I do think it is highly unlikely any wild birds will go through a 30 cm high pop hole though.
So there's your risk assessment.
What prevents wild birds from sharing the food you put out for your poultry?"
"Food is only provided inside the hen house, so it's only accessible to wild birds during the day, when they'd have to go through a 30cm pop hole to reach it. They can't see it from the outside, so they ordinarily wouldn't risk trying. To prevent rats, I only feed the hens when I'm there, so I, and my very excitable dogs are always on hand to chase any wild birds away."
That sounds a lot like 'all practical measures' to me!!