Anthropogenic disturbances and coexistence of wildlife: spatial interactions between wild ungulates, humans and wolves in the Maritime Alps

As part of the study of the interaction between prey, predators and human activities, several master’s and doctoral theses have been developed, which have contributed to improving knowledge on various aspects of these complex relationships.

Wild animals do not use space randomly: each species has its own ecological characteristics that make it more or less adapted to a certain type of environment. Factors that determine the use of space include the availability of food resources, the presence of refuge areas, climatic and geographical characteristics (e.g. slope and exposure), population density, the occurrence of disturbance factors and relationships with other species.

Francesca Rolle’s master’s thesis (University of Turin) analysed precisely the role of interspecific relationships and human activities in the likelihood of the coexistence of roe deer, red deer and wolves in two valleys in the Maritime Alps, the Pesio and Ellero valleys, both in the province of Cuneo, north-western Italy. The valleys include two protected areas (Maritime Alps and Marguareis) and two alpine hunting areas (CACN5 and CACN6).

In particular, the thesis work aimed at:

• assess the role of interactions between different species in determining their distribution: specifically, the competition between deer and roe deer and the predation of both species by wolves.
• to explore the impact of human activities on the distribution of species and the probability of detecting their presence by photo-trapping.
• to investigate the effect of hunting activity on competition and predation relationships, focusing on roe deer.

The data collection and analysis used in this thesis allow for the estimation of what is technically termed ‘occupancy‘, i.e. the probability that a species is present in a given area, also considering all environmental characteristics, and other factors, in this case the presence of wolves and deer and human activities. In addition, the models make it possible to estimate ‘contactability’, i.e. the probability of being able to photo-trap a given species at a site.

For the study, which was conducted over a six-month period (November 2021 to April 2022), 60 camera traps were distributed over an area of 136 km2, and over 45,500 animal passages were collected.

The roe deer is the species most frequently ‘captured’ by the camera traps, appearing in approximately 42% of the images, followed by the wild boar and people. The roe deer was also captured by almost all the camera traps (in 52 out of 60 sites); the species is therefore present throughout the study area, despite potential disturbance factors such as the presence of human activities and deer and wolves. The environmental characteristics of the study area are optimal for the roe deer, but this result also indicates that anthropic activities do not significantly impact the distribution of this species, although this aspect needs to be further investigated through more detailed quantitative studies of population estimation, which would allow numerosity and density to be measured.

Indeed, the study reveals that it is very important, when estimating occupancy, to include interspecific relationships in the models. The analys indicates that the probability of two species occupying the same area varies according to certain environmental characteristics: for example, the probability of deer and roe deer coexistence increases with increasing distance from inhabited areas, while deer show a greater tendency than roe deer to frequent areas close to inhabited areas. Wolves, on the other hand, try to avoid human presence, and their presence and contact is less likely as the number of people in an area increases. With regard to hunting, the study indicates that, during the hunting season, the contactability of roe deer, the only huntable species in the area, decreases, while there is no effect on deer or wolves. This result could indicate a reduction in movement by roe deer during the hunting season, also observed in other similar studies conducted in other contexts, because in fragmented natural environments, moving from one type of environment to another could increase the risk of being hunted.

In conclusion, this study demonstrates the need to consider a multiplicity of factors, which interact and overlap, when trying to understand how and why a given species uses the territory: from environmental characteristics, to the presence of other species with which it may interact (competition and predation), and last but not least, human presence. Human activities (including hiking, or the mere presence of people) play a fundamental role, capable of conditioning the distribution and frequentation of a given habitat and also the relationships between species.

Watch in the video Francesca Rolle explain her research!