Logging

Fire is a dominant ecological process in almost all landscapes of La Frontera. Fire histories from throughout the region on the United States side of the border show that, before circa 1900, extensive surface fires occurred within pine-dominant forests at about the same frequency as wet-dry cycles related to the El Niño-Southern Oscillation, i.e., 2 to 7 year intervals (Swetnam and Betancourt 1990, 1998; Swetnam and Baisan 1996a, 1996b). Regionally synchronous fire events occurred at the rate of about 10 per century and often coincided with the most extreme wet-dry cycles.

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.