Burrow holes can lead to underground rat nests. They are about 2-4 inches with smooth edges. They can be found under plants or items stored outside. Rat nests usually have more than one entrance.
Rat droppings are around 1/2 -3/4 of an inch long. They tend to be found near trash or other food sources. New rat droppings are dark and shiny, while old droppings are chalky and dry.
Rat teeth grow continuously, so they habitually chew on things to file them down and keep them short. Look for recent marks from rats chewing on things like garbage cans, fences, or under porches. Gnaw marks can indicate where rats are getting their food, where they are living, or the routes that they take to travel between the two.