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.
Before World War II, the House Finch was a bird found only in southwestern U.S. and Mexico (where it is widespread and common). In 1940 it was accidentally introduced to New York City. For a decade or more it was barely established in that area, and then it began to spread. Meanwhile, the native population spread north and east until the two met in the center of the continent. Nowadays, the bird is common in most of the populated portions of North America. Audubon's climate model projects a 69 percent loss of current summer range by 2080. The species is essentially non-migratory in the West, but the introduced eastern population has shown some tendency to migrate, suggesting that the eastern population of species could adapt to changing climate by becoming less sedentary.