04. Aggregation and movements of male ocellated lizards [Timon lepidus] during hibernation in mainland France observed with an endoscope

D to environmental constraints, winter aggregations of squamates otherwise considered solitary are becoming increasingly common worldwide (Gardner et al., 2015). Community aggregations in lizards are little known and probably underestimated (Gardner et al., 2015) although certain European species are known to aggregate for hibernation, for example Agama stellio (Loumbourdis, 1983), Chalcides chalcides (Capula et al., 2003), Anguis fragilis (Karch, 2022), and Zootoca vivipara (Hodges & Seabrook, 2022). Ocellated lizards generally hibernate from November to March depending on temperature (Matéo, 2017) but for reptiles suitable hibernation sites are scarce in the wild (Whiting & Wile, 2017) and crucial for their survival (Bonnet et al., 2009). Ocellated lizards occupy a network of refuges both to avoid predation in the reptile active period and to act as a hibernacula (Tatin et al., 2013), but only two or three of these refuges are used regularly (Grillet et al., 2010). It would appear that in continental Europe the ocellated lizard is a territorial and solitary species (Vincente, 1989) but, in contrast, island populations have developed pronounced social behaviour due to environmental constraints. Consequently, in France, on the island of Oléron, communal refuges are known (Doré et al., 2015) and in Portugal, on the island of Berlenga, a communal hibernaculum has been reported (Paulo, 1988). Given that suitable hibernation sites are essential for the survival of ocellated lizards, a knowledge of their physical characteristics and how they are used is crucial for effective conservation. We set out to characterise a hibernaculum in a small population of ocellated lizards in a Mediterranean almond grove. After the discovery and confirmation of the existence of a communal hibernaculum, we filmed the occupants during hibernation and made several associated temperature measurements. The research reported here was undertaken in the framework of the French PNA (National Action Plan) on the ecology of this threatened species (Thienpont, 2020).