Museum of Discovery - Tree Frogs: Bird-voiced Tree frog Calling from April to August Sounds like: Many rapid whistles Listen to call: http://www.herpsofarkansas.com/wiki/uploads/Frog/HylaAvivoca/DS300047.mp3 | Facebook
The Grunt-Like Sound Produced by the Pig Frog (Rana Grylio) | Various Artists | Smithsonian Folkways Recordings