Zygogeomys trichopus

Geographic Range

Michoacan pocket gophers ( Zygogeomys trichopus ) are endemic to Mexico and are found in only four areas of the Sierra Madre of Michoacan; Nahuatzen, Cerro Patamban, Patzcuaro, and Cerro Tancitaro. In Nahuatzen, habitat destruction caused by an increase in agriculture has allowed more aggressive pocket gophers to encroach on its territory. More aggressive pocket gophers have appeared to have out-competed Michoacan pocket gophers in this area as no specimens have been reported from this area recently. Similar deforestation is occurring in the western parts of Cerro Tancitaro and eastern Patzcuaro and pocket gopher habitat is expanding in these areas as well, increasing the chance of Michoacan pocket gophers being extirpated from these areas, as well.

• Biogeographic Regions
• nearctic nearctic
  • native native
• neotropical neotropical
  • native native

Habitat

Michoacan pocket gophers are found in pine-spruce-alder forests with friable soil at elevations between 2200 and 3600 meters. Excavations of their burrows have shown that the central burrow, and likely their nesting chamber, tends to be about two meters below the surface. Lateral tunnels, used for foraging, tend to be 20 to 30 centimeters below the ground. Unlike other pocket gophers, which will forage for food above ground near their burrow openings, Michoacan pocket gophers appear to be entirely subterranean.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• forest forest

Physical Description

In general, pocket gophers are considered medium sized rodents; they have small eyes and external ears, a small, flattened head, short necks, fusiform shaped bodies, their fore paws have large claws, and their short tails are sparsely haired or naked. All gophers have external cheek pouches that are fur-lined and used to transport food through their burrows. To keep soil from getting into their mouth they have skin that grows behind their incisors. The length of Michoacan pocket gophers varies from 290 to 370mm and they typically weigh around 545 grams. Males and females are very difficult to tell apart from each other though males tend to be larger.

Their large incisors each have two grooves and grow continuously; they must gnaw consistently to keep them at the appropriate length. Michoacan pocket gophers have a number of physical characteristics that distinguish it from other pocket gophers. It is smaller than Llano pocket gophers , which inhabit similar habitat. Michoacan pocket gophers have small, deep-set eyes and short, dark grey to brown fur – similar to that of a mole. The fur on the dorsal side of its hind legs is lighter in color (grey to white), they can also have a white patch of fur on their throat. It has a hairless tail, and behind the rhinarium, on the rostrum, there is a hairless pad-like structure.

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

• Sexual Dimorphism
• sexes alike
• male larger

Reproduction

Very little is known about reproduction of Michoacan pocket gophers. Information on the breeding season of Michoacan pocket gophers is very limiting. A single pregnant female carrying one embryo was captured mid-December and the testes of males caught in March and August were around three times smaller, less than 5 mm, than the testes of males caught in December, greater than 14 mm. They are thought to be polygynous.

• Mating System
• polygynous polygynous

Michoacan pocket gophers are solitary and likely territorial aside from when they mate or when females are rearing their young. It is unknown when the breeding season is or if they breed year round. Gestation, weaning periods, and age at sexual maturity are also unknown.

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

Pocket gopher pups are altricial so some form of parental care, provided solely by the female, is required. The extent of this care and how long it’s provided for is unknown in Michoacan pocket gophers as all of it occurs two meters below the ground in the nesting chamber.

• Parental Investment
• altricial altricial
• female parental care female parental care
• 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

No specific information on the longevity of Michoacan pocket gophers could be found. Pocket gophers, in general, tend to have a lifespan of 1 to 3 years in the wild. In many species females are significantly longer lived.

Behavior

All pocket gophers are strictly solitary aside from when they mate or when a female is raising her young. Pocket gophers are highly territorial of their burrows and if they meet outside of the situations listed above a fight, sometimes to the death, is often the result if one does not back down and leave. Michoacan pocket gopher may be slightly different in this respect as they were observed when they were captured and were unusually docile. This less aggressive behavior might be a reason why they are out-competed by other species of pocket gophers that invade their territory when natural barriers are taken down.

