Lunar phase as a cue for migrations to two species of explosive breeding amphibians—implications for conservation

In species with explosive breeding strategies, large numbers of individuals may congregate at a defined location for a very short period of time. Effective synchronisation in arrival at breeding sites is crucial to ensure mating success. Amphibians with explosive breeding strategies often congregate at ponds for only a few days or weeks a year. Previous research has shown that frogs and toads may use a variety of exogenous cues to initiate breeding migrations which include temperature, rainfall and lunar cues. Although the effects of temperature and rainfall on amphibians are widely studied and understood, the impacts of lunar phase are poorly known and vary by species and location. In this study, we examined the effects of lunar phase on the numbers of common toads (Bufo bufo) and common frogs (Rana temporaria) migrating to breeding ponds at 43 sites across the UK over 4 years. Our findings show that peak migration of both common toads and common frogs coincides with the waxing phase of the moon, peaking around the full moon. Temperature and rainfall also had an effect on peak migrations with the highest numbers of common toads and common frogs occurring on warm and damp evenings close to a full moon. Our results have implications for amphibian conservation initiatives such as ‘Toads on Roads’ as they will help inform conservationists on the most effective timing to help toads and frogs across roads.