Rats are not native to the Puget Sound region and are believed to have arrived with the earliest Northwest settlers. (Bothell-Kenmore Reporter, file)

Rats are not native to the Puget Sound region and are believed to have arrived with the earliest Northwest settlers. (Bothell-Kenmore Reporter, file)

A brief history of rats in the Puget Sound region

The adaptable scavengers can sustain themselves by exploiting the sloppy habits of people.

There’s a literal rat race happening right now in the Puget Sound region as rodents thrive alongside the growing human population.

Rats are not native to the region and are believed to have arrived with the earliest Northwest settlers. Rats are commensal creatures, which means they largely depend on living in close proximity to humans.

According to Kurt Trefts, co-founder of Cascade Pest Control and a rat expert by trade, rats likely came to the Puget Sound on the ships of some of Seattle, Tacoma and Olympia’s earliest settlers and traders.

Trefts called people great “enablers” of rats. The large warehouses, canneries and other industrial facilities that made the Puget Sound such an important region of shipping and commerce proved to be more than sufficient shelter for rats to hide, eat scavengable scraps left by people and breed quickly.

Trefts said rats are adaptable scavengers that can sustain themselves on garbage waste and spilled grease, exploiting the sloppy habits of people living in a growing urban sprawl.

Trefts said as people continued to develop farms, towns and cities among the wooded forests surrounding the Puget Sound, rats have followed, enjoying the “bounty” that people provided for them.

Over the years, pest controllers began to notice the same thing.

Trefts has been working in pest control in the Puget Sound region for over 40 years. Year-by-year, he has noticed the changing trends of pest populations and prevalence based on the kind of service calls he was responding to across the region.

“In the ‘70s and ‘80s, the primary problem was carpenter ants,” Trefts said. “Rats were usually pretty confined to the waterfront areas.”

Over time, he and other peers in his industry began to notice a change.

“We realized that control of rats was more intensive,” Trefts said. “It became the main thing. It was obvious that it was widespread.”

He said semi-rural communities, like Bellevue, in which suburban communities were built wall-to-wall next to one another, provided shelter and sustenance for the highly adaptable rodents.

Trefts said the newly built homes, with dark rat-cozy spaces in the walls and crawl spaces, provided “perfect” nests for families of rats. He said simple overlooked details like overfilled birdfeeders and grease from barbecues were just enough for rats to sustain themselves.

Rats have even been noted as having eaten dog droppings from a residential lawn.

Trefts and his peers began to notice they could work to keep the rats out of a home, but not the neighborhood, because they were “really well established.”

Trefts believes that the Puget Sound region has more rats per capita than New York City, mostly because New York has a higher population density and vertical skyrises that can shelter rats.

Near the end of 2020, national pest control company Orkin ranked Seattle as the 12th rattiest city in the country.

Trefts knew that rats were rarer in more eastern inland urban communities like Spokane and Boise, so he wondered why the rat species in the Puget Sound were so pervasive. His theory was that the “unique” climate and geography of the Puget Sound offered ecosystems with food and shelter that allowed the rats to survive independent of people.

He believes that wetlands and greenbelts surrounding the pockets of human development offer just “enough in the wild that they can live on,” breaking the commensal mold in which rat populations and colonies were believed to be almost entirely dependent on people and their dwellings.

Trefts said even the marine intertidal zones of the Puget Sound offer great scavenging for rats with the kelp, dead animals and small marine creatures that can easily be found on the beach.

Effect on ecosystem

If rats have become an invasive species in Puget Sound ecosystems, how is it affecting other native species?

Dave Pehling, zoologist and researcher at Washington State University, said it is difficult to fully measure the extent to which rats have established themselves in native ecosystems because comprehensive population data does not exist. However, he did say it was more than possible for rat populations to disperse among woodlands and greenspaces.

He said wetlands and seashores can be rich in food for rats. He said rats can be a “huge problem” for wetland ecosystems in which they may prey on native species if needed.

