Spermophilus perotensis

Geographic Range

Perote ground squirrels ( Spermophilus perotensis ) are endemic to the Neotropical region and are found in Eastern Mexico within the Trans-Mexian Volcanic Belt. They live in Perote, Veracruz as well as San Salvador and Laguna de las Minas, Puebla.

• Biogeographic Regions
• neotropical neotropical
  • native native

Habitat

Perote ground squirrels occupy the upper Sonoran life zone, which includes desert steppes and chaparrals. They live in large plains and sandy areas, but are threatened due to land conversion for agricultural purposes. Their habitats range in elevation from 2,340 to 2,370 m.

• Habitat Regions
• terrestrial terrestrial

• Terrestrial Biomes
• desert or dune desert or dune
• chaparral chaparral

• Other Habitat Features
• agricultural agricultural

Physical Description

Adult Perote ground squirrels have an average length of 7 in and reach weights between 4 and 9 oz. They have smooth, tan-grey coats with irregular dark speckling across the back. They have thin, short tails pronounced by longer hairs compared to the rest of their coats. Perote ground squirrels have four compact limbs with claws to allow for effective digging. Their forelimbs each have four clawed toes, while their hindlimbs each have five clawed toes. Their ears are not well-defined and lie smoothly alongside their heads. Their two black eyes are located on the sides of their heads, and their noses are somewhat pointed, with whiskers that help them sense their environment. To support their omnivorous diet, Perote ground squirrels have 22 teeth: four incisors, no canines, six premolars, and twelve molars.

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

• Sexual Dimorphism
• sexes alike

Reproduction

Perote ground squirrel females and males both breed with multiple mates, making them polygynandrous (or promiscuous). Males travel between burrows to breed with different females. Both males and females mate multiple times throughout their lives, making them iteroparous.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Perote ground squirrels have a late breeding season and have two litters each year. Although no specific age for sexual maturity is reported, females one-third the size of fully-grown adults can become pregnant. In their close relatives, European ground squirrels ( Spermophilus citellus ), both males and females are sexually mature at around 314 days. Females carry 5 to 7 embryos, each 19 mm in crown-rump length. After mating, male Perote ground squirrels may disperse from their local populations into nearby populations to continue breeding. This behavior results in a low inbreeding effect on population genetics. Perote ground squirrels have a gestation period of 28 to 30 days. They gives birth to four pups per litter, on average.

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

Newborn Perote ground squirrels are raised and nursed by their mothers in elaborate tunnel systems. In one study with a small sample size (n=4), juvenile Perote ground squirrels were observed to be independent from their mothers at four months of age. Exact weaning time is unknown.

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

Lifespan/Longevity

Current research makes no mention of known natural lifespans of Perote ground squirrels because observed populations are highly impacted by predators such as prairie falcons ( Falco mexicanus ), long-tailed weasels ( Mustela frenata ), and domestic dogs ( Canis lupus familiaris ). Perote ground squirrels are also threatened by habitat destruction largely due to agricultural development. For these reasons, a natural lifespan for Perote ground squirrels has not been confirmed. However, their close relatives, European ground squirrels ( Spermophilus citellus ), have a documented maximum longevity of 6.7 years in captivity.

Behavior

Residing in primarily treeless, shrubless, grassy habitats, Perote ground squirrels are generally active between March and November and hibernate from December to February. These periods are rough estimates, but their activity is definitely related to temperature. During active periods, Perote ground squirrels are diurnal (active during the day). Perote ground squirrels are social, working together in groups. Throughout the day they scavenge for food, construct burrows, and care for their young. At night, they retreat to underground burrows. Because they live in these burrows Perote ground squirrels are considered partially fossorial.

• Key Behaviors
• fossorial fossorial
• diurnal diurnal
• motile motile
• sedentary sedentary
• hibernation hibernation
• social social

Home Range

There is no reported home range for Perote ground squirrels.

Communication and Perception

Perote ground squirrels have long whiskers protruding from their noses that help them sense their environment, especially in their underground burrows. Perote ground squirrels use sight, hearing, and smell as their main senses but are also sensitive to vibrations in the ground, which allows for increased perception in their dark burrows. They use various chirps and barks to communicate with one another. During breeding seasons, both male and female Perote ground squirrels are thought to release pheromones to attract mates. During mating season, females likely use pheromones to attract males to their burrows. Males travel to several burrows to mate with multiple females throughout one breeding season.

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

• Other Communication Modes
• pheromones pheromones
• vibrations vibrations

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

Food Habits

Perote ground squirrels are primarily herbivorous, but will sometimes eat small insects. Their diet primarily consists of seeds, as their genus name, Spermophilus (“seed-lovers”), implies.

