Cortisol response of wild ungulates to trauma situations: hunting is not necessarily the worst stressor

Abstract

Animal welfare concerns are becoming a central issue in wildlife management and conservation. Thus, we investigated stress response of wild ungulates to potentially traumatic situations (shooting injuries, vehicle collisions, entanglement, injuries or diseases) and hunting methods (stalking, battues and hunts with dogs) by means of serum cortisol concentrations from blood collected from killed animals. Cortisol levels in roe deer ranged below and in wild boar above levels for moose, red deer and fallow deer (hence, pooled as a group Bdeer^). Apart from species, cortisol concentration in trauma situations was mainly explained by trauma type and presence of disturbance after the trauma event. Effect of trauma type differed significantly for Bdeer^, with animals caught in fences and suffering vehicle collisions experiencing higher cortisol levels than animals injured by shooting. Differences between hunting methods were observed in the cervids (Bdeer^and roe deer), with stalking leading to lower cortisol levels than hunts with dogs (both groups) and battues (roe deer). Events both before and after the shot, such as duration of pursuit prior to shooting, location of injury, trauma length and presence of disturbance after the shot were relevant for cortisol levels in hunted cervids. Our results indicate that search teams tracking and euthanising wounded animals should behave in a calm way to minimise disturbance. Still, it is important to acknowledge that many situations described in the literature, i.e. reindeer handling, roe deer captures and red deer yarding, seem even more stressful, beside vehicle collisions, than most hunting methods.

An approach to stress assessment during hunting: Cortisol levels of wild boar (Sus scrofa) during drive hunts

“…Viewing our results in clusters comparable to levels found by Gentsch et al (2018), it is noticeable that only 54 % of our cortisol values could be considered as increased trauma levels (>350 nmol/L), whereas 38 % of our values could be defined as normal cortisol levels (150 – 350 nmol/L). The remaining 8 % are out of range.…”

“…Our values showed a very high variance with both highly increased, as well as very low cortisol values. We compared the distribution of our values to reference values given by Gentsch et al (2018), who defined both “normal” and “trauma” cortisol levels. They defined cortisol concentrations of undisturbed animals (animals not being followed by humans or dogs and therefore, shot immediately without suffering, e.g.…”

“…Concentrations of cortisol in animals being shot during regular drive hunts, or animals having died after an injury (e.g. due to a traffic accident), were defined as traumatized [37]. With this definition, they set 249.6 ± 36.8 nmol/L as normal and 775.2 ± 64.7 nmol/L as trauma cortisol levels (mean ± standard error) in wild boar.…”

Quality of main types of hunted red deer meat obtained in Spain compared to farmed venison from New Zealand

“…Our results show that pH values were similar for wild deer in SP (pooled values) and farmed deer in NZ, but meat from stalked deer had the lowest values. This is not surprising as transporting deer to the abattoir also involves stress, and furthermore, recently, Gentsch et al 20 have observed that cortisol levels for stalked deer were much lower than those for deer hunted with dogs in driven hunts (21.8 vs. 66.1 nmol/L, respectively). With regard to the effect of seasons, meat hunted in winter had a higher pH than meat hunted in summer.…”

Potential Welfare Impacts of Chase and Capture of Small Cetaceans during Drive Hunts in Japan

“…Glucocorticoids have been used as indicators of stress responses for a wide range of mammals (Sheriff et al, 2011;Atkinson et al, 2015) and has been collected and analyzed from a variety of tissue and biological materials including blood, urine, faeces and hair (Macbeth et al, 2012) in terrestrial mammals, and from blood, muscle, blubber (Trana et al, 2015;Kellar et al, 2015), faeces (Palme et al, 2013) and from the liquid-cellular component of the blow (Thompson et al, 2014) in cetaceans. Glucocorticoid analyses, sometimes linked to analysis of behavioral change, have been used to increase understanding of the negative impact of human activity in a number of wild animal species, including: hair cortisol analysis for environmental stressors in deer (Caslini et al, 2016); for assessment of environmental change in polar bears (Weisser et al, 2016); 'landscape fear' (human persecution) in brown bears (Stoen et al, 2015); capture and handling in brown bears (Cattet et al, 2014); the effects of human harassment in wolves (Bryan et al, 2015); the effects of poaching on elephants (Gobush et al, 2008); tourist pressures on Chamois (Zwijacz-Kozica et al, 2013); and culling and hunting methods in red deer (Cockram et al, 2011) and in other ungulates (Gentsch et al, 2018).…”