No description available.

Note: / During 14 months at San BIas, Nayarit, Mexico, 1 studied the energy èconomlcs of foraging hummingbirds. Amazilia rutila and Cynanthus latirostris were always the commonest species present and l documented their responses to food and competitors as resources changed between habitats and seasons. / Durant 14 mois j'ai 4tudié les aspects énergétiques économiques de la recherche de la nourriture chez les colibris, a San Blas, Nayurit en Mexique. Amazilia rutila et Cynanthus latirosis étaient les espèces les plus communes tout au long de l'année et j'ai étudié leur réponses aux compétiteurs intra- et inter spécifiques à mesure que leur ressources changeaient entre les habitats et au cours des saisons.

No description available.

No description available.

No description available.

Note:

No description available.

No description available.

Birds are one of the best studied animal groups in the world but are also amongst the most endangered. The wealth of ecological information has shown habitat protection to be vital to bird biodiversity, but habitat loss and degradation continue to defeat conservationists. / Community-based biodiversity conservation efforts have been recently recognized as an important option for safeguarding ecosystems while reducing land use conflicts arising from the material, cultural and spiritual needs of local inhabitants. Community involvement is particularly critical for conservation in anthropogenic habitats. Few studies have linked the ecological impacts of community land use practices with the auto-ecological requirements of dependent bird species. In this study I examine the conservation possibilities for the endangered Sierra Madre sparrow (Xenospiza baileyi) by considering three basic elements: the ecological requirements of the bird, the effects of traditional land use practices in shaping the habitat, and the economic and social conditions that influence current and future land use decisions. I draw on ecological field studies, on traditional ecological knowledge systems, and studies of the political ecological context that influences local practices. / The studies were carried out from 2000-2003 and employed a combination of ethnographic, participative and spatial-ecological approaches to address human-land interactions and their impacts on the sparrow habitat. Social data were obtained through nine workshops which included site visits, transect walks, participatory mapping, oral histories and semi-structured interviews. Ecological data were obtained from landscape ecology analysis, vegetation post-disturbance assessments and detailed bird's nest-site selection analysis. / Results indicate that local people, principally herders, hold a rich knowledge of fire use to achieve diverse purposes, including pasture renewal, grassland maintenance and grass species selection, and prevention of dangerous fires. In order to accomplish their goals, herders have established rotational fire and grazing regimes that consider timing, frequency, location and extent of these disturbance-based practices. This rotational system was found to benefit the Sierra Madre sparrow by maintaining the grassland at the scales needed by the sparrow for nesting. Multiscale habitat recommendations for the species' conservation were derived from this socio-ecological interaction and dynamics. / Unfortunately, external conservation perspectives and interests and internal land tenure conflicts have altered this rotational regime and local perspectives on resource management that threaten the resilience of this social-ecological system. Consequently, traditional ecological knowledge on grassland management can be on risk of disappearing and, with it, important native grasses and grasslands are being made vulnerable. The survival of the Sierra Madre sparrow in particular and of associated biodiversity in general, is in peril if these conflicts are not solved in a relatively short time. A community-based fire co-management program is recommended to promote integrative bird conservation-local development scenarios.