Underestimation of avian diversity in the Tumbesian hotspot: Sampling gaps and conservation challenges

Abstract The Tumbesian Region of northwestern South America is one of the most important areas for global biodiversity conservation. However, despite its importance, this region has not undergone a reassessment of its birdlife for more than three decades. Our study evaluated the richness, endemicity, and conservation status of birds in this region using more than 439,000 refined records, from bibliographic sources, field records, and the eBird platform. We found that the area is home to at least 931 species, representing a 16% increase over previous estimates. These included 24 new regional records and 82 endemic species. The greatest species richness increase is found in humid forests (882 species) and dry forests (760 species), while montane grasslands harbor the lowest values. Humid forests have the lowest levels of sampling completeness (50%), which could cause their actual diversity to be underestimated. The spatial analysis revealed clear biases related to accessibility, showing that information gathering efforts are concentrated on the coast and in protected areas, to the detriment of some areas in southwestern Ecuador and the border areas between Ecuador and Peru. No evidence of correlation between species richness and protected area coverage was found, although humid forests, which have high levels of diversity, are underrepresented in the current network of protected areas, while less diverse ecosystems have high coverage. These results indicate a critical misalignment between biological value and conservation efforts. We recommended prioritizing actions in both humid and dry forests, promoting processes that strengthen binational connectivity, and integrating citizen science with systematic monitoring to reduce bias and improve evidence‐based territorial planning.