Geomys texensis

Geographic Range

Llanos pocket gophers, Geomys texensis , are located exclusively in Texas. They can be found as far north as the city of Brady, as far south as La Pryor, as far west as Ulvade, and as east as Llano. They live in the Great Plains, the northern part of the Gulf Coast Plains, and the southern part of the north central plains on Edward's Plateau area. These pocket gophers now live in two isolated areas. Located in south Texas, the subspecies Geomys texensis bakeri is in Medina, Uvalde, and Zavala counties and Geomys texensis llanensis is in Mason and Llano counties.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

Llanos pocket gophers occupy temperate grasslands, city parks, urban and suburban lawns, and roadside ditches at an elevation anywhere from 300m to 750m above sea level. They are most commonly found in deep brown sands and gravelly, sandy soils that are close to streams or small bodies of water.

Pocket gophers are fossorial and spend most of their time burrowing in their vast tunnel systems. Some tunnels lead to chambers, which are used to store food, feces, and nesting. The nest chambers are large and 30cm to 60cm from the main tunnel. Tunnels are used to escape from intruders, find potential mates, or to access a food source. There is one main tunnel and many side tunnels that lead to said chambers or smaller, functional tunnels.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• savanna or grassland savanna or grassland

• Other Habitat Features
• urban urban
• suburban suburban
• riparian riparian

Physical Description

Both sexes of pocket gophers have a pelage that is a mixture of light and dark brown hairs on the dorsum and face while their venter and feet are a creamy white. Both sexes have a dental formula of 1013/1013, with a sum of 20, and have 2 grooves on each upper incisor. During the winter, their coats get darker and their venter turns a pale grey.

While newborns are hairless and helpless, juveniles have tawny brown coats. All age classes have cheek pouches.

Male pocket gophers weigh between 125g to 212g and have a total length of 25.1cm to 24.1cm while smaller females weigh between 105g to 165g and have a total length of 10.5cm to 16.5cm. Male and female average measurements are, respectively, a tail length of 6.9cm and 6cm; hind foot length of 3.2cm and 2.8cm; and length of maxillary toothrow of 9.1mm and 8.6mm.

This species differs from others either by both DNA and appearance, or only by DNA. The species Geomys knoxjonesi , Knox Jones's pocket gopher, and Geomys bursarius , Plains pocket gopher, are distinguishable from Geomys texensis using external characteristics such as shorter nasals, larger bullae, and a slightly narrower rostrum. The subspecies Geomys texensis bakeri and Geomys texensis llanensis can only be separated by DNA analyses.

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

• Sexual Dimorphism
• male larger

Reproduction

There is no information available specifically for the mating systems of Geomys texensis , but there is knowledge available about Geomys as a whole. Each breeding season, males have been observed to lure more than one female into their burrow to begin copulation.

• Mating System
• polygynous polygynous

Llanos pocket gophers' reproductive behaviors are sparse in the literature. These gophers breed once yearly. One pregnant female, or in some cases two, shares a burrow with the male until the young are weaned at about 42 days. Afterwards, adults return to their separate burrows.

Plains pocket gophers ( Geomys bursarius ), their closest sister taxon, are well-studied in terms of reproduction. Plains pocket gophers breed once a year from March through December, giving birth to one to eight pups that weigh 4.9g to 5.4g each. Their gestation period lasts 18 to 19 days, weaning occurs 40 to 44 days after birth, and independence is attained on an average of 51 days later. Females reach sexual maturity around 10 months to a year old, while males reach it at 7 to 9 months old. It's likely that Llanos pocket gophers follow a similar reproductive pattern.

