Large-Scale Sheep Losses to Wolves (Canis lupus) in Germany Are Related to the Expansion of the Wolf Population but Not to Increasing Wolf Numbers

Igor Khorozyan,Marco Heurich

doi:10.3389/fevo.2022.778917

Abstract

Recovery of predator populations triggers conflicts due to livestock depredation losses, particularly in Germany where the wolf (Canis lupus) population grows exponentially and livestock (especially sheep) losses raise public concerns and motivate the authorities to control wolf numbers. Yet, the effects of wolf numbers and alternative factors, such as abundance of prey and livestock, on livestock losses in this country are not investigated. In this study, we collected and analyzed data on the numbers of reproductive units of wolves (packs and pairs together) as a surrogate of adult wolf numbers, sheep killed by wolves, living sheep, red deer (Cervus elaphus), roe deer (Capreolus capreolus), and wild boar (Sus scrofa) in every German state and year from 2002 to 2019. We applied a negative binomial Generalized Linear Mixed Model (GLMM) to estimate the effects of these predictors on the numbers of sheep killed by wolves. We also examined the relationships between the percentages of killed/living sheep and the numbers of living sheep. Ranking of 63 models based on the Akaike information criterion revealed that sheep losses were determined by state, year, and number of living sheep, not by wolf numbers, at high precision and accuracy. The number of sheep killed by wolves increased consistently by 41% per year and by 30% for every additional 10,000 sheep, mainly in the north where most wolf territories are concentrated. This means that sheep are protected insufficiently and/or ineffectively. The percentages of killed/living sheep consistently increased by 0.02–0.05% per state and year, with the maximum percentage of 0.7%, on a backdrop of decreasing numbers of living sheep. In conclusion, we demonstrate that sheep losses in Germany have been driven by the expansion of the wolf population, not by wolf numbers, and by the number of sheep available. We suggest that Germany’s wolf conservation policy should focus on alternative non-lethal interventions, enforcement and standardization of intervention monitoring, and promotion of wolf tolerance rather than on lethal control of wolf population size.

Highlights

The recovery of large predator populations and their return to the areas where they formerly were extirpated have been a fascinating result of long-term and dedicated conservation efforts (Chapron et al, 2014; Hamilton et al, 2020)
We collected the numbers of sheep killed by wolves from official reports of livestock depredation losses for 2016– 2019 (Dokumentations- und Beratungsstelle des Bundes zum Thema Wolf [DBBW], 2017, 2018, 2019, 2020b) and from the information letter 18/10110 of the German Parliament for 2002– 2015
The running of 63 Generalized Linear Mixed Model (GLMM) models led to one best model, in which the number of sheep killed by wolves was best explained by the German state, year, and number of living sheep (Table 1)

Summary

Introduction

The recovery of large predator populations and their return to the areas where they formerly were extirpated have been a fascinating result of long-term and dedicated conservation efforts (Chapron et al, 2014; Hamilton et al, 2020). Perceptions and tolerance are no less important than tangible losses in transforming human-predator conflicts into human-predator co-existence (Patru-Stupariu et al, 2020). All these aspects make human-predator conflicts a long-lasting challenge for biodiversity conservation and local livelihoods, which needs to define the key factors that underlie a problem, specify factor-specific solutions, and mobilize human and other resources for their practical applications (van Eeden et al, 2018; Khorozyan and Waltert, 2019; Sutherland et al, 2020)

Methods

Results

Conclusion