Densities for five key tidal marsh-dependent bird species were modeled using boosted regression trees (Elith et al. 2008). The models are able to fit non-linear functions between environmental variables and the presence/absence or density of a species. Map values represent the probability of occurrence of a species or the density (birds/ha). Higher values in a map indicate a higher likelihood that a species will be present at a site. Bird species modeled: Common yellowthroat, black rail, clapper rail, marsh wren, song sparrow. Model outputs: Probably of occurrence, density (birds per hectare)
