Invasive species (IX) The pig: Frankenstein’s laboratory in the mountains of Spain

The wild boar ( Sus scrofa ) is a species that has lived with man practically forever. The capture and selection of specimens based on useful characteristics for their use, such as the absence of hair or fangs, led to the appearance of pigs that are raised for food.

There are numerous varieties of pigs, but all of them still belong to the same species as the wild variant, the wild boar, and therefore can reproduce among themselves. The pig is one of these hybrids, the result of the love union between a Vietnamese pig and a wild boar.

The Vietnamese pigs would not pose a problem to the environment if they had stayed in Vietnam , but their popularity as pets and subsequent abandonment of animals led to hybridize with wild boar specimens, resulting in cerdolíes.

The Vietnamese pig as a pet

Pigs, although they may seem dirty animals because of their tendency to eat waste and take mud baths (which are intended to keep their skin free of parasites), are quite popular pets. They are docile animals with relatively high intelligence in the animal kingdom.

However, the large size that adult specimens reach does not make them recommended as pets in flats or small houses. There are some varieties of pigs that are raised for sale as pets , one of which is the Vietnamese pig.

The popularity of these animals is partly due to actor George Clooney, who had a Vietnamese pig named Max as a pet. Following Max’s appearance on the Hollywood red carpet, sales of these animals soared.

What few people knew then was that Vietnamese pigs are not small for an indefinite time, but they grow. When Max died, at the respectable age of 18 (the world record for a pig is 21 years old), he weighed almost 140 kilos and had numerous health problems stemming from his weight.

The abandonment of pets is a problem q ue is repeated year after year in our country, especially in the holiday season. One of the main reasons for this is that pets grow and their owners are unable to maintain them.

Some animals go to shelter, while others are not so lucky and are released. This is a big problem for the animals, since they are not able to adapt to the wild life and few manage to survive.

In the case of Vietnamese pigs, which are abandoned when they reach their adult size, survival in the wild is not a difficulty. Their diet allows them to feed on anything, they are big and have no predators. No more than wild boars, whose populations in Spain have exploded due to the disappearance of wolves and are only controlled by hunting.

The piglet as an invasive species

Although the Vietnamese pig and the wild boar belong to the same species, the hybridization of both varieties of pig produces a series of environmental problems.


The first , related to the growth of wild boar populations in the absence of predators, is that the female wild boar has one or two mating periods per year, while the female Vietnamese pig has one each month. This increases the number of offspring that are produced and contributes to populations growing out of control.

In the second place , the mixing between the subspecies characters results in genetic degradation of wild boars. That is to say, those characters that have been selected in a natural way to allow the wild boar to adapt to its habitat in an optimal way are lost over the generations. This can endanger the species in the long term, leading to poorly adapted hybrid populations.

Furthermore, there are behavioral differences between the wild boar and the Vietnamese pig that are passed on to hybrid offspring. On the one hand, wild boars tend to be nocturnal animals, while domestic pigs carry out their activities during the day.

As a consequence of their hybridization, piglets are irregularly active throughout 24 hours . Another difference between the two is that wild boars are elusive animals, while Vietnamese pigs are used to humans.

The consequence of these two traits is that piglets will be more active during the day and will be more likely to approach the growing areas to feed, which could increase the number of traffic accidents due to animals invading the roads .

This is already a problem today, with several fatalities per year due to wild boar runs, and could worsen if the populations of hybrids increase. Although, of course, for now this is pure theory.

Finally, an interesting difference between wild boar and hybrid specimens is that the latter have hardly any culinary use, as their meat is very fatty. For this reason, the effectiveness of hunting in eradicating wild hybrids is diminished.

Various hunter associations have requested the administrations to allow them to eliminate wild specimens of Vietnamese pigs and hybrids of pigs, easily distinguishable from wild boars.

For now hunting seems the only way to deal with this problem . However, public administrations do not see it completely clear. In the Valencian Community and Aragon, the hunting of pigs has been authorized without any type of limitations , since wild specimens represent an environmental problem and this must be tackled before the populations increase.

On the other hand, in Galicia the Xunta has rejected the hunters’ request to carry out hog hunts, as it is not classified as a species of hunting interest. On the other hand, since the Vietnamese pig is classified as a domestic species, its hunting is prohibited .

Whoever kills a specimen during a hunt is exposed to fines of up to 6,000 euros. In this case, the administrations not only do not help to solve the problem but also put obstacles.

The exotic species released can become invasive if conditions are appropriate. For this reason, people who acquire an exotic animal must be aware of the added responsibility that this implies when maintaining a pet.

In any case, whether it is an exotic species or not, the abandonment of pets is reprehensible and is prosecuted by law.

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