Determinants of the Vertical Distributions of Woodpecker Nest Cavities in the Sahuaro Cactus
McAuliffe JR and Hendricks P. 1988. Determinants of the Vertical Distributions of Woodpecker Nest Cavities in the Sahuaro Cactus. The Condor. 90(4):791 - 801
In the Sonoran Desert, Gilded (Northern) Flickers (Colaptes auratus chrysoides) and Gila Woodpeckers (Melanerpes uropygialis) excavate nest cavities within the giant sahuaro cactus. Vertical distributions of nest cavities excavated by the two woodpecker species differ in height and breadth. Flicker cavities are usually restricted to within 3 m of the stem apex. Nest cavities excavated by Gila Woodpeckers are found over a considerably broader vertical range of heights; their average height is also lower. Competitive preemption of potential excavation sites cannot fully explain this differential utilization of vertical space. Rather, the initial positioning of nest cavities is constrained by cactus anatomy. Different nest-cavity sizes and wood-chiseling capabilities of the two woodpecker species limit the vertical range over which nest cavities can be excavated. In addition, an excavation by a flicker often results in death of the sahuaro. With this mortality, a long-running record of flicker nest-cavity heights is not preserved. In sahuaros containing only Gila Woodpecker cavities, the original heights of old excavations are preserved as the sahuaro continues to grow, thus contributing to the greater vertical range of observed cavity heights.
- Type
- Journal Article
- Authors
- McAuliffe, Joseph; Hendricks, Paul
- Units
- ORPI
- Keywords
- Anatomy, Birds (Aves), Botany, Ecology, gila woodpeckers (Melanerpes uropygialis), gilded flickers, Mortality, Nests & Nesting, Ornithology, Saguaro Cactus (Carnegiea gigantea), Sonoran Desert