Print PageHumans seeking to observe wildlife in their natural habitat can disrupt the activity of the individuals they target. One hypothesis is that behavioural reactions emerge from animals perceiving humans as a potential risk. Animals repeatedly exposed to these interactions, in locations where wildlife tourism is established, have to therefore accommodate the presence of risk in their habitat and modify their behavioural ecology accordingly. Whalewatching, taking tourists to see whales and dolphins, is the fastest growing activity in the marine tourism sector. Most coastal cetacean populations on Earth are now exposed to some form of whalewatching in at least part of their range. Understanding the influence of whalewatching on cetacean population dynamics is therefore important to manage these activities at a global scale.
We are here interested in understanding whether repeated elicitation of these behavioural disturbances can lead to influences on the population growth rate of the targeted species. This question is crucial to understand whether non-lethal human impacts might still influence the conservation status of the animal populations that are exposed to behavioural disturbances.
Results/Conclusions
We combine findings from a number of recent studies on both odontocetes and mysticetes to show that whalewatching interactions disrupt the activity budget of targeted individuals. We show that repeated exposure to these anthropogenic disturbances impairs the energetic budget of individuals by decreasing foraging opportunities and increasing energy expenditure. When the exposure rate reaches thresholds at which the whalewatching occupied habitat becomes inadequate, individuals will abandon this part of their home range. However, in situations when whalewatching is pervasive throughout the individual’s home range, females will stop investing in offspring to meet the added energetic demands; hence, leading to decreased survival of yearlings (calving success).
The population growth rate of long-lived, slow reproducing species is most sensitive to the survival probability of adult females. This acts as a selection pressure that shapes the life history strategy and behavioural ecology of these species, with females prioritising their survival probability over other vital rates. We argue that we can expect our findings to be generally representative of the effects of repeated exposure to anthropogenic activity disturbances in such species. While variation in the survival of yearling is less likely to affect population growth rate, the effect sizes we observed can still lead to impacts on population trajectories.
