Effects of climate change and human influence in the distribution and range overlap between two widely distributed avian scavengers

Abstract

SummaryClimate change can cause geographic displacement of the ecological niche of a species, so that similar species that previously did not coexist could begin to face new interactions. Such geographic displacement and increased competition can also be exacerbated by anthropic intervention. Until less than 100 years ago,Vultur gryphusandCoragyps atratusdid not coexist. Nowadays, possibly as a result of climate change, changes in the distributions of both species created areas where they are now sympatric. Through ecological niche modeling, we evaluated the possible effects that future scenarios of climate change and human influence would have on the distribution and sympatry between the two species. Our models predict that the current distribution ofV. gryphuswill be reduced between 18% and 24% by 2050 and between 21% and 32% by 2070. Additionally, they predict that the distribution ofC. atratuswill be reduced by 31–52% by the year 2050 and 15–60% by 2070. The two algorithms predict a reduction in the areas of sympatry. However, for the northern Andes the overlap between the two species will increase, reaching up to 70% in the year 2070. The distribution ofC. atratuswill move towards higher areas in the altitudinal gradient, and this will generate an increase in the current sympatry between both species. No clear trend was observed on the effect of human influences on the areas of overlap between the scenarios evaluated. The possible effects of climate change and anthropic intervention in future scenarios found in this study highlight the need to include these effects in future analyses and conservation programs ofV. gryphusand other threatened vultures.