Should I stay or should I go : an experimental study on reactivity and habituation to acoustic stimuli in free-ranging ungulates

Sammanfattning: Negative consequences of anthropogenic sound on wildlife is a well-established phenomenon and have received substantial attention in scientific literature. This evokes questions of what type of sounds perceived as disturbing or aversive to animals. Further knowledge on this matter may contribute to development of acoustic tools to mitigate human-wildlife conflicts by deter animals from conflict areas. However, the use of acoustic stimuli as a deterrent agent, often lack long-term effects due to rapid habituation. The aim of my experiment is to examine how animals respond to novel acoustic stimuli and what factors that affect habituation to acute sound. I subjected free-ranging roe deer (Capreolus capreolus) to a sudden novel sound with no ecological relevance and followed individual response over time. Individuals was either subjected to low (40 dB, n=19) or high sound volume (70 dB, n=26). My results conclude that novel sound of high volume did not evoke a stronger response than a sound of lower sound volume, and that sound volume had no effect on habituation. Age, and whether individuals were alone or in a group, were factors that have the largest effect on response to sound. Fawns had lower response to the sound at their first exposure and expressed more pronounced habituation compared to older individuals. Animals in groups responded less strong compared to single animals. However, fawns were to a greater extent accompanied by other animals, compared to adults, which might contribute to their lower response. I found no difference in response to sound between males and females. Variation in response to sound were higher between individuals than within individuals, which indicate a personality aspect in sound reactivity. To determine if response to sound was linked to other traits in the tested population, I used data on response to handling during a capture event. However, no correlation between docility and sound reactivity were found. This indicate that the observed inter-individual variation in these behaviours are dependent on context rather than being part of a general personality trait. The results from my study contribute to a greater understanding on how acute sounds affect wild animals and may be of use to estimate habituation rate to sound.