Smooth-toothed Pocket Gopher
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The smooth-toothed pocket gophers, genus ''Thomomys'', are so called because they are among the only
pocket gopher Pocket gophers, commonly referred to simply as gophers, are burrowing rodents of the family Geomyidae. The roughly 41 speciesSearch results for "Geomyidae" on thASM Mammal Diversity Database are all endemic to North and Central America. They are ...
s without grooves on their
incisor Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, whe ...
s. 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.


Natural history

''Thomomys'' gophers are highly
fossorial A fossorial () animal is one adapted to digging which lives primarily, but not solely, underground. Some examples are badgers, naked mole-rats, clams, meerkats, and mole salamanders, as well as many beetles, wasps, and bees. Prehistoric eviden ...
. They rely on their incisors for digging more than most other gophers. They feed on plants, largely from beneath the surface, but they do come above ground at night.
Root In vascular plants, the roots are the organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the sur ...
s, stems,
leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...
, and bulbs are eaten. When not directly in an agricultural field they are a benefit to humans by enriching soil and preventing runoff.


Species

Over one hundred subspecies have been described, but not all are currently recognized by modern authorities. Like many fossorial rodents, ''Thomomys'' shows a great deal of
allopatric Allopatric speciation () – also referred to as geographic speciation, vicariant speciation, or its earlier name the dumbbell model – is a mode of speciation that occurs when biological populations become geographically isolated from ...
variation. *''Thomomys''Search results for "''Thomomys''" on th
ASM Mammal Diversity Database
**Subgenus '' Megascapheus'' ***'' Thomomys atrovarius'' ***'' Thomomys bottae'' - Botta's pocket gopher ***''
Thomomys bulbivorus The camas pocket gopher (''Thomomys bulbivorus''), also known as the camas rat or Willamette Valley gopher, is a rodent, the largest member in the genus ''Thomomys'', of the family (biology), family Geomyidae. First described in :Animals descri ...
'' - Camas pocket gopher ***'' Thomomys nayarensis'' ***'' Thomomys sheldoni'' ***'' Thomomys townsendii'' - Townsend's pocket gopher ***'' Thomomys umbrinus'' - southern pocket gopher **Subgenus '' Thomomys'' ***'' Thomomys clusius'' - Wyoming pocket gopher ***'' Thomomys idahoensis'' - Idaho pocket gopher ***'' Thomomys mazama'' - Mazama pocket gopher (including the extinct subspecies ''
Thomomys mazama tacomensis The Tacoma pocket gopher (''Thomomys mazama tacomensis'') was a subspecies of the Mazama pocket gopher that was restricted to a few isolated populations in the southern Puget Sound area and on the Olympic Peninsula in Washington Washington commo ...
'' - Tacoma pocket gopher) ***'' Thomomys monticola'' - mountain pocket gopher ***'' Thomomys talpoides'' - northern pocket gopher


General characteristics

''Thomomys'', commonly referred to as smooth-toothed pocket gophers, is a group of rodents belonging to the family Geomyidae. Members of ''Thomomys'' are unique among gophers in that they have smooth upper incisors, free of the grooves that are common in other species. All species share the trait of fur-lined, external cheek pockets that allow them to move food material to and from their underground dwellings. Size varies among species, but commonly ranges from the size of a smaller mole to a larger rat. Coloration can range from yellow, to grey, to brown, and even black. They are all full-bodied with squat legs, short hair, and small eyes and ears.Bayley V. 1915
Revision of the Pocket Gophers of the Genus Thomomys
''North American Fauna'', 39. United States Bureau of Biological Survey
Pocket gophers have special visual adaptations to match their extreme and unique subterranean lifestyle. Though the size of their eyes are typical for rodents, the
lens A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), ...
is able to transmit light rays that fall into the ultraviolet range. They possess three different
photopigment Photopigments are unstable pigments that undergo a chemical change when they absorb light. The term is generally applied to the non-protein chromophore moiety of photosensitive chromoproteins, such as the pigments involved in photosynthesis and p ...
s: two cone pigments specific to 367 nm and 505 nm, and a rod pigment at 495 nm. Overall, the pocket gophers have less rod density than nocturnal rodents.


Habitat

Members of ''Thomomys'' inhabit southwestern Canada, the western United States, and a large percentage of Mexico. They thrive in fertile land often used for
agriculture Agriculture or farming is the practice of cultivating plants and livestock. Agriculture was the key development in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that enabled people to ...
, but can be found in many different localities. They prefer areas with high
primary productivity In ecology, primary production is the synthesis of organic compounds from atmospheric or aqueous carbon dioxide. It principally occurs through the process of photosynthesis, which uses light as its source of energy, but it also occurs through c ...
and nitrogen soil concentrations.Huntly, N., & Inouye, R. (1988)
Pocket gophers in ecosystems: Patterns and mechanisms
''Bioscience'', 38(11), 786-793.


