How long does a rat live? What life expectancy?


The rat is a rodent whose life expectancy is quite short compared to that of other rodents. In rats, as in most animals, there is a clear difference between life expectancy in the wild and life expectancy in captivity. We take stock of everything that influences the lifespan of the rat in its different environments.

The life expectancy of the wild rat

The rat living in the wild has an included life expectancy between 2 and 3 years, whether Rattus norvegicus, sewer rat, or Rattus rattus, field rat.

All living species aim to ensure the sustainability of their populations. To do this, in the logic of natural selection, each has developed the most favorable reproductive strategy according to the environment in which it evolves. This strategy is characterized by a set of behaviors and rules that structure the reproductive events of animals and influence the way to choose the sexual partner, the way to mate, the type of fertilization, the presence of parents in the education of little …

Ecologists Robert Mac Arthur and Edward Osborne Wilson identified two main reproductive strategies in the 1960s, called K strategy and r strategy. It is an approach which makes sense but which remains controversial because it is contradicted by counter-examples. However, it highlights important elements concerning the adaptation of animals to their environment and it is valid for the rat.

The K refers to the Kapazitätsgrenze, that is to say the capacity of the environment. The species that adopt it are characterized by a long lifespan and rare and late reproduction. Considering the rat’s short lifespan, this is not the one it adopted.

The rats therefore adopted the r strategy, the r being a reference to the reproduction rate, that is, the reproduction rate. The animals concerned generally have large and fairly large litters, reproduction being favored by early sexual maturity, and experience a high juvenile mortality rate. This strategy is adopted when the environment is unstable and unpredictable.

The precocity of sexual maturity is therefore an indicator of life expectancy. In rats, the majority of individuals are sexually mature around the age of 1.5-2.5 months, the earliest being pubescent from the age of 4-5 weeks. In addition, the spleen can reproduce all year round.

The life expectancy of the domestic rat

The life expectancy of the domestic rat is higher, including between 2.5 and 5 years, 5 years remaining an exceptional situation. This relatively short lifespan is considered an asset for some owners who see it as an ideal combining pet ownership with a limited time commitment.

An animal’s reproductive strategy does not change quickly. Also, even if domestic rats are not dedicated to reproduction, the pattern that governs the management of life energy is the same as that of wild rats: rapid growth, early sexual maturity and therefore early old age.

Regarding domestic animals, it is also important to take into account the lineage to assess life expectancy. The rat is not an animal that requires a lot of selection work, unlike other rodents which are more concerned with genes whether it is to obtain a precise size or a particular coat color.

On the other hand, many pet rats come from lines bred for laboratories. The selection that was eventually made was aimed at supporting scientific research, including good breeding shoes. Genetic diversity suffers from this and the offspring carries greater weaknesses than in lines that have remained wild.

The intelligence of the rat and its survival

The way to approach animal intelligence is changing rapidly. First denied, it was then considered to be an intelligence quite distinct from that of man. Today, animal intelligence is considered to be of the same nature as human intelligence, the human being being, after all, an animal itself. And let us not lose sight of the fact that the main purpose of intelligence is to serve the survival of the species by an ever finer adaptation to the environment. The intelligence of the rat and its strengths were already recognized in old traditions. Symbol of intelligence, ambition and luck in China, mount of the Indian elephant-headed deity Ganesh, appreciated for his ingenuity and curiosity, or even the messenger of Daikokuten, deity of wealth, commerce and trade .

In rats, learning are done in fetal life, in order to maximize the chances of survival of the young. The fetus detects odorous particles, then the newborn completes this learning via breast milk. Finally, the young rat searches for food, guided by the scent markings of the adults. In adulthood, it chooses its food according to the odors that permeate the fur and breath of other members of the colony. The rat is wary of any new food source and, if necessary, will only taste a small amount to test its effects. In addition to individual behaviors, the rat has developed group strategies: a rat is thus able to come to the aid of another rat in difficulty.

Optimal living conditions for a rat

The rat was able to adapt physically to extreme living conditions, being able to swim and jump for lengths of up to 1.30 m, able to survive falls from more than 1 m in height and withstand fasting for two weeks. However, such tests place stress on the body and are only intended to provide the animal with a few extra weeks of life in order to be able to reproduce a little longer. Testing your pet’s resistance and limits is definitely not your goal. You have every interest in taking care of him. The more comfortable your rat’s daily life, the more you will increase his chances of reaching 5 years of life.

First, its well-being depends on the community. It’s an animal gregarious who will be all the better if he has at least one companion. Be careful that all are of the same sex, or that males cohabiting with females are castrated, otherwise you will quickly find yourself at the head of a large family, you now know the reasons.

The environment must be calm, free of devices liable to emit high frequency sound waves, such as a television or speakers, sufficiently ventilated but free of drafts or thermal shocks. The ideal temperature should be constant and between 20 and 24 ° C for adult rats. Light is just as essential, without exposing the rats to direct sunlight.

On the cage side, the minimum surface area for a single rat is 0.50 square meters, with a height of 40 cm. A non-toxic litter that respects the eyes and the bronchi is essential. Games are needed to prevent the rats from getting bored. They must have enough to build their nests.

Food is mainly based on cereals. It must be of high quality and adapted to the age and health of your rat: this is one of the essential factors promoting the longevity of your rat.

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