The Outdoor Discovery Series sponsored by the Butler County Parks and Recreation Department will feature a martial arts demonstration at 7 p.m. Aug. 6 in the Masonic Shelter at Alameda Park, off New Castle Road. Admission is free. Call 724-284-5383.

Jennings Environmental Education Center, Route 528 near the intersection of Routes 8 and 173, Slippery Rock, will be the site of a short hike investigating the natural history of butterflies at 10 a.m. Saturday. The group will look at some common butterflies that frequent the prairie and discover the magic of metamorphosis. Tips also will be given on how to attract the insects to a yard or garden. Call 724-794-6011 to confirm programs.

<B>Powdermill Nature Reserve</B> at 1847 Route 381 in Rector, Westmoreland County, the biological research station of Carnegie Museum of Natural History, is the site of the traveling exhibition "Art for Nature's Sake," which commemorates the 75th anniversary of the Federal Duck Stamp program. The exhibition, organized by the Cincinnati Museum Center, contains 36 signed waterfowl prints and accompanying U.S. postal stamps, created by nature artists like Maynard Reece, the Hautman brothers, John Ruthven, Nancy Howe, and Adam Grimm. Call 724-593-6105.<B>McKeever Environmental Learning Center</B>, 55 McKeever Lane, Sandy Lake, will host a guided, leisurely, two-mile Sunday stroll from 1 to 3 p.m. the second Sunday of each month through October. Call 724-376-1000 or visit www.mckeever.org.

<B>Rodef Shalom Biblical Botanical Garden</B> is open 10 a.m. to 2 p.m. Sundays through Thursdays and noon to 1 p.m. Saturdays through Sept. 15 as well as 7 to 9 p.m. Wednesdays through August. The current exhibit is "Lookin' Good Then and Now." Admission is free. Call 412-621-6566.