searchers at Columbia Engineering, led by Computer Science Professor Peter Belhumeur, have taken bird-watching to a new level. Using computer vision and machine learning techniques, they have developed Birdsnap, a new iPhone app that is an electronic field guide featuring 500 of the most common North American bird species. The free app, which enables users to identify bird species through uploaded photos, accompanies a visually beautiful, comprehensive website that includes some 50,000 images. Birdsnap, which also features birdcalls for each species, offers users numerous ways to organize species -- alphabetically, by their relationship in the Tree of Life, and by the frequency with which they are sighted at a particular place and season. The researchers, who collaborated with colleagues at the University of Maryland, are presenting their work at the IEEE Conference on Computer Vision and Pattern Recognition in Columbus, OH, June 24 to 27.