Spermophilus annulatus is endemic to west-central Mexico.
Biogeographic Regions: nearctic ; neotropical
The coloration of ring-tailed ground squirrels varies seasonally; these squirrels are more brightly colored during the breeding season. The head is predominantly black, while the body is a mix of black, buff, and pinkish coloration. Total length varies from 383 to 470 mm. The tail is narrow and has approximately fifteen annulations, or stripes. It is not as bushy as the tails of other squirrel species and is as long as the head and body of the animal. The skulls of females are generally larger than those of males.
Range length: 383 to 470 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: female larger
Ring-tailed ground squirrels inhabit the tropical lowlands of western Mexico. They are found in dense tropical forests and palm groves, especially in areas with thick, vine growth on larger trees. Spermophilus annulatus create burrows and cavities under cover of thick vegetation, on hillsides and near cultivated areas. These squirrels have been known to live in the walls of barns.
Habitat Regions: tropical ; terrestrial
Terrestrial Biomes: forest
Other Habitat Features: agricultural
Habitat and Ecology
This squirrel eats fruits and nuts, and sometimes it also may feed on insects. Breeding occurs during the dry season (December to June). A female captured in February had four embryos (Best 1995).
Spermophilus annulatus eats fruits and nuts and may also consume insects. Oil palm, mesquite, and cactus seeds are eaten, as well as the fleshy fronds of Opuntia cactus, figs, and other wild fruits and seeds. In agricultural areas they eat corn and the seeds of other agricultural plants. They can climb to the ends of branches in search of fruits and seed pods and will dig for seeds as well.
Animal Foods: insects
Plant Foods: seeds, grains, and nuts; fruit
Primary Diet: herbivore (Frugivore , Granivore )
Although ecosystem roles of S. annulatus have not been described in detail, they impact plant regeneration through their seed predation and may help to disperse the seeds of some plants. They may also act as an important prey base for birds of prey and other predators.
Predation on S. annulatus has not been described but it is likely that they are taken by a variety of small to medium-sized predators, especially birds of prey. They are agile, vigilant, and seek refuge in burrows and cavities to avoid predation.
Known prey organisms
This list may not be complete but is based on published studies.
Life History and Behavior
Communication has not been studied in S. annulatus. However, Spermophilus species in general communicate with sounds, body language, by way of smells, and by touch, as do most mammals. Ground squirrels are known for the range of vocalizations they use, from whistles and chatters to trills and buzzes. S. annulatus is known to emit shrill whistling noises when alarmed. Specific warning vocalizations that distinguish between terrestrial and avian predators are known in other Spermophilus species. Some species have been recorded "kissing" when they meet and using scent marking. Ground squirrels perceive their environment using this same suite of senses.
Communication Channels: visual ; tactile ; acoustic ; chemical
Perception Channels: visual ; tactile ; acoustic ; vibrations ; chemical
The lifespan of S. annulatus is not known. Other Spermophilus species live for a maximum of 11 years (S. beldingi), but typically for about 3 to 4 years in males and 4 to 6 years in females. The higher male mortality is a result of the risks associated with male-biased dispersal.
The mating system of S. annulatus has not been described. In other Spermophilus species, males compete for access to females as they emerge from hibernation in the spring.
The breeding season of S. annulatus is in the dry season (December to June). Little has been published on the reproduction of this species, however other species in the genus Spermophilus breed once yearly, have a gestation period of approximately 30 days, and have 3 to 6 young in a litter.
Breeding interval: Breeding occurs once yearly.
Breeding season: Breeding occurs from December through June.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Parental care has not been studied in S. annulatus. As in all mammals, females nurse and care for their young until they reach independence. In other Spermophilus species, the young are born helpless, are cared for in a nest chamber, and are weaned in the first 1 to 2 months of life. They begin making excursions from the burrow around the time of weaning. Typically male young disperse at independence but female young remain in their natal area.
