This is a paid asset, but now you can download HerdSim Chicken Free.
Detail this asset from Unity Store: Original Link
HerdSim Chicken v1.42
HerdSim Chicken is a simple and easy to use animal roaming simulator.
Simply drag the prefab to the stage and it will move within the roaming area. Instead of RigidBodies this system uses rays to avoid and push away from obstacles. This method is a lot friendlier to CPU usage and allows for a lot more instances.
Demo Page | YouTube Video
Features
• 606 tris animated chicken model
• 1024x1024px texture/bump resolution
• Drag & Drop roaming animal system
• No rigidbodies used – very CPU friendly
• Gizmos that shows roaming areas and herds
• Simple UV map, easy to change texture
• Easily use custom models (legacy animations)
• Works very well on mobile
• Includes mobile prefabs and materials
★ Upgradeable to HerdSim