Spring Bird Walk - Saturday, March 26 - Search for birds of the season on this guided hike. Bring field guides and binoculars, if you have them. 8:30-10:30am @ Patuxent Research Refuge’s National Wildlife Visitor Center, Powder Mill Rd., between B-W Pkwy and Rt. 197, Laurel. free; rsvp: 301-497-5887.