In the mid-20th century, Russian zoologist Nikolai Vereshchagin undertook an ambitious mission through the mountainous landscape of Azerbaijan and neighboring Armenia and Georgia. I wanted to collect as many records as possible of the animals that had disappeared from this region.
Along Azerbaijan’s Caspian Sea coast, cave paintings document an otherworldly savanna where humans hunted aurochs, gazelles, and goats. Vereshchagin toured the Caucasus on his travels and found countless signs of change and damage, including thousands of fossils and bone fragments from lost animals such as steppe mammoths and tigers.
In 1954, Vereshchagin used his findings to write an account of the evolution of the Caucasus over the course of more than 11,000 years, first amid a natural warming of the climate and then due to “chaotic human activity.”
His book, “The Mammals of the Caucasus,” was received by his Soviet superiors as a brilliant and “somewhat unusual” book, not so much an authoritative history as a collage of fragmentary evidence, linking ancient paleontological data with recent stories of great hunts. led by deposed dukes and tsars.
From a modern perspective, the book stands out for a very different reason. Its author was not limited to recording the ecological history of the region, but was changing experimentally.
Vereshchagin attempted to remake the ecosystems he documented, replacing extinct creatures on the landscape with large-scale imported animals. Their efforts left a mark on the region that can still be felt today: Azerbaijan and its neighbors have thriving, stubborn populations of invasive species.
“Acclimatization”
The decades after the 1930s were a time of bold experiments in the wilderness of the Soviet Union. Vereshchagin was part of the team that spearheaded efforts to reimagine these landscapes, providing animals that could be hunted for their meat and hides. Beyond hunting, there was also a more nebulous goal: “enriching” local ecosystems.
Experiments on the so-called “acclimatization” of animals from one country to another were prolific. In Azerbaijan they were introduced nine species of mammalsincluding short-tailed chinchillas from the Andes, raccoon dogs from China, and sika deer from Japan, as well as striped skunks, the famous odorous residents of North America.
Most of these species had difficulty gaining a foothold in Azerbaijan’s varied landscape, but one in particular thrived.
In the 1930s, Vereshchagin had personally supervised the introduction of an initial community of 213 giant South American rodents – known as nutria, nutria, swamp beaver, swamp rat or river rat– whose durable skins could be used to make hats and coat decorations.
Without realizing it, Vereshchagin and his team had proudly brought to the Caucasus an animal that, in the 21st century, would be recognized as one of the 100 worst invasive species in the world.
Today, 70 years after the publication of his book, nutria can be found in almost all wetlands in Azerbaijan, says ecological researcher Zulfu Farajli.
When Farajli leads walking tours through the Gizilagaj State Reserve, a wetland reserve bordering the Caspian Sea, visitors are always interested in this burly rodent with a long bare tail.
“They always ask, ‘What is this animal?’” Farajli says. Few expect to discover that they are native to the swamps of South America and have the ability to destroy their adopted environment.
Over the past five years, Farajli’s curiosity has evolved into a campaign seeking to drive recognition of historic introductions of exotic species and track the extent of nutria’s spread.
First of all, it wants to encourage research on the impact of nutria and answer some basic questions: how many are there in Azerbaijan? How much damage have they really caused over 90 years?
prolific rodent
Adult river rats usually measure 60 cm body and they have a half meter tail long. When they grow, they weigh between 7 and 9 kg. Although their appearance is similar to that of the capybara – the largest rodent in the world – coypu tend to have fewer admirers. Perhaps its most notable feature is its teeth: a pair of long, orange incisors that never stop growing.
In its natural habitat, the Argentine pampa and the southern half of South Americathey live in pairs or in large colonies in wetlands, lakes and riverbanks.
These rodents come out at dusk and feed voraciously on roots and marsh grasses. They are good swimmers thanks to a pair of large webbed hind legs, and can dive for up to five minutes to feed and escape predators such as the alligator, jaguar, puma, ocelot and eagle.
The path of this animal to becoming an invasive pest began with the Spanish settlers in the 18th century. The conquistadors who navigated the Río de la Plata, which divides Argentina and Uruguay, confused it with an otter and gave it the name “otter.”
The name “coypu” comes from the indigenous word mapuche used in Chile and eastern Argentina. Under Spanish rule, nutria skins began to be exported to Europe, especially for hats and neck warmers, and in the late 19th and early 20th centuries live nutria skins were sent to be raised on fur farms in Europe and North America. Rodents easily adapted to domestication.
Today, they can be found on all continents except Antarctica and Oceania.
Populations can multiply rapidly. Females usually give birth to four to five babies in a litter, and can become pregnant a few days later, allowing them to give birth two or three times a year. In many places they are free to multiply without the natural predators they face in South America, although there are signs that they have entered local food chains.
In the 1960s, nutria meat was sold in British restaurants disguised as “Argentine hare,” and in the last decade a Moscow hamburger restaurant sold it as a healthy meat (it is leaner than beef).
Half plan
Outside of Europe and North America, the spread of nutria is less documented. It is believed that its expansion is greatly underestimated and that newcomers are confused with beavers, muskrats or other rodents.
Fugitives from fur farms are common all over the world, but the story of the Caucasus is slightly different. Farajli’s research found that many nutria acclimatized to their new environment in enclosed areas, before being released into open or “semi-wild” areas where they could be retrapped.
In many areas of the former Soviet Union, acclimatization efforts responded to a long history of trapping – capturing animals in traps, often for fur and meat – adds Sandro Bertolino, an animal ecologist at the University of Turin.
When he wrote “The Mammals of the Caucasus,” Vereshchagin believed that his work was only partially completed. One of the pending tasks was the “planned extermination” of species he considered undesirable, such as wolves and jackals, which killed game and livestock.
