The brown rat is also known as the Norway rat, and is one of the most common pest species of rats. Brown rats have a diverse diet, but prefer to feed on nuts, grains, fish, meat and some fruits. They can gnaw holes in food containers and contaminate what they don't eat with their urine and droppings, tear up a building's insulation for nesting material and undermine its foundation with their burrowing. Rats can also cause fires by chewing on wires so it's important to identify rat infestations and eliminate them. A good way to determine if it's brown rats causing problems in your home is by identifying their droppings.
Look at the size of the droppings. Brown rat droppings are much larger than roof rat or mouse droppings. The average brown rat dropping is 3/4 of an inch long, while the roof rat leaves 1/2-inch droppings, and mice just 1/4 of an inch.
Check the shape of the droppings. Roof rat droppings are pointed on one end and mouse droppings are pointed on both ends. Brown rat droppings are blunt.
Check the colour of the droppings. Fresh brown rat droppings are dark, but dry colourless. Roof rat and mouse droppings stay dark.