Rodents Inhabiting the Southeastern Mu Us Desert May Not Have Experienced Prolonged Heat Stress in Summer 2022

SIMPLE SUMMARY: Rodents in the Mu Us Desert may respond to increasing summer heat through behavioral or physiological adjustments. We studied the ambient temperatures that Meriones meridianus and Meriones unguiculatus might experience in their habitats. The results showed that both the heat-sensitive Meriones meridianus and the heat-tolerant Meriones unguiculatus were threatened by extreme summer heat. In addition, although vegetation and rodent burrows increased the variety of ambient temperature in the habitat, only rodent burrows were effective in providing protection from the stress of extreme summer heat. Therefore, behavioral adjustments may be the major way in which small rodents in this region avoid continuous heat stress in summer. ABSTRACT: Climate change combined with human activities has altered the spatial and temporal patterns of summer extreme heat in the Mu Us Desert. To determine how those rodents living in the desert respond to increased extreme heat in summer, in July 2022, during the hottest month, we examined the rodent species, vegetation coverage, and small-scale heterogeneity in ambient temperature in the southeastern Mu Us Desert. The results showed that Meriones meridianus, Meriones unguiculatus, and Cricetulus longicaudatus were found in the study area, where the vegetation coverage is 33.5–40.8%. Moreover, the maximum temperature of the desert surface was 61.8 °C. The maximum air temperature at 5 cm above the desert surface was 41.3 °C. The maximum temperature in the burrow at a depth of 15 cm was 31 °C. M. unguiculatus might experience 4–9.3 h of heat stress in a day when exposed outside the burrow, whereas M. meridianus would experience 8.5–10.8 h of heat stress. Yet, inside the burrow, both species were barely exposed to heat stress. In conclusion, adjustments in behavioral patterns can be the main way that rodents in the Mu Us Desert adapt to the extreme heat in the summer.