Wired.com tells us the story (http://www.wired.com/news/planet/0,2782,68728,00.html) how scientists at Oregon State University equip songbirds with cell phones to monitor their migratory routes.

The mobile cellular devices will weigh 0.07 ounces and will be attached to birds captured in nets in North American breeding grounds. They will allow the scientists to track their locations within a radius of 2 to 3 miles, an unprecedented degree of resolution.

Only don't tell PETA (thinking about radiation hazards).