With UB40’s classic reggae hit echoing in my mind, I pondered this question for the first time since moving to Central Oregon three decades ago. Tipped off by my dogs’ unusual curiosity around the furnace vents from the cellar, sniffing the blowing air, I set a few small snap traps in anticipation of an errant deer mouse or house mouse. An increase in rodent activity with the onset of cold weather is typical in my leaky old home. I was curious, though, when the next morning I found the traps sprung and peanut butter licked clean. “Could be a bigger animal,” I thought to myself, although a true rat was not on my radar. The following morning I checked again and came upon two of the largest house mice I’d ever seen. Armed with my copy of B. J. Verts’ and Leslie Carraway’s 1996 “Land Mammals of Oregon,” a 668-page tome, the authority of which I had no reason to question, I reviewed the range maps for Rattus rattus and Rattus norvegicus and confirmed what I already knew — these animals are restricted to the west side of the Cascade Range.
As a professional mammalogist myself, and protégé of Verts and Carraway while studying at Oregon State University, my confirmation bias held sway until the following day. My next-door neighbor asked me to identify the roadkill out on the street, and sure enough, I was confronted with an unmistakable black rat, Rattus rattus. Its long gracile tail distinguished it from the much larger bodied but shorter tailed Norway rat. I struggled to maintain composure. The thrill of discovery and abhorrence and desire to scream at the thought of large vermin in my house competed for emotional supremacy. My neighbor tipped the scale in favor of abhorrence after producing a video taken the day prior by her husband of a black rat running along the fence in the alley behind our house in broad daylight. This was an infestation! Dazed and confused, I dashed to the hardware store to pick up some large rat-sized snap traps and promptly caught one more black rat behind the wood pile that very night.
The ”old world” rats, or what I consider to be “true” rats relative to the various indigenous woodrats, kangaroo rats, deer mice and ground squirrels native to Central Oregon, are thought to originate in tropical Asia. But their thorough spread around the globe as co-inhabitants of human settlements so many centuries ago obscures their origins somewhat. Rattus arrived in the Americas on the ships of conquistadores and pilgrims, stowaways amid livestock fodder and seafaring filth.
Old world rats in the Americas are represented by three species: The Norway rat, nicknamed the wharf rat; the black rat, known as the roof rat and the house mouse; and Mus musculus, a diminutive cousin of the Rattus. All three old world species are distinguished from native rodents such as the bushy-tailed woodrat, Neotoma cinereus, and deer mouse, Peromyscus maniculatus, by their naked tails without fur covering. I add these scientific names in italics for clarity with confusing nicknames and temptation to lump all as “vermin.” In the sagebrush country east of Bend we can hear reference to “sage rats” which are in fact not rats at all but small ground squirrels.
Old world rats are smart and tame easily. It’s Rattus that is our common household pet and which served as Wormtail, Peter Pettigrew’s “animagus” in the Harry Potter books. Rattus is remarkably adaptable to new environments. A spectacular example from Germany demonstrates how a Norway rat even learned to catch bats in flight. And of course, the Norway rat, black rat and house mouse all have borne the burden of service as medical subjects that allowed for development of modern medical wonders. They are the unsung heroes and unacknowledged co-authors of thousands of New England Journal of Medicine and Lancet articles. We’d still be in the dark ages without the lab rats and mice!
Speaking of the dark ages, Rattus is also responsible for delivering the bubonic plague, the flea-borne disease known as the “black death” that killed millions during the Middle Ages. This may be one reason they freak us out so much more than our indigenous rodents. Cases of bubonic plague still pop up here and there, but rats these days represent not so much a health threat as they do a physical threat. They love to chew on things and they can cause substantial physical and economic damage to homes and businesses. There is cause for concern with increasing numbers in Central Oregon.
Several longtime pest control experts that I spoke with for this article concurred that, much to my surprise, the Norway rat has been in the area in low numbers for decades but that the black rat is relatively new, perhaps arriving sometime around 2015. They too have seen an uptick in reports and encounters this fall. I’ve now uncovered dozens of neighbors with similar stories to my own. One neighbor reported that her cat caught six black rats this summer! Whereas I interpreted the Verts and Carraway range maps as an indication that the cold and dry conditions east of the Cascade Range represented a geographic barrier to spread, the local experts suggested the arrival and successful establishment of the black rat probably has more to do with growing human population in the region. My neighbor with the ratting cat blames the trash accumulations from nearby establishments. There are anecdotal reports that rats are arriving in shipping containers and trucks bringing construction supplies. One builder recounted a specific event approximately 9-10 years ago, witnessed by multiple people, involving rats spilling out of a shipping container. It’s a plausible “founder event” scenario. But regardless of origin, one thing is clear now – black rats are here to stay in Central Oregon.
This article appears in the Source November 20, 2025.
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Many rodents out there and am sure that almost all of them cause health issues. Some may give you virus, some fever and some are also life threatening such as plague. Best is to keep our place neat and tidy and free from food spills. Keeping the garbage bin closed is also good. Apart from that doing a regular pest control work will also help.