It’s important to know the types of rodents found in Victoria as it helps when it comes to preventing rodent problems and carrying out rodent treatments. It is also important to be able to tell the difference between pest rodents and native animals, as there are strict laws that prohibit harming native animals.
There are 3 pest rodents in Australia – the roof rat, the sewer rat and the house mouse.
The house mouse is found in both city and country areas but is the dominant pest rodent in the rural areas of Victoria.
Description: The house mouse is a small rodent, up to 10 cm long with a tail of similar length or shorter. They can be very variable in colour from light brown to grey to black, with a pale underside.
Where does it live: Inside they will nest in any protected area – wall voids, drawers, inside furniture. They will generally nest within 5m of a food source. Outside if they cannot find any natural shelter, they will dig burrows.
The roof rat (also known as the black rat or ship rat) is the most common pest rat in Australia, found in both city and country areas.
Description: Although it is sometimes called the black rat, it can be very variable in colour. With a body of up to 18cm long they are smaller than the sewer rat. However, the tail is longer than the body, a key distinguishing feature. It is an excellent climber.
Where does it live: The roof rat, as its name suggests tends to nest above ground, either in trees or roofs. It will come down from these resting areas to find food.
The sewer rat (also known as the Norway rat or Brown rat) is the largest pest rat in Australia and is more commonly found in urban areas.
Description: The sewer rat can weigh up to 0.5kg, with a body of up to 28cm long. The tail is shorter than the body. It is normally brown or dark grey with the underside a lighter colour.
Where does it live: Sewer rats generally live outside and will, as their name suggest happily set up home in drains and sewers. However, in their natural environment they will dig extensive burrow systems.
Rodent diseases and damage
The presence of rodents will cause obvious food spoilage with their urine and droppings. However, they also carry a range of diseases – Leptospirosis, rat bite fever and a range of gut infections, including Salmonella. When handling rodents or sweeping up droppings, it is important to wear gloves and a mask, and place any material into a bag, which should be sealed before disposing.
However, one of the generally unknown issues with rodent infestations concerns the damage they cause. As their teeth grow continuously, they need to gnaw hard materials to wear them down. As a result, they will damage a wide range of materials including wood, plastic and even soft metals. Of particular concern is the damage they do to pipes and wiring – rodents are thought to be one of the main causes for unexplained house fires!
There are three groups of native animals that can be confused with these pest rodents:
Possums don’t really look like rats and a certainly a lot bigger (and make a lot more noise!). However, since they are often found in roof voids too, sometimes people assume the noises they are hearing are rats rather than possums.
Antechinus are a small, carnivorous marsupial. They are about the same size as a small rat and as the move very quickly it can be easy to think they are a rat, but they have a more point face with lots of sharp teeth.
Visually the bush rat can certainly be confused with the pest rats, but as they tend to be very timid and live in bushland areas, they aren’t often found in and around houses. They can be quite common in heathland areas of Victoria.
Identifying any unwanted house guest is not always easy and it’s important get it right so the appropriate control methods can be put in place. For many it’s easier and safer to call a rodent expert like Go Pest, to get a professional rodent treatment.