Discussion

Prey use

I found seasonal and annual differences in the prey use of wild boar and fallow deer by the wolf. Roe deer use varied slightly between seasons, which is in accordance with previous research on ecosystems where roe deer make up a small part of the wolf diet. However, in those study areas summer was the season with the largest relative roe deer use by wolves, while in this study area the peak of roe deer use by wolves was in autumn. The values of all three estimates of wolf prey use indicated that wild boar was the most used wild ungulate prey in every season throughout the study period. There were however no clear seasonal patterns in wild ungulate prey use by the wolves. This is in accordance with a previous study, that found seasonal differences in all predation estimates measured using both kill rates and prey biomass, yet found no seasonal patterns in kill rates. The kill rates in that study depended on prey availability and prey vulnerability, rather than seasonality. Although availability and vulnerability are expected to vary seasonally, they are influenced by many other factors.

Wolf dietary niche breadth

There was a lack of seasonal patterns in the results of Levins index. This is likely due to the assumption of equal availability of all prey species when using this index. Since the roe deer density was estimated to be lower than the other two wild ungulate prey species, using both scat counts and camera traps, this attributed more importance to the use of roe deer when calculating the dietary niche breadth of the wolves. From the results of the Levins index I did however interpret that the diversity of wolf prey use of ungulates, when disregarding the differences in prey availability between species did not vary with seasonal patterns.

The Hurlbert index was higher in spring-summer and lower in autumn-winter. This supports the idea that wolves, as a generalist predator, would use a wider range of prey when there is a seasonally higher prey availability and prey diversity, and that they would be more “specialised” when prey availability is lower, without being scarce.

Relative prey availability

The seasonal patterns of estimated relative prey availability gave results in agreeance with what we would expect based on the ecology of the prey species with an increase of wild boar and roe deer in the birth period due to relatively higher birth rates. Due to the higher mortality rates of these species we also expect an increase in relative fallow deer availability in winter, which was supported in my results.

Wolf prey selection

The selection of fallow deer in summer could be due to the influx of young vulnerable fawns that are not physically protected against predation by the females, unlike young wild boar piglets. This might make them a more profitable prey due to decreased risk of injury. Also, fallow deer births are generally more synchronised than those of wild boar and could therefore cause a high fawn encounter rate and thus predation. Although wild boar produce more offspring, which could counteract this effect.