Shelter availability, stress level, and digestive performances in the aspic viper

Abstract

Summary The lack of shelter can perturb behaviors, increase stress level, and thus alter physiological performances (e.g. digestive, immune, or reproductive functions). Although intuitive, such potential impacts of lack of shelter remain poorly documented. We manipulated shelter availability, environmental and physiological variables (i.e. access to a heat source, predator attack, feeding status) in a viviparous snake. We assessed sun-basking behavior, digestive performance (i.e., digestive transit time, crude estimate of assimilation, regurgitation rate) and plasma corticosterone levels (a proxy of stress level). Shelter deprivation provoked a strong increase in sun-basking behavior and thus elevated body temperature; even in unfed individuals for which energy savings would have been otherwise beneficial. The lack of heat was detrimental digestive performance (i.e. all the metrics used to assess it). Simulated predator attacks worsened the situation and entailed a further deterioration of digestion. The combination of the lack of shelter with cool ambient temperatures markedly elevated basal corticosterone level and was associated with low digestive performance. This hormonal effect was absent when only one negative factor was involved, suggesting a threshold response. Overall, our results revealed important non-linear cascading impacts of shelter availability on stress-hormone levels, behaviors and physiological performance. These results infer shelter availability is important for laboratory studies, captive husbandry, and possibly conservation plans.