Who’s afraid of the big bad wolf? Variation in the stress response among personalities and populations in a large wild herbivore

Abstract

Faced with rapid environmental changes, individuals may express different magnitude and plasticity in their response to a given stressor. However, little is known about the causes of variation in phenotypic plasticity of the stress response in wild populations. In the present study, we repeatedly captured individual roe deer (Capreolus capreolus) from two wild populations in Sweden exposed to differing levels of predation pressure and measured plasma concentrations of stress-induced cortisol and behavioral docility. While controlling for the marked effects of habituation, we found clear between-population differences in the stress-induced cortisol response. Roe deer living in the area that was recently recolonized by lynx (Lynx lynx) and wolves (Canis lupus) expressed cortisol levels that were around 30% higher than roe deer in the human-dominated landscape free of large carnivores. In addition, for the first time to our knowledge, we investigated the stress-induced cortisol response in free-ranging newborn fawns and found no evidence for hypo-responsiveness during early life in this species. Indeed, stress-induced cortisol levels were of similar magnitude and differed between populations to a similar extent in both neonates and adults. Finally, at an individual level, we found that both cortisol and docility levels were strongly repeatable, and weakly negatively inter-correlated, suggesting that individuals differed consistently in how they respond to a stressor, and supporting the existence of a stress-management syndrome in roe deer.Electronic supplementary materialThe online version of this article (10.1007/s00442-018-4174-7) contains supplementary material, which is available to authorized users.

Under cover of the night: context-dependency of anthropogenic disturbance on stress levels of wild roe deer Capreolus capreolus

“…Consistent with previous studies on other species ( Arlettaz et al ., 2007 on black grouse Tetrao tetrix ; Bourbonnais et al ., 2013 on brown bear U. arctos ; Rehnus et al ., 2014 on mountain hare Lepus timidus ), our results showed that FCM levels increased as roe deer ranged closer to anthropogenic structures. It has previously been suggested that habituation could occur in environments that are regularly disturbed by human activities ( Walker et al ., 2006 ; Cyr and Romero, 2009 ; Bonnot et al ., 2018 ), which could also potentially be the case in our study. However, we found a link between FCMs and exposure to anthropogenic disturbance only under certain conditions, suggesting a plastic response mediated by roe deer behaviour.…”

In utero accumulated steroids predict neonate anti‐predator response in a wild mammal

“…To measure fawn docility during handling, we used a behavioural index similar to that used to measure reaction to capture in adult deer (e.g. Bonnot et al., 2018; Debeffe et al., 2015). We assigned the following categorical scores based on the behavioural reaction during handling: the fawn was calm and did not vocalize or kick (score: 0); it vocalized one or two times and/or gave a few little kicks (1); it vocalized and/or kicked more than twice with calm phases in between (2); the fawn cried and/or kicked frequently throughout the handling (3); the fawn struggled throughout (4).…”

The Adaptive Sex in Stressful Environments

“…The secretion and synthesis of glucocorticoids (GCs) is considered the primary endocrine response (together with the release of catecholamines) to unpredictable or uncontrollable stimuli (stressors) in the environment [92]. In the wild, high GC levels could result from many different types of stressors including predator attack or presence [93], high population density [94], habitat degradation [95], food shortages [96], social conflict [97] or human activities [98]. Here we considered all GCs increase resulting from these stressful cases, although it is worth noting that harsh conditions do not necessarily provoke a stress response [76].…”