Birds, Trees, Water

It's National Wildlife Refuge Week (Oct. 5 through 13), which is timed to coincide with the annual autumn bird migration. The 2,400-acre Wertheim National Wildlife Refuge, on Smith Road in Shirley, will be open to the public on Saturday and Sunday from 9 a.m. to 3 p.m. The birding should be good.

The Group for the South Fork has organized a three-mile hike in the Long Pond Greenbelt for Saturday between 9 and 11 a.m. It will feature autumn colors around freshwater ponds and wetlands. Red maples, black tupelos, and blueberry shrubs will be identified by Steve Biasetti, the leader. For reservations, hikers are asked to call the Group at its Bridgehampton offices.

Also on Saturday, the Group is hosting a forum on groundwater at Pierson High School in Sag Harbor between 10 a.m. and 2 p.m. A panel of groundwater experts will talk about the origin, quality, and future threats to East End drinking water resources. A brown bag lunch is suggested. Again, the Group can be called for reservations.

The South Fork Natural History Society's vice president, Jim Ash, will lead his annual walk to see passerines (small songbirds) during their fall migration. Participants can expect to see warblers, finches, and sparrows, as well as oceanic migrants. The walk is scheduled from 7:30 to 10:30 a.m. Birders are asked to bring binoculars and a field guide and can call the society's headquarters in Amagansett, or its Natureline, to make reservations. The guided hike is free for members, $3 for non-members, $5 for families.

The Wild Bird Crossings shop has scheduled a birdwatching walk through the Morton Wildlife Refuge for Saturday. Birders interested in witnessing the fall bird migration are asked to meet at the shop at Bridgehampton Commons at 7:30 a.m. The shop asks that participants call to make reservations.