Diet

They are fossorial
herbivores A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpart ...
that consume an extensive amount of food for their body size. This could be due to the fact that they expend copious amounts of energy excavating and maintaining their elaborate tunnel systems. It is estimated that burrowing uses 360-3400 times the amount of energy required for above-ground travel. They selectively consume underground parts of perennial and annual grasses,
forbs A forb or phorb is an herbaceous flowering plant that is not a graminoid (grass, sedge, or rush). The term is used in biology and in vegetation ecology, especially in relation to grasslands and understory. Typically these are dicots without woo ...
, and woody plants. They are also known to forage above ground, usually close to their burrow entrances. They are choosy and prefer certain species and parts of plants, perhaps due to their high daily energy expenditure.


Behavior and environmental effects


Tunneling and mounds

''Thomomys'' pocket gophers live underground and create extensive systems of tunnels through which they traverse. They move earth from below ground, and deposit it above ground in piles known as mounds. In snowy regions, they create tunnels through the snow known as earthcores. Earthcores and mounds together can cover up to 30% of the surface in highly excavated areas. The most prominent ecological effect would be that of their tunneling and mounds. The mounds are thought to increase ecological diversity of plants by providing a space for fugitive species that would otherwise have been eliminated due to competition over time. The flora of mounds differs noticeably from the surrounding areas, often with increased numbers of forbs and annuals. The actual mound soil differs in composition from that of the surrounding area as well, creating a different texture and water-holding potential. The ecological impact of this is still relatively unexplored.


Effects on agriculture and development

These gophers are able to alter the mineral availability, organic molecule concentration, texture, and moisture content of soil. This can be either a benefit or a nuisance depending on the soil condition and usage. In arid or semi-arid environments, these changes enhance vegetation growth and
soil quality Soil quality refers to the condition of soil based on its capacity to perform ecosystem services that meet the needs of human and non-human life.Tóth, G., Stolbovoy, V. and Montanarella, 2007. Soil Quality and Sustainability Evaluation - An integr ...
. They are thought to be able to help generate and regenerate prairie lands that have degraded. However, they are commonly known as pests in areas of agriculture and development. They have and can cause a heavy loss to farmers by consuming the roots or underground crops themselves. Farmers try to control and limit their population in crop areas using a variety of means. In the wild however, their presence is encouraged and advantageous.


Control and eradication

Many different methods have been used to try to eliminate overpopulation of pocket gophers. These include chemicals, propane blasting, and trapping. A park in Penn Valley, CA installed owl boxes to encourage the habitation of
barn owl The barn owl (''Tyto alba'') is the most widely distributed species of owl in the world and one of the most widespread of all species of birds, being found almost everywhere except for the polar and desert regions, Asia north of the Himalaya ...
s, a natural pocket gopher predator.Gophers Beware. By: McKnight, Marianne Wilson, E: The Environmental Magazine, 10468021, Jul/Aug2010, Vol. 21, Issue 4 Recommendations released by the
University of California, Davis The University of California, Davis (UC Davis, UCD, or Davis) is a public land-grant research university near Davis, California. Named a Public Ivy, it is the northernmost of the ten campuses of the University of California system. The institut ...
suggest the use of a gopher probe to locate the main burrow. Then a shovel can be used to widen the opening to the main burrow and traps can be set at opposite directions within the burrow. A wide array of different traps can be used, including the choker-style box trap and the pincher trap. Baiting a trap is not always necessary, though it may afford quicker or better results. Lettuce and other vegetables can be used as the bait. It is best to cover the traps with canvas or dirt to conceal the light. If two days pass without success, it is advisable to move the traps. Toxic bait can also be used, but involves a different trap placement strategy.
Fumigation Fumigation is a method of pest control or the removal of harmful micro-organisms by completely filling an area with gaseous pesticides—or fumigants—to suffocate or poison the pests within. It is used to control pests in buildings (s ...
is usually unsuccessful because gophers can quickly seal off their burrows at the first whiff of fumes. The exception to this is fumigation with aluminum phosphide; however, this can only be used by a professional. Gas explosives and flooding have commonly been utilized to force gophers from their burrows, and while sometimes successful, are not guaranteed to achieve full eradication.


References

*Nowak, R. M. 1999. Walker's Mammals of the World, Vol. 2. Johns Hopkins University Press, London.


External links

{{Taxonbar, from=Q1094704 01
Smooth-toothed pocket gopher 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 ...
Mammals of Mexico Mammals of the United States Mammals of Canada Rodents of North America Fauna of the Western United States