jueves, 1 de noviembre de 2012

Reintroducing Large Carnivores to Britain: Grey Wolf, Eurasian Lynx and European Brown Bear. Wildwood (2006)

Grey wolf (Canis lupus)
The implications associated with reintroducing large carnivores into Britain are vast and complicated. Reintroduction is defined as an attempt to establish a species in an area that was once part of its historical range, but from which it has been extirpated or become extinct. The top predators that will be examined here in detail are the grey wolf (Canis lupus), Eurasian lynx (Lynx lynx) and European brown bear (Ursus arctos). Once native in Britain, these species became extinct primarily due to human activities. We therefore have an ethical and moral responsibility at least to consider reintroducing such animals, allowing them to re-take their designated place as top predators within our ecosystem.

Eurasian lynx (Lynx lynx)
The wolf, lynx and bear are all part of the Large Carnivore Initiative for Europe (LCIE). Its mission statement is ‘to maintain and restore, in coexistence with people, viable populations of large carnivores as an integral part of ecosystems and landscapes across Europe’.

International treaties, such as the Bern Convention (1979) and the Rio Convention (1992), oblige the UK to encourage the restoration of populations of native species, while the EC Habitats Directive (1992) obliges the UK to  consider the desirability of reintroducing former British natives such as the wolf, lynx and bear.

European brown bear (Ursus arctos)
These three species are keystone species; their impact on community structure is disproportionately large for their abundance. Removal or decline of such a species will have a pronounced effect on ecosystem parameters. Carnivores are indicators of ecosystem function and can serve as keystones in the top-down regulation of ecosytems. This means that top carnivores (occupying the highest trophic level) exert control on species at the next lower level (prey) and this continues down through the trophic levels. Top predators are believed to exert a regulatory role on ecosystems. Without their presence, the ecosystem becomes simplified and extinctions may occur.

Large carnivores (top predators) are capable (depending on the circumstances) of controlling not only the distribution but also the abundance of their prey. This can enhance the overall biodiversity and ecological integrity (native components are intact) of the environment.

The Grey Wolf
Scientific knowledge of the role of the wolf in ecosystems has increased greatly. In some areas there has been a marked change in public attitudes towards the wolf and this change in attitudes has influenced governments to revise and even eliminate archaic laws. In Europe, wolves are still killed even when compensation is paid and when economic incentives are provided for better damage prevention.

Distribution of wolves in Europe
Factual and educational programmes are essential for wolf survival on reintroduction to Britain. Without the full support and participation of local people no significant conservation objective can be reached. People’s opinion of the wolf remains prejudiced, and this poses a serious problem for obtaining support for the reinstatement of the species into this country.

History in Britain. The Wolf
The wolf was the last of the large carnivores to become extinct in Britain, disappearing in the 17th century. Hunting by humans was the primary cause; either due to the perceived threat to livestock or for sport. Wolves have also been hunted and trapped in countries such as Alaska and Canada for their fur. The wolf now ranges across parts of the United States, including Alaska, Idaho, Michigan, Minnesota, Montana, Wisconsin and Wyoming as well as Canada, Russia and a few eastern European countries.

Although extinct in Britain, the wolf is recovering naturally in Europe, where it is believed its population may have reached numbers of up to 18,000. It was once present on every continent of the Northern hemisphere, where it played a critical role in maintaining the ecosystems to which it belongs.

Wolves were part of the natural wild fauna of Britain from inter-glacial times, approximately 50,000 years ago. As the glaciers of the last Ice Age retreated, about 10,000-12,000 years ago, wolves again re-colonised the British Isles. Mesolithic population estimates for the wolf stand at 7,000 individuals. The wolf was common throughout Britain in Saxon times where it thrived during wars. It disappeared from southern Britain about 800 years ago, although it was locally common at the time of the Battle of Hastings, where it scavenged the dead. A fossilised wolf jaw was discovered in Kent which was dated to 1300AD, a time in which the wolf was supposedly extinct from the area. The last British wolf is reputed to have been killed in Scotland in 1743, but the species disappeared from England by 1680.

People’s negative view of wolves is often due to myths and superstitions that have been passed down through generations. Very few validated encounters of wolves attacking humans have ever been documented. When humans were hunter-gatherers the wolf was seen as a resourceful, powerful fellow-hunter. When we began tending livestock, the wolf remained a hunter, but then became a competitor. This is when the demise of the wolf began.