Parental Investment: altricial ; female parental care
This species has a global conservation heritage status of G4 that indicates that S. annulatus is uncommon but not rare. Although population numbers are decreasing, they are not considered in danger of extinction.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
IUCN Red List Assessment
Red List Category
Red List Criteria
Relevance to Humans and Ecosystems
Much of the natural habitat of these ground squirrels is being cleared for agricultural purposes. They are considered agricultural pests in some areas because they eat fruit from orchards, corn, and other crops.
Negative Impacts: crop pest
It is not known what, if any, benefits this species provides to humans. They may act to disperse the seeds of some wild, native plants.
Ring-tailed ground squirrel
The ring-tailed ground squirrel (Notocitellus annulatus) is a species of rodent in the family Sciuridae. It is endemic to the Pacific coast region of central Mexico. It is a common species and feeds mainly on fruits and nuts. The IUCN has assessed it as being of "least concern".
The ring-tailed ground squirrel is between 383 and 470 mm (15 and 19 in) long, half of this being the tail. Compared to the California ground squirrel (Otospermophilus beecheyi) it is slightly smaller, has more slender legs and broader, less-pointed ears. The incisors are orange and the large cheek pouches open inside the mouth. The crown of the head and upper parts of the body have mixed blackish-brown and buff hairs. The chin, throat and underparts are buff. The tail is slender and not bushy, the colour being mixed buff and black above and brownish beneath, with about fifteen dark rings.
Distribution and habitat
The ring-tailed ground squirrel is endemic to western Mexico, with a range extending from the State of Nayarit to the State of Guerrero. It is a lowland species, ranging up to elevations of about 1,200 metres (3,900 ft). It occupies a range of habitat types. It may live in deciduous forests of vine-clad trees or on more open slopes among rocks. The species also inhabits the borders of cultivated fields, and oil palm (Elaeis guineensis) plantations where the ground is littered with fallen palm fronds and mesquite scrub. Its burrows are often in walls or dykes, or hidden under spreading cacti or scrub. It sometimes inhabits holes in trees.
The ring-tailed ground squirrel eats corn and other seeds, but mainly feeds on fruit and nuts. Food includes oil palm seeds, wild figs, mesquite seeds and the fleshy fruits of prickly pears (Opuntia). The squirrel may also consume insects. It mostly moves about on the ground, scurrying from one piece of cover to another, sometimes pausing to dig up some morsel or sit on its haunches to eat, holding the food in its forepaws. It sometimes climbs a few metres up a small tree and gathers food from low branches. When startled, it may rush a short way up a tree, peer at the intruder, retire round the back of the trunk and descend to the ground, running away under cover to the nearest burrow. If startled in the open it may freeze, or may run directly to a burrow, often stopping at the entrance to utter a short whistle or emit chirping notes. When moving about, it sometimes stops and stands upright on its hind feet, propping itself up with its tail. When it runs, it carries its tail in a curve, and is altogether more dainty and agile than most ground squirrels.
The ring-tailed ground squirrel is common in suitable locations within its range. The International Union for Conservation of Nature has identified no particular threats and has assessed its conservation status as being of "least concern".
- Álvarez-Castañeda, S. T.; Castro-Arellano, I.; Lacher, T.; Vázquez, E. (2008). "Spermophilus annulatus". IUCN Red List of Threatened Species. Version 2014.3. International Union for Conservation of Nature. Retrieved 3 January 2015.
- Thorington, R. W., Jr.; Hoffman, R. S. (2005). "Family Sciuridae". In Wilson, D. E.; Reeder, D. M. Mammal Species of the World (3rd ed.). Johns Hopkins University Press. p. 804. ISBN 978-0-8018-8221-0. OCLC 62265494.
- Helgen, Kristofer M.; Cole, F. Russel; Helgen, Lauren E.; and Wilson, Don E (2009). "Generic Revision in the Holarctic Ground Squirrel Genus Spermophilus". Journal of Mammalogy 90 (2): 270–305. doi:10.1644/07-MAMM-A-309.1. Archived from the original on 22 October 2011.
- Best, Troy L. (1995). "Spermophilus annulatus". Mammalian Species 508: 1–4. JSTOR 3504104.