They said outdoor activities - tracked by national and state park admissions, game licenses, hiking permits and surveys of leisure activities - have fallen by more than 20 percent since the 1980s.
"The average person in America used to go to the national parks every year. It was the iconic American family vacation. Now, there are less people doing that," said Patricia Zaradic, a biologist with the Environmental Leadership Program, Delaware Valley , in Bryn Mawr , Pennsylvania .
The conservationists believe that the electronic world has supplanted the natural world as the leading diversion. Their statistical analysis shows that the increase in video games, movie rentals and other electronic entertainment most closely matches the decrease in camping and park visits, as opposed to income, vacation time, park overcrowding, foreign travel or other potential causes.
But Richard Louv, chairman of the Santa Fe , N.Mex.–based Children and Nature Network and author of Last Child in the Woods, ascribes the change more to increasing school and work pressure on children and parents as well as the rising cost of park visits. Plus, he says, there's the fear factor. "You didn't have the concept of stranger danger [in the past]," Louv says. "If you are raising a generation under protective house arrest, will they have a joyful experience in nature?"