Transboundary Monitoring of the Wolf Alpine Population over 21 Years and Seven Countries

Abstract

Wolves have large spatial requirements and their expansion in Europe is occurring over national boundaries, hence the need to develop monitoring programs at the population level. Wolves in the Alps are defined as a functional population and management unit. The range of this wolf Alpine population now covers seven countries: Italy, France, Austria, Switzerland, Slovenia, Liechtenstein and Germany, making the development of a joint and coordinated monitoring program particularly challenging. In the framework of the Wolf Alpine Group (WAG), researchers developed uniform criteria for the assessment and interpretation of field data collected in the frame of different national monitoring programs. This standardization allowed for data comparability across borders and the joint evaluation of distribution and consistency at the population level. We documented the increase in the number of wolf reproductive units (packs and pairs) over 21 years, from 1 in 1993-1994 up to 243 units in 2020-2021, and examined the pattern of expansion over the Alps. This long-term and large-scale approach is a successful example of transboundary monitoring of a large carnivore population that, despite administrative fragmentation, provides robust indexes of population size and distribution that are of relevance for wolf conservation and management at the transnational Alpine scale.

Keywords: Alpine; estimate; monitoring; population; transboundary; wolves.

Figure 1

Study area defined by the Alps range as reported by the Alpine Convention (red line), country boundaries and indications on the Apennine and Dinaric–Balkan wolf populations that originated the Alpine wolf population based on Chapron et al. 2014.

Figure 2

Distribution of reproductive units in the Alps in 1996–1997 (a), 2003–2004 (b) and 2008–2009 (c), together with wolf occurrence for 2011–2012 (d), 2015–2016 (e) and 2020–2021 (f).

Figure 3

Hierarchical Bayesian exponential model fitted to the time series of wolf reproductive units N (black squares are collected data from 1993–1994 to 2020–2021, white circles and continuous black line are medians of the model-inferred population sizes when direct estimates were not available and dashed lines are 95% credible intervals).