Influence of cereal harvest on adrenocortical activity in European hares (Lepus europaeus)

Nicolas Cybulska,Rupert Palme,Stéphanie C Schai-Braun,Alfred Frey-Roos,Klaus Hackländer

doi:10.1007/s10344-020-01430-w

Abstract

Anthropogenic disturbances, such as habitat modifications and machines, are associated with increased levels of faecal glucocorticoid metabolites (fGCMs) in mammals, an indicator of a stress response. One human-caused process provoking incisive habitat alterations is harvesting arable crops. We investigated the effect of cereal harvest on fGCM concentrations in European hares (Lepus europaeus) in arable landscapes in lower Austria during the year 2018 by collecting 591 faecal samples before, during and after cereal harvest. fGCMs were analysed using an enzyme immunoassay, and data were analysed using linear mixed-effects models. We found that neither cereal harvest nor farming practice (organic vs. conventional) caused an overall increase in the hares’ stress level. Lower vegetation density and higher proportions of bare ground were negatively correlated with fGCM concentrations, whereas the proportion of stubble fields was significantly positively correlated with fGCM concentrations in European hares. A change to more open landscapes might decrease time spent avoiding predation, and fallen grains may provide a beneficial additional food source for the hares. This indicates that European hares are well adapted to an opening up of the landscape and short-term disturbances such as cereal harvesting. In conclusion, cereal harvest had no large impact on European hares’ adrenocortical activity in an arable landscape with small average field size and enough available non-farmed areas.

Highlights

Increasing evidence and documented examples suggest that disturbances and habitat alteration as a result of human activity can act as stressors in different mammals (Navarro-Castilla et al 2013; Rehnus et al 2014; Lunde et al 2016; Zbyryt et al 2018) and birds (Thiel et al 2008; Casas et al 2016)
The influence of cereal harvest and farming practice on faecal faecal glucocorticoid metabolites (fGCMs) concentrations We found no significant differences in fGCM concentrations between collecting periods (Fig. 1, each P > 0.1, Tables 2 and 3) or farming practice (Fig. 2, each P > 0.1, Tables 2 and 3)
Vegetation height had no effect on fGCM concentrations, whereas vegetation density had a significant influence on fGCM concentrations

Summary

Introduction

Increasing evidence and documented examples suggest that disturbances and habitat alteration as a result of human activity can act as stressors in different mammals (Navarro-Castilla et al 2013; Rehnus et al 2014; Lunde et al 2016; Zbyryt et al 2018) and birds (Thiel et al 2008; Casas et al 2016). One part of the physiological stress response is the activation of the hypothalamic–pituitary–adrenal (HPA) axis and subsequent secretion of glucocorticoids (GCs). The primary role of GCs is basic energy regulation, whereas increased secretion allows animals to mobilize stored energy to cope with stressful situations (Möstl and Palme 2002; Sheriff et al 2011a). Nowadays, wellvalidated non-invasive methods are available to measure faecal glucocorticoid metabolites (fGCMs) and assess the impact of stressful situations on wildlife (Sheriff et al 2011a; Palme 2019). We used fGCMs to evaluate whether harvesting of arable landscapes acts as a stressor

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