He said roof rats have been known to get into birds’ nests to prey on them, and will even eat native mice.

“They can live on anything,” Pehling said.

Even though Pehling admitted to the possibility of widespread invasive rats establishing themselves in local ecosystems, he maintained that rat populations are largely a human-driven problem.

“Humans are sloppy. They throw away nearly half their food,” he said.

With Americans collectively throwing out roughly 40 percent of the food they have grown, raised or prepared, Pehling said the rat problem could be dependent on whether people “clean up their act.”

Justin Bush, executive coordinator for the Washington Invasive Species Council, admitted that there seems to be a data gap that exists when it comes to the population dynamics or prevalence of invasive rats in native ecosystems.

He added that while the Washington Invasive Species Council has not recognized or focused on invasive rats at this point in time, that does not mean that they won’t examine the issue in the future.

This story originally appeared in the Bothell-Kenmore Reporter, a sister publication to The Herald.

Talk to us

More in Northwest

A marijuana grow is seen on Sept. 2, 2021, in an aerial photo taken by the Deschutes County Sheriff's Office the day officers raided the site in the community of Alfalfa, Ore. On the 30-acre property in the high desert they found 49 greenhouses containing almost 10,000 marijuana plants and a complex watering system with several 15,000-20,000 gallon cisterns.   (Deschutes County Sheriff Via AP)
‘Blatant theft’: Illegal pot farms take West’s scarce water

Meanwhile, farmers are spending thousands of dollars drilling deeper wells as aquifers dry up.

In photo provided by the Washington State Dept. of Agriculture, an Asian Giant Hornet wearing a tracking device is shown Thursday, Oct. 22, 2020 near Blaine, Wash. Scientists have discovered the first nest of so-called murder hornets in the United States and plan to wipe it out Saturday to protect native honeybees, officials in Washington state said Friday, Oct. 23, 2020. (Karla Salp/Washington Dept. of Agriculture via AP)
‘Concerning’: Possible murder hornet 20 miles from known nests

The insect was spotted in the foothills near Sumas Mountain.

FILE - In this Oct. 24, 2016, file photo, the AT&T logo is positioned above one of its retail stores, in New York. A Pakistan resident has been sentenced on Thursday, Sept. 16, 2021, to 12 years in prison for a conspiracy to "unlock" phones from AT&T's network, a scheme the company says cost it more than $200 million. Muhammad Fahd, 35, of Karachi, recruited an employee of an AT&T call center in Bothell, Wash., via Facebook in 2012, and began bribing that employee and his coworkers to use their credentials to unlock phones. (AP Photo/Mark Lennihan, File)
Bothell workers helped Pakistani in $200 million phone fraud

The Karachi man recruited employees of an AT&T call center to use their credentials to unlock phones.

Boeing sells land for $200M in plan to shrink holdings

Boeing has sold 310 acres of undeveloped land next to its Frederickson manufacturing plant.

King County to require vaccine or test for events, eateries

Proof of a COVID-19 vaccination or a negative test will be required to enter certain establishments.

Biden slammed for challenging Hanford workers’ health law

The 2018 rule made it easier for nuclear reservation employees to qualify for compensation benefits.

Carpenters in Seattle area go on strike

The walkout for higher pay by carpenters in the state is the first in nearly 20 years.

FILE - In this Feb. 2021, file photo released by California Department of Fish and Wildlife, shows a gray wolf (OR-93), seen near Yosemite, Calif., shared by the state's Department of Fish and Wildlife. A top federal wildlife official on Friday, Aug. 20, 2021, said there is growing concern over aggressive hunting rules adopted by states in the Great Lakes and northern Rocky Mountains. (California Department of Fish and Wildlife via AP, File)
US: Wolves may need protections after states expand hunting

Former President Trump lifted protections across most of the U.S. in his last days in office.

Staffing shortages disrupts ferry service near Anacortes

There were 51 canceled sailings on the Anacortes/San Juan Islands route from Sept. 9 to Sept. 13.

Most Read