Multi-season occupancy reveals benefits of predator control for an endangered venomous snake

Restoring small, fragmented populations often requires addressing predation pressure alongside habitat restoration. We evaluated whether a targeted predator management contributes to the recovery of the critically endangered Hungarian meadow viper (Vipera ursinii rakosiensis) in the Pannonian sand steppes of central Hungary. We monitored viper detection–nondetection in 63 permanent plots over ten primary survey seasons, each with ten secondary survey replicates, and fitted multi-season occupancy models to estimate initial occupancy (ψ), detection (p), colonisation (γ) and extinction (ε). Detection heterogeneity was modelled with operative temperature, day of year and observer skill. Predator control effort was calculated from the results of targeted predator control on red foxes, European badgers, golden jackals, hooded crows and magpies that were area-standardised by hunting associations and expressed as proportional control relative to the season-specific total removal. Naive occupancy across primary seasons averaged 0.32 ± 0.03 (mean ± SE), with at least one detection in 82.5 percent of plots. Model selection and averaging indicated that the probability of viper colonisation increased, whereas that of extinction decreased with intensity of predator control. Effects of reintroduction of ex situ bred vipers did not influence occupancy dynamics at the study scale. Mean site occupancy increased by about 11 percentage points over the study, consistently across the two assessed viper populations. Our results show that predator control can complement viper-friendly grassland management and reintroductions to improve population persistence in open habitats.