Peter Alden will lead a nature walk in western sector of Walden Woods on "secret" trails near Fairhaven Bay including two of Concord's highest cliffs and a beaver pond for Thoreau Society.

Peter Alden of Concord is co-compiler of the U.S.'s largest Christmas Bird Count, founder of Biodiversity Days with E.O.Wilson, author of 15 nature books (sales of 1.5 million units), and ecotourism guide in 100 countries and lecturer on cruises on the seven seas.