Perote Ground Squirrel

Perote ground squirrels have traits similar to those of spotted ground squirrels (X. spilosoma pallescens) found in the northern Mexican Plateau; however they are larger, have shorter tails and yellow backs. Its skull is relatively narrow with a large braincase and they have heavy, thick teeth. Perote ground squirrels have two annual cycles, an active phase (March–November) and a hibernation phase (December–February). Some overlap may occur in March and November however. X. perotensis was first described as a species in 1893. Much research is being done recently, and many scientists think it should be classified as a subspecies of X. spilosoma. "In either case, and regardless of the position one might adopt around species concepts, it is evident that X. perotensis constitutes an independent and isolated biological entity that has evolved under restricted geographical and ecological contexts as a consequence of recent Pleistocene events".

The habitat range of the Perote ground squirrel is in the Oriental Basin (5250 km2) between Puebla and Veracruz. The basin is surrounded by high mountains thought to have arisen from volcanic activity. This also accounts for the pockets of arid and semiarid land. The semiarid land in Perote is the most humid in the area with an average rainfall of 369.77 mm between June and September. The average temperature is 11.9 °C with highs of 14.73 °C and lows of 8.80 °C. Perote ground squirrels only live in alkaline grasslands, arid scrubs and hilly, rocky areas where they will dig their burrows. However, due to agriculture, overgrazing, and the urbanizing of the area, the suitable habitat for the squirrel is down to 16 small localities. These areas are mostly narrow strips (20–50 m) separated by an average distance of 15.8 km. This species is threatened by extensive habitat fragmentation and deforestation within its restricted range due to timber extraction and clearing of forest for agriculture. While the squirrel once occupied a range of approximately 5250 square kilometers, it now only occupies an area totaling 2457 square kilometers. The Oriental Basin is surrounded almost entirely by a belt of temperate mountain ranges, which prevent the squirrel from dispersing to new habitat. …

X. perotenses is a generalist species in its diet. It is mostly found in croplands and open areas with low vegetation. In most studies, researchers bait traps with oats in order to catch individuals.

Perote ground squirrels form family groups within individual burrow systems. In some cases males will leave the burrow to locate females in dispersed areas. This causes aggression between adults and yearling males that ultimately leads to further male migration. Adult males become active in March (before sub-adults and females). Copulation occurs between April and May and pregnant and/or lactating females were most common in June–August. The average number of embryos was found to be six, where the average number of live juveniles was four. Due to the habitat destruction and fragmentation of land, there are fewer opportunities for breeding between genetically diverse individuals. Perote ground squirrels have been seen mating within their own family, which may lead to inbreeding. However, results have shown that "no inbreeding coefficient value for any population was significantly different from zero, implying that inbreeding had little effect on genetic structure."