Harnessing social media data to track species range shifts

Biodiversity monitoring programs and citizen science data remain heavily biased toward theGlobal North. Especially in megadiverse countries with limited biodiversity records, incor-porating social media data can help address existing data gaps. However, whether such datacan significantly improve our understanding of range-shifting species is still unknown. Wetested whether social media data improved our knowledge of the range dynamics of a rapidrange-shifting butterfly, the tawny coster (Acraea terpsicore). We collated locality data fromFlickr and Facebook and compared these with occurrence data from the Global Biodiver-sity Information Facility (GBIF). We used species distribution models (SDMs) and nicheassessments, which we calibrated with data from GBIF alone and both sources combined (GBIF and social media data) to analyze range shift dynamics. Social media data increasedoccurrence records by 35%, and the proportion of social media data was higher in coun-tries poorly represented in GBIF. In addition, we obtained new distributional informationfrom well-represented countries (e.g., Australia and Malaysia). Over time, the SDMs cali-brated with GBIF and social media data showed greater expansion rates than SDMs basedsolely on GBIF data. The niche assessments revealed that GBIF-only data failed to captureregions with relatively low maximum temperature, relatively low precipitation and high ele-vation. Our results highlight the potential of harnessing social media data to track rapidbiodiversity redistribution in response to climate change.