Species occurrence data reflect the magnitude of animal movements better than the proximity of animal space use

Abstract

. 2018. Species occurrence data reflect the magnitude of animal movements better than the proximity of animal space use. Ecosphere 9(2):e02112. 10. 1002/ecs2.2112 Abstract. Animal ecologists often use stationary point-count surveys, such as camera traps, to collect presence-absence data and infer distribution, abundance, and density of species. Rarely do these surveys explicitly consider variations in the magnitude of animal movement despite movement assumptions being implicit in their interpretation. For example, ecologists assume the frequency of species detections at a site is associated with the intensity of local space use, but it may be more indicative of transit through that point en route to other areas. This assumption remains untested, and a resolution is critical to accurate interpretation of species occurrence data. We compared fisher (Pekania pennanti) detections collected from a camera trap array with detailed Global Positioning System-telemetry data to test whether, at the population level, the spatial and temporal patterns of detections reflected the proximity of space use to sampling sites, or variability in the magnitude of animal movement across the study area. We also used an occupancy modeling framework to quantify the relative contributions of space use proximity and movement magnitude to estimated probabilities of site occupancy and detectability. We demonstrate that, at the population level, detection frequency and estimates of detection probability and occupancy are more closely associated with the magnitude of animal movement around a survey device than the proximity of animal space use. Variations in the magnitude of animal movement within and between species should receive greater consideration when interpreting occurrence data to correctly infer ecological processes. Not accounting for species movement, especially in multi-species surveys, may bias inferences of ecologic processes and result in misspecified management recommendations.

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