The Fairfax County Park Authority puts it diplomatically: “People,” reads its brochure, “have mixed feelings about gray squirrels.” The same cannot be said of The Joy of Cooking, which expresses itself quite unambiguously on this point. “Gray squirrels are preferred to red squirrels, which are quite gamy in flavor,” it notes, suggesting they be served with walnut catsup and polenta. In a lecture titled “Nuts R Us,” a Fairfax County park ranger attempts a more disinterested argument for the squirrels’ merits. At 1 p.m. at Lawrence Park, Walney Visitor’s Center, 5040 Walney Rd., Chantilly. FREE. For reservations call (703) 631-0013.