Stream community richness predicts apex predator occupancy dynamics in riparian systems

Streams and adjacent riparian habitats represent linked terrestrial and aquatic ecosystems that exchange materials and energy. Recognized relationships among apex predators and ecosystem biodiversity led us to hypothesize that these predators in riparian-stream systems were more likely to be found in sites with high stream quality, defined as increased ecosystem function and integrity. In our freshwater study system, river otter (Lontra canadensis) and mink (Neovison vison) play critical roles as apex predators. We used multi-season occupancy modelling across 3 sampling years (2012-2014) to compare aspects of the stream communities that explain occupancy dynamics of river otter and mink, including their interactions with other semi-aquatic mammals. We surveyed for semi-aquatic mammals at 77 sites in 12 major watersheds in southern Illinois, USA (44,526 km2). Naïve occupancy differed among years but generally increased for river otter, and remained high (≥93.5%) for mink. Increasing subs...