Ecology and Behaviour
Wolf ecology
The grey wolf was once the most widely distributed of all land mammals. Although only found in northern latitudes, wolves can live in a variety of habitats, as long as prey density is high enough to sustain a viable population. Wolves are opportunistic predators, feeding primarily on large ungulates such as deer, elk and wild boar. […]

[…] The wolf is the largest member of the dog family, with the ability to hunt and kill animals of a larger size than itself. The wolf’s physical traits and adaptations reflect its predatory instincts. […]

[…] Wolves have amazing hearing and can detect other wolves howling from 6 miles away in forests and 10 miles away across open countryside. Wolves may howl to call the pack together, as a ritual or to find and identify each other and outsiders. […]

Wolf Social Structure and Organisation […]
Ecological Niche
Ecological niche is defined as the place or function of a given organism within its ecosystem. Different organisms may compete for the same niche. The wolf’s niche is as a predator of the northern hemisphere that preys upon large mammals. Found within the same ecological niche as wolves are the felids such as the lynx, mountain lions in North America and tigers and leopards in Asia. Humans would also be found within this ecological niche.

Wolf. Impacts on large herbivores
There are numerous arguments for and against the reintroduction of large carnivores such as the wolf back into Britain. Attitudes to reintroductions of carnivores tend to be favourable among the general public, but negative amongst those seen to be adversely affected. There have been no reintroductions of large carnivores in Britain to date. […]

[…] There is a large discrepancy between support from individuals that live within the proposed reintroduction site and those that live elsewhere. It is inevitable that if wolves are released into the wild, farmers at some point will lose a proportion of their livestock to wolves. […]There has been much discussion on reintroducing the grey wolf to the Scottish highlands, where it survived the longest in Britain. The main advantage would be the control of red deer (Cervus elaphus) and roe deer (Capreolus capreolus) populations. Humans kill 75,000 red and roe deer annually in Britain, whereas wolves only kill around 20 deer a year each. […] At present deer numbers are controlled by annual culling by humans. It is impossible to allow deer populations to grow exponentially without serious implications for natural habitats. There is not enough woodland in Britain to support ever increasing deer populations.

Ciervo rojo (Cervus, canadensis), en Rannoch Moor, Escocia.
Foto de A. Thompson, 2008. Fuente.
This situation would not be sustainable as there are not enough resources to satisfy such a large number of individuals. Wolves could manage deer populations by regulating numbers and therefore grazing patterns, allowing a revival of flora and fauna in the area.

If wolves were reintroduced, farmers would not have to pay people to come onto their land to cull deer which are damaging it. Human trophy hunting involves taking the fittest specimens from a deer population. Wolves do not take individuals in this manner. Instead their instinct is to weed out the old, lame, young and sick individuals leading to smaller, fitter deer populations.

La Isla de Rhum. Fuente.
The Island of Rhum off the West coast of Scotland has been suggested as a suitable site for a pilot reintroduction scheme. Wolves have never been inhabitants of the island. Suitability stems from the overabundance of deer and no local human inhabitants, other than Nature Conservancy Council staff. A similar reintroduction occurred in 1960 onto Coronation Island in Alaska, which is of similar size and prey density. The small island size and few hiding places for deer eventually led to the demise of the wolves there. Deer populations declined significantly leaving the wolves with an insufficient diet.

Attacks on humans and livestock
Wolf attacks on humans are extremely rare; the majority of attacks occur in rabid individuals. Although wolves do not act as reservoirs for rabies, they can catch it from other species. […] Linnell et al identified four factors that are associated with wolf attacks on humans; rabies, habituation (wolves that had lost their fear of humans), provocation and highly modified environments. […]

Ganadería en las Highlands escocesas. Fuente
Wolves, like all other wildlife, have the right to exist in a wild state in viable populations, co-existing with humans as part of natural ecosystems. There are numerous ethical arguments surrounding the reintroduction of the wolf to Britain. Wolf ecotourism and jobs provided from this may aid in providing compensatory schemes for farmers who lose livestock to wolves. A vast amount of money would be paid to see animals such as the wolf in their natural environment.

At present in Britain there is no state compensation for damage caused by wildlife and it is likely that any such scheme would have to be funded by the voluntary sector. The damage to livestock has the potential to be high, due to the free ranging unsupervised stock which is found throughout the Scottish Highlands, coupled with wolf dispersal distances of up to several hundred kilometres. Wolves will take domestic livestock if wild prey is scarce, primarily sheep and goats. Although wolf predation on livestock within specific regions is low, impacts on individual farmers can be high. A return to more traditional livestock management practices, for example attending herds and guarding at night, could be considered to avoid sheep losses.

