Gila Woodpecker, Peterwchen
Introduction
Well-known saguaros (Carnegiea gigantea) host a surprising community of animals that literally carve out homes in living cactus. Gila woodpeckers and gilded flickers excavate nest chambers in the saguaro’s soft inner tissue, creating waterproof cavities (“boots”) that later shelter other species — including the diminutive elf owl. These relationships illustrate how one plant can structure entire animal communities in the Sonoran Desert.
The Details
Woodpeckers initiate the process each spring by chiseling an entrance and hollowing the chamber. Sap initially oozes and hardens, lining the cavity; months later the chamber is dry, insulated, and ready for eggs. After woodpeckers fledge or abandon a cavity, secondary cavity nesters move in — elf owls, screech-owls, purple martins, finches, and occasionally kestrels. Hawks such as Harris’s use saguaros for stick nests and hunting platforms. Because nest-site availability can limit breeding, saguaro density, height, and arm architecture indirectly govern local bird assemblages. Urban saguaros in Tucson similarly support these guilds, though pruning and lightning scars can alter cavity persistence.
Additional Reading: Physiological adaptation in desert birds
