On a cold and crisp December morning in New York City, tens of thousands of pieces of broken ceramic, glass, and mirror glinted under the sun that fell on the corner of West 163rd Street and Broadway. Guatemalan artist Juan Carlos Pinto and Brooklyn-native John Sear methodically glued each into the giant mosaic taking shape on the wall. Passers-by stopped to watch, and then contribute, as the artists invited them to help. After about 40 hours of work and many dozens of spontaneous volunteers, the final tile was placed into the 20- by 7-foot frame—and two Trumpeter Swans appeared to fly out of it. The residents of Washington Heights have grown accustomed to seeing birds pop up on walls around their neighborhood, thanks to a public-art initiative of the 吃瓜黑料 and Gitler &_____ Gallery. The 吃瓜黑料 Mural Project has for the past six years enlisted artists to paint avian species threatened by climate change throughout Northern Manhattan, where the famed 19th...