Loading ...Where you find humans, you will find rats. We have a unique symbiotic relationship with rats. We generate waste and the eat much of it. There is a great book by Robert Sullivan about rats filled with wonderful information and anecdotes. Check it out.
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| Rattus norvegicus |
The Brown Rat (Rattus norvegicus) is one of the most well-known and common rats, and also one of the largest. Traditionally the dominant rodent of Europe and thought to have originated in northern China, the Brown Rat has spread to all continents, and is a common pest wherever humans live, particularly in urban areas and degraded environments. It has been given a number of different names, including Ship Rat, Norway Rat, Wharf Rat and Common Rat.
The Brown Rat is a true omnivore and will consume almost anything, but prefers grains, and eats up to a third of bodyweight a day. Brown Rats are known to catch fish or small rodents. They are usually active at night and are good swimmers, but poor climbers.
The fur is coarse and usually brown or dark grey, the underparts are lighter grey or brown. Length can be up to 40 cm, although 25 cm is more common, with the tail a further 15 cm or so (less than half the body length). Adult body weight averages 320 g in males and about 200 g in females, but a very large individual can reach 500 g, rats weighing over a kilogram are very rare, so stories of rats as big as cats are exaggerations. Brown Rats have acute hearing and are sensitive to ultrasound. Their average heart rate is 300-400 bpm, with a respiratory rate of around 100 per minute. Their vision is very poor and they are unable to detect colour and are blind to long-wave light.
Rats live wherever people live. It is often said that there are as many rats in cities as people, but that is an untrue urban legend. It is probable that New York City, for instance, has only 250,000 rats, not eight-million.
Rats in cities are not wanderers. They stay within 65 feet (20 meters) of their nest, and take the same trails to their food source every time they go out. They will cross an alley, but not a street.
The Brown Rat can breed throughout the year if conditions are suitable, a female producing up to eight litters a year. The gestation period is only 21-23 days and litters can number up to fourteen, although seven is common. Lifespan is up to three years, although most barely manage one—a mortality rate of 95% is estimated: predators, intraspecific conflict, and cannibalism are major causes. Brown Rats live in large hierarchical groups, either in burrows or subsurface places such as sewers and cellars. when food is in short supply, the lower-down rats are the ones to die. If a large fraction of a rat population is exterminated, the remaining rats will increase their reproductive rate, and quickly restore the old population level.
The only way to truly combat the rat problem is reduce the food supply, i.e., garbage left out on the street.
Brown Rats make excellent pets and are the focus of attention at shows of fancy rats. Brown Rats are clean, social and intelligent pets.
Brown Rats carry a number of diseases, including bubonic plague, Weil’s disease, cryptosporidiosis, haemorrhagic fever (often HFRS), Q fever and hantavirus pulmonary syndrome. They are one of the most significant mammal pests.
Brown rats in science
Selective breeding of the Brown Rat has produced the albino laboratory rat. Like mice, Brown Rat albinos are frequently subjects of medical, psychological and other biological experiments. This is because they grow quickly to sexual maturity and because they are easy to keep and to breed in captivity. Scientists have bred many strains or “lines” of rats specifically for experimentation. Generally, these lines are not transgenic, however, because the easy techniques of genetic transformation that work in mice do not work for rats. This has disadvantaged many investigators, who regard many aspects of behavior and physiology in rats as more relevant to humans and easier to observe than in mice, but who wish to trace their observations to underlying genes. As a result, many have been forced to study questions in mice that might be better pursued in rats. In October 2003, however, researchers succeeded in cloning two laboratory rats by the problematic technique of nuclear transfer. So rats may begin to see more use as genetic research subjects.
Rattus norvegicus is also the title of an album by the Stranglers.
Wikipedia Information
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