Serious hikers and backpackers tend to become supporters of environmental and conservation groups while casual woodland tourists do not, a new study says -- and a recent fall-off in strenuous outdoor endeavors portends a coming decline in the ranks of conservation backers.

PHILADELPHIA _ It's windy. Rain is imminent. The path is muddy. But Patricia Zaradic is loving it all. What's important is that she is out in nature, a place her research tells her fewer and fewer Americans are heading.

In the last two decades, park visits, permits for camping or fishing, and other data show a fundamental, pervasive shift away from outdoor activities, the Bryn Mawr ecologist concludes in a study published recently.

"Take a hike!" isn’t just a rebuff. Now it's also a plea from environmental scientists.