How do I prevent my 4 week old fully integrated chicks from being taken?

[Theorrin]

Day, they are kept in the coop at night

if they are being taken during the day then it could be cats, hawks, foxes. all of which can easily get over those fences. unless u roof it they arent secure and youll continue to keep losing them

 

[McChooky]

An open fenced lot (yard) offers some protection during the day but won't prevent foxes or hawks from killing your birds. Free ranging chicks usually results in losses because they're small and easy prey for any predator.

 

[McChooky]

Keeping them in a secure covered run until they're the size of the adults gives them a better chance of surviving. Birds and cats like to snack on baby birds and chicks