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

During the breeding season, Geomys are less aggressive in protecting their territory than in non-breeding intervals. This behavior lasts beyond breeding season, suggesting males are invested in protecting their young. Males have been found to share burrows with two pregnant females. They continue to share burrowing systems until the young are weaned then go back to living a solitary life until next breeding season. Young are born underdeveloped, hairless, and with their eyes and ears closed and unable to care for themselves, feed, and move without the help of the parents. The dispersal of Geomys young occurs more frequently in June when they weigh between 80 and 100g, although there have been a few exceptions of solitary young weighing 60 to 80g, and a couple of rare cases of less than 60g. Due to pocket gophers' subterrestrial nature, information about post-natal care is lacking.

• Parental Investment
• altricial altricial
• male parental care male parental care
• female parental care female parental care
• pre-fertilization
  • protecting
    • male
    • female
• pre-weaning/fledging
  • provisioning
  • protecting
    • male
    • female
• pre-independence
  • provisioning
    • female
  • protecting
    • male
    • female

Lifespan/Longevity

There is no information about the longevity of Llanos pocket gophers, but a study conducted on all pocket gophers provides some insight into their lifespan. DeVries (2012) explained that pocket gophers can be kept in captivity for 2 to 3 years, with a maximum life expectancy of 3.5 to 4 years. In the wild, they are expected to live 1 to 3 years, although there has been a case of a gopher living to be 7 years old. It's uncertain whether these data directly pertain to Llanos pocket gophers, which typically are not kept in captivity.

Behavior

Llanos pocket gophers are solitary and sedentary. Each individual aggressively protects their own burrow system. They are specialized for digging and moving dirt with much of their time consumed by excavating tunnels both day and night. When pushing excess soil to the surface, gophers execute this as quickly as possible, and with little exposure to the surface. If gophers encounter a hole in their burrow leading to the surface, they immediately seal it by packing dirt on and below the surface, making it difficult for snakes, badgers ( Taxidea taxus ), and other predators to access their burrow. Rainfall places an impact on the construction of new burrows. During droughts, there is little to no burrow excavating for a month or longer. It is unknown what happens when there is little to no excavating. When a fair amount of rain occurs, the excavation of burrows increases and multiple new mounds appear.

When Llanos pocket gophers come into contact with any living organism other than their young, they react fiercely to protect their territory and themselves. There is no vocal or seismic mode of communication reported for this species. The only time there is interaction amongst pocket gophers is during breeding season. Territorial behavior tends to die down, and male and females are known to share burrows to mate and to care for their young. The females leave their own burrow untended and unprotected during the entire duration of breeding season.

Pocket gophers dig tunnels used for foraging underground and to connect burrows to nest during breeding season. They venture out of their burrows to collect food from above ground and store extra food in caches inside their burrow.

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

Home Range

While there is no information of burrow length and area specifically for Geomys texensis , their closest relatives, plains pocket gophers ( Geomys bursarius ), have been studied. Home range size and shape depends on the energy cost of excavating burrows (360 to 3400 times greater than moving the same distance on the surface), location of neighbors, and the need to acquire food. Burrow systems are generally 2m to 3m apart from each other while some have been found to be only several centimeters apart. The total length of each gopher's burrow is 40.1m to 63.5m and the total area is 66.7 to 123.9 square meters.

Individuals extend their burrows to find mates within a fixed area or to find new sources of food. During breeding season, female gophers share the male's burrow and leave their burrows untended and unprotected for the duration of the season.

Communication and Perception

While there is little reported about communication in Llanos pocket gophers, reports for the genus as a whole pertain to these gophers. Members of the genus Geomys have poor hearing. Their visual ability enables them to distinguish different intensities of light and moving objects. Because they cannot see very well, an object held in front of them may not elicit a response. When touched they react fiercely, turning and snapping at whatever touched them. Although they use olfactory receptors to guide them to food, they do not use chemical cues to communicate with each other. No vocal or seismic mode of communication has been reported for this species.

