Ivy, Fruit Trees and Roof Rats in San Francisco Backyards

Ask anyone who's lived in a San Francisco flat with a backyard: the rats show up on the fence at dusk. Most of the time those are roof rats, and most of the time they live in the yard before they ever get in the house. This guide covers what draws them and what to change, based on the University of California's IPM pest notes on rats.

Vines Are the Big One

UC IPM says roof rats usually nest above ground in shrubs, trees or dense plants like ivy. It recommends removing climbing ivy, star jasmine and honeysuckle from fences and buildings and thinning dense vegetation. A fence covered in ivy is a roof rat apartment building with a hallway running to every yard on the block.

You don't have to rip out every plant. Pull vines off the house and fences, thin shrubs so you can see through them and keep plants from touching the walls and roof.

• Pull ivy, star jasmine and honeysuckle off fences and walls
• Thin shrubs and ground cover so burrows aren't hidden
• Keep branches away from the roof, wires and fence tops

Fruit Trees

UC IPM says roof rats like fruit, nuts, berries, snails and slugs, and often eat citrus and avocados while they're still on the tree. A Meyer lemon tree in a city backyard can feed rats from several houses, since UC IPM says roof rats may travel 300 feet or more for food. Pick fruit as it ripens and clean up fallen fruit and nuts.

Compost, Pet Food and Bins

Keep garbage and compost in containers with tight lids, per UC IPM. Feed pets only what they'll eat in one sitting and store pet food in rodent-proof containers. Store firewood and lumber off the ground. The city's health department adds that garbage containers should be pest-proof and watertight, and stored items should be at least six inches off the ground.

Then Seal the House

Yard work makes your place less attractive, but rats already living nearby will still look for a way in. Close the gaps at the roofline and attic vents with half-inch mesh, never chicken wire. Roof rat control and rodent exclusion cover the rest.

See also: Rodent Exclusion, Roof Rat Control, Garage and Basement Rodents