Case Study: Yellowstone National Park, USA […]

Natural Selection and Survival of the Fittest
Natural selection is the theory which states that those individuals best adapted to their environment tend to survive and produce offspring, passing on their genes to successive generations. Large predators tend to prey on sick, injured, diseased and old animals over healthy individuals. These animals would be expected to be less effective reproducers and they may also slow down the herd. Hence they are not as well adapted to their environment.

Genetic drift is the natural consequence of sexual reproduction and the random mixing of genes which this involves. A small population has a greater chance of completely losing a gene. Inbreeding depression can also be a problem, reducing the overall genetic variability, and introducing harmful and potentially lethal genes into the population.

Predators such as wolves can aid in removing congenital abnormalities or proneness to disease from the population, preventing these traits from being passed down through successive generations (survival of the fittest). […]

[…] Humans tend towards trophy hunting and therefore do not choose individuals to hunt in the same way as would a wolf. Unless professional deer stalking for herd management is undertaken, natural selection does not occur in the same way as it would were the deer being hunted by predators such as wolves. […]

Las montañas de Cuillin en las Highlands escocesas ofrecen un
entorno virgen para la reintroducción del lobo.
Why is Captive Breeding not the answer?
The outcome of reintroductions tends to be very different for captive bred carnivores, compared to wild caught ones. This is due to the numerous limitations of reintroducing animals who have never had to fend for themselves. In the wild, parents would teach their offspring how to hunt their own food as well as how to build dens, select a suitable mate, avoid humans and compete with other top predators occupying the same ecological niche. They would learn that if food reserves are low in a particular area, they must move to a new area in order to survive. If captive bred carnivores were to be reintroduced to the Scottish highlands lacking these required skills, they would find it difficult to survive for prolonged periods of time.

[…] If reintroductions were to occur, it would be more successful if young, dispersing animals were caught and translocated from other regions in Eurasia where their numbers are sustainably high. The large home ranges and low population densities of large carnivores mean that the Scottish Highlands is the only UK region with the potential to support a viable population. […]

Evolutionary theory predicts that in the absence of predators, prey species will lose their defensive behaviour. This is especially prevalent in island populations. Deer and other prey species of wolves, lynx and brown bears have evolved over the past 300 years in Britain without the presence of a top predator. Have humans suitably filled this niche, preventing such animals from becoming accustomed to a predator free environment? How will deer fare with the reintroduction of wolves and the lynx in terms of their behaviour? Will it have any affect on their breeding success? Will translocated wolves from abroad adapt to a sudden change in prey species? Reintroduction of large carnivores comes with numerous questions and issues that must be addressed prior to release.

Paul Lister logró reintroducir el alce en la reserva natural de Escocia.
Paul Lister, a multimillionaire who owns 23,000 acres of land, hopes to reintroduce wolves, lynx and bears to his Scottish estate in the highlands. He believes that the predators can be satellite tracked, allowing farmers to be compensated if their livestock is attacked. In order to have enough space for wolves and bears, he would need to acquire a further 27,000 acres from the neighbouring estates.

The biggest foreign landowner in Scotland, the late Paul van Vlissingen, also wanted to reintroduce wolves and lynx to the Scottish countryside. A three year study of his 80,000 acre Letterewe estate showed that traditional culling was having little impact on deer numbers. These results demonstrated that deer were not being properly managed and that reintroduction of large carnivores would be a more effective method of control. Both Paul Lister and Paul van Vlissingen believe that wolves and lynx would provide a basis for ecotourism in the region.

El nicho ecológico del lobo y el paisaje. Fuente: Howling for Justice
Large carnivore reintroductions are widely debatable, and those least likely to show a positive attitude are farmers, deer stalkers and inhabitants of rural areas. In a poll carried out in Switzerland, 82% of the people asked were in favour of lynx reintroduction, 64% for the wolf and 54% for the bear8. How would this compare in Britain, where suitable habitat is substantially lower? How can we expect other members of the EU to reintroduce or top-up populations of large carnivores if we ourselves make no such effort? Lynx reintroduction is the most plausible for the foreseeable future, but without the support of the public any such effort will never succeed.

Reintroducing Large Carnivores to Britain: Grey Wolf, Eurasian Lynx and European Brown Bear. Wildwood (2006) http://bit.ly/Oq0TPN wildwoodtrust.org)

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