Looks like mice decided to make their home there. Did you look around to see if some of your sound deadener is missing: hood, firewall, fenders, etc.
My Caravan used to sit outdoors 24/7. When I removed the speedometer bezel behind the steering wheel to replace a light bulb, I found the beginnings of a mouse nest made from kleenex tissue. Go figure.
Keep an eye on your engine for symptoms of hantavirus.