Clare deKay Thompson, 89, of Newburyport, died from pneumonia on Friday, April 13, 2007, at Merrimac Valley Hospital in Haverhill.Born on October 1, 1917, in Boston, the daughter of Maurice deKay Thompson and Lillian Hastings Thompson, she grew up in Brookline, attended the Winsor School and Bryn Mawr College, Class of 1941, graduating with a bachelor’s degree in English. She worked for the Brooklyn Art Museum in the early 1940s, and in the 1950s for an art gallery in Washington, D.C. A devotee of ocean sailing, she moved to Rockport in the early 1970s.She was a skilled tennis player, and avid amateur naturalist and active supporter of wildlife defense and environmental causes. During the 1970s and 1980s she was a research assistant at the Massachusetts Audubon Society writing for their publication, Sanctuary, on a variety of subjects from natural history to emerging energy technologies. She volunteered for cultural and charitable groups, such as the Rockport Library and the Hammond Castle. She participated in play readings and was a regular member of an amateur recorder ensemble. She traveled widely in the American West, the Far East, the South Pacific, Hawaii and Alaska. She lived in Rockport until she moved to an assisted living facility in Newburyport in 2000.A New Englander to the core, she was strong-willed and independent and had a wry sense of humor. She was kind and compassionate, cared deeply about animal welfare and was devoted to her cat, Mask.Sister of the late Janice Massy and Evelyn Riesman, Class of 1935. She is survived by two nieces, Jennie Riesman and Lucy Loewenstein; two nephews, Neil Goodwin and Michael Riesman; two cousins, Jessamine Warren and Sally Hogan; and several grandnieces and grandnephews.Arrangements: A private memorial gathering for her family and friends to honor her and celebrate her life will be held in Rockport. Arrangements are by Paul C. Rogers & Sons Family Funeral Home, 334 Main St., Haverhill.