Clarifying habitat niche width using broad‐scale, hierarchical occupancy models: a case study with a recovering mesocarnivore

摘要

A species’ habitat niche width informs its position on the generalist-specialist continuum, which is central to life history theory and crucial to conservation planning. However, assessments of niche width are often based on local-scale studies or qualitative descriptions rather than broad, quantitative assessments conducted in heterogeneous landscapes. Here, we show how broad- scale, hierarchical occupancy models can clarify a species’ niche width and degree of habitat specialism by evaluating the woodland-specialist classification of the European pine marten (Martes martes). We deployed 526 camera-trap stations at 27 sites throughout a vast extent (~50,000km2) in Scotland and modeled pine marten occupancy as a function of habitat characteristics using a hierarchical Bayesian analysis. Our model was flexible to trap-happiness due to baiting at camera-traps and accounted for spatial autocorrelation among and imperfect detection at camera-trap stations. We detected a positive association between pine marten occupancy probability and wooded habitats. However, pine marten occupancy probability was also high in numerous non-wooded habitats, including agricultural land, heather and heather grassland, semi-natural grassland, and areas near anthropogenic structures. Our study is the first to record high pine marten occupancy in open habitats at broad spatial scales and thereby corroborates recent smaller-scale indications that pine martens are more of a habitat generalist than previously thought. Our results guide ongoing conservation efforts by identifying that pine martens are not strict woodland-specialists, but rather inhabit a mosaic of habitat types in the landscape. More broadly, our case study exemplifies how coupling hierarchical occupancy models with large-scale experimental designs can clarify a species’ niche width and associated position on the generalist-specialist continuum.