Monitoring reproduction in cryptic small mammals; using body temperature to identify parturition in an endangered rodent

As biodiversity continues to decline, accurate monitoring of endangered species reproduction has become essential for informed conservation strategies. However, tracking reproductive events in cryptic species, such as burrowing mammal, can pose serious technical challenges. Reproduction often affects body temperature (T°b) in mammals. In this study, we propose to exploit T°b monitoring as an alternative method to detect parturition events in a cryptic rodent, the common hamster Cricetus cricetus. The T°b of hamsters was monitored throughout the reproductive season in controlled conditions (n=19 females) and in a mesocosm (n=67 females). In the laboratory, females showed elevated T°b from male arrival to the end of pup rearing. T°b characteristically varied on parturition days, when females showed a rapid rise in mean daily T°b (<0.5°C) to levels exciding 38.5°C. The following T°b trend was impacted by the number of pups reared by the mother. In wild like conditions, this pattern allowed us to estimate a total of 123 parturition events. T°b analyses thus provide a reliable mean to estimate litter numbers and birth dates in the wild. This method represents an efficient complementary tool for monitoring reproduction in the common hamster, that could be easily extended to other cryptic mammals.