Differential longevity in free-living smooth snakes Coronella austriaca

During a 31-year study (1992–2022) of reptiles inhabiting a 10 ha area of lowland heath, within a planted coniferous forest in southern England, UK, smooth snakes Coronella austriaca Laurenti, 1768, were individually marked with passive integrated transponder tags. New-born smooth snakes were also captured, measured and weighed to estimate size at birth. Growth curves were estimated for females and males which, combined with their estimated size at birth, provided an estimate of age at the time of death. The estimated mean age at death of females (7.8 years) was significantly lower than that of males (10.1 years), with females and males reaching a maximum age of 15 and 25 years respectively. Reproductive effort was considered as a possible explanation for the observed reduced longevity of females compared to males. Female reproductive success increased between 4 and 10 years of age and then declined in the largest breeding individuals, regardless of age. This finding suggested the possible presence of size/growth-related reproductive senescence. This is the first known study to provide reliable estimates of longevity in free-living smooth snakes. It demonstrated a significant difference between females and males in both mean and maximum ages attained, and the potential impact of breeding stress as an explanatory factor for increased female mortality and reproductive senescence. Keywords: predicted age, body size, SVL, reproductive output, senescence