The Geographic Distribution of a Tropical Montane Bird Is Limited by a Tree: Acorn Woodpeckers (Melanerpes formicivorus) and Colombian Oaks (Quercus humboldtii) in the Northern Andes
Fig 2
Species distribution models generated for Acorn Woodpecker in northern Andes.
Habitat suitability is shown as a continuous variable, in which green colors indicate highly suitable habitat, with (A) abiotic variables alone, (B) Quercus presence alone, and (C) abiotic variables + Quercus presence. We converted continuous measures of habitat suitability into binary presence and absence models by setting the threshold to the value that maximizes the parameter Kappa, which is an index of model performance. Binary conversions were done for (C) abiotic variables alone and (D) abiotic variables in addition to presence of Quercus. Excluding Quercus occurrence points generated species distribution models that over-predict the occurrence of Acorn Woodpeckers in South America.