Rats!

Western Washington has climate conditions that make it a haven for rats,
with Seattle being one of the rattiest cities in the country. 

Data from the American Housing Survey, 2011 and 2013. 

Visualized by Alex Bruell.

By Alex Bruell

They’re the bane of renters and homeowners alike, scuttering in through unsealed vents and resisting the tactics that would scare off lesser pests.

Rats and mice are already difficult pests to go to war with, and they’re especially bad in the Pacific Northwest, which has many of the perfect conditions for rodents to breed. A fertile female rat can have hundreds of children in a year, and as construction rates surge across King County, many of those rats are being forced to move and find new homes.

“It’s a very wet and lush, green environment for them to thrive in,” Ryan Miller, district manager of Western Exterminator Company said. “There are lots of food resources and habitats, which are prime for them to reproduce and grow in both number and size.”

Rat-proofing a house before they become a problem is something everyone can do.

“The rats are there for a reason,” Miller said. “With extermination, all you’re doing is killing what’s there at the time, not resolving the underlying issue of why are they there and how did they get in.”

Dense vegetation on the property can provide a nesting area for rats, who tend to stay outside and only venture in for food. Mice are more likely to try to find small nooks inside the house to live in.

For both animals, resolving structural entrance issues can go a long way to keeping rodents out for good.

Based on Miller’s experience, there aren’t any specific Shoreline neighborhoods that have particularly bad rodent issues. Any area can become a problem, however, if it has properties with overgrown vegetation, excessive bird feed, or abandoned structures.

Rats can make friendly and energetic pets, but an unwelcome 

rodent can quickly become a headache. Photo by Alex Bruell

John Griffin is the director of urban wildlife at the Humane Society of the United States, which features advice on dealing with wild rats. He points out that the most proactive solution is also the most humane one.

“The biggest thing is prevention,” Griffin said. 

“It’s something that’s so overlooked. When you’re looking at a house, have a general understanding of how animals are getting inside. 

"That means looking at the way your door closes, looking for openings around electrical or water supply, utilities, where the air conditioner connects to the wall. If those things aren’t closed up properly, they’re susceptible to intrusion.”

Mice, like many small mammals, are only limited by the size of their heads when fitting through small spaces. With larger animals like raccoons able to fit into spaces as small as 3 to 4 inches, a mouse can squeeze its way through a dime-shaped opening. This can make the hunt to seal up a home feel daunting.

“It can be extensive,” Griffin said. “Look at the foundation, windows, vents, even the roofline. Behind the gutter. Attic vents. Vents on the top of the house. Houses are rarely built with keeping animals out in mind.

“It’s challenging to go around the house and exclude everything at that size,” Griffin said, “ but you can have a bi-annual inspection, just to stay aware of things to address.”

When openings are present, tactics that work on other animals aren’t always as effective with rats. Katelynn Overton is the wildlife admissions specialist for PAWS, a Lynnwood non-profit that rehabilitates and cares for injured and orphaned animals. PAWS advocates for humane solutions to dealing with wild animals.

“Light, sound and smell deterrents work well against mammals like squirrels, but rats are a special case,” Overton said. 

“They’ve evolved to be around people and they’re very tolerant. The whole idea is to make it as annoying as possible so that they move out on their own. So obviously, don’t leave food around.”

Rat and squirrel sharing a meal
of dropped bird seed
Photo by Tom D. Bewley in Shoreline / LFP

Griffin pointed out that even a small amount of food can become a feast to a hungry rodent.

“It could be compost or garbage attracting them,” he said. 

“With mice, people can be unaware of how much food they’re supplying. It doesn’t take much and you can have these eruptions of mice. Cutting off food could mean going through your pantry and storing things in rodent proof containers, like glass or heavy plastic.”

When diplomacy fails, it’s often best to use traps or techniques that kill the rodent as quickly and painlessly as possible.

You’re not just doing the rat or mouse a favor; methods like poison are difficult to confirm success, and can end up causing more problems down the road.

“We don’t use rodenticides,” Miller said. “Poisoning is not instantaneous like with traps. You can know they fed on the poison, but not how much or when. It takes several days for them to die, and at that point they’re wandering around, lethargic.”

“If you feel ill, your first instinct is to say, ‘I want to go home and lay down,’” Miller added. 

“Rodents feel the same way. So it’ll usually lay down to rest in its nest and won’t get back up; now you’ve got a decomposing animal in a likely inaccessible area. You can even affect off target animals like a cat or dog.”

If you’re going up against a rodent yourself, the humble snap trap might be the best way to go. The trap works by severing the animal’s spine rather than causing them prolonged suffering. This can work especially well for mice, who are more inquisitive and curious than rats and already spend more time indoors.

Rats are more wily, and will often avoid traps even when baited with a food source. Rats can learn to avoid poison and traps when they see other dead rats fall to those methods, and might avoid new traps for several weeks or months. They also tend to forage outside a house, and only come inside if there’s something especially attractive inside for them.

“With mice, they sometimes live there their whole lives,” Griffin said. “They’re not leaving to go outside. You can evict a rat with a one-way door; with mice, that’s harder to do.”

While getting rid of rodents can become stressful and scary, getting them out humanely doesn’t have to end in unnecessary suffering.

“People don’t usually want to do harm,” Overton said. “They just don’t want them on their property.”