Rewilding Portugal has confirmed the presence of a beaver in Douro International Nature Park: "It is a symbol of hope for nature."

After vanishing for five centuries, the European beaver is back in Portugal, which represents not only the return of an extinct species but also a significant step in the rewilding of the country's rivers, according to biologists of the non-profit Rewilding Portugal.

During wildfires, beaver ponds act as a refuge for riverside plants, providing them with enough moisture to resist devastation, according to Smokey the Beaver: Beaver-dammed riparian corridors stay green during wildfire throughout the western United States, Ecological Applications, Ecological Society of America (September 2, 2020).

After monitoring an area bordering Spain since 2023, scientists from Rewilding Portugal detected the presence of the herbivore in the municipality of Mogadouro, in Douro International Nature Park in mid-May, according to More than 500 years later, the beaver is back in Portugal, Rewilding Portugal (June 12).

"After two decades of population recovery in Spain and, recently, with documented signs of its approach to the Portuguese border confirmed in several monitoring actions carried out on the ground by Rewilding Portugal, unequivocal signs of its presence in national territory were finally found.

"Gnawing marks began to appear on trees and watercourse manipulation structures, typical of the activity of this species, and the timely placement of photo-trapping cameras confirmed, in video and photograph, the presence of a young adult individual, already in Portuguese territory."

In Expresso (June 12), biologist Pedro Ribeiro of Rewilding said:

"From what we've collected so far, we think it's a young adult from a family of beavers from the Tormes River, a tributary of the Douro River, on the Spanish side."

European Beavers

Europe's largest rodents can remain underwater for up to 15 minutes at a time. They have large heads; long chisel-like incisors; thick, soft brown fur; flat, hairless tails (known as scoops), and webbed feet, according to Eurasian beaver guide: how to identify, why they became extinct in the UK, and where they've been reintroduced, Discover Wildlife, BBC Wildlife Magazine. They usually measure more than a meter (3.28 feet) from head to tail, similar to a medium-sized dog, such as a Labrador.

The two species of beaver -- European or Eurasian beaver (Castor fiber) and the North American beaver (Castor canadensis) -- differ in skull and tail shape as well as fur color. Generally, Eurasian beavers are slightly larger and heavier than North American beavers, weighing up to 30 kilos (66 pounds). Also, European beavers have 48 chromosomes while North American beavers have 40.

The average lifespan of a European beaver is seven to eight years, but many have been known to live up to 25 years old, according to Eurasian beaver guide.

Male and female beavers are monogamous. Female beavers give birth to between one to four kits, or baby beavers, per year. Kits usually stay with their parents for up to two years before leaving the family unit to find a mate and set up a new family.

Predators

The main predators of European beavers are red foxes, lynx and wolves. In the past, humans were the predominant killers.

Historically, both European and North American beavers have been hunted for their fur, meat and castoreum secretion. Castoreum has been used in medicine, perfume and food flavoring. Before protections began in the 19th and 20th centuries, both species faced likely extermination.

North American Beavers Make a Comeback

The North American beaver was near extinction by 1900. The population of the Castor canadensis has rebounded to an estimated 15 million compared to the 400 million which European colonizers found in the late 1400s and early 1500s, according to Beavers: How Nature's Engineers are Making a Comeback, Natural Habitat Adventures, World Wide Fund for Nature (WWF) (February 6, 2023).

To some, the beaver is an important symbol of North America's diverse wildlife. To others, it is a pest. The bucktoothed critter has a bad reputation among some landowners because of its true behavior as well as false information. It has a tendency to chew down trees and make dams capable of stopping rushing rivers and flooding agricultural land. Yet, beavers actually create more habitats than they destroy. Also, many believe the myth that they damage valuable salmon stock in rivers. However, beavers eat only plants, not fish.

Nonetheless, there are projects of beaver relocation from private to public land, such as the Methow Project in Washington state. Also, in the state's Puget Sound, beavers are being reintroduced to enhance salmon stocks because baby salmon (alevins or fry) prefer a slow-water habitat, such as a pool or backwater, to the main current.

1890s fur trader at Fort Chipewyan, in Alberta, Canada

(Photo by C.W. Mathers and Ernest Brown)

European Beaver's Comeback

Destruction of the beaver's habitat hastened its disappearance from Portugal, according to More than 500 years later, the beaver is back in Portugal, Rewilding Portugal (June 12).

Today, beavers are back in Europe.

According to Rewilding Europe's European Wildlife Comeback report (2022), there were about 1.2 million beavers in Europe compared to 60 in Italy in 2023, reported Living With Beavers: Europe's largest rodent makes an Italian comeback, Rewilding Europe (July 31, 2023) .

In 2016, the European or Eurasian beaver was listed as a species of least concern by the International Union for Conservation of Nature (IUCN) Red List of mammals, which is an inventory of the global conservation status and extinction risk of biological species, according to Castor Fiber: Eurasian Beaver, IUCN Red List of Threatened Species (2021).

"A series of management measures and reintroductions have enabled the beaver to return to much of its former range. . . . Free-living populations of beavers are now established or establishing in most regions of their former European range, the main exceptions to date being Portugal, Italy, the south Balkans and Great Britain."

Nine years later, Portugal may well be on its way.

Two years ago, Expresso (June 4, 2023) reported that the beaver was about 150 meters (492 feet) from the Portuguese border in the Arribes del Duero Natural Park.

Spanish researchers noted that the beaver's reappearance was associated with "an unauthorized translocation". At the time, the animal's population in Spain was estimated to be about 600 to 700, reported Expresso.

