Nesting Ecology of Thick-Billed Parrots

Abstract

During a four-month search for nesting Thick-billed Parrots (Rhynchopsitta pachyrhyncha) in 1979, we found 55 active nests at elevations of 2,300 to 3,070 m in northwestern Mexico's Sierra Madre Occidental. All nests were in cavities of live trees or standing dead trees (snags). Pine (Pinus spp.) snags contained over one-half (58%) of these nests. These parrots laid two to four eggs (x̄ = 2.9; SD = 0.65) between mid-June and late July and young flew from their nests between early September and late October. Nesting density was apparently related to availability of suitable cavities and was variable, with some nests as close as 2 m apart in the same tree. The nesting season corresponded with the maturing of pine seeds, the parrots' principal food. Commercial logging of live pines for lumber, and of pine snags for pulpwood, is eliminating large numbers of proven and potential nest sites. Forest management practices should be modified to leave some suitable trees throughout the forest as potential nest sites for Thick-billed Parrots.