Habitat heterogeneity is an important ecological determinant of species richness. We evaluated the diversity within bird feeding guilds as related to habitat heterogeneity and land-use cover in a human-modified tropical landscape. To quantify this process, fine-scale bird census and habitat heterogeneity data were collected for a bird community in a 22.5-km2 fragmented landscape in southern Mexico. Land-use cover data derived from field surveys were used to calculate habitat heterogeneity index values and the extent of each land-use cover type in 239 grid cells of 300 × 300 m. Bird diversity values were obtained based on 1195 point-counts in these cells. Product-moment correlations and linear regression analyses were used to evaluate the relationship between bird-guild diversity values and habitat heterogeneity. A total of 109 resident bird species grouped in six feeding guilds were recorded: insectivores (42%), frugivores (21%), granivores (17%), nectarivores (9%), omnivores (8%) and carnivores (3%). Diversity values for the entire bird community were significantly positively related to habitat heterogeneity, but feeding guilds showed contrasting responses to habitat heterogeneity and the amount of land-use cover: insectivores and frugivores were more diverse and abundant in secondary forests than in any other land-cover. Our findings illustrate the importance of small landscape fragments as potential key refuges for the most diverse and specialized feeding guilds, such as granivores and insectivores.