.dropcap { color: #838078; float: left; font-size: 82px; line-height: 60px; padding: 5px 8px 0 0; } .art-aside-tmp { height: auto !important; min-height: auto !important; } The night of June 10 was warm, but not too much so. After days of rain, Concord, Massachusetts, wrung itself dry. The moon edged toward fullness. Rarely in need of an excuse to wander, Henry David Thoreau took it anyway. He followed Concord’s train tracks out of town and into a moonlit meadow. There, he encountered an iconic bird of the United States: the Eastern Whip-poor-will. With their cryptic plumage and nocturnal habits, Eastern Whip-poor-wills are rarely seen, but the male’s loud, rhythmic song is hard to miss. Thoreau heard them that evening—five or six at once. A few nights later, when the moon was full, he encountered a dozen or more. “Perhaps this is the Whip-poor-will’s Moon,” he wrote in his journal in 1851. Thoreau wasn’t the only one who kept vigil...