Wild Republic has been producing its Audubon Birds Series for many years. Many of their birds with song have been retired, but the more popular types are still being made. These plush birds are popular, due to the tremendous popularity of Birding, the second most popular US hobby. Wild Republic Audubon Birds are 5 to 6 inches long and sing their own particular song when squeezed.They are made by Wild Republic in partnership with the Audubon Society. The bird sound recordings are made by the Cornell Lab of Ornithology.