Site-Occupancy Distribution Modeling to Correct Population-Trend Estimates Derived from Opportunistic Observations

摘要: Species' assessments must frequently be derived from opportunistic observations made by volunteers (i.e., citizen scientists). Interpretation of the resulting data to estimate population trends is plagued with problems, including teasing apart genuine variations in observation effort. We devised a way correct for annual variation effort when estimating occupancy (species distribution) faunal or floral databases observations. First, all surveyed sites, detection histories strings detection-nondetection records) are generated. Within-season replicate surveys provide information on detectability an occupied site. Detectability directly represents effort; hence, means correcting Second, site-occupancy models applied detection-history set without aggregation site and year) species distribution (occupancy, i.e., true proportion sites where occurs). Site-occupancy also unbiased estimators components distributional change colonization extinction rates). illustrate our method large citizen-science project Switzerland which field ornithologists record analyzed collected four species: widespread Kingfisher (Alcedo atthis) Sparrowhawk (Accipiter nisus) scarce Rock Thrush (Monticola saxatilis) Wallcreeper (Tichodroma muraria). Our requires that observed recorded. was <1 varied over years. Simulations suggested some robustness, but we advocate recording complete lists (checklists), rather than individual records single species. The representation its effect provides solution problem differences encountered extracting trend haphazard expect widely applicable global biodiversity monitoring modeling distributions.