Roof Rat: Facts, Identification & Control
Latin Name: Rattus rattus
Black or brown, can be over 40 cm long, with a long tail, large ears and eyes, and a pointed nose. Body is smaller and sleeker than the Norway rat’s. Fur is smooth.
Nests inside and under buildings, or in piles of rubbish or wood. Excellent climber that can often be found in the upper parts of structures. Roof rats are highly adaptable. They prefer to live in high places, but may live in a variety of environments. They are nocturnal by nature and are accomplished climbers. As their name suggests, roof rats may be found in elevated areas such as trees, rafters, attics and roofs. Roof rats can also nest on the ground if necessary.
In dense populations, roof rats will establish a social hierarchy, wherein dominant males mate more than subordinate males.
They prefer to consume fruits (sometimes referred to as the “fruit rat” or “citrus rat”) and nuts, although roof rats are omnivorous and will feed on almost anything available to them. These rodents have been known to consume tree bark, meat and grain. Roof rats are also food hoarders, stashing supplies of food such as seeds and nuts.
Becomes sexually mature between two and five months, producing four to six litters per year that consist of six to eight young each. Lives up to one year.
Roof rats are prodigious breeders. Females can breed year-round. Within a year, one female may be responsible for up to 40 new rodents.
Signs of Roof Rat Infestation
Visual sightings of live or dead rodents indicate rodent activity. If roof rats are seen exposed, it often indicates their hiding spaces are all filled by other rats or that they have been disturbed, such as by construction. Droppings are another good indicator of roof rat activity. Roof rat droppings are 12 to 13 mm with pointed ends, whereas Norway rat droppings are 18 to 20 mm and capsule shaped. Other indicators can include grease marks along surfaces as well as nests. Grease marks are produced as the rodent travels along an edge, and the oils in their fur are deposited. Indoor nests usually are constructed in insulation such as in attics.
Roof rats can be carriers of diseases. They can transmit these diseases through physical contact, bites, by contamination or by fleas that are feeding on the rodent.
Historically, infected fleas have transmitted serious plagues from rats to humans. Bubonic plague was a scourge in Europe several times throughout history. There are still outbreaks of plague around the world today. Trichinosis may be contracted through eating undercooked meat of animals that have fed on rats. Rats contaminating food or food preparation surfaces can transmit food poisoning. Rats can also transmit rat bite fever through bacteria in their mouth.
Hantavirus pulmonary syndrome is transferred via inhalation of rodent urine, droppings or saliva. Although roof rats have not yet been connected to HPS, everyone is advised to use caution when dealing with an infestation. It is best to contact pest management professionals for an inspection and evaluation.
The first step in controlling a roof rat infestation is to properly identify the rodents. Roof rats have hairless, scaly tails that are longer than their heads and bodies. These rats are nocturnal and are excellent climbers.
To prevent a colony from nesting in your home, make sure that all the windows and vents are screened. Roof rats can also enter openings in walls, eaves and roof from the branches of trees. Trim all tree branches to further prevent entry.