Breeding Woodcock Ireland survey data and analysis

This data contains the data and code required to replicate analyses for a two-step species distribution modelling approach to estimate the distribution and abundance of breeding Eurasian woodcock (Scolopax rusticola) across the Republic of Ireland. Quantitative species occurrence data was collected at 238 randomly-selected forest sites by volunteers who counted displaying (roding) male woodcock at dusk in May and June of 2017, 2019 and 2021. Environmental data used consisted of historical bioclimatic variables downloaded from www.worldclim.org, and landcover (forest and urban settlement) derived from datasets provided by Coillte, DAFM Forestry Division, DAERA Forest Service and CORINE landcover. The first step was an ensemble model using biomod2 in R, to estimate the geographical range of breeding woodcock in Ireland using bioclimatic variables at a 1 * 1 kilometre resolution. The second step was a Generalised Additive Model (GAM) using 'mgcv' in R to determine the bioclimatic and landcover drivers behind woodcock abundance, conditional on presence (falling within the geographic range estimated in the first step). The GAM was then projected across 1 km squares with a minimum threshold of forest habitat (0.1 km2) within the estimated range to predict the distribution and abundance across Ireland. Finally, the predicted density from all relevant 1km squares were summed to produce a national population estimate, with standard errors.