Roof Rat

Roof Rat  (Rattus rattus)

Roof rats, also called black rats, are smaller than Norway rats, but cause similar issues. This rodent gets its name from its tendency to be found in the upper parts of buildings.

Habitat

Roof rats live in colonies and prefer to nest in the upper parts of buildings. They can also be found under, in and around structures.

Food

Roof rats are primarily nocturnal. They forage for food in groups of up to ten and tend to return to the same food source time after time. These rats follow the same pathway between their nest and food. They will eat most anything, but they prefer: fruit, vegetables, and cereal products.

Biology

Roof rats mature in 2-5 months, and are adults for 9-12 months. Pregnancy takes 3 weeks. Newborns get hair after 1 week, open eyes after about 2 weeks, are weaned at 3-4 weeks. Female has 4-6 litters per year, with 6-8 young per litter. They have keen hearing, smell, taste and touch (long whiskers), but bad vision, and are color blind. They are good at running, climbing, jumping, even swimming. They are nocturnal and explore a lot, but are cautious and shy away from new objects.

Threat

Roof rats secured their place in history by spreading the highly dangerous bubonic plague. Though transmission is rare today, there are still a handful of cases in the U.S. each year. Roof rats can also carry fleas and spread diseases such as typhus, jaundice, rat-bite fever, trichinosis and salmonellosis.

Detection

Signs of a roof rat infestation include; rodent droppings, gnaw marks, damaged goods and greasy rub marks from their oily fur.

Prevention

To prevent roof rats from entering a home, seal up any holes or cracks larger than a quarter with silicone caulk. Keep trees and shrubs trimmed away from the building and cut back limbs overhanging the roof. Roof rats are drawn to any accessible food sources, so clean up fruit that may fall from trees in the yard and keep garbage in tightly covered receptacles.