Annual estimates of occupancy for bryophytes, lichens and invertebrates in the UK (1970-2015)

These data were generated using observations of species occurrence as the input data for a Bayesian occupancy model. The modelling framework implemented was based on that developed to improve precision of occupancy estimates when using biological records type data (Outhwaite et al., 2018; https://doi.org/10.1016/j.ecolind.2018.05.010). This allowed the estimation of species occupancy for the largest set of UK species to date.

The input data used for this study consisted of species occurrence data collated from 29 UK recording schemes and societies. These data are presence only data that consist of a record of a species at a known time and location. Where possible, these input data were supplemented with additional occurrence data in the same form from the Biological Records Centre database and the wildlife recording app iRecord (https://www.brc.ac.uk/irecord/)

These input datasets were then standardized according to the requirements of the model and to desired coverage. Observations of species had to meet the following criteria to be included in the final input dataset:
- Date of the record known to the day
- Location of the record known to 1x1km square precision
- Record was from 1970 onwards
- The location of the record was in the UK (strictly England, Northern Ireland, Scotland and Wales)

Species names were checked with guidance from the scheme organisers, duplicate records were then removed from the dataset.
The occupancy modelling framework used here was based on the random walk model tested by Outhwaite et al., 2018. Alterations made to the modelling framework include country level year effects in the state model and a categorical specification of list length in the detection model. For a complete description of the model and the changes implemented, see the associated data paper.