Biotic assessment of crowdsourced data defines four ecoregions in Thar: A novel approach for community engagement in conservation

Distinct ecosystems have representative biota that can allow delineation of ecoregions. Despite being one of the most populated desert ecosystems in the world with extreme climatic conditions, Thar has been classified as a single ecoregion by WWF. The present study aimed to test this on the basis of biotic assessment using community science, also known as citizen science or crowdsourced data from eBird (492 species of birds through 50,000 checklists of 4000 birders). Unsupervised clustering (k = 4) and mathematical validation using cosine similarity revealed the presence of four distinct ecoregions- Eastern Thar (ET), Western Thar (WT), Transitional Zone (TZ) and Cultivated Zone (CZ) in Thar. Most strikingly, these ecoregions when overlaid on geographical regions of Thar show that the CZ ecoregion was split between three distant and distinct geographic regions. Further spatial diversity estimates show CZ had the least α diversity (273) and highest β diversity (1.8) indicating the least similarity between the districts that comprised this ecoregion. The results suggest CZ as an evolving ecoregion or a consequence of habitat fragmentation due to anthropogenic effects. The presence of least number of exclusive species in CZ (0.2%) and TZ (0.8%) including the near-threatened species like Laticilla burnesii (Rufous-vented grass babbler) and Pelecanus philippensis (Spot-billed pelican) and an endangered species Athene blewitti (Forest owlet) highlights the need for restoration of these threatened biota and ecoregions. This study for the first time proposes crowdsourced bird data as an important biota-based tool to understand (a) established ecoregions in an ecosystem, (b) anthropogenic effects of agri-farmlands and (c) relation between geographic regions and biota. •Avian diversity revealed four ecoregions, Western Thar, Eastern Thar, Transitional Zone and Cultivated Zone in Thar Desert.•Formed of geographically and physiographially unrelated districts, Cultivated Zone is an evolving unstable ecoregion in Thar.•Cultivated Zone and Transitional Zone were least diverse due to anthropogenic activities like agri-farmlands and mining industry.•With near threatened and endangered exclusive bird species, Cultivated Zone and Transitional Zone highlights need for restoration.