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The brown rat and the common mouse: their identity sheet

The sewer rat (Rattus norvegicus) is a rodent which belongs to the Muridae family, it came to us from Asia in the Middle Ages. It cannot be confused with a mouse since it is much stronger and stockier with its weight of 300 to 600 g and its 25 to 30 cm long without counting the non-hairy tail almost as long. On the other hand, the black rat (Rattus rattus), or attic rat or even field rat, is similar with a slightly smaller size (20 cm) but a longer tail. As is often the case, sexual dimorphism in rats is marked since males are larger than females.

If this animal bears the name brown rat or gray rat, it is directly related to the color of its coat which is gray-brown, while the black rat is darker. It does not have a clearly marked neck and its thin, pointed head extends from its body. Its black or red eyes and ears are small, but its "whiskers" or vibrissae are prominent, allowing it to compensate for its poor eyesight. Its very powerful jaw has 16 teeth including 4 incisors - very long at the bottom - which grow constantly.

Whether it is the front or rear legs of the brown rat, they have 5 lighter colored toes. They are powerful and allow him to run very fast, jump high and swim. The black rat does not swim. Contrary to popular belief, the rat is very clean and cleans itself carefully using its front paws.

The reproduction of the brown rat is very prolific since with a gestation which lasts only 3 weeks, the female can have 4 to 7 annual litters, each of 3 to 12 pups which are born blind and hairless, in the nest that she has prepared. The rat breastfeeds its young, which in turn reach sexual maturity after a maximum of a month and a half. At one year old, rats stop reproducing, but their life expectancy is only 18 months in the wild.

The brown rat is a nocturnal, gregarious animal and observes very hierarchical social codes: the dominant male has authority and his highly coveted place can give rise to violent fights between males. Members of the same group, which has an average of around fifty heads, recognize each other by smell, which is why they sniff each other and communicate with each other using ultrasound. Rats, female and male, are not loyal to just one partner. The division of tasks is well defined: the rats raise the pups, the rats fetch food for the group. Their place of life is often located close to homes where rats can make their nest with branches by digging a sort of burrow with different galleries. In cities, they appreciate the humidity of the sewers in which they nest.

Wild rat food

The rat is omnivorous and feeds on what it can find, even if it prefers animal matter (meat) to plant matter (cereals, fruits, berries). Depending on where they live, their diet will vary: cereals and various crops in the countryside, household and food waste in the city. It consumes almost 10% of its weight per day! With its powerful teeth, it will also nibble on a whole bunch of various materials such as paper, wood, metals, electrical cables. However, he will not rush towards a food that is unknown to him, he will test it to see if it suits him: this kind of attitude shows that he is not devoid of a certain form of intelligence.

The field rat really harmful?

Farmers see the rat as a pest that pillages their stored crops. That's not all, by gnawing on electrical wires, which are coated with corn starch to fuel their appetite, rats cause electrical and mechanical breakdowns in technical installations. Rats are also vectors for the spread of diseases such as leptospirosis, salmonellosis, rabies and plague, among others.

These very real nuisances must be weighed against the fact that rats make it possible to treat domestic waste by ingesting part of it, which would prevent pipes from being blocked in the sewers. Moreover, in France, although rats are classified as an invasive species, they are not part of the harmful species defined by prefectural decree in each department.

How to deal with sewer rat

The rat has its natural predators which are essentially birds of prey (barn owl, owls, buzzards, kites, etc.), snakes, mustelids (marten, skunk, ermine, etc.), foxes, cats, etc. But Man is the main predator of the rat. rat with the traps it sets and above all, chemical rodent control using products causing internal bleeding, respiratory paralysis or cardiac arrest. Be careful of these poisons which not only can your children and your pets come across but which are also likely to poison the predators of the rat which has ingested them, the principle of the food chain requires. Leave these operations to certified professionals.

As a preventative measure, to prevent rats from settling in your home, in an outbuilding, pile your trash in closed containers, do not leave food lying around that could attract them (pet kibble, storage of fruit, vegetables, etc.). leftovers of hard bread, etc.) and plug any holes you might spot that could be access routes for them; without forgetting that the presence of a cat in the area will play a repulsive role!

Before making mistakes that will arouse the suspicion of rodents, make them more attentive and cautious, consider consulting a professional in the field. All advice is good to take.