Evidence of artificial-refuge avoidance in the Ladder Snake (Zamenis scalaris) and the Montpellier Snake (Malpolon monspessulanus)

Artificial refuges are increasingly used as mitigation tools to provide alternative shelters for reptiles affected by habitat disturbance, but their short-term effectiveness remains poorly assessed, particularly in Mediterranean snakes. During construction works in southern France, six snakes (3 <i>Zamenis scalaris</i> and 3 <i>Malpolon monspessulanus</i>) were captured in the impacted area, fitted with VHF transmitters and released directly into artificial shelters within large-mesh fenced enclosures that allowed snakes and other fauna to move in and out freely. These enclosures preserved fragments of natural habitat from heavy construction impacts, while remaining connected to surrounding habitats. Radio-tracking (September 2024 - May 2025) revealed that all individuals left the artificial refuges immediately after release and never reused them, even during or after hibernation. Instead, they consistently selected nearby natural shelters, mainly sun-exposed rodent burrows. During this period, home ranges (MCP) varied between 2.86-8.79 ha in Z. scalaris and 0.54-3.78 ha in M. monspessulanus, a seasonal pattern that does not reflect their annual space use. This study provides the first experimental evidence that, in these two species, artificial refuges are ineffective in the short term, even when used as initial re-introduction sites. In contrast, fenced enclosures proved effective as an immediate mitigation measure, whereas artificial shelters may require long-term ecological stabilisation before becoming functional.