In which California range did Edmund Jaeger find a hibernating common poorwill in 1946?

Edmund Jaeger found a hibernating common poorwill in California’s Chuckwalla Mountains in 1946. The discovery occurred in a desert mountain range in Riverside County and became the foundation for his later description of the bird’s extraordinary winter torpor.

The common poorwill was found inactive and concealed among rocks, a setting that provides shelter from exposure while the bird’s metabolism and body temperature fall. Unlike ordinary nightly torpor, this state can last for weeks or months, making it one of the most unusual physiological adaptations known in birds.

The Chuckwalla Mountains lie in the transition zone between the Colorado and Sonoran deserts. Their connection with the poorwill is now commemorated by the Edmund C. Jaeger Nature Sanctuary, established in 1986. The discovery is sometimes described as “hibernation,” although biologists often use “extended torpor” because the terminology is more precise for birds. Jaeger published the phenomenon definitively in 1948.