Norway rats, Rattus norvegicus, their management and control. Robert M. Timm. Superintendent and Extension. Wildlife Specialist. Hopland Research and Extension Center. University of California. Hopland, CA 9. 54. Norway Rat (Rattus norvegicus). Click image for larger picture. For additional Norway rat control information click. Diagram that helps one distinguish rats from mice. Click for larger image. North America by settlers who arrived on ships from Europe. Also called the brown rat, house rat, barn rat, sewer rat, gray rat, or wharf rat, it is a slightly larger animal than the roof rat (Fig. Adult Norway rats weigh an average of 1 pound (4. Their fur is coarse and usually brownish or reddish gray above and whitish gray on the belly. Blackish individuals occur in some locations. It is generally found at lower elevations but may occur wherever humans live. In urban or suburban areas they live in and around residences, in cellars, warehouses, stores, slaughterhouses, docks, and in sewers. On farms they may inhabit barns, granaries, livestock buildings, silos, and kennels. They may burrow to make nests under buildings and other structures, beneath concrete slabs, along stream banks, around ponds, in garbage dumps, and at other locations where suitable food, water, and shelter are present. Although they can climb, Norway rats tend to inhabit the lower floors of multistory buildings. When given a choice, they select a nutritionally balanced diet, choosing fresh, wholesome items over stale or contaminated foods. They prefer cereal grains, meats and fish, nuts, and some types of fruit. Rats require 1/2 to 1 ounce (1. Food items in household garbage offer a fairly balanced diet and also satisfy their moisture needs. They usually become active about dusk, when they begin to seek food and water. Some individuals may be active during daylight hours when rat populations are high. They are considered color- blind. Therefore, for safety reasons, baits can be dyed distinctive colors without causing avoidance by rats, as long as the dye does not have an objectionable taste or odor. Read about Rattus norvegicus (brown rat) on the Animal Diversity Web. TEXAS GHOST TOWNS Vanishing Texas - The deserted, forgotten, abandoned towns. Their sense of taste is excellent, and they can detect some contaminants in their food at levels as low as 0. Nests may be lined with shredded paper, cloth, or other fibrous material. Litters of 6 to 1. Newborn rats are hairless and their eyes are closed, but they grow rapidly. They can eat solid food at 2 1/2 to 3 weeks. They become completely independent at about 3 to 4 weeks and reach reproductive maturity at 3 months of age. Breeding often peaks in spring and fall, with reproductive activity declining during the heat of summer and often stopping completely in winter, depending on habitat. These seasonal trends are most pronounced in more severe climates. The average female rat has 4 to 6 litters per year and may successfully wean 2. All you need to prepare a successful trip to Madeira. Sea Turtles Sea Turtles are one of the most attractive, yet vulnerable, of all marine vertebrates. Wild Boar Classification and EvolutionThe Wild Boar is a species of Wild Pig, native to the forests of Europe, north-west Africa and it is also found throughout Asia. Common Name: Norway rat, brown rat, common rat. Scientific Name: Rattus norvegicus. Classification: Phylum or Division: Chordata Class: Mammalia. All About Norway Fun Science Facts for Kids. Learn more all about Norway with our Geography for kids website. Kids Science Fun Facts on Norway. Also known as the Norway rat, this species is a supreme generalist and has colonised practically every part of the world. Information, photographs and movies. We know exactly where to find wild animals in Sweden. Wanna know the secret how to find a Moose a Beaver or a Wolf? This is the ultimate guide. For more detailed information on their physical abilities and the resulting need to design rodent- proof structures, see the chapter Rodent- Proof Construction and Exclusion Methods. Rats seldom travel farther than 3. They quickly detect and tend to avoid new objects placed into a familiar environment. Thus, objects such as traps and bait stations often are avoided for several days or more following their initial placement. Rats will quickly find them and after a short period of avoidance, will cautiously investigate them. Baited but unset traps will aid in overcoming rats’ fear of them; expanded- trigger traps set directly on travel routes may immediately catch rats. They may eat very small amounts, and subsequent feeding will depend on the flavor of the food and its physiological effect. If the food contains poison or some other substance that soon produces an ill effect but not death, the food will often be associated with the illness. This “bait shyness” was a major problems when single- dose acute toxicants were the main rodenticides in use. Today, only two rodenticides registered for Norway rat control, red squill and zinc phosphide, possess characteristics that make bait shyness a potential problem. Pre- baiting, that is, training rats to feed repeatedly on nontoxic bait for a period of days prior to applying the toxicant in the bait, will largely prevent sublethal doses and thus bait shyness. It will also lead to successful control, with very few rats left to become bait- shy. Prebaiting will almost always increase control success when zinc phosphide or red squill baits are