• Primary Diet
• herbivore herbivore
  • granivore granivore
• omnivore omnivore

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

Predation

Long-tailed weasels ( Mustela frenata ) are a prominent predator of Perote ground squirrels because these weasels can hunt ground squirrels in their burrows. Prairie falcons ( Falco mexicanus ) are also known to be successful predators of Perote ground squirrels because these squirrels primarily reside in habitats with few trees and shrubs to provide protection. Domestic dogs ( Canis lupus familiaris ) may also be considered a predator, as humans - and subsequently domestic dogs - encroachment on the native territory of Perote ground squirrels.

Ecosystem Roles

The interactions of Perote ground squirrels with other species of plants and animals are not well documented. However, based on their known behaviors of eating seeds and burrowing, it may be predicted that they aid in seed dispersal and soil aeration. Additionally, there may be other small burrowing animals that inhabit Perote ground squirrel burrows. This is based on the fact that other organisms have been documented to take over or coexist in European ground squirrel ( Spermophilus Citellus ) burrows.

• Ecosystem Impact
• disperses seeds
• soil aeration soil aeration

Economic Importance for Humans: Positive

There are no known positive economic benefits of Perote ground squirrels on humans.

Economic Importance for Humans: Negative

There are no known negative economic benefits of Perote ground squirrels on humans.

Conservation Status

Perote ground squirrels are considered an endangered species on the IUCN Red List. Perote ground squirrels are at risk of extinction due to their narrow geographic range, small number of remaining populations, and small population sizes, which leads to lower genetic diversity. Increased agricultural practices in their natural habitats has led to the destruction of burrowing systems, reduction of shrubs and trees that provide cover, and reduced amounts of vegetation due to livestock grazing. They have been given no special status on CITES, the U.S. Federal List, or the State of Michigan list.

Other Comments

Another scientific name for Perote ground squirrels is Xerospermophilus perotensis . Additionally, due to the small abundance and narrow territory of Perote ground squirrels, there is relatively little information that has been confirmed about the species. However, through analyzing close relatives such as European ground squirrels ( Spermophilus citellus ), inferences can be made about the life history of Perote grounds squirrels.

Additional Links

Encyclopedia of Life

Contributors

Meagan Rockow (author), Colorado State University, Kate Gloeckner (editor), Colorado State University, Galen Burrell (editor), Special Projects.

References

Best, T., C. Gerado. 1995. "“Spermophilus Perotensis”" (On-line pdf). JSTOR. Accessed April 01, 2019 at https://www.jstor.org/stable/3504194?seq=1#page_scan_tab_contents .

García-Domínguez, J., E. Priego-Hernández. 2014. "Predation record of a Perote ground squirrel (Xerospermophilus perotensis) by a prairie falcon (Falco mexicanus)" (On-line pdf). De Gruyter. Accessed April 01, 2019 at https://www.degruyter.com/view/j/mamm.2015.79.issue-2/mammalia-2013-0151/mammalia-2013-0151.xml .

García-Domínguez, J., O. Rojas-Soto, J. Galindo-González. 2014. "Present and future potential distribution of the endemic Perote ground squirrel (Xerospermophilus perotensis) under different climate change scenarios" (On-line pdf). De Gruyter. Accessed April 01, 2019 at https://www.degruyter.com/view/j/mamm-ahead-of-print/mammalia-2013-0077/mammalia-2013-0077.xml .

Montero-Bagatella, S., A. González-Romero, G. Sanchez-Rojas, S. Gallina. 2018. "Annual cycle of the Mexican ground squirrel (Xerospermophilus perotensis)" (On-line pdf). Research Gate. Accessed April 01, 2019 at https://www.researchgate.net/publication/325534125_Annual_cycle_of_the_Mexican_ground_squirrel_Xerospermophilus_perotensis .

Ochoa, A., J. Gasca-Pineda, G. Ceballos, L. Equiarte, V. Sánchez-Cordero. 2012. "Spatiotemporal population genetics of the endangered Perote ground squirrel (Xerospermophilus perotensis) in a fragmented landscape" (On-line pdf). JSTOR. Accessed April 01, 2019 at https://www.jstor.org/stable/i23259774 .

Valdéz, M., G. Ceballos. 1997. "Conservation of Endemic Mammals of Mexico: The Perote Ground Squirrel (Spermophilus Perotensis)" (On-line pdf). JSTOR. Accessed April 01, 2019 at www.jstor.org/stable/1382640 .

2017. "AnAge Entry for Spermophilus Citellus" (On-line). Human Ageing Genomic Resource. Accessed April 01, 2019 at genomics.senescence.info/species/entry.php?species=Spermophilus_citellus .