My father had a pond full of very pricey coy fish. Lost all of them to a big blue heron. It really ticked him off. Each fish was worth roughly $100.Yea I see them and big white egrets around in fields hunting and successfully capturing rodents.
There are videos of them catching gophers, rats.. and ducklings on youtube. In Africa, some herons regularly hunt the doves that come to watering holes. I would only worry with "mouth sized" chicks.
Poor dad. lol