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Orthogeomys heterodusvariable pocket gopher

By Benjamin Klopf

Geographic Range

Orthogeomys heterodus is found in central and southern Costa Rica in the Cordillera Central and Cordillera de Talamanca mountains. (Emmons, 1997)

Habitat

Orthogeomys heterodus tends to be found in clearings and agricultural areas. Its burrow consists of a central nest, food storage areas, excrement areas, and several paths to different foraging areas. (Emmons, 1997)

Physical Description

Orthogeomys heterodus weighs between 402 and 670 g. The fur is thick and relatively long and is gray-brown on top and pale gray on the underside. Orthogeomys heterodus has several adaptations for fossorial living: such as long claws, reduced ears and eyes, and a flattened skull. (Hafner, 1991; Patton, 2001)

  • Range mass
    402 to 640 g
    14.17 to 22.56 oz

Reproduction

Although taltuzas are usually solitary, females will move into an adjacent male burrow to breed. (Patton, 2001)

Females are reproductively active after about 70 days. Females will breed from one to four times a year depending on environmental factors such as temperature, moisture, and vegetation quality. Gestation period is approximately 17 to 21 days. The young are born with eyes, ears, and mouth pouches closed. The eyes, ears, and pouches open after approximately 25 days. The young are then weaned at about 40 days. (Patton, 2001)

  • Breeding interval
    Variable pocket gophers breed 1 to 4 times throughout the year.
  • Breeding season
    Mating occurs throughout the year.
  • Range number of offspring
    1 to 3
  • Range gestation period
    17 to 21 days
  • Average weaning age
    40 days
  • Average age at sexual or reproductive maturity (female)
    70 days

The female will care for the young for approximately 40 days before weaning them. The male plays no apparent role in the upbringing of the young. (Patton, 2001)

Lifespan/Longevity

No lifespan for Orthogeomys heterodus was specifically mentioned. However, members of the pocket gopher family generally live for only a year in the wild. (Patton, 2001)

  • Average lifespan
    Status: wild
    1 years

Behavior

Orthogeomys heterodus is a solitary species, only sharing burrows during breeding season for a short period. Males tend to compete among themselves for burrows. Orthogeomys heterodus is most active in the morning hours but is also somewhat active day or night. Orthogeomys heterodus spends almost its entire life underground, unless it is foraging for food, or building a new burrow. (Patton, 2001)

Home Range

No information could be found on the extent of the variable pocket gopher's home range.

Communication and Perception

No specific information was found on communication in variable pocket gophers. Because they are fossorial, the pocket gopher family has enhanced olfactory and tactile senses. Their vision and hearing are reduced because of the reduced size of their ears and eyes. (Patton, 2001)

Food Habits

Orthogeomys heterodus feeds on grasses, seeds, and forbs above ground, but most of its diet comes from below ground in the form of grass roots and tubers. (Patton, 2001)

  • Plant Foods
  • leaves
  • roots and tubers
  • seeds, grains, and nuts

Predation

The main adaptation of the variable pocket gopher to avoid predation is its fossorial lifestyle. Hawks were the only predators mentioned for this species, although snakes are also likely to prey on them. (Patton, 2001)

Ecosystem Roles

Orthogeomys heterodus plays an important role in its ecosystem. These gophers aerate the soil by burrowing and disperse seeds when foraging. (Patton, 2001)

Economic Importance for Humans: Positive

Humans benefit from the variable pocket gopher because this species increases soil porosity, thereby decreasing water runoff. (Patton, 2001)

Economic Importance for Humans: Negative

Even though they are burrowing mammals, there was no mention of the variable pocket gopher being an agricultural nuisance because they live in a region that is not heavily farmed. However, other members of the genus Orthogeomys are considered agricultural pests.

Conservation Status

Orthogeomys heterodus is listed on the IUCN red list due to habitat destruction and fragmentation. It is not listed on CITES or on the US ESA. ("2002 IUCN Red List of Threatened Species", )

Contributors

Benjamin Klopf (author), University of Wisconsin-Stevens Point, Chris Yahnke (editor), University of Wisconsin-Stevens Point.

Glossary

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

agricultural

living in landscapes dominated by human agriculture.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

crepuscular

active at dawn and dusk

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

folivore

an animal that mainly eats leaves.

fossorial

Referring to a burrowing life-style or behavior, specialized for digging or burrowing.

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

polygynous

having more than one female as a mate at one time

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

soil aeration

digs and breaks up soil so air and water can get in

solitary

lives alone

tactile

uses touch to communicate

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

year-round breeding

breeding takes place throughout the year

References

International Union for Conservation of Nature and Natural Resources. "2002 IUCN Red List of Threatened Species" (On-line ). Accessed 10/30/02 at http://www.redlist.org/search/details.php?species=15548.

Emmons, L. 1997. Pocket Gophers (Geomyidae). Neotropical Rainforest Mammals: A Field Guide. Chicago: The University of Chicago Press.

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

Patton, J. 2001. Pocket Gophers. The Encyclopedia of Mammals. Oxfordshire, United Kingdom: Andromeda Oxford Limited.

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