Types of Rats in Washington State

Rats & Their Behavior: Part 1 Vexing vermin Okay, I hate to admit it, but I have rats on my property. I feel embarrassed by the fact that I have rats, like I’m some kind of unfortunate third world country without proper sanitation, but rats I have. I suspected I had something other than cute little mice when something began chewing holes in my full- size trash cans. Large holes, in about two weeks. They were fast. It was creepy. So I bought metal garbage cans and set some traps. Yep, rats. Several native species of animals in Washington are described as “rat” but none of them are technically rats, and they don’t generally invade your home or property: the kangaroo rat (Dipodomys ordii) not a rat, bushy- tailed woodrat (Neotoma cinerea) not a rat either, and the muskrat (Ondatra zibethicus) not a rat. If you have an infestation of muskrats, check with the Department of Fish and Wildlife for effective management. The Norway rat and the black rat, also known as the roof rat are the only official rats residing in the State of Washington. Neither of them are native. Just a note: The pet rat your child is always asking for is actually a specially bred strain of Norway rat. Doesn’t this make you feel better about the critter under your house? Nope, me neither. These two non-native rat species were introduced into North America from Asia and Europe via ships bringing settlers to America. They are found around the world. They adapt easily. Norway rats are probably the rat you think about, when/if you think about rats at all. They average about sixteen inches in length with tail, which is scaly and shorter than the body of the rat. Normally they’re grayish-brown in color but this can vary. They prefer to nest in burrows, woodpiles or in the lower levels of buildings, like basements or crawl spaces. Roof rats are similar in length but darker and less stocky. Their tails are longer than their bodies and they prefer to live higher, building nests in trees, attics or shrubbery. Rats live together in groups, usually a dominant male with a bevy of females, and they often have several nest sites moving from one to another every few days. Rats need to nest where there is available water. That covers almost every neighborhood, including yours. Both species of rats breed year round, producing a litter of six to ten after a three week gestation period. The babies are weaned after about three weeks and can start reproducing themselves at three to four months. Luckily for us, the average life span of a rat is less than one year because much like rabbits, they provide food for many small predators. Top Left: The black rat is also known as the roof rat. Bottom Left: The Norway rat. (Photos courtesy of Google Free-to-Use Images.) Unfortunately for us, rats like to eat almost everything we do. They prefer fresh foods over garbage but are realistic and eat whatever is available including garbage, other rodents and even animal droppings. Rats can live on a diet of dog poop! They forage at night and will store food away in hidden areas. Other than seeing rats running about, which they’re probably not going to be doing during the day unless something has disturbed them or you’ve got a lot of rats, you need to look for rat “signs”( such as holes being gnawed in your garbage cans). Rats have to gnaw. Their teeth can grow up to five inches a year so rats need to work at keeping them worn down. Look for holes with teeth marks around them, not necessarily big holes. Rats can easily squeeze through cracks as small as half an inch. Look for rat droppings. They are larger than mouse scat and are pointed at each end. Look for missing food, gnawedthrough packages, and rub marks along walls. Rats typically use the same pathways over and over again usually following a wall, fence or other vertical boundary. You can sprinkle a light dusting of flour along the sides of suspected rat pathways, then check for little footprints or tail dragline markings. Listen for them, at night after it gets quiet. You may hear them in walls or attic. Rats are very destructive. Needing to gnaw, gnaw they will- on structures, on wiring, on anything tasty or anything they think might be nesting material. Their droppings and urine contaminate human and animal food, so they spread diseases. Do not ignore your rat problem; it will only get worse. Take steps to get rid of these non-native, disease-spreading, destructive creatures. The sooner you act, the better. Next month, we will discuss, “How to get rid of your rats.”