

The Wyoming pocket gopher is a species of gopher that is endemic to the United States. Between 1915 and 1979, it was generally considered to be a subspecies of the northern pocket gopher.

<span class="mw-page-title-main">Idaho pocket gopher</span> Species of rodent in the family Geomyidae

The Idaho pocket gopher is a species of rodent in the family Geomyidae. It is rather small, with a lightly built skull. Its fur color varies through the body and between individuals. Found in the western United States, it inhabits savannas, shrubland, and grasslands. Individuals live alone in burrows, staying active year-round. Many aspects of its behavior and biology are not well understood. The species is classified as being of least-concern by the International Union for the Conservation of Nature.

<span class="mw-page-title-main">Mountain pocket gopher</span> Species of mammal

The mountain pocket gopher is a species of rodent in the family Geomyidae. It is endemic to California and Nevada. The Sierra Nevada are part of its range.

<span class="mw-page-title-main">Townsend's pocket gopher</span> Species of pocket gopher endemic to the northwestern United States

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<span class="mw-page-title-main">Southern pocket gopher</span> Species of rodent in the family Geomyidae, found in Mexico and the United States

The southern pocket gopher is a species of rodent in the family Geomyidae. It is found in Mexico and the United States, usually in high altitude grassland and shrubland. It feeds on plant material and has an extensive burrow above which is a large heap of earth on the surface of the ground.

The Michoacan pocket gopher is a species of rodent in the family Geomyidae. It is monotypic within the genus Zygogeomys. It is endemic to Mexico where its natural habitat is temperate, high-altitude forests. Its numbers are declining and it is listed by the IUCN as "endangered".

References

  1. ↑ Lacher, T.; Timm, R. & Álvarez-Castañeda, S.T. (2017) [errata version of 2016 assessment]. "Thomomys bottae". IUCN Red List of Threatened Species . 2016: e.T21799A115163311. doi: 10.2305/IUCN.UK.2016-3.RLTS.T21799A22216368.en . Retrieved 15 December 2023.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 Jones, C.A. & Baxter, C.N. (2004). "Thomomys bottae". Mammalian Species (742): Number 742: pp. 1–14. doi: 10.1644/742 .
  3. ↑ "Thomomys bottae". Smithsonian Institution. Retrieved 2014-06-05.
  4. 1 2 Daly, Joanne C.; Patton, James L (May 1986). "Growth, Reproduction, and Sexual Dimorphism in Thomomys bottae Pocket Gophers". Journal of Mammalogy. 67 (2): 256–265. doi:10.2307/1380878. JSTOR   1380878.
  5. 1 2 Morejohn, G.V. & Howard, W.E. (1956). "Molt in the pocket gopher, Thomomys bottae". Journal of Mammalogy. 37 (2): 201–213. doi:10.2307/1376679. JSTOR   1376679.
  6. ↑ Bole B.P., jr. (1938). "Some altitude records for mammals in the Inyo-White Mountains of California". Journal of Mammalogy. 19 (2): 245–246. doi:10.2307/1374623. JSTOR   1374623.
  7. ↑ Dalquest, W.W.; et al. (1990). "Zoogeographic implications of Holocene mammal remains from ancient beaver ponds in Oklahoma and New Mexico". The Southwestern Naturalist. 35 (2): 105–110. doi:10.2307/3671529. JSTOR   3671529.
  8. ↑ Gettinger, Ronald D. (June 1984). "Energy and Water Metabolism of Free-Ranging Pocket Gophers, Thomomys Bottae". Ecology. 65 (3): 740–751. doi:10.2307/1938046. JSTOR   1938046.
  9. ↑ Vleck, David (April 1979). "The Energy Cost of Burrowing by the Pocket Gopher Thomomys bottae". Physiological and Biochemical Zoology. 52 (2): 122–136. doi:10.1086/physzool.52.2.30152558. S2CID   87133178.
  10. ↑ Cox, G.W. (1990). "Soil mining by pocket gophers along topographic gradients in a Mima moundfield". Ecology. 71 (3): 837–843. doi:10.2307/1937355. JSTOR   1937355.
  11. ↑ Cantor, L.F. & Whitham, T.G. (1989). "Importance of belowground herbivory: pocket gophers may limit aspen to rock outcrop refugia". Ecology. 70 (4): 962–970. doi:10.2307/1941363. JSTOR   1941363.
  12. ↑ Stromberg, J.C. & Patten, D.T. (1991). "Dynamics of the spruce-fir forests on the Pinaleno Mountains, Graham Co., Arizona". The Southwestern Naturalist. 36 (1): 37–48. doi:10.2307/3672114. JSTOR   3672114.
  13. ↑ Lessa, E.P. & Thaela C.S., jr. (1989). "A reassessment of morphological specializations for digging in pocket gophers". Journal of Mammalogy. 79 (4): 689–700. doi:10.2307/1381704. JSTOR   1381704.
  14. ↑ Gettinger, R.D. (1984). "A field study of activity patterns of Thomomys bottae". Journal of Mammalogy. 65 (1): 76–84. doi:10.2307/1381202. JSTOR   1381202.
  15. ↑ Bandoli, J.H. (1987). "Activity and plural occupancy of burrows in Botta's pocket gopher Thomomys bottae". American Midland Naturalist. 118 (1): 10–14. doi:10.2307/2425623. JSTOR   2425623.
  16. ↑ Baker, A.E.M. (1974). "Interspecific aggressive behavior of pocket gophers Thomomys bottae and T. talpoides (Geomyidae: Rodentia)". Ecology. 55 (3): 671–673. doi:10.2307/1935160. JSTOR   1935160.
  17. ↑ Patton, J.L. (1973). "An analysis of natural hybridization between the pocket gophers, Thomomys bottae and Thomomys umbrinus, in Arizona". Journal of Mammalogy. 54 (3): 561–584. doi:10.2307/1378959. JSTOR   1378959. PMID   4744930.
  18. ↑ Patton, J.L.; et al. (1984). "Genetics of hybridization between the pocket gophers, Thomomys bottae and Thomomys townsendii in northeastern California". Great Basin Naturalist. 44 (3): 431–440. JSTOR   41712092.
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