• Communication Channels
• visual visual
• tactile tactile

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

Food Habits

Llanos pocket gopher diets consist of roots, potatoes and other tubers, stems, nuts, and grains. Grass and hard vegetable substances are sometimes consumed as well. To get to this food, they dig tunnels that lead to crop fields where they can forage underground or sometimes venture out of their burrows and collect food from above ground. Immediately after gophers eat, they store extra food in cheek pouches and return back to their burrows and then dispenses the extra food in caches inside their burrow. They rarely need fresh water to drink, as they get most of the moisture they require from the vegetation they eat.

• Primary Diet
• herbivore herbivore
  • eats sap or other plant foods

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

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

Predation

The source of potential predators is limited due to Geomys fossorial lifestyle. They are safe from most predators, with the exception of snakes, badgers ( Taxidea taxus ), coyotes ( Canis latrans ), and weasels ( Mustela ). Pocket gophers are at their most vulnerable when they are at the surface feeding or moving debris and soil. They might be preyed upon by red foxes ( Vulpes vulpes fulva ) grey foxes ( Urocyon cinereoargenteus ), coyotes ( Canis latrans ), bobcats ( Lynx rufus ), owls, hawks, American hog-nosed skunks ( Conepatus leuconotus ), striped skunks ( Mephitis mephitis ) and domesticated cats ( Felis catus ). The only anti-predator adaptation Llanos pocket gophers have is camouflage, the color of their fur tends to blend in with the soil in their environment, and burrowing, which lessens the amount of exposure to proprietorial birds and larger mammalian predators.

Subadult mortality rates are exceptionally high as they move to establish their own burrow. Young have a high survivability due to the safety of the burrow and their mothers aggressive protectiveness.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Although Llanos pocket gophers are crop pests of central Texas farmers, they do aerate the soil when they burrow. After consumption, the seeds of these plants are dispersed by excretion or by the seed getting stuck on the gophers' fur. Abandoned burrows become habitats for other animals such as snakes, plains pocket gophers ( Geomys bursarius ), raccoons ( Procyon lotor ), nine-banded armadillos ( Dasypus novemcinctus ), black-footed ferrets ( Mustela nigripes ), long-tailed weasels ( Mustela frenata ), striped skunks ( Mephitis mephitis ), American hog-nosed skunks ( Conepatus leuconotus ), and burrowing owls ( Athene cunicularia .

When looking at 7 species and 9 subspecies of Geomys and 1 species and 2 subspecies of Cratogeomys , Llanos pocket gophers had the highest rate of infestation. Many acarine parasites use this species as a host. Chiggers ( Euschoengastoides and Pseudoschoengastia farneri ) are found exclusively on Llanos pocket gophers. Mites ( Echinonyssus geomydis and Androlaelaps geomys ) are also found on these gophers. They were also examined for helminth parasites of the digestive system. Both a nematode ( Protospirura ascaroidea ) and cestodes ( Monoecocestus and Hymenolepis ) were found.

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

Economic Importance for Humans: Positive

Llanos pocket gophers have a positive impact on humans by aerating the soil as they burrow through crop fields.

Economic Importance for Humans: Negative

Llanos pocket gophers have negative impacts on humans because the economic loss they may cause. They are known to eat parts of agricultural crops such as roots, tubers, stems, nuts, grains, and sometimes vegetables. Burrowing can damage crops as well as erode the soil.

• Negative Impacts
• crop pest

Conservation Status

The IUCN Red List indicates Llanos pocket gophers are a species of "Least Concern." These gophers have no special status on the US Federal List, CITES, and State of Michigan List.

There are no listed threats to this species. Humans are a possible threat, given they will lay out traps and pesticides to keep gophers out of their gardens and crop fields.

The geographical range of this species includes some in-place protected areas that happen to cover their entire range, according to the IUCN Red List. This provides indirect protection for the species.

Additional Links

Encyclopedia of Life

Contributors

Mallory McKnight (author), Radford University, Layne DiBuono (editor), Radford University, Lindsey Lee (editor), Radford University, Kioshi Lettsome (editor), Radford University, Karen Powers (editor), Radford University, Tanya Dewey (editor), University of Michigan-Ann Arbor.

References

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