Orthogeomys cavator

Geographic Range

Orthogeomys cavator (Chiriqui pocket gophers) can be found in the neotropical regions of Costa Rica and Panama, specifically the Isthmian-Pacific moist forests and Talamancan montane forests. These moist tropical rainforests compose the central and western regions of southernmost Central America. These areas are characterized by high temperatures, humidity, and dense, varied vegetation.

• Biogeographic Regions
• neotropical neotropical
  • native native

Habitat

Members of the genus Orthogeomys spend the majority of their lives underground, in self-created, permanent tunnel systems. These tunnel systems, known as burrows, are shallow, usually 0.1 to 0.3 meters below the surface. A pocket gopher’s tunnel can be detected by the mounds of dirt left behind after tunnel excavation. The burrow’s entrance is a hole characterized by a fan-shaped mound of soil, which seals the tunnels from flooding. Chiriqui pocket gophers prefer higher mountain valleys and exist at higher elevations than other Orthogeomys species. Some researchers say that pocket gophers are generally found up to 3,000 meters, but Chiriqui pocket gophers have been commonly found as high as 4,000 meters. On rocky mountains, however, Chiriqui pocket gophers are unable to dig burrows easily, so areas with soft soils are preferred. Chiriqui pocket gophers can be found in rainforest areas, where broad-leafed trees block most sunlight from reaching the ground.

• Habitat Regions
• tropical tropical
• terrestrial terrestrial

• Terrestrial Biomes
• rainforest rainforest
• mountains mountains

• Other Habitat Features
• agricultural agricultural

Physical Description

Like other gophers , Chiriqui pocket gophers are characterized by thickset bodies, large heads, and stout but powerful fore and hind limbs. The skull is distinguished by strong ridges, a flattened profile, and large jaw muscles, which are adaptations to accommodate burrowing. They have small eyes, which are protected from dirt by eyelids that seal very tightly. The small, external ears are equipped with flaps for closing the auditory canal. Like other pocket gophers , they have external, fur-lined cheek pockets on each side of the face, extending back onto the shoulder. When the cheek pouches are full, the head appears to be twice its normal size. All teeth grow continually, sometimes as much as 1 mm per day. The dental formula is I 1/1, C 0/0, P 1/1, M 3/3. The two front-most teeth are exposed even when the mouth is closed, which enables Chiriqui pocket gophers to cut roots or remove burrowing obstacles without allowing dirt to enter the mouth. They have a deep, center groove on the upper incisors. Male Chiriqui pocket gophers are approximately 280 mm in length. Females are considerably smaller, or about 215 mm. Chiriqui pocket gophers have unusually coarse and sparse pelage. The fur fits loosely, so that individuals can execute sharp turns in a constricted space, and is the color of upturned soil so that they are camouflaged when they leave their burrows. The underbody is slightly lighter than the dorsal fur, which is almost black. Their short, powerful limbs are of equal size, and are used, in conjunction with long claws, to excavate soil from burrows. The center three claws of the forefeet are used extensively, and grow twice as fast as any others. In Chiriqui pocket gophers, the hind foot averages 25 mm for males and 50 mm for females. Other differences between sexes include growth patterns; males grow continuously throughout their lives, while females stop growing when sexually mature, at around 3 months of age. Chiriqui pocket gophers have tails that make up about 30% of their overall length. In males, this means an average tail length of 100 to 120 mm while female tails are usually 104 to 110 mm. These tails are nearly naked and very sensitive to touch. This tail, in conjunction with long vibrissae along the body, help these animals navigate in tunnels.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger

Reproduction

Like other pocket gophers , Chiriqui pocket gophers are mainly solitary, maintaining separate territories regardless of sex. They are very territorial and will fight to the death when placed in limited quarters. This territoriality breaks down once a year during the mating season. At this time, adult males move into female territories, where they fight for the right to breed. Though there are territorial conflicts between males, breeding season is the only time when female pocket gophers allow adult males into their burrows without hostility. After mating has taken place, males may then leave the burrow to reproduce with another female. Female pocket gophers then begin to aggressively defend their territories after mating. While there may be as many as four males for every one female, most young are sired by only a few, dominant males. Many males never mate and the males that do reproduce usually do so with three or four females.

