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Evaluation of various climate change factors on Mexican bird populations shows temperature has the strongest influence.

Seasonal and temporal patterns of species diversity and abundance in the avifauna of Chamela, Jalisco, Mexico, were studied in different habitats in the coastal tropical dry forest. Species richness did not differ among three different transects. The number of species was temporally homogeneous. Species diversity was similar for all three transects, but it changed to higher values during the rainy season at arroyo habitats and during the dry season (winter) at disturbed habitats. Population fluctuations observed in the second year of the study suggest that stochastic events such as droughts in this region may influence local population dynamics. Patterns of population fluctuation of resident species are discussed with regard to censusing methods and conservation priorities.Restimen. Se estudiaron 10s patrones estacionales y temporales de diversidad y abundancia de la avifauna de Chamela, Jalisco, Mtxico en distintos habitats de la selva baja caducifolia de la costa. La riqueza de especies no difiere entre transectos y es homogknea temporalmente. La diversidad de especies es similar entre transectos, pero el valor de1 indice aumenta durante la Cpoca htimeda a lo largo de 10s arroyos y durante la Cpoca de secas (inviemo) en las zonas perturbadas. Las fluctuaciones en el tamaiio de las poblaciones observadas durante el Segundo aiio de1 estudio sugieren que eventos estoc&icos coma las sequias en la regiBn pueden afectar la din&mica de las poblaciones a nivel local. Los patrones de fluctuaciones de las poblaciones de especies residentes son discutidos en Grminos de la metodologia usada para censar y en cuanto a su prioridad de conservaci6n. Palabras clave: Diversidad de especies; perfiles de variabilidad; Jalisco; MPxico;jhctuaciones de poblaciones; conservacih. INTRODUCTION in tropical regions (see Karr 1981 and Blake Monitoring temporal changes of avifaunas can 1992). provide invaluable information about factors in-We were interested in determining what facfluencing population dynamics, interactions, tors modify avian behavior, producing fluctuacommunity structure, and conservation. Season-tion in diversity and density of each species al changes in density and number of species have throughout time. In this study, we examined been studied in several temperate avian com-variation in avian numbers and species richness munities (e.g., Best 198 1, Anderson et al. 198 1; over two years at specific sites in a tropical dry for a review see Ralph and Scott 198 I), but rarely forest in western Mexico, and investigate the factors that account for variation. Our study of two of the driest years recorded (M&quez-Valdelamar 1987) suggests that: (1) forest resident spe-I

Biological monitoring is a powerful tool for understanding ecological patterns and processes, implementing sound management practices, and determining wildlife conservation strategies. In Mexico, regional long-term bird monitoring has been undertaken only over the last decade. Two comprehensive programs have incorporated bird monitoring as the main tool for assessing the impact of human productive activities on birds and habitats at local and regional levels: the Integrated Ecosystem Management (IEM) and the Mesoamerican Biological Corridor Mexico (CBMM). These programs are implemented in supremely important biodiverse regions in the southern and southeastern states of Mexico. Bird monitoring activities are based on the recruitment and participation of local people linked to sustainable productive projects promoted by the CBMM or IEM. Through a series of training workshops delivered by specialists, local monitors receive equipment and coordinate to become part of a large monitoring network that facilitates regional covertures. This data currently being obtained by local people will enable the mid- and long-term assessment of the impacts of sustainable human productive activities on birds and biodiversity. Community-based bird monitoring programs are a promising opportunity for enhancing scientific knowledge, improving sustainable practices, and supporting wildlife conservation in areas of high biodiversity

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