An improved pitfall trap design for large-scale removal of invasive Podarcis siculus on Mediterranean islets

Pitfall traps are widely used to capture surface-active reptiles, but standard designs may involve logistical constraints and risks of trap-induced mortality when used intensively under extreme environmental conditions. Efficient trapping systems are particularly important in management programmes targeting invasive lizards on small islands, where large numbers of individuals must be removed, while minimising bycatch and heat-related mortality. Here, we describe a modified pitfall trap design developed during a large-scale removal campaign, targeting the invasive Italian wall lizard ( Podarcis siculus ) on two small Mediterranean islets (Aeolian Archipelago, Italy). The modified traps include a removable upper chamber for rapid specimen retrieval, an integrated shading system and structural elements designed to reduce predator access and trap overheating. A total of 346 traps were deployed and activated for 88 days (30,448 trap-days) between June and November 2025, yielding 4,965 captures of P. siculus (mean 14.4 individuals per trap; 0.16 individuals per trap-day) with very low mortality (< 1.5%) and limited arthropod bycatch (< 10% of traps). Mean trap inspection time was 38 s per trap, allowing two operators to inspect the entire network daily in 1 h 50 min on average, thereby facilitating rapid trap inspection and lizard retrieval in large-scale operations. All traps remained structurally stable throughout deployment. Our results indicate that the modified trap design provides a robust, low-cost and low-mortality option under extreme Mediterranean summer conditions and appears especially suitable for large-scale intensive management and removal programmes targeting invasive lacertid lizards on small islands.