Also known as Norway Rat, Sewer Rat, Wharf Rat, Street Rat
Brown rats are highly adaptable, social rodents that live in complex, hierarchical packs dominated by a single male. They excavate extensive burrow systems near water sources or human structures, using their keen senses of hearing and smell to navigate in near-total darkness. Their remarkable breeding capacity and ability to chew through wood, lead pipes, and cinder blocks have made them one of the most successful mammals on Earth.
ThreatsPest control measures, rodenticides, and habitat exclusion
HabitatsUrban areas, sewers, agricultural fields, and riverbanks
Life span1 to 3 years in the wild
Size / weightNot available
Classification
FamilyMuridae
SpeciesRattus norvegicus
Range & activity
Native Introduced
Native range in olive; established introduced range in rust.
Safe observation
Interaction riskModerate
Low
Moderate
High
Very high
Why interaction risk is moderate
Can carry pathogens and bite if cornered; observe from a distance and do not handle.
Why it is dangerous
Can transmit serious diseases such as leptospirosis, rat-bite fever, and salmonellosis through bites, scratches, or contact with their urine and feces.
How to recognize a risky encounter
Look for a robust, brownish-grey body up to eleven inches long with a bald, scaly tail that is slightly shorter than the body.
What to do
Never attempt to corner, touch, or handle wild individuals; contact professional pest control for indoor infestations.
Responsible observation
Secure waste: Keep garbage in tightly sealed metal or heavy plastic bins to avoid attracting them.
Observe from afar: Watch their nocturnal foraging from a distance to avoid triggering defensive bites.
Seal entry points: Block gaps larger than a quarter-inch in buildings to prevent them from nesting indoors.
