Impacts of outdoor recreation on mammals and birds in mountain landscapes: A systematic review of the past two decades and directions for future research

Mountainous areas are popular destinations for outdoor recreation, which can have environmental impacts on wildlife. We assessed research from the past 20 years about the impacts of recreation on mammals and birds in montane, subalpine and alpine zones using a systematic literature review methodology to identify trends and gaps. Such knowledge is key to developing strategies that balance recreation and biodiversity conservation. Research has concentrated on specific regions, seasons, infrastructure, activities and taxa. Most of the 108 articles reviewed were from Europe (50.0%) or North America (38.9%). Studies were primarily conducted in subalpine habitats (37.0%) and often focused on winter infrastructure such as ski lifts (19.5%). However, most studies were carried out during summer (51.3%). Research was not taxonomically representative but focused on cervids ( Cervidae , 21.6%), canids ( Canidae, 14.1%), felids ( Felidae , 13.2%) and ursids ( Ursidae , 11.1%). It included few species of high conservation value. Most research (70.7%) found significant effects, which were predominantly negative (53.3%). Infrastructure, such as trails, had the most evidence for negative effects, followed by activities such as hiking and skiing. Much of the research looked at impacts at individual (40.0%) or population level (27.3%) responses, such as behavioural changes or habitat reductions, with limited research on communities (4.0%) or for popular activities such as mountain biking. We invite researchers to close knowledge gaps on population- and community-level effects of recreation, to make use of emerging technologies, such as remote sensing, and to evaluate measures to assess their effectiveness.