When Eighty Bug moved to a quarter-acre property near Vancouver in 2017, it seemed the perfect place to sink into a hobby for which residents across the Pacific Northwest are widely known: backyard chicken farming. The flock grew from six to eight hens, and while scattering their feed on the grounds outside their coop did sometimes attract the interest of an occasional rat, Bug, by day an animator and musician, managed the rodents with snap traps—at first.

Then came a housing construction boom in her once-rural neighborhood, and as marsh and woodland areas gave way to new apartment complexes, refugee rats swarmed Bug’s and her neighbors’ properties. By the middle of the pandemic, Bug could look out at her yard and see dozens of rats scurrying this way and that in broad daylight. Setting traps was clearly going to be a finger-in-dike kind of solution, so she set out to learn everything she could about the fuzzy gray rodents. The results weren’t promising. Rats can have dozens of babies each year, and those babies reach sexual maturity within weeks. Bug knew this would be “untenable.”

One particularly adventurous rat nosed its way through the dog door and then into her kitchen, ducking behind the stove and into a ventilation hose before scurrying up to her attic. “It was chewing through the ceiling for a week, to get out,” she says. “It was mayhem.” Rats chewed through plastic dog food containers, even through the walls of the chicken coop, where there is no food. “They were just looking.”

Bug’s ordeal is among the most common ways people in the metro area encounter rats, says Multnomah County rat inspector and self-proclaimed “rat guy” Chris Roberts. The region’s rodent numbers have stayed fairly consistent over the last several years, aside from a mysterious spike about six years ago. Food sources left outside draw rats, and that aligns pretty well with backyard chicken, squirrel, and bird feeding. Compost bins used to be a big factor in Portland until the city launched its compost pickup program. During the pandemic, squirrel feeding became a top source, as isolated residents fed furry new friends. These days, “it’s the same thing, over and over again: people feeding birds, squirrels, chickens,” Roberts says.

The rat guy, however, has some pointers for fixing the problem. Step one: remove the source, for at least 30 days, he says. When you reintroduce it, set up feeders in a way that doesn’t lead to them spilling on the ground and making rat snacks. Chickens can be put on a feeding schedule, for 15 or 20 minutes, twice a day. Coops can be rebuilt so that they’re rodent-proof, but this is labor-intensive. “If you can keep food away from tree branches and fences,” Roberts says, “you can feed birds without attracting rats.”

Bug tried everything, hoping she’d find a mitigation measure that wouldn’t also hurt her chickens or her pets. She added hot peppers and cinnamon to the chicken feed and planted peppermint, hewing to the old adage that these were all naturally occurring rat deterrents. They weren’t. The critters kept coming.

She investigated an option that has had some reportedly good effects in New York. A feed that sterilizes rats had led to a big reduction in the population of America’s largest city, but in the long term it was too expensive. Finally, she and her neighbors found something that worked: a type of pellet called RatX, which dehydrates the rodents until they’re dead but doesn’t harm other critters.

Multnomah County Vector Control offers free property inspections and advice about how to identify attractants and to address rat problems, whether it be clearing blackberries, sealing holes, or rearranging wood piles. The county also hands out snap traps, which are a better option than poison because they don’t harm other animals and don’t lead to rats dying inside walls, he says. There are expensive solutions like carbon dioxide traps, but those aren’t generally worth the cost, he says. “If it’s a really severe problem, we do recommend people hire a professional. They can get rid of it in the most timely manner.”