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.
All the Empidonax flycatchers are hard to identify, but the Cordilleran and Pacific-slope species are particularly challenging. They are ordinarily impossible to distinguish in the field except by voice. The two are ecologically quite similar, as well, but separated by range: Cordilleran in the Intermountain West, Pacific-slope farther west. Suitable climate space for breeders is forecast by Audubon's climate model to decline by roughly two-thirds overall, and only 15 percent of the current range in climatically favorable condition is expected to remain that way by century’s end. Like so many other forest birds in the Interior West, the Cordilleran Flycatcher is likely to face summer range disruptions in a changing climate.