Confirmation of previously unknown overwintering habitat for the endangered Thick-billed Parrot Rhynchopsitta pachyrhyncha

Summary

The Thick-billed Parrot Rhynchopsitta pachyrhyncha is an endangered, cavity‑nesting psittacine restricted to increasingly fragmented high‑elevation pine forests of Mexico’s Sierra Madre Occidental, yet its non‑breeding ecology remains poorly known. We analysed multi‑year movement data from parrots to delineate the species’ overwintering range and seasonal habitat, and ground‑truthed predicted core areas during field surveys. The overwintering range lies 380–570 km south of the breeding range in the northern Sierra Madre Occidental, primarily in western Chihuahua and adjoining Durango and Sonora, and is dominated by cool, high‑elevation montane pine and mixed pine–oak forest. We observed large overwintering flocks of 300–900 birds and confirmed intensive use of these core habitats, suggesting that previous wild population estimates of c.2,500 individuals may be conservative. Only a small proportion of the overwintering range is currently under formal protection, with most habitat occurring within managed communal forest landscapes. Our findings provide the first empirical delineation of the Thick-billed Parrot’s overwintering range and highlight priority areas where strengthened habitat protection and conservation agreements with forestry communities will be critical for the species’ recovery.