To understand the spatial and temporal variation of the understory bird diversity, we estimated species diversity in four sites (Las Grutas, Vivero, Yalmutz y Yalhuech) with different vegetation type and management regimes in the Lagos de Montebello National Park, Chiapas from July 1997 to June 1998. We identified 71 bird species; 50 residents and 21 migrants. Families with more species were Parulidae (15), Tyrannidae (9) and Turdidae (8). Most of species were recorded to a single site (63.4%) and only 9.8% were distributed in all four sites. The highest relative frequencies of total captures were for Chlorospingus ophtalmicus (0.197), Catharus ustulatus (0.110), Lampornis viridipallens (0.083) and Myioborus miniatus (0.072). Capture number varied among sites, while Vivero showed the maximum values, Las Grutas showed the minimum. Yalmutz had the highest species richness (36), and Las Grutas the lowest (24). The highest diversity (Simpson reciprocal 16.41) and evenness (0.68) was recorded in Las Grutas, which was the site less disturbed and showed one of the last remnants of montane cloud forest. However, Yalmutz showed the highest values of Shannon diversity (4.37), and high values of both exclusive (14) and rare species (21). Yalmutz showed a mix of elements of pines and broadleaves and it was the second site with less disturbance by human activities. The higher species richness and abundance was during the dry season. The National Park Lagos de Montebello showed an important bird species diversity for the environmental variation and different stage of disturbance. The persistence of bird populations and their conservation in the region will depend on the remaining of nondisturbed environments and the quality of secondary and managed forests.
