Got rats? Wildlife expert from county vector control shares tips for vanquishing vermin

Spring. Time for warming weather, blooming flowers – and rodent infestations?

While rodents are active year-round in the Bay Area, their presence indoors often becomes more readily apparent during the spring as residents take on seasonal cleaning tasks around the home, according to Peter Gotcher, Santa Clara County Vector Control wildlife specialist.

In an interview with the Town Crier last week, Gotcher provided pointers for evicting the most common local species of vermin houseguest: the roof rat.

Q: What evidence suggests a roof-rat infestation?

A: We’ll look for things like rubbing marks where their fur has rubbed off. We’ll look for openings in the roof and the basement or lower areas of the house where the roof rats will get in. We’ll look at the droppings as well. They can tell us a lot about what kind of rat it is or if it’s a squirrel.

Q: Are certain homes more susceptible to infestations than others?

A: Building codes have changed over the years, so if somebody has a very old roof, it may not be adequately sealed. The old building codes used to require simply that it not leak water, and they could leave openings in the roof where rodents could get into it.

Also over the years, as plumbing changes, as people add different cable lines, different phone lines, satellites and things, a lot of times the contractors will end up creating holes in the roof to put those wires through. Sometimes those holes are just big enough for rats and mice to get into.

Q: How do you recommend tackling infestations?

A: The first thing we recommend is to seal up those openings. Anything bigger than the size of a quarter is big enough for a rat to worm its way into. So we want to have homeowners seal up those openings first and then proceed to trap the rats.

Q: What kind of traps do you recommend?

A: The old-fashioned snap traps are the best that we’ve found. The next question people always ask is what bait should they use. We’ve found that just a little section of a peanut butter cup – just cut a little section off of it – works really good on roof rats.

Q: Vector Control offers free household inspections. What does a visit entail?

A: We will go out and look for entry points. We will look for things that are attracting the rats in. It could be something like having a cherry tree too close to the house so then the rats have a food source and a source of access onto the roof or into the attic.

We’ll look at other things like ivy – which is also a habitat for rats and mice – and advise on cutting back certain kinds of vegetation. We will provide the homeowners with some traps and show them how to use them.

Q: What about applying poison?

A: Never use a poison bait inside of a house. The reason being is you don’t know where that rat is going to die. It could fall down between the walls, it could die in a hard-to-get-to area of the attic.

Q: Is it possible to relocate rats?

A: Some people think they’re doing the right thing by live-trapping the rat and taking it up to the hills, and it just doesn’t end up good; either the rat’s going to find its way to the next, closest house, or it’s not going to survive. Most animals don’t survive being relocated any way. … Taking it to a new area, there’s competition from the other animals. They don’t know where to find food, water and shelter.

Q: What health risk can indoor rodents pose?

A: They do carry fleas on them. There are some kinds of mites as well. The droppings are a bit unsightly and, of course, rats being rats, walking around through their daily course of business, they pick up a lot of bacteria; they have a lot of germs that they’re carrying around. Theoretically, they are carriers of typhus and, theoretically, carriers of plague, but we have not had any evidence of that in this county.

Q: Is there anything else residents should keep in mind?

A: In the case of the roof rat, they’re what we call “commensal” rodents. That’s a big fancy word that means “lives with people.”… Roof rats are non-native to America. You’ll recall from history books, back in 1848, we had a gold rush, and everybody came over here, including the rats, on ships, and they jumped ship. So that’s how these animals got out here. And they really have a hard time surviving in the wild; they have to be around people to survive. You don’t find any roof rats up at Mountain Umunhum. We make it easy for them.

To make a Vector Control service request, visit

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