It's a strenuous business, keeping up with nature. Going where it's not carpeted. Venturing beyond the Blue Line. MAPLE SYRUP-MAKING -- To better appreciate March, tap into the art of maple syrup-making at Cunningham Falls State Park in Thurmont, Maryland, this weekend and next. Park Rangers will demonstrate the sap-to-syrup process each Saturday and Sunday, 10 to 4. A film on maple candy-making will be shown, free "finger-dipping" samples will be available and maple sugar products will be sold. Take U.S. 15 north to Thurmont, go west on Route 77 for about three miles. Turn left on Catoctin Hollow Road and follow signs to the William Houck Area.

At Sweetwater Tree Farm in Aurora, West Virginia, the maple sugaring season runs through early April. Visitors are advised to bring boots, the better to hike through mud to the maple groves. The store and plant are open 8 to 6, Monday through Saturday and "most Sundays and holidays." It's on U.S. 50, three miles from Redhouse, Maryland. Call 304/735-6602. NEW WINE -- In keeping with what they call the "Spirit of the Green," Berrywine Plantations Winery will introduce their new Mint Wine, made with local field mint, on Saturday and Sunday, 1 till dusk. Owner Lucille Allen describes the vintage as "very light and minty, excellent with lamb or added to iced or hot tea. It's nothing like creame de menthe." They also offer a full complement of dry grape and apple wines.

Admission is $1.60 for adults; children under 18 free. Take I-270 toward Frederick, exit at Damascus and pick up Route 27 to Mount Airy. Follow the winery signs to glisan's Mill Road. BIRDWATCHING -- What's a spring thaw without birds? A park naturalist will conduct an hour-long birdwatchers' walk at Kenilworth Aquatic Gardens, Anacostia and Douglass Streets NE, Saturday morning at 8:30. And Sunday, Great Falls Park in Virginia sponsors a walk for early risers, "Breakfast with the birds," leaving the visitors center at 8. LOST & FOUND -- "Orienteer" role call: Catoctin Mountain Park (Route 77 in Thurmont) offers a free course in "Finding Your Way" with compass and map, which are provided for the first 30 registrants. Groups meet at the Visitors' Center at 1:30, Saturdays and Sundays, beginning this weekend, through April 12. Likewise, the National Park Service offers orienteering workshops, at 10 and 1 in Prince William Forest Park, off I-95 near Quantico. LATE WINTER WALKS -- "How Did Justice Douglas Save the C&O Canal?" That's the title of a walking talk, leaving the Great Falls Tavern in Potomac at 1 on Sunday. A park ranger will discuss why the canal needed saving and how William O. Douglas came to the rescue.

Saturday at 2, also at the Great Falls Tavern, kids 8 to 14 are invited along as "Samantha Tracks Spring." Park Ranger Donna Donaldson will lead the hike, pointing out animal tracks, buds and other hints of the season.

Another canal walk on Saturday leaves the Seneca parking lot at 2 for a one-hour hike along the C&O. The regular Rock Creek nature walks continue Saturday and Sunday at 3, with an introduction to the wildlife and vegetation of the park. It's early in the season for wildflowers, but there's still plenty to see. Meet at the Nature Center, 5200 Glover Road NW.

Theodore Roosevelt Island will be scoured for "Signs of Spring," by Park Ranger Philip Jenny every Saturday and Sunday through March. Park Ranger Philip Jenny every Saturday and Sunday through March. The curious are invited to meet at the memorial in the park at 2 to search out the silver maple buds, the spice bushes about to bloom and the arrow arum swamp plants. "It's too early for flowers," Jenny says, "but the May apples, a little annual that will eventually have a white blossom, are coming up." BLUE RIDGE RACES -- Berryville, in the heart of Virginia's apple country, hosts point-to-point racing Saturday. The Blue Ridge Hunt will stage a seven-race card over the course at Woodley Farm. A turf (flat) race opens the program at 1; four races over timber and two hurdle races follow. Take Route 7 west to Berryville, left on U.S. 340, three miles to Woodley Farm on the left. For information call 703/837-1032 ro 703/837-1719.