We report observations of a population of Military Macaws (Ara militaris) within the Tehuacán-Cuicatlán Biosphere Reserve in northern Oaxaca, Mexico during 2002–2004. Macaws used a series of barrancas for roosting and nesting, and foraged widely in surrounding areas. Most of the population of ∼100 individuals could be counted flying to or from the major roosting areas of El Sabino Canyon and Barranca de Las Guacamayas. Reproduction appeared to be restricted to vertical cliffs of El Sabino Canyon. Most movements were associated with seasonal foraging and depended upon availability of fruits.