Insights from a 30-year study demonstrate an inverse correlation between
recreational activities and red deer fecundity, with bodyweight as a
mediator
Abstract
Human activity is omnipresent in our landscapes. Animals can perceive
risk from humans similar to predation risk, which could affect their
fitness. We assessed the influence of recreation on bodyweight and
pregnancy rates of red deer (Cervus elaphus) between 1985 and 2015. We
hypothesized that stress, as a result of recreational activities,
affects pregnancy rates of red deer directly and indirectly via a
reduction in bodyweight. Furthermore, we expected non-motorized
recreational activities to have a larger negative effect on both
bodyweight and fecundity, compared to motorized recreational activities.
The intensity of recreational activities was recorded through visual
observations. We obtained pregnancy data from female red deer that were
shot during the regular hunting season. Additionally, age and bodyweight
were determined through post-mortem examination. We used two
Generalized-Linear-Mixed Models (GLMM) to test the effect of different
types of recreation on 1) pregnancy rates and 2) bodyweight of red deer.
Recreation had a direct negative correlation with the fecundity of red
deer, with bodyweight as a mediator as expected. Besides, we found a
negative effect of non-motorized recreation on fecundity and bodyweight
and no significant effect of motorized recreation. Our results support
the concept of humans as a ‘super predator’ affecting wild animal
populations at a population level and plead to regulate recreational
activities in protected areas that are sensitive. The fear humans induce
in large-bodied herbivores and its consequences for fitness may have
strong implications for animal populations and the regeneration,
structure and composition of forests and related fauna.