How to tell Norway rats apart from other common rodents

Late summer and early fall is when many rodent species are on the move in search of winter quarters and new territory.

It is also when Alberta Agriculture and Rural Development receives the greatest number of suspect rat sightings.

“Young muskrats, pocket gophers, ground squirrels and mice are often misidentified as Norway rats,” said Phil Merrill, rat and pest specialist with Alberta Agriculture and Rural Development.

“Misidentifying rats happens for many reasons, but mostly because young muskrats, pocket gophers, ground squirrels and mice are seen for the first time during the daylight hours by people who suspect they must be rats.”

Norway rats are nocturnal meaning they prefer to be active under the cover of darkness to avoid predators.

“In spite of the similarities common to all small rodents, there are many great differences between our native rodents and Norway rats,” said Merrill. “Adults can weigh up to one pound and measure over 15 inches in length, which includes a six to seven inch tail. A young muskrat is almost exactly the same size and weight, but will appear larger because of its soft, thick undercoat.

“The distinguishing features of a Norway rat, apart from its size, is the cylindrical or rope-like, tapered tail that is nearly as long as the body and is covered with short bristly hairs. Another major feature is the rat’s colouring; the underbelly is whitish or buff while the sides and back are distinctly grey or brownish in colour. The hair is short with no undercoat or guard hairs. Rats also have long facial whiskers.”

Norway rat droppings are unique. They are best described as the size and shape of a black olive pit or “cold medicine capsule” (1/2 to 3/4 inch), shiny black in colour and blunt at both ends. Numerous droppings are usually seen near their habitat and feeding areas.

“The most important steps to take in reporting a suspicious rodent is to contact an Alberta Agriculture office as soon as possible and, where applicable, preserve as much evidence, such as animal remains, as possible,” said Merrill.

To report a Norway rat sighting, call Alberta Agriculture at 403-310-3276 (FARM).