How are Norway rats distinguished from other rats?

Norway rats can be distinguished from other rat species primarily by their tail length in relation to their body size. The specific characteristic that sets Norway rats apart is that their tails are never longer than the combined length of their head and body. This physical attribute helps in identifying them, as it differs significantly from other types of rats, which often exhibit different tail-to-body ratios.

For instance, in contrast to Norway rats, some species, like the roof rat, typically have longer tails that can exceed the length of their heads and bodies combined. This tail length is a key identifying factor, making it one of the most reliable traits to distinguish Norway rats from other rat species found in various environments. Hence, recognizing that Norway rats have a more proportionate tail helps in accurately identifying them in the field or during pest management assessments.