Rodents are the most populous species among pest mammalians on the planet Earth. A case of extreme proliferation on their side may cause significant problems in the fields of public health, animal hygiene, and economy, not to mention general human disposition. In agriculture or, more specifically, in animal husbandry, and in human environments, there are two salient types of rats, the most pestiferous of rodents. These are black rats, or roof rats, or old-English rats (Mus rattus/decumanus), and grey/brown rats, or Norway rats (Empimys decumanus/norvegicus). Like mechanical “vectors,” rats carry pathogens clinging to their hairs and soles. They are prone to contaminate grain crops, domestic animals’ feeding areas, pens, sties or stables, as well as food items and other articles in silos and wholesale storage facilities with their urine, excrement and/or other bodily discharges, thus inducing or maintaining epidemics. (Just consider how few of us would think of washing the top of a can of soda before drinking from the can…) In major animal farming plants, they can cause serious harm in the actual buildings, with locations ranging from the cellar up to the attic. What they normally do is they nibble and gnaw at virtually everything, even at electric wires and insulations because of their ever-growing incisors. Despite the fact that they like to stay out of sight if possible, they still upset domestic animals, thus decreasing the optimal amount of animal products.
The majority of these pests are attracted to move to large cities by a huge singular food source: communal waste. Sewage systems, discarded food, and garbage containers provide them with a unique source for nutrition upon which the life of a whole food chain of other animals is based. Among these scavengers, rodents are the dominant species.
Nonetheless, a proper way to control them, despite “all acquiescent counter-arguments,” is possible to implement.
Biology and behavior
Norway rats: prefer to reside in areas close to or beneath the ground surface (in elaborate systems of burrows, sewage pipelines, or manure pits). They nest directly underneath the buildings, in a protected area but they oftentimes might pick an underground cavity they find, which they then expand. There are at least 2 but, on average, 3 to 4 exits connected to a rat’s nest. In big cities, rats may also live in the sewer system or they can even construct their nests under material (e.g., clutter in the home, debris, piles of wood or brick, construction lumber, stacks of hay and straw, etc.) piled up and stored for longer periods of time inside or around the buildings
Roof rats: live in the immediate environment of human beings. They like to construct their nests in the attics of houses, in a dry, warm place, especially where grain (e.g., corn) is stored, although they might nest inside a clutter of piled-up stuff as well. On board of ships and in storage facilities of ports, it is mostly this latter type of rats that would be frequent.
Norway rats: are omnivorous, and their daily intake of food on average would be between 50 and 100 grams. Due to their fast metabolism and to the speed at which their incisors grow, they have to be gnawing or eating almost all the time. They like a varied menu, and can cover a certain portion of their needs from waste. If they can afford it, they can even be choosy; they try a lot of different kinds of food, yet eat only the one that is appropriate for them. They fancy food of at least 50-70% moisture content but, if they cannot find such food sources, they might go for dry food. At such times, however, their need of liquids increases. They are not fond of putrid, fusty or moldy food, and they cannot tolerate hunger or thirst very well. For lack of proper food to eat, they might even devour their own babies or sick fellow rats. They try to feed among quiet and safe circumstances.
Roof rats: are also omnivorous but tend to be rather choosy and prefer grain produce if they can afford it. Similarly to Norway rats, their diet is largely dependent on the quality of their habitat.
Norway rats: are typically nocturnal animals, who like to hide or stay in their nests during the daytime. They are very careful when leaving their nests; they move along routinely chosen paths, always in such a fashion that one of their sides should be close to some sort of surface. They quickly scurry across open areas. They live in packs or gangs, made up of several nests or families of rats. Their behavior is typically territorial, i.e., the individual groups mark and protect their own territories. Within the groups though, each individual rat claims their own “personal” territory and, if they are not granted this, their behavior may turn rather aggressive. Norway rats are pretty fast learners as well as very cagey and suspicious animals, who normally stick to the sort of food they are used to, but they are also fairly curious. They are fast runners, good climbers and swimmers, and equally fine jumpers. Their personal hygienic instinct is considerably well-developed, so they make sure that they get rid of the stains stuck on their bodies during feeding or moving from one location to another as soon as they find safe circumstances for that. They simply lick these off their fur until it becomes completely clean.
Roof rats: are more ingenious than Norway rats but they are protected by their instincts to a lesser degree. They are extremely nimble and avid climbers but not very good swimmers. Roof rats are extraordinarily inventive and adaptive, and (just like cockroaches) they can survive almost all adverse conditions.
They are also curious and playful animals. As they are more often infested with fleas than Norway rats would be and, because they live closer to human beings, they represent a greater degree of hazard for potential epidemics.
Despite the fact that they like to stay out of sight if possible, they still upset domestic animals, thus decreasing the optimal amount of animal products.
Disproportionate proliferation of roof rats may be successfully prevented only as long as we know their behavior, feeding, and movement patterns as well as their organism and anatomy. It is exclusively with a good knowledge of all these aspects that it is possible for us to responsibly undertake an act of rodent extermination with the professional application of pesticides. For the sake of maintaining a “rat-free” environment after a successful instance of pest control, the preventive and maintenance activities have to be continued. These activities are partly of a preventive nature, partly of a curative one. While the first category consists of the regular completion of check-ups scheduled by the professional experts and the maintenance or replacement of poisonous baits, the second one comprises continuous follow-up and consultation, with the caretakers of the livestock or with the managers of the stock-farms.
The newest pesticide bait with an active anticoagulant agent normally eliminates rats and mice just after the consumption of one single dose. Its application is safe, since it contains the active agent in lower concentration than all the previously developed and used rodenticides, yet it eliminates rodents that have acquired resistance to or immunity from other pesticides. Due to its special additional ingredient, it is less hazardous to non-target animals and humans.
Some “food for thought”:
Rats reach reproductive maturity within as short a time period as three months. They have a gestation period of only three weeks, with a female roof rat producing annually 2 to 4 litters, while a female Norway rat may give birth to litters of about 10 pups between 3 and 7 times a year. As rats require an annual 15 to 20 kg of food on average, the direct amount of harm they cause can fairly easily be calculated by simple mathematics. According to estimates, as much as 1/5 of the world’s grain stock is destroyed by rats. (W.H.O. figure)
However, the proportion of crops they contaminate is three times the above amount. Rat excrement may contain up to 200,000 Salmonella bacteria, and rats defecate about 16,000 times a year. The diseases spread by rats include the contagious foot and mouth disease, swine plague, leptospirosis,etc. (W.H.O. data)