Invasive species (VI): the rump: a very (very) controversial species
The Rui, Barbary ram or Atlas mouflon ( Ammotragus lervia ), is a bovid related to goats ( Caprinae subfamily ) whose natural habitat is the mountainous areas of North Africa, in the Sahara and the Maghreb. It is believed that in the past the species had a much greater distribution than today, due to the impact that hunting and other human activities have had on it.
Its only predator in the wild is the leopard , whose populations in North Africa are decimated, and occasionally the young can be attacked by a caracal , a medium-sized feline similar to a lynx but related to the serval.
The ruff has an appearance similar to the mouflon. Both males and females have horns, larger and curved back in the case of males. These horns grow throughout the life of the animal. The distinctive feature of the species is the enormous plume that hangs from its neck and front legs, which is non-existent in mouflon or goats.
It is a kind of mountain that does well in arid and semi-desert areas. Animals are most active at dawn and dusk, due to an adaptation to avoid being exposed to the excessive heat of the Sahara during the day. Their diet is based on herbs, lichens and browsing shrubs and small trees.
Introduction of the ruffle in Spain
The ruffle was introduced in Spain in the 1970s for hunting purposes. 9 males and 18 females from different zoos were released in the Sierra Espuña Natural Park , in Murcia.
The absence of predators and the high birth rate of this species caused it to spread to neighboring areas in a few years, such as the Sierra del Cambrón and the Sierra del Gigante. At present it is also present in the Valencian Community and Andalusia. Some sources cite a population growth from 30 individuals released to more than 2,000 in just two decades.
In addition, the species was introduced to the island of La Palma, where it soon reached the Caldera de Taburiente National Park. While the populations of Murcia were controlled by hunting, this is prohibited in the Natural Park, so the number of individuals increased considerably in a short time.
This endangered the native island flora, to such an extent that the island council took action on the matter and authorized the elimination of part of the population. However, the steepness of the terrain made this task very difficult.
Rui, invasive species, or naturalized exotic?
In 2013, the ruff was included in the Spanish catalog of invasive alien species. The species on this list pose a serious threat to biodiversity and the conservation of the environment, so they cannot be used or exploited for economic purposes.
To avoid a negative impact on the economy, the government “pardoned” several species on that list, such as rainbow trout, red crab, American mink, and rump. But in 2016, a Supreme Court ruling reaffirmed the invasive nature of these species and with this their economic exploitation was definitively prohibited .
Different hunting associations, such as the Artemisan Foundation, have raised their voices against this ruling, arguing that hunting ruin generates significant income in the communities where the species is present. Of course, this does not seem like a sufficient argument to hunt any species, much less to introduce an exotic species in our country with the sole purpose of hunting it.
Another argument that has been used is that the indiscriminate killing of specimens of a species is unethical, ignoring the fact that the hunting associations intended to control the rui populations by hunting indefinitely, due to the absence of predators of this species in Spain.
In spite of everything, hunting associations have not been the only ones to voice their voices against the Supreme Court ruling. One of the main problems with invasive species is that they competitively displace native species.
That is, when competing for food or territory, invasive species are more effective and therefore native populations decrease until they disappear. This is what happens to the red crayfish or the American mink when it comes to competing with their native relatives.
With this in mind, it has not been shown that the ruff is capable of displacing any species native to Spain, but rather that it is limited to occupying mountainous areas too arid to allow the survival of other species. The opposite effect seems to occur, with the ibex displacing the rump when it is in the habitat of the native species.
Another interesting fact, as pointed out by those who have studied the behavior of the ruff in our country, is that it does not uproot the vegetation on which it feeds, making the land arid, but rather limits itself to nibbling the leaves, leaving the plants alive. In arid environments, this would help prevent fires and promote plant biodiversity.
Therefore, despite the fact that the Supreme Court ruling is final and all species classified as invasive must be treated as such throughout the Spanish territory, what some scientists demand is that the classification of the ruff as an invasive species be reviewed, before the non-existence of negative impacts of the species in our country.
However, the principle of prevention suggests an action in the opposite direction and the total eradication of the blight in our country as it has no natural enemies and there is a risk that it will spread uncontrollably to new areas. For now, despite the Supreme Court ruling, it does not appear that existing populations in mountainous areas with difficult access will be eradicated in the short term.