The round-tailed ground squirrel (Xerospermophilus tereticaudus ), known as "Ardillón cola redonda" in Spanish, live in the desert of the Southwestern United States and Northwestern Mexico. They are called "ground squirrels" because they burrow in loose soil, often under mesquite trees and creosote bushes.
Round-tailed ground squirrels are comparatively small animals with grayish-brown coloring that matched the sandy soils of their environment. Their unique characteristics are, most noticeably, their long, slender, rounded tail, and secondly, their long, wide, hairy hind feet. Their claws and their small ears positioned low on the head, enable them to live underground in a lifestyle that is semi-fossorial. They are often mistaken for prairie dogs or gophers, but prairie dogs are much larger and gophers do not forage above ground. There is scarce information about the lifespan of this species but one individual born in the wild lived to 8.9 years in captivity.
Round-tailed ground squirrels inhabit northern Mexico and the southwest United States, including Arizona and California. They live in parts of the Mojave, Colorado and Yuma deserts where the habitat features extreme temperatures and low humidity. They favor flat, sandy areas like creosote scrub vegetation.
These squirrels are diurnal and most active during the morning and evening, avoiding the most extreme heat by going into their burrows at midday or finding shade under a plant. They will climb into bushes to obtain leaves and also to avoid the sun and the hot sand. Their social organization is semi-colonial, but they have individual burrows, and other squirrels are chased away if approaching too closely. Males are dominant during the breeding season (January to March) and females during the period of raising the young (March to April). They don't hibernate, but during the colder months, from late September or the beginning of October these animals are in a state of torpor, except for some areas where they remain active all year round. Round-tailed ground squirrels communicate with whistles, a warning being a single whistle, whereupon another squirrel in the area will run to its burrow and then look around.
Round-tailed ground squirrels are omnivores. The diet includes a big proportion of green vegetation (80% or more), and also seeds and some insects.
Round-tailed ground squirrels are polygynandrous (promiscuous), with both males and females having multiple mates. Breeding is from January to April and gestation lasts 25 to 35 days. The average little size is 6, the largest litter recorded being 12. The average weight at birth is 3.7 g, and babies are hairless and their eyes and ears are closed. At 25 days old a squirrel is capable of coordinated running. Weaning occurs at 5 weeks. Round-tailed ground squirrels become reproductively mature when they reach 10 to 11 months of age.
There are no major threats to Round-tailed ground squirrels at present.
According to IUCN, Round-tailed ground squirrel is common to very common throughout its range but no overall population estimate is available. Today this species’ numbers remain stable and it is classified as Least Concern (LC) on the IUCN Red List.
Due to being omnivorous, it is likely that this species has some impact on insect and plant and populations and their digging of burrows contributes to soil aeration.
