There are 48 million birdwatchers in the U.S., according to the U.S. Fish and Wildlife Service. Most of them rely on printed field guides to identify and learn about the birds they find, while some use mobile apps that just translate those books into digital form and take up more than a gigabyte of phone storage, according to Jeff Simeon, who co-developed Birdeez with Patrick Toerner and Thomas Kuo.

Though they'll be at Demo Fall this week in Santa Clara, California, pitching yet another app to go on consumers' iPhones, the three partners are really trying to work at cross-purposes to the plugged-in, always-on society.

"We're really passionate about getting people outside, exploring nature again. Kind of unplugging from their computer screens," he said. Simeon has worked as an environmental educator, while Toerner is a recent graduate in economics and Kuo is an electrical engineer. Their company, EcoLek, grew out of a business-school project at the University of California at Santa Barbara.

The mobile age opened the door to a new way of identifying birds, taking advantage of the peculiar capabilities of smartphones, Simeon said. He calls Birdeez "Foursquare for birds."

"A lot of what determines what birds are around you is your location and the time of year," Simeon said. "The device knows both of those things."