• Mating System
• polygynous polygynous

Chiriqui pocket gophers, like other montane gophers, breed after the melting of the snow, when vegetation is abundant and lush. The gestation period is short, 17 to 20 days, and usually 2 young are born, although larger litters are not uncommon. Birth weight is unknown, but most pocket gophers weigh between 3 and 9 grams when born. Newborns are completely dependent on their parents for the first 30 days after birth. Their cheek pouches open after 24 days, followed by the ears and eyes approximately two days later. Weaning usually takes place after 40 days, but the young gophers are not chased from their burrows until they are two months, or 60 days old. Male and female young leave their birth burrow at the same time. At this time, females dig new burrows for themselves near the mother’s territory, while male young are chased farther from nesting grounds. Females reach sexual maturity when they are approximately 70 days old and may begin to breed during the same season in which they were born. Older females may breed as many as four times each year, depending on environmental conditions. Young male pocket gophers live in shallow burrow systems in a peripheral habitat until the beginning of the next year’s breeding season. At this time, they disperse to establish developed territories through fighting. Therefore, males will not mate until they are at least one year old. At this time, if they have initiated a burrow successfully and have been able to fend off intruders, they will breed. Because the population is strongly polygynous and mating rights are competitive, however, male O. cavator rarely mate during their first year.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• viviparous viviparous

Young Chiriqui pocket gophers are raised exclusively by females. Females nurse and protect young until they are old enough to feed on stored vegetation. Because all gophers give birth and raise their young underground, little is known about the details of parental investment.

• Parental Investment
• altricial altricial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female
  • protecting
    • female
• pre-independence
  • provisioning
    • female
  • protecting
    • female

Lifespan/Longevity

Male and female pocket gophers have drastically different lifespans. Wild males typically only live 1.5 years while their female counterparts survive for 3 years or more.

Behavior

Little is known about Chiriqui pocket gopher behavior because they live most of their lives underground. They are solitary and there is little interspecific interaction outside of the breeding season. They communicate with teeth-chattering, squealing, and tactile cues. Chiriqui pocket gophers are considered aggressive and territorial. When threatened, they lie close to the ground, extend their short necks and make hissing noises or bare their teeth while sitting up on their hind legs to make themselves appear larger. Chiriqui pocket gophers are aggressive and territorial and will fight with conspecifics. They live in burrow systems for their entire lives. Though an individual’s burrow may be enlarged seasonally, they usually consist of a nesting chamber that is cushioned with dry grasses and a storage area, which is sealed from the main tunnel. Though pocket gophers are generally solitary, some Chiriqui pocket gophers have been observed sharing common tunnels and nesting chambers with adjacent males and females. When this territorial sharing does occur, each individual still maintains a private burrow for exclusive use. Chiriqui pocket gophers do move around on the surface and even travel above ground when relocating to a new habitat. Time spent above ground, however, is generally minimal and limited to time spent excavating earth or gathering food in the immediate proximity of the burrow entrance. Chiriqui pocket gophers travel above ground on an almost strictly nocturnal basis to avoid predators. Social hierarchies only occur during the breeding season, when larger, older individuals are the most likely to breed. Dominance is based entirely on an individual's ability to fend off invaders.

• Key Behaviors
• fossorial fossorial
• diurnal diurnal
• nocturnal nocturnal
• motile motile
• sedentary sedentary
• solitary solitary
• territorial territorial
• dominance hierarchies dominance hierarchies

Home Range

Home range sizes of Chiriqui pocket gophers are not reported, but individuals remain within their burrow system for their entire lives.

Communication and Perception

Because they are fossorial, Chiriqui pocket gophers have reduced eyes and ears and subsequently cannot see or hear as well as many other mammals. Olfactory and tactile senses in these species, however, are highly developed. Little work has been done to study the communication patterns of O. cavator . In captivity, individuals have been known to use their mouths to make loud noises. The most common of these sounds is a rattling that occurs when the animal is stressed or angry. During aggressive or territorial interactions, they create a chattering noise by clicking their large teeth. During mating season, a different kind of clicking noise has been described as a method of “talking” with conspecifics. Other sounds may include scolding shrieks when frightened and human-like crying sounds when in pain.

