What is happening?

[collies19]

I am a first time chicken and duck mom. I'm trying to feel my way through this. Today something different happened, the chicks were going after another chicks' tail feathers and pulling them out. Making them bleed. I removed the two that it was happening too, but don't know why this happening. Can anyone help?

 

[tsmith91]

They could be overcrowded or too hot

 

[collies19]

Thank you, that was the problem.