Effects of large‐scale heathland management on thermal regimes and predation on adders Vipera berus

Abstract

Management prescriptions for species of conservation concern often focus on creating appropriate habitat conditions, but the spatial scales over which these actions are applied can potentially impact their success. In north-western Europe, preventing further loss of lowland heathland through successional changes often involves the mechanical removal of vegetation, creating large blocks of open homogenous habitat. We investigate the influence of this broad-scale habitat management on a heathland specialist, the adder Vipera berus. By deploying temperature loggers and Plasticine adder models in heathland areas with and without complex vegetation cover, we show that (1) cleared areas lack both the temperature variation adders need to thermoregulate effectively and suitable refuges from dangerously high summer temperatures, and (2) attacks by dogs and trampling by grazing livestock are significantly more frequent in cleared areas and closer to footpaths. Habitat management strategies that retain some structural complexity of vegetation within cleared areas, and diverting footpaths away from cleared areas and/or strategic placement of barrier hedging around these areas could potentially reduce the exposure of adders to high predation risk and thermal extremes.

Predation risk is a function of seasonality rather than habitat complexity in a tropical semiarid forest

“…In addition, birds selectively attacked the replicas' head and more often on replicas placed in trees than on the most available microhabitats with them (soil and rock), indicating that they perceived lizard replicas as real prey items and were aimed to attack the most vital body region of their target organism in its main foraging microhabitat. This outcome was expected based on behavior of predators observed in other studies 14 , 18 , 19 , 22 , 46 – 48 .…”

Fine‐scale vegetation complexity and habitat structure influence predation pressure on a declining snake

“…Previous studies working on similar topics have observed comparable results. For instance, Worthington‐Hill & Gill (2019) demonstrated the effect of large‐scale clearance in UK heathlands inducing higher predation risk for adders. Another study demonstrated the effect of reduction in vegetation complexity on ski runs resulting in similar observations for lizards (Sato et al., 2014).…”

“…The reduction of structural complexity in basking sites can also expose reptiles to altered thermal and hydric conditions notably during summer (Dezetter et al., 2022). These stressors can lead to lethal temperatures in adders (Sato et al., 2014; Worthington‐Hill & Gill, 2019), but can also, by inducing physiological alteration, influence key life history events such as reproduction (Dezetter et al., 2021). It is therefore important to consider vegetation structural complexity with respect to abiotic (thermal and hydric quality of microhabitats) and biotic (predation pressure) consequences.…”

“…One can assume that simplified microhabitat used for basking sites do not provide appropriate shelters, leading to an increased success in predation attempts, as previously reported (Sato et al, 2014;Stellatelli et al, 2015;Worthington-Hill & Gill, 2019). On the other side, terrestrial predator efficiency is greatly improved by structural simplification as it facilitates movements across the landscape (Ferreira et al, 2018) and increases the visual detection of prey (Allen et al, 2013;Law et al, 2020).…”

Dog attacks on adders; a comment on Worthington‐Hill & Gill (2019)

“…In conclusion, we believe that the frequent dog attacks recorded by Worthington-Hill & Gill (2019) should not be regarded as predation. Instead, we suggest that, similarly to what was recorded in rodents in by Madsen (1987) and L. Luiselli (unpublished data), the dogs were attracted to the models by olfactory cues, resulting in that the dogs nibbled on the models to investigate whether they were edible.…”