• Communication Channels
• tactile tactile
• acoustic acoustic
• chemical chemical

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Chiriqui pocket gophers are folivorous and cache food in special storage areas of their burrows. Storage areas are sealed from the main tunnel and are especially important for feeding females when they are nursing their young and cannot travel far from the nesting chamber. Food is taken to the storage area in the animal’s large cheek pouches. When roots and vegetation are cut and gathered, the pockets are filled. The amount of food that can be stored in the stomach, the appendix, which is large, and the large intestine may be as much as 21% of the animal’s overall weight. Approximately 25% of a Chiriqui pocket gopher’s diet consists of roots, which are obtained below ground, from the tunnels. They are especially adapted for feeding on the roots and tubules of a large variety of monocots. The other 75% of the food is obtained above ground, around the burrow entrance. This consists of grasses, seeds, and forbs.

• Primary Diet
• herbivore herbivore
  • folivore folivore

• Plant Foods
• leaves
• roots and tubers

• Foraging Behavior
• stores or caches food stores or caches food

Predation

Few natural predators of Chiriqui pocket gophers are known. In general, gophers are eaten by snakes, weasels, coyotes, wolves, and birds of prey, especially owls. Chiriqui pocket gophers are well camouflaged by their fur, which is the color of upturned soil. They are careful to search for food above ground primarily at night, which eliminates many non-nocturnal animals as predators. Another important adaptation is the sealing of burrow entrances, which makes it difficult for similar-sized animals, such as snakes and weasels, to find and enter tunnels. In Central America gophers are often killed by humans. Chiriqui pocket gophers are crop pests, so many traps and poisons are used to kill them. They are also eaten in some areas of Central America.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Chiriqui pocket gophers benefit their ecosystem in several key ways. By upturning soil and thereby spreading nutrients to the surface, they help with soil nutrient cycling. This not only fertilizes plants, it also loosens the dirt so that native plants can more easily put down roots. In addition, Chiriqui pocket gophers consume seeds and may help to disperse them. Chiriqui pocket gophers are also hosts to several species of parasites, especially lice. Chewing lice and their pocket gopher hosts are commonly used as examples of cospeciation.

• Ecosystem Impact
• disperses seeds
• soil aeration soil aeration

Economic Importance for Humans: Positive

Humans do not directly benefit from the existence of Chiriqui pocket gophers, which are often regarded as pests. What many farmers to not realize, however, is that their burrowing is beneficial to the soil in which their crops are grown. Their near-constant digging creates a vertical cycling of soil, which brings nutrients to the surface, where they are more accessible to plant roots. They also prevent soil run-off and erosion, because the naturally tilled soil is significantly more porous.

• Positive Impacts
• produces fertilizer

Economic Importance for Humans: Negative

Chiriqui pocket gophers are considered economically detrimental because of their voracious appetite for vegetation. One pocket gopher can destroy a family’s garden in less than a month. In Costa Rica and Panama, Chiriqui pocket gophers are an especially serious problem because they damage banana and sugar cane farms.

• Negative Impacts
• crop pest

Conservation Status

Chiriqui pocket gophers are not considered threatened on any conservation list. In fact, Chiriqui pocket gophers are widely considered to be pests that destroy crops and are a nuisance to humans.

Additional Links

Encyclopedia of Life

Contributors

Ellen Cartmell (author), Centre College, Javod Sewell (author), Centre College, Stephanie Fabritius (editor, instructor), Centre College, Tanya Dewey (editor), Animal Diversity Web.

References

Akersten, W. 1973. Upper Incisor Grooves in the Geomyinae. Journal of Mammalogy , 54/2: 349-355.

Hafner, M., J. Demastes. 1996. Phylogeographic variation in two Central American pocket gophers. Journal of Mammalogy , 77/4: 9-17. Accessed April 05, 2009 at http://search.ebscohost.com/login.aspx?direct=true&db=aph&AN=9703114008&site=ehost-live .

