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By Sally Griffin

This is the yuckiest story about wildlife in our city that I have ever had to write, but I felt this story needed to be told.

According to pest control company Orkin, the Denver area is the 10th “rattiest” city in the United States. We beat out Minneapolis for this spot. (Not that I think Minneapolis minded their displacement!) We are now in the same league as Chicago, Los Angeles and New York. The ranking is based on the number of new residential and commercial rodent treatments performed between September last year and September this year.

Yuck, right?! So, let me tell you about some pretty disgusting creatures.

If you think this is just a problem in the seedier areas of Denver, think again. Last year, Jefferson County Public Health had to deal with a massive rat invasion of a house in Lakewood. There were rats on the downspout, rats on the roof and rats on the rocks leading down to the neighborhood reservoir. One neighbor declared, “I’ve never smelled anything quite as bad in my life.”

At the same time, Littleton noted that cases of mange had culled the number of predators (think coyotes) that feed on rodents, thus contributing to a noticeable increase in rats.

Arvada also had sightings of rats near a dumpster not far from a string of businesses.

Denver parks, including Civic Center, have telltale signs of rat infestations.

Rat experts (can you imagine that as a job title?) say that you are going to find a lot more rodent activity in those places that have water, food and shelter readily available. That means a home by a lake or stream can be a rat vacation spot.

Rats Don’t Like New Construction, Either

There are other things that can cause rat problems. According to Ryan Riley, Orkin branch manager, part of the problem is caused by the building boom in the Denver area.

“Whenever you have new construction, whatever was living there before you started building has to go somewhere,” said Riley. This means rats can be a problem near any construction site whether it is in the heart of Denver or the western suburbs.

And now is the worst time. Once the snow starts these mammals don’t hibernate, they look for warmer places to spend the winter. They only need a hole the size of a quarter to enter their new winter residence. In case you didn’t know, rats can climb walls or climb trees to jump to roofs. Rats will eat any food that humans or their pets will consume. They love bird feeders, dog pens, vegetable gardens, chicken coops, garbage cans, dumpsters and compost piles. They are ultimate omnivores. The food not eaten is hoarded in walls, furniture or appliances.

Rats reproduce in the spring and fall. A female rat can have 20 or more offspring in a year. Although the average lifespan of a city rat is only five to 12 months, they will infest the same area, returning to produce more litters.

They spread more than 35 diseases worldwide. These diseases are spread through direct contact, contact with their waste or saliva, and through the ticks, mites and fleas that have fed on a diseased rat.

They will chew through almost anything and cause structural damage. They will gnaw on electrical wires, including electrical wires in cars. They can even take out gas lines, plumbing line and support beams. One estimate is that almost 25 percent of unexplained fires start from rodent chewing.

Know Your Rat Neighbor

The most common kind of rat in Colorado is the Norway rat, also known as brown rats. But Colorado also has pack rats. Norway rats have coarse fur that is reddish to grayish brown with a gray belly. They are large and robust, weighing in at 12 to 16 ounces. Pack rats have long tails that are covered in fur, white feet and a white underbelly. Pack rats are larger than other types of rats and can grow to almost eight inches in length. While most rats live in fairly large groups, pack rats usually live alone. At any rate, if you see what looks like a very large and not so cute mouse, you are probably seeing a rat.

Now, the real reason for this article: to give you some ideas on how to avoid and solve rat problems. Keeping things well sealed and keeping food where they can’t get to it are two best ways to prevent a rat problem.

Cats may help, but some cats have an aversion to hunting rats. And I really can’t blame them.

Managing the landscape around your house can help. Avoid low shrubs and tree branches next to the house. Keep grass and weeds mowed down. Remove any clutter, both inside and outside. Don’t store firewood next to the house. Remove old cars, old furniture and appliances.

Manage food sources. Store pet food and birdseed in metal or heavy-duty plastic. Secure compost piles and recycling bins. Remove animal waste: rats will eat it!

Carefully inspect the outside of the house and seal any hole bigger than a quarter; bigger than a dime if you want to keep mice out, too. Use steel wool, copper mesh, wire screen or sheet metal to keep those pesky rats from chewing through it.

The Big Three No-No’s

Three things to remember: 1) Avoid giving rats a place to hide; 2) Don’t give rats a home; 3) Don’t give rats a food source.

To know if you have a rat problem there are several things you can look for. Look for them to be most active at dawn or dusk. Look for nests in drawers or boxes in the garage or shed. Look for rat droppings — 40 to 50  pellets a day. Look for burrows about three inches in diameter with compacted and smooth entrances that are close to the building, under slabs or along foundations. Look for gnawing damage around openings. Look for rub marks caused by their fur rubbing along walls. Lastly, scrambling or squeaking noises and a musty smell are dead giveaways that you have rats.

If you think you have a rat problem, you may want to call an exterminator. If you want to try to deal with the emergency yourself, snap traps are recommended. Use ones that are like a standard mouse traps but bigger. Poison is not usually recommended because of the risks to children, pets and other wild animals. There are also environmental concerns with poison.

If you want more information on how to use the traps effectively, the Internet Center for Wildlife Damage Management has lengthy rat information at http://icwdm.org/wildlife/NorwayRat.aspx.