Almost nobody wants to see a rat in or outside of their home. Most people know from history that the Plague or Black Death came from rodents and their fleas, starting in the 14th century. Over the next five years, the mysterious Black Death would kill more than 20 million people in Europe–almost one-third of the continent’s population. Current research indicates that it may have started with gerbils (another rodent). Here in Las Vegas, we have two rat species that are found in southern Nevada. They range from Spanish Trails to Green Valley, Floyd Lamb Park to Mountains Edge. They love golf courses and both natural and man-made wash and drainage areas. The Old-World or European rats, roof rats (Rattus rattus) and the Norway rat (Rattus norvegicus), are the ones we deal with here in the valley.
According to the Southern Nevada Health District, the Norway rat is the larger of the two, also known as the brown rat. The Norway rat has a short tail, shorter than the head and body combined, with a blunt nose and small ears. The Norway rat may weigh 12-16 ounces and grow to a total length of 13-18 inches. These rats thrive in unsanitary conditions and are usually nocturnal opportunistic scavengers. The femals can give birth approximately seven times per year, and after a short gestation period of 22 to 24 days, the litter of approximately 8 pups is born. Norway rats are excellent swimmers, and are often referred to as “water rats.” Norway rats are excellent foragers. Using their sense of smell and touch, they are able to survive quite easily given that there is a steady supply of any type of food. In metropolitan areas, they survive mainly on discarded human food, and anything else that can be eaten like pet food left out and garbage.
Roof rats are not native to Las Vegas, and are belived to be associated with imported palm trees, with first sightings starting in the 1990’s. These rats usually prefer seeds, nuts, vegatables and friuts. They out number Norway rats and roof rats and their associated parasites can transmit plague, typhus, salmonella, leptospirosis, rat bite fever, and other diseases. Both species require a reliable source of water. They will drink from swiming pools, irrigation sources and washes. Females can produce up to 5 litters in one year. The gestation period ranges between 21 and 29 days, and young rats are able to reproduce within 3 to 5 months of their birth.
The following measures come from the Southern Nevada Health District:
Weatherproof your home’s windows and doors (eliminate light from around doors).
Seal outer openings, pipe chases and wire entrance gaps with steel wool, aluminum, or wire mesh.
Secure pet doors at night.
Eliminate any unnecessary clutter, material, brush or foliage from your property.
Keep bushes trimmed and clean out leaf litter and clutter that collects below bushes.
Remove landscaping debris quickly.
Stack firewood 12 inches off the ground and keep the area clean.
Keep trash cans (plastic or metal) covered.
Do not put out “food” garbage in plastic bags.
