Supplement 1. R and WinBUGS code for fitting the model of species occurrence and detection and example data sets.

File List breedingBirdData.txt<br> butterflyData.txt<br> ExampleSession.txt<br> MultiSpeciesSiteOcc.R<br> MultiSpeciesSiteOccModel.txt<br> CumNumSpeciesPresent.R Description “breedingBirdData.txt” is an example data set in ASCII comma-delimited format. Each row corresponds to data for a single species observed in the avian survey. The 50 columns correspond to 50 sample locations. “butterflyData.txt” is an example data set in ASCII comma-delimited format. Each row corresponds to data for a single species observed in the butterfly survey. The 20 columns correspond to 20 sample locations. “ExampleSession.txt” illustrates an example session in R where the butterfly data are read into memory and then analyzed using the R and WinBUGS code. “MultiSpeciesSiteOcc.R” defines an R function for fitting the model of species occurrence and detection to data. This function specifies a Gibbs sampler wherein 55000 random draws are computed for each of 4 different Markov chains. These computations may require nontrivial execution times. For example, analysis of the avian data required about 4 hours using a computer equipped with a 3.20 GHz Pentium 4 processor. Analysis of the butterfly data required about 1.5 hours. “MultiSpeciesSiteOccModel.txt” contains WinBUGS code for specifying the model of species occurrence and detection. “CumNumSpeciesPresent.R” defines an R function for computing a sample of the posterior-predictive distribution of a species-accumulation curve whose abscissa ranges from 1 to nsites sites.