Hafner, M., D. Hafner. 1987. Geographic Distribution of Two Costa Rican Species of Orthogeomys, with Comments on Dorsal Pelage Markings in the Geomyidae. The Southwestern Naturalist , 32/1: 5-11. Accessed April 20, 2009 at http://www.jstor.org/stable/3672003 .

Hafner, M., S. Nadler. 1990. Cospeciation in Host-Parasite Assemblages: Comparative Analysis of Rates of Evolution and Timing of Cospeciation Events. Systematic Zoology , 39/3: 192-204. Accessed May 13, 2009 at http://www.jstor.org/stable/2992181 .

Hafner, M. 1991. Evolutionary Genetics and Zoogeography of Middle American Pocket Gophers. Journal of Mammalogy , 72/1: 1-10.

Page, R. 1996. Temporal Congruence Revisited: Comparison of Mitochondrial DNA Sequence Divergence in Cospeciating Pocket Gophers and Their Chewing Lice. Systematic Biology , 45/2: 151-167. Accessed May 17, 2009 at http://www.jstor.org/stable/2413612 .

Patton, J. 2007. Pocket Gophers. The Encyclopedia of Mammals . Oxford University Press. Accessed April 05, 2009 at http://www.oxfordreference.com/views/ENTRY.html?subview=Main&entry=t227.e112-ss2 .

Powell, G., S. Palminteri, J. Schipper. 2001. "Terrestrial Ecoregions-- Talamancan montane forests" (On-line). Wild World WWF Full Report. Accessed April 05, 2009 at http://www.worldwildlife.org/wildworld/profiles/terrestrial/nt/nt0167_full.html .

Powell, G., S. Palminteri, J. Schipper. 2001. "Terrestrial Ecoregions--Isthmian-Pacific moist forests" (On-line). Wild World WWF Full Report. Accessed April 05, 2009 at http://www.worldwildlife.org/wildworld/profiles/terrestrial/nt/nt0130_full.html .

Salmon, T., W. Gorenzel. 2002. "Pest Notes: Pocket Gophers" (On-line). UC Integrated Pest Management Online. Accessed April 05, 2009 at http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7433.html .

Samudio, R., J. Pino. 2008. "IUCN 2008 Red List- Orthogeomys cavator" (On-line). The IUCN Red List of Threatened Species. Accessed April 05, 2009 at http://www.iucnredlist.org/details/15544 .

Woods, C. 1990. Pocket rodents. Pp. 131, 134-137 in Grzimek's encyclopedia of mammals , Vol. 3, 1st Edition. New York: McGraw-Hill.

World Wildlife Fund. 2008. "Ecoregions containing Chiriqui Pocket Gopher, Orthogeomys cavator" (On-line). WWF Wildfinder Search. Accessed April 05, 2009 at http://www.worldwildlife.org/wildfinder/searchBySpecies.cfm?fClass=&fOrder=&fFamily=&fGenus=&fAdvancedSearch=closed&fSearchMode=simple&fIUCN=&fSpecies=Orthogeomys%20cavator&startIndex=1&orderBy=1&fWildCard=Contains&speciesID=15594 .

1989. Family Geomyidae. Pp. 337 in Mammals of the Neotropics, the Northern Neotropics , Vol. 1, 1 Edition. Chicago: The University of Chicago Press.

NatureServe. 2007. "Orthogeomys cavator- Chiriqui Pocket Gopher" (On-line). InfoNatura: Animals and Ecosystems of Latin America. Accessed April 05, 2009 at http://www.natureserve.org/infonatura/servlet/InfoNatura?searchName=Orthogeomys+cavator .

1989. Orthogeomys cavator. Pp. 339 in Mammals of the Neotropics, the Northern Neotropics , Vol. 1, 1 Edition. Chcago: The University of Chicago Press.

2004. Pocket gophers. Pp. 185-197 in Grzimek's animal life encyclopedia , Vol. 16, Mammals 5, 2nd Edition. Detroit: Gale Group.

1985. Pocket gophers. Pp. 628-631 in The encyclopedia of mammals , Vol. 2, 1st Edition. New York: Facts on File Publications.