PHILADELPHIA â A group of songbirds recently turned up dead in Nottingham, Chester County, Pa. But their cause of death is a mystery for scientists, wildlife officials, and bird lovers. Scores of similar bird deaths have been reported in 27 Pennsylvania counties, including Philadelphia, since June. And more and more deaths have been logged in Delaware and eight other states and Washington, D.C., stretching back to April. Officials and wildlife experts are stumped by the illness and deem the rash of deaths unusual. They are pleading with the public to stop feeding birds from feeders and providing water in bird baths until the cause is found, as they believe congregating birds may contribute to the maladyâs spread.