Community science data provides evidence for upward elevational range shifts by Eastern Himalayan birds

The ongoing climate crisis is a significant threat to global biodiversity. As Earth warms, many species respond by shifting their geographical ranges either polewards, or in mountainous regions, upslope towards higher elevations, presumably to track suitable thermal environments. Upslope range shifts are of particular concern in tropical mountain ranges because: (a) tropical species are particularly thermally sensitive, (b) species moving upwards could become locally extirpated as they run out of habitable space, and (c) tropical mountains harbor a high fraction of Earth's terrestrial biodiversity. Rapid upslope shifts can therefore result in significant biodiversity losses. We used community science data over a 13-year period to evaluate whether 93 Eastern Himalayan bird species might be shifting to higher elevations. To do this, we analyzed changes in their occurrence probabilities in eBird checklists from birdwatching hotspots at fixed elevations. We found patterns consistent with upslope range shifts; species with elevational ranges primarily below hotspot elevations show increases in their occurrence probability over time, and those with most of their elevational ranges above a hotspot elevation decline in occurrence probability. Our findings are suggestive of rapid responses to climate change by Eastern Himalayan birds. We caution that Eastern Himalayan bird species might be at special risk from increasing global temperatures because of heightened thermal sensitivity coupled with high rates of warming in the region. To remain resilient in the face of climate change, Eastern Himalayan birds likely require undisturbed habitats spanning entire elevational gradients, to track rising temperatures by moving to higher elevations.R is required to run the .R code, and any program that reads .csv files is needed to open the species_traits and ebd_data files. The .nex file may be opened in a text editor, or in any software that can render phylogenetic trees.Funding provided by: N/ACrossref Funder Registry ID: 0Award Number:This data was collected from eBird, an online community science database of bird sightings. The data for species elevations and traits is from the book Birds in Bhutan: Status and Distribution by Peter Spierenburg (2005). The phylogeny in the .nex file was generated from birdtree.org. The .R code details how these 3 datasets have been processed to show the results seen in our manuscript