Field plate · Rattus norvegicus
Norway rat
Heavy, blunt-nosed burrowing rat of basements, sewers, and lakefront alleys. Unmistakable by size alone.
Plate 5 of 28. Drawn in profile to the identification marks named below; the scale rule is a drawing convention — sizes are given in the text.
Identification marks
Heavy body roughly 20–25 cm plus a shorter, scaly tail, coarse brown-grey fur, blunt muzzle, and small ears. Droppings are blunt-ended capsules about 18 mm — far larger than any mouse dropping.
Look-alikes it is confused with
A young Norway rat is the only common confusion with a large mouse; check the feet and head, which are disproportionately big, and the dropping size. Roof rats are rare this far north.
Where it hides in a house
Burrows along foundations, under porches and slabs, in crawlspaces and low basements, and around dumpsters and sewer lines — a particular pattern in older lakeside streets and commercial alleys.
Health & property risk, stated plainly
Serious. Rats bite stored goods, gnaw wood, plastic pipe, and wiring, undermine slabs with burrowing, and contaminate food-preparation areas. Any rat indoors is a same-week problem, not a watch-and-wait one.
What actually works
Deny food and water first: bins with lids, no pet food out overnight, fix dripping exterior lines. Fill burrow entrances after activity stops, screen foundation vents with heavy mesh, and cut cover along the foundation. Trapping by an experienced hand works on small numbers.
What doesn't
Loose poison bait tossed into a basement — uncontrolled, dangerous to dogs and children, and illegal to use off-label. The label is the law, for rat poison above all.
When to call a licensed pro
Almost always. Rats mean burrows, sewer connections, and repeat entries that need mapping, and bait programs that need a licensed applicator and careful placement records.