Spring has come for Unity3D game developers. Package full of individual phrases of various bird calls is available here. Unlike looped audio this package of oneshot sound samples you can achieve desired density of birds in your virtual forest. Get what you want and wherever you like with a little bit of C# scripting. If you like it dense, then you might to watch and listen to this short stroll there…
Now also available for Unreal Engine developers: https://www.unrealengine.com/marketplace/forest-birds-sounds
If you wish to experience WebGL online demo yourself go to this location below. It loads about 50 MB of data:
https://grogon.com/t/forest_birds/