Age-Dependent Utilization of Shelters and Habitat in Two Reptile Species with Contrasting Intraspecific Interactions

Abstract

Simple SummaryIntraspecific interactions are known to affect habitat use in birds and mammals but their role in spatial ecology of reptiles is far less recognized. Our comparative study shows that species known to exhibit intraspecific predation (smooth snake Coronella austriaca) express clearly different patterns of habitat and shelter occupancy than a species with no such cannibalistic behavior (slow worm Anguis fragilis). Specifically, juvenile smooth snakes prefer sites and shelters not occupied by the adults, even despite suboptimal habitat conditions. We propose that such division indicates an avoidance of predation pressure set by larger individuals on the younger and smaller ones. On the contrary, in slow worms no tendency for intraspecific avoidance are observed, since specimens of different ages commonly share the same area and shelters. This points to higher flexibility in habitat use in slow worms, while the smooth snake population is spatially structured, with juveniles dispersed to the margins of the population range. For endangered smooth snakes, habitat conservation should therefore include a wide buffer zone to maintain the youngest fraction of the population. Future studies on habitat utilization in squamates needs to pay more attention to the social cues, a commonly overlooked aspect in the spatial ecology of reptiles.AbstractReptiles undergo worldwide decline driven mostly by habitat change. Detailed recognition of factors underlying spatial structure and habitat utilization is therefore a prerequisite of effective conservation of this group. While the body of data on spatial ecology of reptiles is rapidly growing, studies on social factors remain still underrepresented. We studied age-specific patterns of shelter use, range size, and habitat preferences in the context of intraspecific interactions in the smooth snake Coronella austriaca—known to exhibit intraspecific predation—and the limbless lizard slow worm Anguis fragilis—with no such behavior observed. Despite smaller availability of preferred microhabitats, juveniles of smooth snakes occupied habitat and shelters located at the edge of the population range that did not overlap with adults. No such pattern was observed in the slow worm. Our study indicates that intraspecific interactions affect the spatial ecology of squamates. Passive and active protection of habitat must include wide buffers to preserve the poorly detectable young fraction of the population.

Ontogenetic Habitat Use and Density of the Green Lizard (Lacerta bilineata) in Contrasted Landscapes in France and Italy

“…All these three patterns should be discussed in the light of the theory and the empirical data available for the ontogenetic habitat changes of lizards (e.g., [25][26][27]). Indeed, there is a wealth of studies highlighting that ontogenetic habitat shifts are not unusual in lizards, as they have been observed for instance in Teiidae [25], Scincidae [28], Anolidae [29], Lacertidae [30], Chamaeleonidae [31], Varanidae [32], and Anguidae [33], among others. However, previous data were relatively contrasting even on the same groups of lizards: for instance, in Anolis lizards, some studies documented a clear ontogenetic shift in habitat use (e.g., [29]), whereas other studies did not find any ontogenetic effect on the structural niche use [34].…”

Coronella austriaca (smooth snake) - mortality after prey ingestion

“…This, in turn could provide an additional explanation of why ophiophagy, including cannibalism, is relatively rarely reported in snakes (Jackson et al, 2004) and why slow worms seem not to avoid shelters already inhabited by potential predators, i.e. smooth snakes (Kolanek et al, 2019) or Vipera berus (R.J. Hodges, personal communication).…”

Habitat Use by the Rock-Dwelling Karoo Dwarf Tortoise, Chersobius boulengeri

“…Conservation action and investigations benefit from baseline knowledge of how species use their habitats. For example, juvenile Smooth Snakes ( Coronella austriaca ) used habitat not inhabited by cannibalistic adults, requiring conservation of buffer zones to facilitate juvenile survival (Kolanek et al, 2019), and the rediscovered Barbados Leaf-Toed Gecko ( Phyllodactylus pulcher ) was more successful than introduced House Geckos ( Hemidactylus mabouia ) in exposed rocky habitat, emphasizing the need to conserve natural cliffs (Williams et al, 2020). In a protected national park, the identification of seasonal habitat use by Latifi's Viper ( Montivipera latifii ) informed the park's management procedures (Behrooz et al, 2015).…”