Altitudinal distribution of birds in the Sierra Madre del Sur Guerrero, Mexico

Altitudinal patterns of distribution, diversity, and species turnover in the avifauna of the Sierra de Atoyac, Sierra Madre del Sur, Guerrero, Mexico, were studied along a transect freom the tropical coastal plain to highaltitude coniferous forests. Species richness is highest at low elevations and declines with increasing altitude. Richness is relatively uniform within habitat types, but high levels of species turnover are found at habitat ecotones. Altitudinal ranges of congener species pairs overlap more freequently than predicted by null models, suggesting that competition may not have played a dominant role in structuring the community. Patterns of diversity, endemism, and habitat destruction are discussed in terms of conservation priorities

Alternate species concepts as bases for determining priority conservation areas

Analysis of geographic concentrations of endemic taxa is often used to determine priorities for conservation actio

A new taxon in the Amazilia viridifreons (Chordata : Aves : Trochilidae) complex of southern Mexico

We examined variation among populations of the complex assemblage of hummingbirds presently considered to constitute Amazilia viridifreons (Elliott, 1871), of Guerrero, Oaxaca, and Chiapas. A previous author had correctly suggested recognition of most Oaxaca populations as a full species, A. wagneri Phillips, 1964. We found that the Chiapas populations are also recognizable as a distinct taxo

Aquatic bird distributions in Mexico: designing conservation approaches quantitatively

The aquatic birds of Mexico include both a rich fauna of residents and a significant proportion of migratory species that breed in Canada and the United States, yet their distribution and richness patterns remain poorly known. We developed a detailed database of occurrences, and estimated distributions using niche modeling interpolations for 134 species associated with wetlands. Validations of the resulting maps indicated that the nichemodeling approach yields a useful picture of aquatic bird species distributions in the country. Richness patterns among aquatic birds differ freom those for landbirds: species richness is concentrated in coastal areas, but endemism is focused in the Transvolcanic Belt and the Altiplano. Place prioritization exercises identified sets of areas that would maximize the protection of this diversity

Rates versus counts: Fall molts of Lucy's Warblers (Vermivora luciae)

New specimens freom Sinaloa, Mexico, as well as two older specimens, show that both adult and recently fledged Lucy's Warblers (Vermivora luciae) often move far south of their breeding grounds to molt in the tropical deciduous forests of northwestern Mexico. Remarkably, the first preformative (= first prebasic) molt is complete in Lucy's Warblers, including the replacement of flight feathers, primary coverts, and rectrice