In his opinion, nutria should be introduced much more, even in a semi-wild state in new areas such as the Lenkoran lowlands, neighboring the Gizilagaj State Reserve, on the edge of the Caspian Sea. Taken together, he saw these efforts as a way to make the environment was more suitable to support human residentsat a time of rapid economic development in the Soviet Union.
No one knows if Vereshchagin got his wish for a mass release in the Lenkoran lowlands or if the nutria got there anyway, says Elshad Askerov, director of the World Wildlife Fund (WWF) in Azerbaijan.
But in 1966, a report looked at whether there were “biotechnical measures,” such as hunting down predators, that could help the species spread, and found that many nutria were eaten by predators such as wolves. Throughout the 20th century, Soviet authorities supported the hunting of these predators.
There are no wetlands “without nutria”
Of the initial 213 nutria introduced into Azerbaijan by Vereshchagin, there could now be thousands, says Farajli – with populations extending to Armenia and Georgia.
“I don’t remember any wetland I’ve been to and haven’t seen their tracks,” he says. The total nutria population and its range in Azerbaijan are key data that would allow ecologists to understand their impact and how to respond, but there are no comprehensive estimates of either.
“Vereshchagin mentions that in five years their number increased to 400-500 animals and they only released just over 200 animals. So they doubled in five years,” says Farajli.
In Azerbaijan, the impacts of nutria are being felt in one of the hot spots of global biodiversity. The Caucasus region is situated at a “biogeographical crossroads” where the flora and fauna of Europe meet Central Asia and the Anatolian Peninsula, earning it recognition by Conservation International as one of the 25 most biologically rich and most threatened terrestrial ecosystems in the world.
Farajli realized its impact in the Gizilagaj State Reserve on the coast of the Caspian Sea.
The reserve, a Ramsar wetland (a wetland that has been designated of international importance under the Ramsar Convention on Wetlands) is a particularly important area for migration and wintering, hosting threatened species such as the white-headed duck, the pochard brown and gray teal.
An experiment led by Bertolino in central Italy showed that nutria pose an additional risk to birds by crush the eggs when they sit awkwardly to rest in the nests.
As a birdwatcher, Farajli says he wants more research into the interactions between nutria and Azerbaijan’s avifauna. “During birdwatching excursions or trips, we always see them in exactly the same habitats where we see wetland birds,” he explains.
Even without new research to understand its impact in places like this, we have the knowledge from experiments abroad, like Bertolino, to make wise decisions, Askeov and Farajli believe, including that populations should be managed in protected areas like the Reserve Gizilagaj State.
The reward problem
Few countries have managed to completely eradicate nutria. However, the United Kingdom is the “classic example” of a country that has achieved this, says Bertolino.
After being imported in the 1920s, the nutria population reached around 200,000 animals by the early 1960s. After a coordinated hunting and capture effort, the Laboratory The British Ministry of Agriculture’s Coypu Research Center caught the last wild specimen in the United Kingdom in 1989.
But such complete elimination is much more difficult in countries where numbers have grown greatly, resources are scarce, and new nutria can be reintroduced across national borders.
Instead, many countries and US states are focused on managing nutria populations to minimize their harmful effects.
In Louisiana, where millions of nutria are at home, the state pays rewards of $6 or more for each nutria tail turned in, with an average of more than 200,000 each breeding season. This method has managed to reduce the amount of healthy marshes that become open water.
In Azerbaijan, WWF’s Askerov advocates a similar approach, bringing back some of the Soviet-era bounties, but for invasive pests rather than native predators.
But these programs involve riskswarns Friederike Gethöffer, a wildlife biologist at the University of Veterinary Medicine in Hannover, Germany. Bounties often improve hunting rates, he says. “However, they are controversial, because they can also create a market and give rise to management that does not pursue eradication“he states.
According to Bertolino, the rewards attract hunters to areas of high population density of the target species, where they can shoot many in a day. This can reduce large populations, but rarely eliminates them completely from a location.
“When trapping or shooting stops being profitable, you move to another area and then another because you want to maximize your income,” he says. Instead, effective management, as in the United Kingdom, continues once the population has begun to decline.
In Azerbaijan, Farajli says the most important thing is to cancel the current fee system that forces hunters to pay if they shoot a nutria. Since 2004, Azerbaijan’s Council of Ministers has charged about $1 for each otter tail, and can also fine hunters an additional $13 for “damage to nature” in case of illegal hunting.
These fines exceed those paid for hunting some protected species listed in Azerbaijan’s Red Book of Threatened Species, Farajli notes. Azerbaijan’s government did not respond to a request for comment.
Know the history
But the first step, says Farajli, is for the local population to better understand the history of the nutria. Nine decades after its first releases, the nutria exists today in the wetlands near the Gizilagaj State Reserve. Local herders and fishermen see the animals every day and pay little attention to them, Farajli says.
“It’s not dangerous, it doesn’t affect their lives,” he says. “So they don’t really care.”
Farajli wants that to change. Some nine decades after acclimatization strategies were put in place, the animals in danger are those like the Siberian crane, whose last individual, named Omid (“hope” in Persian) was not seen in Azerbaijan last year.
On each excursion, Farajli sees this ecosystem and how important it is for rare birds. “And then one man or one group decides, ‘Let’s bring another completely new animal into the environment,’ and destroys everything, in a sense,” he says.
Although Vereshchagin and his colleagues believed they were replenishing the fauna of the Caucasus, it now seems clear that invaders like the nutria are depleting it.
This article was published on BBC Future. Click here to read the original article (in English).
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