UK Biodiversity Indicators 2015. Technical background document: Deriving indicators from occupancy models

Recent studies have highlighted the value of Bayesian occupancy models for estimating species’ status and trends from unstructured biological records (van Strien et al. 2013; Isaac et al. 2014). Based on these developments, it is now possible to produce biodiversity indicators from biological records, using occupancy models. However, the process of fitting occupancy models and generating indicators raises a number of technical, statistical and conceptual challenges. This document describes these challenges, and how they have been addressed for the 2015 biodiversity indicator set. The procedure described here represents a shared methodology for two current UK biodiversity indicators: C4b (Priority Species) and D1c (Pollinating Insects).