Detail this asset from Unity Store: Original Link
This is a paid asset, but now you can download Bird Flock Bundle Free.
Bird Flock Bundle v2.4.2
Bird Flock Bundle is a collection of bird flock assets. This asset features a variety of birds and behaviors at a discounted package price.
• Easy to use
• Low poly
• Obstacle avoidance
• Landing spots
• Includes skybox and feather particles
• Sound Script and Sound Effects
• Added C# scripts
• Improved scripts (Release notes)
★ Bird Flock Sparrow
★ Bird Flock Pigeon
★ Bird Flock Crow
★ Bird Flock Vulture
★ Bird Flock Seagull
★ Bonus Butterfly
Combined value $80~
Compatible with Unity 5.1 up to new versions of Unity(2020+)
Support available for assistance if any problems should occur.