Abundance models of endemic birds of the Sierra Nevada de Santa Marta, northern South America, suggest small population sizes and dependence on montane elevations.

This article focuses on estimating population density, area of occupancy (AOO), and effective population size for 11 endemic bird species of the Sierra Nevada de Santa Marta (SNSM) in northern Colombia, a globally irreplaceable ecosystem. Using nine years of systematic bird surveys and hierarchical distance-sampling models in the "Cuchilla de San Lorenzo" Important Bird Area, the study reveals that most species peak in abundance at montane elevations (1,800–2,650 m) with limited habitat-related variation. Range-wide extrapolations indicate that at least four species likely maintain populations of fewer than 15,000–20,000 mature individuals, suggesting some may exceed criteria for threatened species listing. The findings underscore the urgent need for effective protection of native vegetation in premontane and montane ecosystems to conserve critical habitats for these endemic birds and call for further range-wide abundance studies to refine population estimates.