When the Birds Fly South is a lost race fantasy novel by American writer Stanton A. Coblentz, defined as a "significant tale ... involving avian theriomorphy." It was first published in hardcover by , Mill Valley, California in 1945 and reprinted in 1951. Its importance in the history of fantasy literature was recognized by its republication by the Newcastle Publishing Company as the twenty-third volume of the Newcastle Forgotten Fantasy Library in April, 1980. The Newcastle edition was the first paperback edition, and had a new introduction by the author. Later editions were issued by Arno Press (1978) and Borgo Press (1980).