kathy2691
In the Brooder
Thank you, I edited my post to share my location. I was thinking of maybe replacing the standard window screen with hardware cloth.Welcome to BYC.
If you put your location into your profile people can give better-targeted advice because climate matters -- especially when it comes to housing.
The general recommendation for ventilation is 1 square foot of permanent, 24/7/365 ventilation per adult, standard-size hen. The way you protect vents from predators is to cover all openings with 1/2" hardware cloth.
Here's my article on coop ventilation: Repecka Illustrates Coop Ventilation