Derivation of Predator Functional Responses Using a Mechanistic Approach in a Natural System

The functional response is at the core of any predator-prey interactions as it establishes link between trophic levels. use inaccurate can profoundly affect outcomes population and community models. Yet most responses are evaluated using phenomenological models which often fail to discriminate among shapes cannot identify proximate mechanisms regulating predator acquisition rates. Using a combination behavioral, demographic, experimental data collected over 20 years, we develop mechanistic model based on species traits behavior assess generalist mammalian predator, arctic fox ( Vulpes lagopus ), various tundra prey (lemmings nests geese, passerines, sandpipers). Predator rates derived from were consistent with field observations. Although slightly decrease high goose nest lemming densities, none our simulations resulted in saturating all species. Our results highlight importance searching components interactions, especially speed, while not limited by handling processes. By combining theory observations, study provides support that rate systematically highest densities observed natural system. also illustrates how empirical estimates main predation generate specific range wild. Such needed fully untangle drivers dynamics improve understanding predator-mediated communities.