Pine/Oak Woodland

The pine-oak woodlands of the Sierra Madre Occidental of Mexico extend for about 1100 km from the northern end ofthe Sonoran-Chihuahuan border southward to the region ofthe common borders of Zacatecas, Nayarit, and Jalisco. On the eastern side of the sierra the pine-oak woodlands grade into mesquite-grassland on the Mexican Plateau in the foothills. The steep escarpment on the west and its deep barrancas allow for complex interdigitation of the pine-oak woodland vegetation and the tropical deciduous forests in the lowlands.

We studied annual variation in reproductive activity and productivity of the Thick-billed Parrot (Rhynchopsitta pachyrhyncha) during a five year period (1997-2001), in five nesting areas at the Sierra Madre Occidental in Mexico. Two breeding areas continue to be the breeding strongholds for the species. We documented 491 nesting pairs and determined the outcome of 162 accessible nests. A nesting pair laid in average 2.7 eggs, and produced 1.6 fledlings per egg-laying pair.