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.
The life history of this furtive bird is intimately connected with caterpillars. Where there are caterpillar outbreaks, there are Black-billed Cuckoos; where caterpillar numbers are depressed, often because of overzealous pesticide use, these cuckoos are scarce. Audubon’s climate model forecasts a sizeable expansion of suitable summer climate space, extending from current strongholds in the northeastern U.S. and southeastern Canada to much of the present-day boreal forest and taiga biomes. However, only 28% of the current summer range is included for the future. If forest insects, especially moths and butterflies, are able to track north and west with the model’s predictions and if the birds can follow—and those are two big ifs—then the Black-billed Cuckoo may be in for a range expansion.