Persistence of an Endangered Amphibian in a Fully Anthropogenic Forested Pondscape

Anthropogenic habitats can play a pivotal role in species persistence within human-modified landscapes. We examined aquatic habitat use by Bombina variegata, an endangered amphibian that relies entirely on a dense network of 157 human-made temporary ponds created by historical cart tracks and maintained through ongoing off-road vehicle activity. Over three consecutive years (2021-2023), including one year of extreme drought (2022), we investigated how pond characteristics and connectivity influenced pond occupancy, reproduction, and colonization-extinction dynamics in this anthropogenic pondscape. Pond availability closely followed precipitation: wet years (2021, 2023) supported ~25 ponds/km², while drought in 2022 led to a 90% reduction in pond formation. Adult occupancy was high in 2021 and 2023 (ψ > 0.8), and egg/larval occupancy in 2021 reached ψ = 0.70. Detection probabilities exceeded 0.75 for adults and 0.5 for larvae. In 2021, adult occupancy was best explained by connectivity metrics, suggesting dispersal-driven pond use. By 2023, occupancy was influenced by both connectivity and pond-specific features (hydroperiod, area, depth), indicating a shift toward selective site use. Between 2021 and 2023, the colonization rate was 0.50 and the extinction rate was 0.13. These findings confirm B. variegata's flexible breeding strategy and highlights the ecological value of anthropogenic pond networks for patchy populations. Conservation efforts should focus on preserving both the spatial configuration (connectivity) and functional properties (hydroperiod, pond density) of such systems. A key challenge is to manage human disturbance to sustain pond formation while avoiding stressing the amphibians and habitat degradation.