# Rata parda

*Rattus norvegicus*

**Confianza en la identificación:** Identificable con cuidado — Tail-to-body ratio separates Norway from roof rats decisively.

## Cómo reconocerla

- The tail is shorter than the head and body combined — laid back along the animal it does not reach the shoulders. This separates it from the roof rat.
- Heavy-bodied and blunt-nosed, 200 to 250 mm excluding tail, with small ears that do not reach the eyes when folded forward.
- Fur is coarse, brown to grey-brown above with a paler grey underside.
- Droppings are 18 to 20 mm with blunt, rounded ends — capsule-shaped, and about three times the length of mouse droppings.

## Qué rastros deja

- Burrows 50 to 100 mm across in soil next to foundations, under slabs, beneath decking, and along fence lines.
- Well-worn runways with dark greasy rub marks along walls at floor level.
- Gnaw marks about 4 mm wide, and damage to wiring, plastic pipe, and structural material.

## Por qué persiste una infestación

Norway rats are ground-dwelling and burrow, so they occupy basements, crawl spaces, sewers, and the ground floor rather than the attic. They are strongly neophobic — genuinely wary of new objects in their environment, which is the opposite of mouse behaviour and means monitoring devices are often ignored for days. They pass through a gap of about 20 mm and gnaw through many materials, so exclusion has to use resistant materials.


## Dónde se encuentra

Throughout the United States, concentrated in urban areas, ports, and near waterways and sewers.

## Qué la previene

- Seal gaps of 20 mm or more using metal mesh, sheet metal, or mortar rather than foam or plastic.
- Remove harbourage — dense ground cover, woodpiles, stored material against walls, and neglected outbuildings.
- Secure refuse in rigid bins with tight lids, and manage compost, fallen fruit, and pet food outdoors.
- Fit covers on floor drains and repair broken sewer laterals, which are a common and overlooked route.

## Se confunde con

- **Rata de tejado** (*Rattus rattus*) — The tail is longer than the head and body combined — laid back it reaches past the shoulders. This is the decisive separator from the Norway rat.
- **Ratón doméstico** (*Mus musculus*) — Droppings are 3 to 6 mm, rod-shaped with pointed ends, and scattered widely rather than deposited in one place — a single mouse produces dozens per day.

**Verdict:** professional-recommended. Established rat populations damage structure and wiring, carry genuine health risk, and usually extend beyond one property. Exclusion is essential and does the lasting work, but an established population normally needs coordinated help as well.


Source: https://againstpest.shop/es/identificar/roedores/rata-parda/