Hi, we own two story house down here in Ontario and there are several
ventilation holes on sides of the house.

On two of them (one from kitchen ventilation, another from 1st floor
washroom ventilation), outside cover of the hole is flip up time.
(cover opens from outside by flipping up, made of 3 plastic covers,
hole size is 4 inch)

I have no idea how but there was small mouse making problem at first
then there seems to be multiples of birds LIVING THERE.

It must be dark there in the hole and I have no idea why they are
living there making noises.

Someone said they might have nested there for child birds to get ready
to fly, etc.

Anyways, they are making way too much noises that I need to do
something about it.

For the cover, since they learned how to open the flip and get in, I
plan to put some additional cover to prevent that to open in the
future.

But how do I get rid of them??
Trap, poisin, glues all might catch them but they will decay in there
giving me bigger problem.

Any recommendations?