The darker the color, the more favorable the climate conditions are for survival. The outlined areas represent approximate current range for each season. More on reading these maps.
This uncommon vireo breeds at the upper edge of the northern hardwood forests. A bit north, there are too many conifers; a bit south, the species just doesn’t occur, for whatever reason. Audubon's climate model projects an unstable future for the Philadelphia Vireo. On the one hand, an overall increase, by close to one-half, of total suitable summer climate space is forecast. On the other hand, less than 10 percent of climate space suitable at the present time is forecast to be in that condition by century’s end. The key for the Philadelphia Vireo and for so many other northern forest breeders is habitat—and how or whether it responds to climate change.