PHILADELPHIA (REUTERS).- Researchers have found the first published illustration by John James Audubon, America’s most famous bird artist, ending decades of searching for the prized but elusive work. Audubon had made two references to the illustration in his diaries, but it had never been seen until it was found on a sheet of sample images produced in 1824 by a New Jersey engraver who specialized in illustrations for banknotes. Eric Newman, a numismatic, or currency, historian working with Robert Peck, a senior fellow with Philadelphia’s Academy of Natural Sciences who had spent the last decade looking for the long-lost illustration, discovered it. “It’s the holy grail of Audubon scholarship,” said Peck. “It’s significant because it was at a significant turning point in his life.” Some researchers doubted its existence and even