Alternative common names:
House rats are generalist omnivores and so eata wide variety of plant and animal material. They are serious pests in the natural worldnature as they eat birds and beneficialinsects, and to farmers as they eat a wide range of agricultural crops. They are vectors of many diseases, including the bacteriumYersinia pestis, an agent ofbubonic plague. Despite its alternative common name-black rat – this rodent exhibits several colour forms.
Where does this species come from?
What is its invasive status in South Africa?
NEMBA 2020 Category 1b.
Where in South Africa is it a problem?
Limpopo, KwaZulu-Natal and Gauteng but may have a wider distributional range.
How does it spread?
Through indigenous forests, scrublands and urban parks.
Why is it a problem?
House rats are considered to be one of the world’s worst invasive species because they cause a huge amount of environmental degradation. It is also frequently blamed for damaging food supplies and other goods and spreading diseases such as Lassa fever, leptospirosis and hantavirus.
What does it look like?
Description: A house rat has relatively large ears and a tail that is almost always longer than its body. Individuals weigh between 70 and 300g and are between 16 and 22cm in head and body length, with a tail length of 19cm or longer. Males are longer and heavier than females. Many members of the species are black in colour with a lighter-coloured ventral belly. The species is often divided into subspecies based upon colour patterns, which can occur in any combination of black, white or grey. The skull and nasal bones are narrow.
Habitat: In urban areas they are found around warehouses, residential buildings and other human settlements. They are also found in agricultural areas such as in barns and crop fields. They prefer to live in the dry, upper levels of buildings and so are often found in wall activities and false ceilings.
Breeding: House rats are able to breed throughout the year if conditions allow it. Their peak breeding season is summer and autumn. The gestation period ranges between 21 and 29 days and young rats are able to reproduce within 3 to 5 months of their birth.