This sound effect can be found on The Premiere Edition Volume 1, which was made by The Hollywood Edge. A slightly similar sound effect, FOREST, DAY - BIRDS, CRICKETS, DISTANT CREEK, AMBIENCE, is available on The General Series 6000 Sound Effects Library (produced by Sound Ideas). In another slightly similar sound effect, Sound Ideas, FOREST, DAY - MORNING AMBIENCE: LIGHT BIRDS, BREEZE THROUGH TREES, one of its elements sounds identical to this ambience, and it's available on the Series 6000 Extension I Sound Effects Library (also produced by Sound Ideas).
Sound Effect Description
Forest Ambience 2 [special Mix]; Happy Bird Chirps And Calls, Close And Distant Perspective With Light Wind.
Clean, Full Length and Unedited Link to the Sound Effect