Old homes, busy alleys

Berkeley grew in the early twentieth century, and many blocks still have brick bungalows and foursquares with basements or crawl spaces, detached garages and alleys. Newer infill homes and duplexes sit between them. Tennyson Street's restaurants and the alleys behind them support rats, while Berkeley Lake and Rocky Mountain Lake parks add squirrels, raccoons and birds.

In older houses, animals use gaps around basement windows, settled foundations, old coal chutes and unscreened attic vents. A rat that dies under a back porch or in a basement wall can smell as strong as a much larger animal, especially in summer.

Mouse or rat?

The animal changes how long the smell lasts and where to look.

Mouse

  • Small, often inside a wall or under a cabinet
  • Odor strong for about one to three weeks
  • Often found close to where the smell peaks
  • Common in fall when nights turn cold

Rat

  • Larger, often in a crawl space, garage or under a porch
  • Odor stronger and can last longer
  • Burrows and runways outside near the foundation
  • Active year-round near alleys and restaurants

Narrowing down a Berkeley odor

  1. Start with the lowest level.In homes with basements or crawl spaces, check there first; many carcasses end up near the foundation.
  2. Check the garage.Detached garages hold stored food, seed and trash that attract rodents, and the smell can drift to the house.
  3. Look outside.Fresh burrows along the foundation, gnawed siding corners or droppings near the back door show where animals get in.
  4. Use the nose at dawn.After a night with doors closed and fans off, walk the rooms slowly; the smell concentrates near the source.

After the carcass is out

In Berkeley's older houses, the cleanup often involves more than the animal. Basement and crawl space soil, old wood framing and loose insulation all hold residue. Ask for the material under the carcass to be removed or treated, and for droppings along runways to be cleaned carefully. Then fix the entry points, which in these homes are often old foundation vents, gaps at utility lines, coal chute doors and settled basement window frames.

Neighbors along shared alleys often see the same problems at the same time. Comparing notes about where rats are active can show whether a block-wide issue, such as uncovered trash, is feeding them.

Map of Berkeley and neighboring northwest Denver blocks viewed geographically. It shows an area, not an office or a job site.

Common questions

Should I put bait out in the alley?

Outdoor bait can kill other wildlife and leaves rodents dying in walls and crawl spaces. Trapping and sealing entry points are usually better for odor.

General information for Sloan's Lake, not a quote or professional advice. In an emergency, call 911.