A look at the Cornell Lab of Ornithology's Merlin Bird ID app, which has been downloaded 42M times since launching in 2014 and can identify 11,000 bird species (Claer Barrett/Financial Times)

The Merlin Bird ID app, released by the Cornell Lab of Ornithology in 2014, has been downloaded 42 million times and can identify roughly 11,000 bird species worldwide, offering users audio recordings, photos and location-based suggestions to aid field identification.