Age and size of wood frogs, Rana sylvatica, from Kuujjuarapik, Northern Quebec

Abstract

Length and age of 53 Wood Frogs, Rana sylvatica, from Kuujjuarapik in northern Quebec (55°17'N) were compared with similar data from populations in more southern latitudes. Age was estimated by skeletochronology. Mean snout-urostyle length and age were 47.1 mm and 6.1 years in adult males (n = 41) and 50.9 mm and 7.7 years in adult females (n = 8). There was no significant correlation between age and size. The youngest mature males and females were 4 and 6 years old respectively. Mean physiological longevity (mean age in years multiplied by annual number of frost-free days) was 397 days for males and 504 days for females. Comparisons with other populations suggest that sexual dimorphism in size, age, and longevity are species characteristics. Size and age increase with latitude in lowland populations. Physiological longevity is positively related to body size in males from lowland and upland populations. The data do not support the hypothesis that maturity at an early age in males curtails their potential life span. They are consistent with the prediction of longer life span at lower ambient temperatures. In female Wood Frogs, physiological longevity does not follow geographical variation in adult body size.