Shawan Chowdhury , Niloy Hawladar, Ripon C Roy, César Capinha, Phillip Cassey, Ricardo A. Correia, Gideon Deme Gywa, Moreno Di Marco, Enrico Di Minin, Ivan Jarić, Richard J Ladle, Jonathan Lenoir , Mohammad Momeny, Jooel J Rinne, Uri Roll, Aletta Bonn

Biodiversity monitoring programs and citizen science data remain heavily biased towards the Global North. Incorporating social media data can complement existing gaps, especially in megadiverse countries with limited records, but whether such data can significantly improve our understanding of range-shifting species is unknown. Here, we collated locality data from Flickr and Facebook, in addition to occurrence data from the Global Biodiversity Information Facility (GBIF). We tested whether social media data improved our knowledge of the range dynamics of a rapid range-shifting butterfly, tawny coster (Acraea terpsicore), when compared to GBIF-only data. Social media data increased occurrence records by 35%. The proportion of social media data was higher in countries poorly represented on GBIF; however, we also obtained new distributional information from well-represented countries (e.g., Australia and Malaysia). We constructed ecological niche models (ENM) with data from both sources. ENMs based on the social media data highlighted greater expansion rates to higher latitudes and elevations compared to ENMs based on GBIF data only. Our results highlight the potential of harnessing social media data to track biodiversity redistribution in response to climate change.