How far can a tortoise walk in open habitat before overheating? Implications for conservation

Sylvain Moulherat (1, 2, 3) , Virginie Delmas (1) , Tahar Slimani (4) , El Mouden El Hassan (4) , Tarik Louzizi (4) , Frédéric Lagarde (1) , Xavier Bonnet (1)

1 CEBC - Centre d'Études Biologiques de Chizé - UMR 7372
2 SEEM - Station d’Ecologie Expérimentale du CNRS à Moulis
3 TerrOïko
4 Faculté des Sciences Semlalia [Marrakech]

Terrestrial chelonians are threatened worldwide by habitat destruction and illegal harvesting. Tortoises are slow moving animals susceptible to dehydration and overheating during movements in open habitats. Many species inhabit arid steppes where the availability of thermally buffered refuges (e.g. burrows) is a limiting factor. Determining the maximal distance between refuges that individuals can safely traverse during the active season is thus essential. We examined the relationship between body temperature variations and movement patterns in adult Testudo graeca in the arid steppes of Morocco. Using physical and mathematical models, our results suggest that during the active season adults cannot travel more than 1 km without serious risk of overheating. However, radio-tracking suggests that free-ranging individuals are behaviourally limited to 0.5 km trips between refuges. Overall, maintaining a distance less than 0.5 km between refuges (e.g. through bush planting) is essential to limit fragmentation and to retain healthy populations. This restoration would also benefit to many other species that depend on bush-refuges.

Mots clés: Body temperature; Conservation management; Ecophysiology; Functional connectivity; Refuges

Domaines: Sciences de l'environnement

Sylvain Moulherat, Virginie Delmas, Tahar Slimani, El Mouden El Hassan, Tarik Louzizi, et al.. How far can a tortoise walk in open habitat before overheating? Implications for conservation. Journal for Nature Conservation, 2014, 22, pp.186-192. ⟨10.1016/j.jnc.2013.11.004⟩. ⟨hal-00977524⟩