Possible implications of weather variation on reproductive phenology of European common toad in southeastern Europe

We tracked yearly variation in breeding phenology in relation to weather parameters in a common European toad population from the southeastern part of its range. Phonological data were collected from 2001 to 2003 and from 2011 to 2017 and compared to open-access daily weather data from a nearby weather station. Data analysis revealed no significant effect of weather on initiation of breeding and a negative relationship between mean daily humidity and mean cloud cover on the duration of breeding season (P = 0.03). Further analysis showed a decreasing trend in breeding season humidity in the past 70 years. Our results predict a tendency toward longer toad breeding seasons in years with drier winter/spring. A projected decrease in humidity in this region could prolong toad breeding season, potentially exposing adults to higher predation. Therefore, the scenario of further decline in our study population should be considered and conservation measures planned accordingly.