I personally accomplished this by building a pen from fences, and putting in a few cows. Then I placed 3 different types of Chickens in the pen with the cows and made sure that they're tiles were touching.
Geometric Cube had a different situation, here's what they did:
Edit: ok, mixing cows, chickens, pigs don’t work. It needs to be the same type of animal but a different variant. When it popped I had a leghorn chicken, New Hampshire chicken, and a aylesbury duck. So all birds in this case.