I would hire a pest control company to seal up any entry points to prevent this from happening. 

Quote from @Enrique Toledo:If it is just window seals yes list it now.

Salting a couple times and return trips for new ice . 

I'm a new investor looking at the Mid-Term Rental (MTR) strategy in the Salt Lake and Utah County markets.

(But, full disclosure, I'm a bit of an amateur, so take it with a grain of salt!)

Toss 1½ cups of seeds with 3 tbsp melted butter, 1 tsp cinnamon, and a pinch of salt, bake at 300°F for 40 minutes, then sprinkle 2 tbsp sugar over them while warm.

I look for moisture around radiators/baseboards, bathroom fans, GFCI outlets, window guards, fridge door seals not cracked (tenants will never report this, your electric bill will), under-sink P-traps for slow drips.

Virgin steel to stand up to Salt water environments.

The area is a harbor with a beautiful beach, seals, whales, otters and  lots of tourism and mixed uses.  

Pest control service Seal up the house Poison bait/traps in the attic Tell the tenants to stop leaving their nasty food and trash out and attracting rodents.