A flock of pigeons fitted with mobile phone backpacks is to be used to monitor air pollution this year. The 20 pigeons will be released into the skies over San Jose, California, US in August. Each bird will carry a GPS satellite tracking receiver, air pollution sensors and a basic mobile phone. Text messages on air quality will be beamed back in real time to a special pigeon “blog,” a journal accessible on the Internet. Miniature cameras slung around the pigeons’ necks will also post aerial pictures. The idea is the brainchild of researcher Beatriz da Costa, of the University of California at Irvine, and two of her students. They have built a prototype of the pigeons’ equipment, containing a mobile phone circuit board with SIM card and communication chips, a GPS receiver, and sensors capable of detecting carbon monoxide and nitrogen dioxide. The pigeons will take to the air at the inter-Society for Electronic Arts’ annual symposium in San Jose on August 5. The data they send back will be displayed on the blog in the form of an interactive map.