Other Names: Brown Rat, Gray Rat, Common Rat, House Rat, Wharf Rat, Water Rat, Barn Rat, Sewer Rat, Super Rat
These "super rats" can reach 16" in length. Each female rat can give birth to 20 pups in her lifetime. Some factors affecting rat populations in cities include continuously mild winters, weather-related disasters, and encroachment of their habitats by new urban development.
Evidence of recent gnawing is an excellent sign for determining the presence of Norway rats.
Rats tend to gnaw on wooden structures such as corners, floor joists, and wall studs. When Norway Rats gnaw holes into cartons and boxes, the holes typically measure about 2 inches in diameter and often contain rough, torn edges.
Another indication that rats are present is a strong musty odor. Cats and dogs may excitedly sniff and probe an area where rats or mice are present, and often indicate this by scratching or making unusual sounds.