The Eurasian ground squirrel that spends nearly nine months of the year asleep

Nature · Published 3 October 2026 Swipe more like this →

In short: Known as sousliks or spermophiles, these resilient rodents are masters of the Eurasian steppe. While they are social creatures that rely on high-pitched alarm calls to evade predators, they are also champions of dormancy, capable of hibernating for up to eight and a half months to survive harsh, arid conditions.

The genus Spermophilus, whose name translates from Greek as seed-lovers, comprises 18 distinct species of ground squirrels native to Eurasia. Once a much broader classification that included North American relatives, the genus has been refined through genetic study to exclude groups like prairie dogs and marmots. These animals are uniquely adapted to open, low-growing habitats, ranging from the Eurasian steppe to agricultural fields and even airports. Their reliance on open space is a survival strategy; because they are diurnal and lack complex camouflage, they depend on clear lines of sight to spot predators like eagles and polecats.

Life for a Spermophilus is defined by extreme cycles of activity and rest. To cope with the scarcity of food and water in their arid environments, they spend significant portions of the year in hibernation or, in particularly dry regions, aestivation. In some species, this period of dormancy can stretch to nearly eight and a half months. When active, they live in colonial burrows, which serve as both nests and essential refuges. Their social structure is maintained through vocal communication, with high-pitched calls used to warn neighbors of approaching threats.

The evolutionary history of the genus is complex, with four major clades diverging during the Late Miocene. Recent research, including a 2024 study by Simonov et al., has clarified their taxonomy, even incorporating fossil evidence from the Pleistocene. While they are ecologically important, their relationship with humans has historically been fraught. Beyond their role in the ecosystem, these squirrels have been known to carry fleas capable of transmitting diseases, and their extensive tunneling can cause structural damage to human settlements. Despite these conflicts, they remain a vital component of the grassland biodiversity they inhabit.

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