Cannot see the diversity for all the species: evaluating inclusion criteria for local species lists when using abundant citizen science data

Abundant citizen science data on species occurrences is becoming increasingly available and enables identifying composition of communities occurring at multiple sites with high temporal resolution. However, for species displaying temporary patterns of local occurrences, i.e. that are transient to some sites, biodiversity measures are clearly dependent on the criteria used to include species into local species lists. Using abundant opportunistic citizen science data from frequently visited wetlands we investigated the sensitivity of α- and β-diversity estimates to the use raw vs. detection-corrected data and to the use of inclusion criteria for species presence reflecting alternative site use. We tested 7 inclusion criteria (with varying number of days required to be present) on time series of daily occurrence status during a breeding season of 90 days for 77 wetland bird species.
We show that even when opportunistic presence-only observation data is abundant, raw data may not produce re...