They get the blame for spreading the Black Death through Europe. They can gnaw through cinder block and squeeze through pipes or holes not much wider than a half-dollar. They’re strong swimmers, climbers and burrowers, can survive a five-story fall, and will eat nearly anything. From their twitchy whiskered snout to the tip of their naked tail, some can grow nearly as long as the width of this newspaper page.
They’re rarely seen, because they’re nocturnal. But for North Bay residents, the sound of skittering in the walls at night and gnawed fruit and droppings on the floor in the morning are unmistakable signs that they’ve moved in. Rats!
According to the Marin/Sonoma Mosquito & Vector Control District, who provide free rat inspections and detailed information about evicting them, there’s been a nearly 10 percent increase in public calls about rats this year. Their staff has gone out to make 171 home rat inspections in the last six months, and helped about three times as many distressed residents by phone.
As upsetting as it may be, says Nick Picinich, a rodent specialist at MSMVCD, “Rats are here to stay, everywhere in Sonoma and Marin Counties.”
And, he notes, they don’t discriminate. He’s just as likely to find their trails in new, multimillion-dollar Marin mansions as in old, rural Sonoma County farmhouses. Few pests likely cause as much revulsion and discomfort among homeowners.
But the rats causing problems today are largely a problem of our own making.
First of all, as wildlife specialists are quick to point out, the rats running through our homes and businesses are not native to California. The wild wood rat, a native species, is shy and reclusive, builds nests of twigs and leaves up to 6 feet tall, eats woodland foods and lives out of sight of most people.
The rats that give rats a bad name, the roof rat and the Norway or sewer rat, hitchhiked to the Golden State on canvas-sheeted sailing ships and landed in droves with European voyagers and gold seekers. By 1850 the rat infestation in San Francisco streets, wharfs and hotels was so bad officials were forced to launch an all-out eradication campaign. Which failed.
Today these imported rats are not only widespread, officials at the California Department of Fish and Wildlife acknowledge, there’s actually no chance their populations will ever be controlled. That’s because, in a year, a single female can produce from 4 to 9 litters, with 8 to 12 pups per litter. And each new female can begin bearing in just 90 days.
So why don’t they just stay out in nature? The reason roof and Norway rats move into human spaces, experts like Picinich note, is because humans make the perfect roommates. From the rat’s eye point of view, where there’s people, there’s often a messy abundance of garbage, waste and other wonderful things to eat and lots of cozy places to shelter. So, they gladly follow us wherever we go.
Overflowing dumpsters outside restaurants, unharvested fruit in yards and the rat buffet known as outdoor pet and bird feeders all encourage them to settle in and breed. “Hoarding issues,” Picinich says, from weary experience, “will become rodent issues.” Overgrown yards and woodpiles on the ground, ivy patches and small openings in foundations and rooflines provide perfect entries and nesting spots that are warm, dry and secure from most of their natural predators.