Citizen science contribution to national wolf population monitoring: what have we learned?

Evidence-based management of large carnivores is a crucial step towards their effective conservation. However, monitoring of these populations is demanding and generally requires substantial fieldwork effort. Lately, citizen science has become an increasingly important part of wildlife monitoring, but can that endanger studied species? In this paper, we describe our experiences with recruiting and involving volunteers in annual howling surveys of grey wolf (Canis lupus) population in Slovenia and present the framework about the use of citizens for collecting data. Huge effort of participants in a 7-year-long monitoring at a national scale has yielded a total of 116 wolf vocal responses, including 53 confirmed litters. Annually, between 5 and 12 reproductive packs were detected and an increasing trend in wolf population throughout the study period was observed. Volunteer-based howling surveys proved to be a cost-effective method for detection of reproductive packs on a large spatial scale, offering an insight into wolf population trends across a longer time period and we provide some recommendations for organisation and coordination of surveys. We also discuss ethical issues raised from our experience in using citizen science for this purpose.