Join Lee Baker and Rich Taylor for a moderately strenuous, 4-mile hike through the Otter Brook Preserve in Sullivan (not to be confused with Otter Brook Dam). Bring lunch and meet at 10 a.m. at the Granite Gorge parking lot on Route 9 in Roxbury. Back by 2 p.m.

Cosponsored by the Harris Center for Conservation Education and the Nature Conservancy.