Warm Spring Weather Alters Calling Phenology of Four Sympatric Early-Breeding Anurans

Changes in phenological patterns in breeding behavior are useful for determining the effect of climate change on amphibian communities, many of which are declining and at risk of extinction. Most climate change research focuses on long-term warming trends with less consideration for the increasing frequency of extreme weather events. The calling probability of four early spring-breeding anurans, including the boreal chorus frog (Pseudacris maculata), spring peeper (Pseudacris crucifer), wood frog (Boreorana sylvatica), and American toad (Anaxyrus americanus), was determined using autonomous recording units from 2022 to 2025. An unusually warm March in 2024 ("false spring") followed by freezing temperatures allowed us to assess the impact of a weather event on the calling probability of the four anuran species. Coinciding with the warmer temperatures in March, the first date of calling was advanced by 11-18 days in 2024 compared to 2022. However, the probability of calling was reduced in 2024 for all species except the spring peeper, which had the highest probability of calling in that year. The probability of calling in boreal chorus frogs decreased from 69% in years with average weather to 49% in 2024, which may lead to negative fitness consequences for this declining species. This study exemplifies the species-specific response of spring-breeding anurans to seasonal and environmental variables, highlighting the potential impact of weather events on calling behavior. Phenological shifts can create mismatches between the timing of reproduction and the availability of resources important for the survival of offspring, thus negatively impacting recruitment and persistence of local anuran populations.