Artificial Shelters as a Monitoring and Conservation Tool for Terrestrial Breeding Frogs

Amphibians are among the most threatened vertebrate groups, yet monitoring cryptic, fossorial species is difficult and often risks disturbing both their microhabitats and the individuals themselves. We tested whether artificial shelters could serve as a monitoring and potential conservation tool for cryptic fossorial amphibians in natural habitats. We deployed two different artificial shelter designs (concrete and wood) in the Australian Wet Tropics and assessed the number of Austrochaperina robusta, a terrestrial-breeding microhylid frog, using them over 2 years. Monthly shelter surveys recorded the highest frog numbers in the cooler, drier months, indicating clear seasonal trends. Sliding-window analyses showed that frog numbers under concrete, but not wooden, shelters declined with warmer minimum temperatures over the 6 days pre-survey. Frogs used concrete shelters more (75% of records) compared to wooden shelters. This was partly because the concrete shelters did not degrade with time, but also likely reflects thermal buffering benefits. Microclimate logging indicated that concrete shelters provided greater daytime heat storage and slower nocturnal heat release than the wooden shelters. Invertebrate presence was weakly negatively associated with frog numbers, while greater understory cover and closer shelter spacing were stronger positive predictors of frog abundance. While most observations were of adult frogs, juveniles and metamorphs were also observed under both shelter designs. Additionally, six egg clutches were recorded, all under concrete shelters. Collectively, these results show that artificial shelters, especially concrete designs, offer a robust, low-impact method for long-term monitoring of fossorial frogs and may contribute to conservation by providing thermally favourable refugia and protection from disturbance.