Busy as a toad: Movement patterns and daily activity in the terrestrial amphibian Rhinella arenarum

Animals exert daily rhythms where they switch between active behavior, such as foraging, mating or exploration, and periods of quiet rest. This activity balance is regulated by both circadian factors, such as the daily photoperiod, and behavioral and physiological needs that drive the search for food, water or social interaction. In this pilot study we aimed to determine the main activity patterns in the terrestrial toad, Rhinella arenarum. Our hypothesis, based on a previous field study, is that R. arenarum displays crepuscular/nocturnal activity and that its movement out of the shelter is mainly governed by ambient humidity and water availability. We captured adult male and female toads (n=7) and habituated them to lab conditions. We recorded each toad’s activity for a week using a designed home-cage with two available shelters, a wet and a dry zone and an IR camera on top. Animals were tracked using machine-learning-based tools and customized software to extract home occupancy, movement patterns and distance travelled. According to our field findings, toads spent a considerable amount of time in their preferred shelter, especially during the light phase. During nighttime, toads significantly increased their movement and distance travelled. The results are being compared with other amphibian species studied in a similar setup. Our longer-term aim is to use this activity information to study sleep/wake habits and extract neurophysiological activity in these amphibians.