The Greater Seattle Area has undergone a large population boom as tens of thousands flock to the urban areas, darting through alleyways, scavenging for food and breeding more often every year.

Rats have been a growing problem in Seattle and on the Eastside over the past decade. Their natural attraction to urban areas creates numerous problems for locals — some are simple inconveniences while some cost thousands of dollars.

“They eat from my antifreeze and transmission fluid,” said Igor Rozmarih. “Every morning I wake up and I don’t know if I [can] drive or not… I’m afraid.”

Rozmarih lives in a Bellevue condo complex near the Bellevue Aquatic Center. He and his neighbors recently and suddenly were infested with rats that were climbing into their cars and causing severe damage.

An engine compartment emulates a rat’s natural habitat as an enclosed, warm space with various tubes and wires they see as vines and branches. They’ll climb into the compartment during the night and by the time Rozmarih wakes up and starts his car, the damage is already done.

“The wires to them in their world is a blade of a leaf, which causes devastating problems to us as humans,” said Ron Wikstrom, technical director of Eastside Exterminators. “It’s becoming a bigger problem. I’ve been doing this for 30 years and I can tell you that there was a time when it might be once every five or six years we get a call about someone’s vehicle… Now it’s more on the magnitude of every few weeks.”

As the rat population grows, the problems they cause for humans become more common. Wikstrom added that populations have really exploded within the past decade and there are areas with rat infestations that have never had a problem before.

According to a spokesperson for Rozmarih’s homeowners association, the condos hadn’t ever been infested with rats until the past month. The spokesperson, who asked to remain anonymous, added that the problem is currently under control thanks to professional exterminators.

Rats and humans

Rats have a deep-rooted history with humans going back to the earliest large population centers. They’re likely most well-known for carrying diseases — particularly, rats carry fleas that spread the plague. That combined with dense, unsanitary populations is believed to have caused the Black Death, an pandemic which killed 30 to 60 percent of Europe’s population in the 14th century.

“[Rats] are vectors of 60 different disease that aren’t good for humans,” Wikstrom said. “There is a healthy fear that, not that it’d be the plague, but that something could come of the overpopulation of rats.”

Diseases have become far less of a problem in modern urban areas with the advent of modern medicine and increase in overall health. So, while rats are inherently a large health problem, the most immediate problem for humans is the damage they cause.

Experts have numerous theories as to why rat populations are booming, according to Wikstrom.

“There are only theories, even the Ph.D. taxonomists, entomologists and rodentologists spend their lifetime studying these issues,” Wikstrom said.

He points to the overall rise in average temperature in the past 10 to 15 years as the one he believes to be most likely.

“Measurably speaking we know there’s been a change in the earth’s climate,” Wikstrom added. “How it got there is a whole different discussion of course.”

Rats reproduce very rapidly throughout the year, Wikstrom said. One rat can produce 20 to 40 rats in a year with four to six litters of six to 14 rats. However, rats will reproduce as long as the weather permits, so as it stays warmer later in the year, rats are able to produce one or two more litters each year.

Thus, the population increase becomes exponential as each of those rats can produce more rats each year.

Efforts to control

The rat population has grown to such a degree that some cities have building codes in place to prevent the spread of infestation. Particularly, there is a code Kirkland that requires developers to exterminate a rat infestation prior to demolishing a building. That prevents rats from escaping into neighboring areas.

Issaquah also has codes in place to prevent rat infestations, despite being more rural than other Eastside cities and therefor less susceptible to the problem. There are several standards in place to protect property values by specifically guarding “against the creation of rodent and pest harborage, and reduce the impact on the natural environment from the leaking of motor vehicle fluids,” among several other methods.

Rozmarih and some of his neighbors believe local government should be working to help with the problem, however Wikstrom pointed out that it’s not so simple.

Extermination services don’t even have the resources to completely handle the rodent populations, Wikstrom said, so city governments greatly lack the resources and workforce to solve the issue.

Despite this, there are several ways to help prevent the increasing rat population.

“There is action being taken. Trash service becomes very important. Even if it’s something as simple as having secured closed trash cans,” Wikstrom said. “That’s great because rats can’t get into that… and that’s something that can be legislative. It’s those kind of measures that have to be taken.”

Individuals can also protect themselves from potential infestations through various means. Wikstrom specifically recommends getting rid of bird feeders, keeping an eye on the exterior perimeter of a home to make sure there’s no potential entrances and trimming bushes and shrubs to ensure they’re hollow enough to not be used as a nest.

The King County Public Health department also offers resources to prevent rat infestations and file complaints on its website, www.kingcounty.gov/depts/health/environmental-health/animals/rat-prevention.aspx.

Rats are likely a pest that will never disappear completely. They’ve been tightly intertwined with the human population throughout recent history and have caused numerous problems. That said, the problem is not nearly as bad as it has been in the past and will likely not cause another Black Death.

“It’s disappointing to say that [business] has been great,” Wikstrom said with a laugh. “I don’t think there’ll ever be an end to it, so one of the greatest things we can do for the community is share how to prevent these issues. There are already enough rats anyway — we don’t need to encourage their populations to increase business and we live in these communities, right? So all these things would be great if they can be done to keep the population down because business is great, and it’s only getting better, which is scary.”