Kora
The Diet of Wolves in Switzerland – Part 2
In Switzerland, wolves primarily feed on wild ungulates, with the red deer (Cervus elaphus) being the most significant prey item. Overall, wild animals constitute 88.3% of the wolves' diet.
We previously published initial findings from the study "DNA Metabarcoding Reveals Wolf Dietary Patterns in the Northern Alps and Jura Mountain" on our website in June 2024. Since then, the study has been expanded: the study period has been extended by two years, additional scat samples have been analysed, and new aspects have been considered. This now enables us to illustrate, for instance, differences in the diet depending on the region and the animals' social status. However, the central conclusion remains unchanged: the wolf in Switzerland feeds primarily on wild animals; livestock such as sheep, goats, or cattle were found only in small proportions, varying by region and season.
Wild animals account for 88.3% of the wolf's diet in Switzerland, primarily red deer (Cervus elaphus), roe deer (Capreolus capreolus), and chamois (Rupicapra rupicapra). Livestock contributes 11.7%, mainly sheep.
The diet of wolves is observed to vary according to social status, season, and region.
Social Status
The study investigated whether the wolves' diet differed based on whether they lived in a pack or were solitary. Indeed, the social status appears to influence feeding behaviour: solitary wolves consume a relatively higher proportion of roe deer. To reliably assess further differences, more data and a more precise distinction between dispersing and resident solitary wolves are required.
Season
In addition to social status, the season also plays a role. Roe deer are consumed more frequently during winter, while chamois are more frequently consumed during summer and autumn, particularly in the eastern Swiss Alps and Valais. The proportion of livestock generally increases during summer, likely due to the greater presence of livestock in the mountains during the alpine pasture season. Red deer consumption shows no seasonal variation.
Region
Regional differences were also analysed. In the Valais Alps, roe deer and chamois constitute a larger proportion of the wolf's diet than red deer, contrasting with other areas. This can be partly explained by the higher local prevalence of these species. In the Southern Jura, cattle were a more frequent component of the diet. No significant differences were observed in the remaining regions.
Investigation Method
The analysis is based on the DNA metabarcoding procedure, which allows DNA fragments to be assigned to the respective prey species. Between 2017 and 2024, 698 scat samples from 250 different wolves were collected and included in the study. DNA fragments from prey animals were successfully detected in 653 of these samples in the laboratory.
Limitations of Scat Analysis
When interpreting the results, one must be aware of the inherent limitations of analyzing scat samples. The results indicate what wolves have consumed, not necessarily what they have preyed upon. Thus, animals may have been consumed as carrion after dying from other causes, or animals may have been killed by wolves but not eaten. The latter is thought to occur predominantly with livestock. Furthermore, the location of sample collection is relevant: as expected, the proportion of livestock is higher when focusing only on scat samples collected near livestock carcasses compared to samples collected randomly or near wild animal carcasses.
Collaboration
This dietary analysis was conducted within the framework of the KORA project "Integrated Monitoring and Management" (IMM). It is part of the PhD project of Florin Kunz, realized in collaboration with the Department of Ecology and Evolution at the University of Lausanne (UNIL). Samples were primarily collected and submitted by cantonal game wardens. The genetic analyses were carried out at the LBC (Laboratory for Conservation Biology) at UNIL with financial support from the FOEN (Federal Office for the Environment) and a private non-profit foundation. We thank all participants for their excellent collaboration.
To the first part: The Diet of Wolves in Switzerland (in German)
© Christian Grand