Rept4pop model for the simulation of foraging, dispersal and population processes of UK common lizards

Rept4pop is a process-based model, written in R, that simulates the foraging, dispersal and population processes of reptiles around their basking sites. It accounts for amount, configuration and shading of habitat resources to predict spatially-explicit relative abundance and foraging rates, for a given input landscape. The input landcover information must be in raster format. The model can ingest a base landcover raster as well as edgecover rasters, which represent the locations of small habitat features that occupy only a fraction of a pixel. It also requires an input digital elevation raster to incorporate habitat shading effects. Model outputs are raster stacks with the same spatial extent and resolution as the input landcover raster.

The rept4pop model was co-developed by the UK Centre for Ecology & Hydrology and the Amphibian and Reptile Groups of the UK. It has been parameterised for one UK reptile species (common lizard; Zootoca vivipara). These parameter files (rept_guild_params.csv and rept_habitat_params.csv, along with rept_shading_params.csv) are included. The model’s predictions have been validated against observations of this reptile species collected in Surrey, UK, by Surrey Amphibian and Reptile Group.

Data in rept_guild_params.csv includes typical movement ranges (foraging range in meters, dispersal range in meters), population growth parameters (maximum basking density per hectare, maximum offspring produced per breeding female per year, growth parameters in arbitrary units) and survival parameters (yearly adult survival probability, yearly juvenile survival probability) for common lizard, used in the rept4pop model.

Data in rept_habitat_params consists of scores representing the relative availability of suitable basking sites (on a scale from 0-1, where 0 = none and 1 = very high) and the relative availability of foraging resources (on a scale from 0-5, where 0 = none and 5 = very high) for common lizard and the 78 landcover classes, used in the rept4pop model. Given scores are the mean values across n contributing experts. The data also include the number of contributing experts, the standard error on the mean score, and the alpha and beta values that describe a beta distribution consistent with the measured mean and variance for each score. Data in rept_shading_params.csv consists of assumed approximate canopy heights.

This model is intended to help support understanding of how common lizards might be using landscapes. No decisions should ever be made solely on the basis of this model’s predictions – on-the-ground ecological surveys and integration of local knowledge are always required before any landscape-level or site-level decisions are made, due to real-life common lizard activity levels potentially differing from predicted levels. Users are recommended to get in touch with the model developers to ensure they have the most up-to-date version of the code and to receive support on model use and interpretation.