A hardy, aggressive, adaptable and sly mammal. The Norway rat has been particularily successful in North America
and has garnered more attention and urban myths than any other rat species. Introduced in the 1770’s by European Settlers and trading ships, by 1827 the Norway rat was already a common sight in the eastern states and is now found all over North America. It is often refered to as a sewer rat, barn rat or even a super rat depending on the region it inhabits. Such names further indicate the impact this mammal has had on North American culture.
The Norway rat is a relatively large rat measuring on average 16in/41cm in length and 12-16oz/340g. Sizes of this rat are often exagerated in popular media. At first glance one would notice that the tail is shorter than it’s body and a relatively shorter snout than other rat species. It’s not reliable to make an identification on fur color alone as they can vary signifigantly from brown, white to pure gray or reddish brown.
Generally these rats breed in the fall and spring and breeding decreases in the summer and winter but this is highly subject to climate and sanitation of their living environment. Gestation usually lasts for 22 days and a female will often produce a litter of about 8 to 12 pups. The pups will then reach sexual maturity in eight to twelve weeks. A Norway rat can live up to 3 years in captivity but in the wild they often only live from 5 to 12 months.
The Norway rat is by nature a ground dwelling mammal, constructing it’s nest within subterranean burrows. They will often begin burrows near heavy or large rocks, along buildings beneath slabs and alongside foundations. Burrowing can also be triggered by clutter which further stresses the need to keep areas clutter free. Aside from the entrance they will also have one or two escape holes for a quick emergency exit.
This rat can best be described as an opportunistic foraging omnivore. It will eat almost anything it encounters including human refuse, grain, insects or any other natural food items in the environment. However, they do tend to display “neophobic” tendancies and will often avoid new foods that suddenly appear in their environment, including bait!
Norway rats are most active during dusk and just prior to dawn, but can be found foraging several times over the course of a 24 hour period.