Birds building nest

[Jdeal1]

Birds keep building a nest behind this shutter anyway to stop?

 

[JoeD]

Block the hole with screen.

 

[Snoonyb]

Resist the temptation to name and feed them.

 

[Jeff Handy]

BB gun.

You can get black spray foam cans, used for garden pond building,
You could carefully apply it behind the shutter, in the big voids near the edge, but keep it from getting so full that it shows too much.
Apply in small doses so it does not distort the shutter as it expands.

 

[oldognewtrick]

I'd suggest some stainless steel wool. Easy to tear some off and block the hole and it won't rust like regular steel wool. Available at the Big Box Stores.

https://www.lowes.com/pd/Scotch-Bri...skC50MM8KtBhkfyjlZcaAr4aEALw_wcB&gclsrc=aw.ds