Squirrel or rat; and do I trap first or exclude first?

Question

Over the past month we have noticed insulation in the yard appearing every once in a while. I wondered if it was coming from my house and I found a corner of the house which has a sizable gap between the siding and the house. So, I think it is pretty clear that the insulation is from my house and this is the entry/exit point.

I put a trap outside of the house, right under the siding gap, with peanut butter as bait and trapped 3 squirrels over the course of a few days. The traps were not trapping anything after the night but then were occupied at the end of the day. So, this fits with the diurnal squirrel behavior and the lack of rats entering the trap at night is also good to note.

I have no idea if the trapped squirrels were also going into the house, or if they were just passing by and smelled something yummy. I did put the trap very close to the house and behind a folded dog crate, so that it wasn't in the normal flow of squirrel traffic.

Also note that there is no way for me to look inside the house to find any nesting, since these are all finished rooms which are adjacent to the hole, and there are no unfinished spaces in my house.

So, I have two questions:

1. Do rats want to remove insulation from a house to bring to a nest somewhere else in the yard or neighborhood, or is this a squirrel behavior?
2. Should I fix the hole (with wood, steel wool and pestblock foam) before or after I try to do more trapping? I am worried that if I do the exclusion during the day, then if these are rats which are sleeping in my house and I seal off their exit, then there would be no way for them to leave, so then they would panic and start chewing through my walls and pipes and wiring in an effort to find their way out, or they might just die in my walls and make everything very stinky. If this is a squirrel problem, then I could possibly assume the squirrels are running around the neighborhood during the day so I could do the exclusion and not worry about them getting stuck in my walls.

Thanks for your advice about rodent behavior and timing of exclusion.

Answer 1

Get tin snips and a soup can. Cut 'teeth' so that each tooth is about 1/6 of the circumferrence of the can and staple them points pointing toward each other, but spaced out a bit. The curve should point away from the wall. My first guess is that you should be able to slide a broom handle through the space between the teeth. Your squirrels may vary, but they are smaller than you think. Another estimate 3/4 of the size of the hole they carved.

The idea is that a squirrel can push the teeth aside to exit, but they jab when trying to enter.

Another method may be to tack a piece of hardware cloth with fence staples as a hinge. In essence you are building a 1 way pet door. Tie a small weight to the bottom edge so that if fits fairly close. This one may be opened by smart squirrels.

You may want to run a microphone on a stick into the hole and see if you can hear inhabitants.

Answer 2

I had the exact situation. In my case the rat was getting to my roof via the rain gutter down pipe. I blocked all of the down pipes and that very nigh I saw that he was running circles around the roof trying to find a way down. These were roof rats and they needed to get down to find food. Luckily they had no access to the house.

So with a hungry rat trapped on the roof, the next day I put a trap on the roof. That night as i was lying in bed I heard SNAP! from the roof and got him. After making sure all the down pipes were blocked, they never came back.

Rats love insulation for nesting. Try to limit, block any way for them to get to the roof and start a program of setting traps in the yard to keep the population down and you should be good. I think having a cat helps as well.