• Key Behaviors
• fossorial fossorial
• motile motile
• sedentary sedentary
• solitary solitary

Home Range

The range of Michoacan pocket gophers are that of their burrow system. Information about how large these burrow systems are could not be found.

Communication and Perception

No information could be found on specific forms of communication used by Michoacan pocket gophers. Its life underground has led to reduced eyes and ears and enhanced olfactory and tactile senses. It is likely these are the senses it uses to perceive its environment and to communicate with others.

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

Food Habits

No information could be found on the specific diet of Michoacan pocket gophers, however pocket gophers in general are strict herbivores. They eat a variety of different plants and plant parts, including; stems, corms, forb shoots, tubers, roots, grass shoots, rhizomes, seeds, nuts, and stolen. It has been speculated that unlike other pocket gophers Michoacan pocket gophers do not leave their burrow to forage and are instead entirely subterranean. This would limit their diet to subterranean plant tissues. Pocket gophers , such as Chiriqui pocket gophers , which are closely related to Michoacan pocket gophers, are known to cache food when supply is high. Michoacan pocket gophers may also display this behavior.

• Primary Diet
• herbivore herbivore
  • lignivore

• Plant Foods
• roots and tubers
• wood, bark, or stems
• seeds, grains, and nuts

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

Predation

No specific list of predators could be found for Michoacan pocket gophers. In general pocket gophers are preyed upon a number of species which include badgers, domestic dog, weasels, bobcats, several snake species, skunks, house cats, foxes, coyotes, and several species of hawks and owls. As it was noted before Michoacan pocket gophers spends very little of its life above ground, this would severely limit opportunity for predators such as bobcats, dogs, coyotes, and raptors to prey upon it. Thus the lifestyle of Michoacan pocket gophers acts as a form of anti-predator adaptation.

Ecosystem Roles

No information could be found specifically for the ecological role that Michoacan pocket gophers play in their environment; the information provided here is about pocket gophers in general. Animals such as mice, snakes, weasels, lizards, toads, and salamanders use abandoned burrows as refuges from predators and the weather. Pocket gophers are an important food source for many different species of predators. They continuously turn the soil, increase fertilization (via bury vegetation and feces), and aerate the soil, increasing its overall quality. Finally, burrows at higher elevations catch water from rainfall and snowmelt and hold onto it, decreasing soil erosion. Pocket gophers are also the obligate host of chewing lice ( Geomydoecus and Thomomydoecus )

• Ecosystem Impact
• disperses seeds
• creates habitat
• soil aeration soil aeration

Economic Importance for Humans: Positive

The action of their tunneling causes pocket gophers to increase soil porosity, promote the mixing of soil chemicals, and decrease water runoff. Humans benefit from all of these actions.

Economic Importance for Humans: Negative

In areas where the habitat of Michoacan pocket gophers is encroached upon by people, usually for agricultural purposes, it has been known to cause damage to crops such as potatoes, corn, and wheat. Generally it is not in populated areas and causes little disturbance to people.

• Negative Impacts
• crop pest

Conservation Status

Michoacan pocket gophers are listed as endangered on the IUCN Red list due to extreme habitat fragmentation, a decline in the population of mature individuals due to competition with aggressive pocket gophers , and a decline in the quality of habitat. It is not listed on the US Federal list or CITES list.

Other Comments

Unlike other species of pocket gopher the surface mound Michoacan pocket gophers create is unique. They are volcano shaped, lack a terminal opening and/or plug, have a more conical shape, and are significantly taller than the mounds of other species. The uniqueness of the mound of Michoacan pocket gophers may be evidence of it having habits that differentiate it from other species of pocket gophers.

Additional Links

Encyclopedia of Life

Contributors

kate Wilcox (author), University of Wisconsin-Stevens Point, Christopher Yahnke (editor), University of Wisconsin-Stevens Point, Laura Podzikowski (editor), Special Projects.

References

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