Studies in Texas revealed a number of parasites associated with S. mexicanus, including nematodes, spirachaete, two species of mites and one species of flea. (Doran 1955; Eads and Hightower 1952; Whitaker and Wilson 1974; Edwards 1946)
Perception Channels: tactile ; chemical
The species is not threatened and by all accounts thriving in its southwestern habitat.
IUCN Red List of Threatened Species: least concern
Due to its burrowing and digging, the Mexican Ground Squirrel can cause a bit of damage to farmland and golf courses. They can also damage crops in the spring when they typically consume grain, nuts, seeds and fruits.
As an insectivore during the summer months, S. mexicanus greatly benefits man by controlling the insect population and reducing the need for harmful and costly pesticides.
The Mexican Ground Squirrel,is omnivorous and like other ground squirrels is adapted for life on the ground foraging for seeds, nuts, roots, bulbs, plant stems, leaves, mice, insects and eggs (Walker 1975). Like other ground squirrels, S. mexicanus typically is active and feeds during the day. Once it finds seeds, nuts or grains, it is able to store them in cheek pouches and carry them to storage chambers within the burrow (Walker 1975). The food habits vary seasonally. In the spring the diet is distinctively herbivorous, consisting of mesquite beans and leaves, nuts and fruits. Studies in New Mexico suggest that S. mexicanus occasionally climb low bushes and forage for seeds and fruits (Bailey 1932). However, in the early summer, half the diet is composed of insects commonly encountered in the squirrels burrows. The species also consumes meat and can be seen eating roadkill on highways, and does seem to have cannabalistic tendencies (Davis 1974).
The Mexican Ground Squirrel ranges from Northern Mexico to along the Gulf coast of Texas, extending to western and central Texas and into southeastern New Mexico (Young and Jones 1982).
Biogeographic Regions: nearctic (Native ); neotropical (Native )
The species inhabits level grasslands and typically avoids rocky areas. It is typically found in sandy and mesquite regions of savannas. The species is well adapted for digging and burrowing and makes its home in underground burrows. The burrows are not marked externally. An individual occupies more than one burrow, with many escape burrows in addition to the home. The home burrows are 60 to 80 mm in diameter and reach a depth of 125 mm, while the refuge and escape burrows are not as deep. The burrows can also be found on golf courses, cemeteries, and along highways (Young and Jones 1982).
Terrestrial Biomes: savanna or grassland
The pelage of S. mexicanus is dense and of moderate length; the dorsal coloring is variable and ranges from olive gray to brown with rows of squarish pale and whitish spots. The head has the same coloring as the the dorsum except the tip of the nose is either yellow or cinnamon and there is a white orbital eye ring. The feet and undersides are white to pinkish (Davis 1974)
The tail is flattened and somewhat bushy with a cylindrical base; the color is grayish white mixed with black and its length ranges from 110 to 134 mm and is less than half the total body length, which ranges from 300 to 350 mm (Mearns 1907; Young and Jones 1982). The skull length is 43 to 44 mm and lightly built with prominent pareital ridges. The dental formula is the same as other scuirids. These squirrels have narrowly triangular cheek teeth with high crowns and lophs (Young and Jones 1982).
The species S. spermophilus is distinguished from other species in the subgenus Ictidomys by its 9 rows of pale and whitish spots on the dorsum, and from other ground squirrels by the absence of a continous metaloph on the fourth premolar (Young and Jones 1982).
Other Physical Features: endothermic ; bilateral symmetry
The breeding season occurs in late March and early April, lasting one to two weeks. The period of gestation is 23 to 28 days, with parturition occuring in early May with a litter size from 2 to 13 (Walker 1975). Unlike many other species of scuirids, S. mexicanus only produces one litter per year (Lawlor 1979; Walker 1975). The mother builds a brooding chamber off of the deepest portion of a burrow that is 180 to 200 mm in diameter. The chamber contains a nest of mesquite and grasses. After the young have left, the nest is removed to the sleeping area and the brooding chamber is filled in (Young and Jones 1982). At birth the young weigh from 3 to 5 grams, and are toothless, naked, blind and are covered with and unpigmented fuzz. Although rather helpless and altricial at birth, the young develop rapidly and are completely independent 3 months after birth. The young occupy old or refuge burrows and do not breed until the following spring. (Young and Jones 1982). The lifespan of S. mexicanus is from 2 to 5 years (Walker 1975).
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sexual
The Mexican ground squirrel (Ictidomys mexicanus) is a species of rodent in the family Sciuridae.[2] It is found in Mexico and the United States. One of its closest relatives is the thirteen-lined ground squirrel (Ictidomys tridecemlineatus).[2]
The Mexican ground squirrel is a small to medium-sized rodent with nine rows of white spots on its back.[3] It is about fifteen inches in length and the males are larger than the females.[3] It also has small white circles of fur around its eyes and small ears.[3]
The Mexican ground squirrel is found in northern Mexico, the Texas Gulf Coast, western and central Texas, and southeastern New Mexico.[4] The Mexican ground squirrel lives in flat, brushy, or grassy areas and usually prefers areas with gravelly or sandy soil or areas with that have mesquite.[4]
While much of its original habitat has been destroyed by humans, it has adapted well to human civilization and can now be found on golf courses and other grassy areas such as the sides of highways.[4] Each squirrel normally has more than one burrow and each of them have as many as five escape tunnels.[4] The tunnels are not marked by a mound of dirt on top. Most burrows have a sleeping chamber for the offspring which is lined with grasses.[4]
The Mexican ground squirrel is omnivorous, but eats primarily seeds and grains.[4] Its diet includes seeds, nuts, grains, roots, bulbs, plant stems, leaves, mice, insects, and eggs.[4] It often stores seeds, grains, and nuts in its cheeks pouches and takes them back to its den to eat later. In the summer it eats insects. It has also been documented seen eating roadkill.[4]
The mating season of the Mexican ground squirrel lasts from April to mid July, with a peak in May.[5] Females can mate after their first season of hibernation.[5] It is common for most Mexican ground squirrels to hibernate, but there have been cases where they have not.[5] The species is normally solitary, but come together in groups during the mating season.[5] It has been found that female hormone levels change during this period to allow the coming together of groups without aggression.[5] During the mating season, The female will prepare a nesting chamber in her burrow and line it with mesquite and grass. The average litter size is five, but can range from one to ten.[5] The young are born toothless, without fur, and will stay with their mother for three months before leaving to live on their own.[5]
The Mexican ground squirrel has evolved an interesting adaptation to help it survive after being attacked by some snakes.[6] It has developed resistance to the venom of the western diamondback rattlesnake.[6] The squirrel has an antihemorrhagic factor which neutralizes hemorrhagic activity of this specific species of rattlesnake. In addition, the squirrel's small, rear-pointing ears are effective for detecting predators.[4]
{{cite web}}: Missing or empty |url= (help) {{cite journal}}: Cite journal requires |journal= (help) The Mexican ground squirrel (Ictidomys mexicanus) is a species of rodent in the family Sciuridae. It is found in Mexico and the United States. One of its closest relatives is the thirteen-lined ground squirrel (Ictidomys tridecemlineatus).
