National Center for Geographic Information and Analysis, University of Maine, Orono, ME 04469, USA. mdolan@informatics.jax.org|National Center for Geographic Information and Analysis, University of Maine, Orono, ME 04469, USA. mdolan@informatics.jax.org|National Center for Geographic Information and Analysis, University of Maine, Orono, ME 04469, USA. mdolan@informatics.jax.org|National Center for Geographic Information and Analysis, University of Maine, Orono, ME 04469, USA. mdolan@informatics.jax.org