Detail this asset from Unity Store: Original Link
This is a paid asset, but now you can download Roaming Bats Free.
Roaming Bats v3.1
Roaming Bats is a easy to use model that comes with a simple behavior script that makes the bats roam around in a designated area.
• Area Roaming Bats
• 888 Tris Model
• Obstacle avoidance
• Landing spots
• Includes Skybox
• Simple UV map, easy to change texture
• C# scripts
• Easily customize how bats behave
Upgradeable to Bird Flock Bundle 2
Compatible with Unity 5.1 up to new versions of Unity(2019+)
Support available for assistance if any problems should occur.