Fall Open House, Hidden Valley Nature Center, Jefferson. 10 a.m. to 4 p.m. today. Learn about fly fishing, including creating flies, and test your skills in Little Dyer Pond. All equipment and materials will be provided. There will be other activities for kids and families, including forestry games and a nature walk. FMI: Call 586-6752 or visit www.hvnc.org.

Fall tree and plant identification walk and trail clean-up, 10 a.m. to noon Monday, at the West Branch Preserve in Somerville. Hosted by Spectrum Generations Coastal Community Center. Gather at Damariscotta Lake Watershed Association, 38 Lake Farm Circle in Jefferson at 9:45 a.m. and car pool to the head of the trail. To register, call 563-1363 or email [email protected] generations.org. 

Evening with Bill Irwin, author of “Blind Courage” and the only blind person ever to complete the 2,168-mile Appalachian Trail, 7 p.m. Friday, at Trinity Episcopal Church, 580 Forest Ave., Portland. Free and open to the public. A reception will follow Irwin’s slide show and talk. FMI: Call the church at 772-7421 until 2 p.m. Monday to Thursday.

Kennebec Land Trust Outing Club hike and mushroom walk followed by a harvest potluck, 2 p.m. Saturday at the trust’s Small-Burnham property in Litchfield. Bring a dish to share. To register for this free event, call 377-2848 or email Gina Lamarche at [email protected]  FMI: www.tklt.org.

Night hike for families, 7:30 p.m. Saturday at Merryspring Nature Center in Camden. Free program offered to all ages, but it is not appropriate for very young children who might be uncomfortable in the darkness. Bring your own flashlight or head lamp. FMI: Call 236-2239 or visit www.merryspring.org.

Looking Ahead

Fall foliage walk, 9:30 a.m. Oct. 9, Wells Reserve at Laudholm. $7/$5. Reservations required. Call 646-1555. FMI: wellsreserve.org.

Mushroom walk, Oct. 15, at Macdonald Woods in North Wayne. Bring a basket with paper bags, a knife for collecting and field guides. Meet Howard Lake, property steward, at the Macdonald Conservation Area parking sign on Kents Hill Road in North Wayne. Rain or shine. Please pre-register by calling the Kennebec Land Trust, 377-2848, or emailing [email protected]

York County Audubon field trip, 7 a.m. to 9:30 a.m. Oct. 16, to the Sanford Sewage Treatment Plant, 192 Gavel Road, Sanford. Meet Andrew Aldrich at the plant office and look for migrating waterfowl, warblers and others. FMI: Call 698-4461.

Farm to Farm Ultra Run, Oct. 16, starts at Wolfe’s Neck Farm, Freeport. Race 50 miles, 50 kilometers or 25 kilometers to raise awareness of conservation and local foods. FMI: Call 865-4469, ext. 107, or visit www.farmtofarmultrarun.com.

Ongoing

Mid-Coast Audubon Birdseed Sale, orders must be received by Oct. 20, email [email protected] or call 380-1370. FMI: Visit www.midcoastaudubon.org.

Guided trail walks at Inland Woods/Pine Ridge trails in Waterville. 8 a.m. Mondays through October. Free; all welcome. Meet at trailhead behind Inland Hospital, 200 Kennedy Memorial Drive. FMI: www.kmtrails.org or 861-3292.

Weekly Bird Walk, 7 a.m. Thursdays at Gilsland Farm, off Route 1, Falmouth; $5 for Maine Audubon members, $8 for nonmembers. Bring binoculars and a field guide and meet in the visitor center parking lot. FMI: Call 781-2330, ext. 209.

Casco Bay Bicycle Club hosts several weekly road bike rides and special one-time rides. Members and nonmembers are welcome. FMI: www.cascobay bicycleclub.org.