Distribution and abundance of vultures along an altitudinal gradient in Chiapas, Mexico

Ecological studies on tropical raptors are limited, even for common species such as some vultures. This study analyzed the altitudinal distribution and abundance of four species — Black Vulture Coragyps atratus , Turkey Vulture Cathartes aura , Lesser Yellow-headed Vulture C. burrovianus and King Vulture Sarcoramphus papa — in Chiapas, Mexico. Records were obtained from various bird surveys conducted between 2003 and 2015, which followed transects of 2 to 3 kilometers. A total of 693 sampling points were used for this analysis, and records for each species were grouped based on the presence of more or fewer than 100 individuals at three altitudinal gradients (0–300 m, 300–1,400 m, and 1,400–3,000 m a.s.l.). Black and Turkey Vultures were found across all three altitudinal levels, with greater abundance at lower elevations. Lesser Yellow-headed Vultures were found only at lower elevations, while King Vultures were more prevalent at mid-elevations and less common at higher elevations. Long-term studies using standardized methodologies are needed in tropical regions to understand temporal and spatial variations in the distribution and abundance of these vultures, as they depend on the unpredictable and scarce availability of food.