New Soffit Screens?

Two nights ago while laying in bed, we heard something fall inside the wall. Then there was scratching and scrabbling INSIDE the wall. I'm still not sure what it was (bird, bat, squirrel, mouse, etc) but hope it made it out!
The easiest method of entry to the attic for wildlife is through the large gaping hole in the soffit over our bedroom window. Every spring we end up with a noisy nest of birds right over our bedroom. In the past I've tried laying boards inside the soffit to cover the hole but they just get pushed out of the way. And of course I forget to do anything about the hole until Spring, after the birds have returned.
So last night I cut a large piece of screening from the side door (removed for repairs, including new screen) and stapled it over the hole. Not attractive but not glaringly obvious from street level either. It's not a tight fit partially due to standing on the window sill and leaning precariously out to reach all the way across the deep soffits. But I read on a bat website recently that it should be slightly loose because it will allow any trapped bats to crawl out but not fly back in.