The decline of global pollinator biodiversity in the Anthropocene

Pollination underlies the functioning of ecosystems globally. Therefore, the endangerment and extinction of pollinator species are predicted to trigger cascade effects with the potential to alter the demographic collapse of complex ecological networks. However, although some studies have investigated the endangerment levels of pollinator species, the lack of global-scale analyses providing a universal overview of their extinction risks remains a major pending challenge in a world where climate change is rapidly decimating biodiversity. Here, we present the first truly global study of the endangerment level of vertebrate pollinators from across the tree of life. Based on a 1,666 species dataset, we investigate the macroecological patterns of species diversity and extinction risk of bird, mammal, and reptile pollinators of the world. We found higher extinction risk for mammal relative to bird and reptile pollinators. Globally, 1 in 3 mammal pollinators are currently threatened with extinction than 1 in 12 bird and 1 in 8 reptile pollinators. The hotspots of threatened bird pollinators mostly confined to Colombia and Hawaiian Islands, whereas the hotspots of threatened mammal and reptile pollinators are confined to Madagascar and various isolated islands. Notably, the endemic pollinators are more threatened than the widespread pollinators. The increasing decline of population will alter the status of threatened pollinators in future. While highlighting the quantity of threat and decline, we also show that the evolutionary predisposition along with habitat destruction for agriculture, and exploitation for bushmeat and pet trade are combinedly eroding the vertebrate pollinators biodiversity across the world at multiple scales. We suggest special environmental priorities such as controlled land-use, legislation on hunting, collaborative efforts between various stakeholders and community outreach programmes are essential for effective conservation of vertebrate pollinators.