Seasonally dry tropical forest is the least known and most threatened ecosystem in the Neotropics. In December 2009, we surveyed 3 tropical dry forest remnants in the arid Cúcuta valley, northeast Colombia. We recorded 140 of the 171 maximum species expected for the study area. Another 20 species were observed outside the inventory, totaling 160 species for the whole region. Results of the similarity analysis showed that the Cúcuta valley avifauna is biogeographically more related to the arid inter-Andean river valleys than to the Caribbean plains of Colombia and the Caribbean lowlands of northern Venezuela. This pattern of biogeographical affinities of dry forest bird communities in northwestern South America seems to be explained by the effect of geographic distance rather than environmental differences shaping species composition (β-diversity) and phylogenetic relatedness (phyloβ-diversity) across space. Our results highlight the uniqueness and need to protect the topical dry forest remnants of the Cúcuta valley.