Not just for bird-watchers, the National Audubon Society (tel. 212/979-3000; www.audubon.org) has its Ecology Camp on Hog Island off the Maine coast and another in the Grand Tetons of Wyoming, and it sponsors ecology excursions to such places as California's Death Valley. The Sierra Club maintains base camps in the Rockies and sponsors a variety of nature- and conservation-oriented trips (tel. 415/977-5500; www.sierraclub.com). On a tour sponsored by a conservation association, you'll learn more about our national parks than you could than just by driving through them. To find out what's available, contact the individual park you plan on visiting.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.