The annual haunted bonfire at Alameda Park will be held at 6:30 p.m. Saturday. Take a lawn chair to enjoy an evening of ghost stories, hot chocolate, popcorn, hot dogs, a pinata and the Alameda treasure scramble. Registration is $9 per child. Call 724-284-5383.

Audubon Society of Western Pennsylvania will host “Creatures of the Night” Friday at Succop Conservancy, Penn Township. Hikers will encounter larger-than-life costumed nocturnal creatures, hear stories from a great horned owl, observe the acrobatics of the flying squirrel, and go batty with little brown bat. Cost is $6 for members and $10 for nonmembers; those younger than 2 will be admitted free. Registration is required at 412-963-6100 or www.aswp.org.

Slippery Rock University's Robert A. Macoskey Center for Sustainable Systems Education and Research will host a Harvest Fest from 1 to 5 p.m. Saturday. It will be followed by Halloween hikes beginning at 7 p.m. The free, family-friendly event at the center located on Harmony Road, across from Mihalik-Thompson Stadium, will include local sustainable merchants and vendors offering food, apple cider and apple butter demonstrations, live music, and a 2 p.m. scarecrow-building contest. Visit www.sru.edu/RAMC.

Jennings Environmental Education Center, Route 528, Brady Township, presents “Black Cats and Witches' Hats” to investigate the mysteries of an autumn night at 7 p.m. Sunday. Jennings is open from 8 a.m. to 4 p.m. weekdays and on weekends as scheduled. The trails are open daily from sunrise to sunset. Call 724-794-6011.

An October Dark Sky star party, sponsored by the Amateur Astronomers Association of Pittsburgh, is planned, weather permitting, for 6:25 p.m. Saturday at Nicholas E. Wagman Observatory, Deer Lakes Regional Park, Allegheny County, near Russellton. Call 724-224-2510.McConnells Mill State Park, Slippery Rock Township, Lawrence County, has the mill open from 11 a.m. to 4 p.m. Fridays, Saturdays and Sundays through October. Tours, which last about 45 minutes, are available at 1 and 3 p.m. Call 724-368-3612.