Peter Alden, a past president of the Nuttall Ornithological Society, has led nature tours to more than one hundred countries. He is the principal author of the National Audubon Society’s Regional Field Guides, eight books each covering approximately 1,000 species of the flora and fauna of different regions of the United States. He was born and grew up in Concord, Massachusetts, where he now lives. Because Thoreau and other naturalists in Concord kept detailed journals, more is known about its biological history than about that of any other place in North America. On July 4, 1998—a date commemorating the 153rd anniversary of the day Thoreau moved into the cabin he had built at Walden Pond—Alden and Edward O. Wilson conducted the first of what came to be called a Biodiversity Day, and more than one hundred field biologists found 1,905 species (larger than one millimeter) in or near Walden. Alden will discuss the changes in the birdlife of the Concord area over the years. Thoreau, of course, never saw a Northern Cardinal or a Red-bellied Woodpecker, but he never saw a Wild Turkey either. The ups and downs of birds tend to reflect changes in climate, agriculture, forestry, hunting, transportation, gardening, architecture, cuisine, fashion, poetry, everything.
