Here's your chance to get in touch with nature.

* Veteran birdwatcher Grace Sims will direct a two-hour "sights and sounds" bird walk along the Maryland side of the C & O Canal this Sunday morning. She'll point out winter residents such as great blue herons, northern shovelers, buffleheads, cedar waxwings and Canada geese. Snow geese have not been sighted but are expected shortly. It's free but you'd better bundle up. Meet at 8 a.m. at the Great Falls Tavern, Great Falls Park, which is just outside the Beltway along the canal. Call 299-3614.

* If that's too early for you, try boning up with some bird books. Catch Ray Legge's seminar on "Field Guides to Everything" from 1 to 2:30 Sunday afternoon. The Fairfax County Park Authority naturalist will offer hints on selecting and buying a wide variety of books to identify birds, wildflowers, butterflies, reptiles, trees, mushrooms and even one-celled creatures. It's free, too, at Huntley Meadows Park, Harrison Lane and Lockheed Boulevard in Hybla Valley. Call 768-2525.

* If those doings won't do, then take a hike to the National Zoo. The winter series of Sunday afternoon activities kicks off at 1 with a concert by the Navy Band Brass Quintet and a performance by the Archarsus Mimes. Also on tap is an animal sketching workshop provided by the zoo's art staff. The free series is held each Sunday through early March in the Education Building. If you're taking Metrorail, exit from the Red Line at the Woodley Park/Zoo stop. Zoo parking is $3. 673-4717.