Gap between deck edge and siding

There's an intentional gap between the edge of my deck and the siding to allow a water pipe, downspout and a/c wiring and lineset to pass through. See pic below. This morning I noticed from a distance a cat trying to get through the gap. I'm assuming there might be kittens underside the deck. I've also seen squirrels near the gap on occasion. I'd rather not have animals nest underneath the deck. What can I use to cover the gap with the ability to remove the covering? However, I'll proceed only when I can affirm that animals down below have already exited. It is not my intention to harm any animals.

 

A gap is also a good idea to keep moisture from sitting on the deck board next to the house. I would look at other ways of discouraging critters from being underneath but cannot imagine how this would be the only access without being there to see it.

 

Stickshift, this gap turns out to be the only access available. The other 3 sides of the deck not next to the siding, have a lattice skirt all around, see pic. The lattice gap is 1 1/8" which is too small for kittens and squirrels to pass through. Concerning the moisture issue, I was thinking of using a mesh type of material but am not sure how to secure it.