used. These baits serve, in effect, as their own prebait. They may damage crops in fields prior to and during harvest, and during processing and storage. Rats also damage containers and packaging materials in which foods and feed are stored. They undermine building foundations and slabs, cause settling in roads and railroad track beds, and damage the banks of irrigation canals and levees. Rats also may gnaw on electrical wires or water pipes, either in structures or below ground. They damage structures further by gnawing openings through doors, window sills, walls, ceilings, and floors. Considerable damage to insulated structures can occur as a result of rat burrowing and nesting in walls and attics. Plague is a disease that can be carried by a variety of rodents, but it is more commonly associated with roof rats (Rattus rattus) than with Norway rats. They may be as large as 3/4 inch (2 cm) long and 1/4 inch (0. Fresh droppings are soft in texture. A tracking patch made of flour can be placed in pathways overnight to determine if rodents are present. Urine stains may occur along travelways or in feeding areas. Rats memorize pathways and use the same routes habitually. Fresh accumulations of wood shavings, insulation, and other gnawed material indicate active infestations. Size of entry holes (often 1 1/2 inches . Rats keep their paired incisor teeth, which grow continuously at the rate of about 5 inches (1. Estimating Rat Numbers. Rat sign and visual sightings are of limited value in accurately estimating rat numbers, but they are the simplest and often the only practical method available. Search premises thoroughly when looking for rats. In structures, searches should include attics, basements, around foundations, crawl spaces, and behind and under stored materials. The following estimates can then be made. No sign: no rats or few present. If only a few rats are present they may have invaded only recently. Under certain conditions, rats may become quite bold in the presence of humans, and then a high percentage of the population may be visible. You can do this by feeding the rats for a while on finely ground grain (whole grains or pelleted foods may be carried off uneaten). When offered over a period of time, the ground grain will usually be accepted and eaten by rats. Consumption may gradually increase to a maximum level over the period of a week or so as the rats’ natural fear of novel foods is overcome. Divide the total amount of food eaten per day by 1/2 ounce (1. Some rats eat more than 1/2 ounce (1. If too much alternative food is available, this technique will not give an adequate estimate. They may be controlled with any pesticide registered by federal or state authorities for this purpose, or they may be controlled by use of mechanical methods such as traps. It is a relatively permanent form of rodent control that prevents damage from occurring. Rodent- proofing should be done with heavy materials that will resist rodent gnawing. These include concrete mortar, galvanized sheet metal, and heavy- gauge hardware cloth. Poor sanitation is one of the basic reasons for the continued existence of moderate to high rat populations in urban and suburban areas. In agricultural environments, proper sanitation cannot always eliminate rat populations, but it can often prevent rats from flourishing in large numbers. Warehouses, granaries and grain mills, silos, port facilities, and similar structures may provide excellent habitat for rats. Store bulk foods in rodent- proof containers or rooms. Stack sacked or boxed foods in orderly rows on pallets in a way that allows thorough inspection for evidence of rats. In such storage areas, keep stored materials away from walls. A 1. 2- inch (3. 0- cm) white band painted on the floor adjacent to the wall will aid in detecting rodent droppings and other rat sign (Fig. Sweep floors frequently to permit ready detection of fresh sign. Keep all such materials stored in metal rodent- proof containers. Feed pets only what they will eat at a single time. A proper refuse storage container is heavy- duty, rust- resistant, rat- and damage- resistant, and equipped with a tight- fitting lid. Galvanized steel trash containers in good condition are better than those made of vinyl or plastic. Racks or stands prevent corrosion or rusting of containers, reduce rat shelter under containers, and minimize the chance of containers being overturned (Fig. Large metal refuse containers (dumpsters) sometimes have drain holes to facilitate cleaning. These drain holes should be fitted with a wire mesh screen or a removable plug; otherwise, the container becomes a huge feeding station for rodents (Fig. Sanitary landfills and incinerators seldom have conditions that will allow rat populations to exist. On the other hand, open refuse dumps are often infested by Norway rats. At a properly operated sanitary landfill, garbage and rubbish are compacted and covered with earth daily. Modern incinerators completely burn refuse, and the resulting residue does not provide food for rats. Rats may enter at outlets and through manholes, catch basins, broken pipes, or drains. Since Norway rats are excellent swimmers, water traps do not impede their movement; in fact, they can travel upstream against a current. The problem of rats in sewers is usually greatest in places where sanitary sewers are interconnected with storm sewers, thus providing multiple entry points for rats.
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