Such unofficial releases also have taken place in central and southern Italy, according to Living with beavers: Europe's largest rodent makes an Italian comeback, Rewilding Europe (July 31, 2023). The International Union for the Conservation of Nature (IUCN) strongly discourages reintroductions carried out without feasibility studies and genetic analysis of released individuals because of the potential damage to native ecosystems. Therefore, the global conservation organization has developed guidelines for reintroductions.

When the beaver was confirmed near the Portuguese border two years ago, Rewilding Portugal said that it only would be a matter of time before the beaver returned to Portugal.

"It is great enthusiasm that we confirm its return," said Pedro Prata, team leader at Rewilding Portugal, in More than 500 years later, the beaver is back in Portugal. "The beaver is a natural ally in restoring the health of our rivers and wetlands and has a fundamental role to play in our river ecosystems."

"Natural Defense Lines Against Forest Fires"

Aside from humans, few other animals appear to do more to shape their environments' landscape and biodiversity than beavers. By building dams, these ecosystem engineers change the paths of rivers, create wetlands, marshes and areas of still water, which are habitats for a huge variety of species: amphibians, aquatic insects, water birds, fish and small mammals. These wetlands also act as natural filters, retaining sediments and pollutants as well as reducing the speed of surface runoff, which mitigates the effects of flooding and erosion.

"We are talking about a species that provides ecological services that no modern equipment can replicate with the same efficiency and scale, without costs and without bureaucracy. The beaver improves water quality, creates refuges for other species and helps us combat phenomena such as drought and fires," said Pedro Prata.

"There is growing evidence that habitats created by beavers act as natural defense lines against forest fires, by maintaining permanently wet areas which break the advance of fire and provide shelter for numerous species during the most critical periods."

In the study, Smokey the Beaver: Beaver-dammed riparian corridors stay green during wildfire throughout the western United States, Ecological Applications, Ecological Society of America (September 2, 2020), satellite data of the year before and the year after a major wildfire in the five states of California, Colorado, Idaho, Oregon and Wyoming showed that vegetation in beaver-dammed riparian areas stayed green during wildfire.

The study also showed that creek sections which did not have beaver were, on average, more than three times as affected by fire compared to those with beaver.

"When a fire does ignite, our data suggest that the beaver-dammed riparian areas have stored water that kept plants hydrated enough to make it energetically unfavorable to burn. It's similar to trying to start a fire with a pile of wet leaves versus with dry kindling."

Pedro Prata of Rewilding Portugal said: "The return of the beaver to Portugal is a symbol of hope and change. It shows that if we give nature space and time, it will respond. It is now up to us to ensure that this return is welcomed and protected."

A beaver-gnawed tree on the Peene River, Anklam, Germany-- Beavers are known for their prominent, strong incisors, which they use to gnaw the trunks of trees, such as aspen, willow and yew. Iron impregnates the incisors' enamel, giving their teeth an orange color and strengthening them. The teeth protrude from their lips to allow beavers to chew underwater. Even strong teeth get worn down by chewing through trees. However, beaver teeth never stop growing, according to Discover Wildlife, BBC Wildlife Magazine. (Photo by Solvin Zanid/Rewilding Europe)

Beavers, an Invasive Species in Argentina

There is an instance where beavers, which have been introduced to non-native habits, have brought destruction.

Wildlife managers introduced just 20 North American beavers (Castor canadensis) from Canada to Tierra del Fuego and other parts of Patagonia, Argentina, in 1946, to bolster the fur trading industry, according to Wild Cam: How Feasible Is Beaver Eradication in Argentina, The Wildlife Society (April 28).

For the first three decades, there was a ban on hunting beavers. The invasive species thrived, while it devastated the ecosystem, whose native species were unable to adapt to the beavers' handiwork.

Trees, for example, died after drowning. In its native ecosystem, when a beaver fells a tree, it doesn't kill it. It simply turns it from an upright, vertical structure into a horizontal one, which continues to grow and provides refuge for many other species, according to Why should tree lovers care about beavers? In conversation with Beaver Trust, The Tree Council (United Kingdom) (August 25, 2020.

In 2014, the Argentine government started an eradication pilot program.

European Response to Beavers' Return

In Europe, there have been conflicting proposals with regard to the return of the native Castor fiber, largely due to the origin of the return.

For example, the paper, The strange case of beaver return in Italy: origins and management, Hystrix, The Italian Journal of Mammology (February 2023), deduced that multiple unlawful releases probably led to the return of the beaver. It recommended removal of these animals.

Other European countries have shown that coexistence is possible and desirable through mitigation measures, information, technical support and dialogue with communities, according to Rewilding, in More than 500 years later, the beaver is back in Portugal.

"In Sweden, for example, beavers were reintroduced in the last century and financial compensation programs were set up for farmers and forest owners affected by flooding caused by dams.

"In Germany, Beaver Managers have emerged to mediate conflicts between beavers and human activities, installing water level control devices (e.g. pipes in dikes to regulate the height of the water without destroying the dams) and promoting natural engineering solutions, such as protective barriers around agricultural fields and valuable trees, practices also adopted in Switzerland.

"In France, several environmental education and awareness campaigns have been carried out on the importance of beavers, and several illustrated guides have been produced on the benefits of beavers and methods for dealing with potential problems."

Brown Bear Sighting, Disappearance

Nuno Banza, president of the Institute for Nature Conservation and Forests (ICNF) said that the government body "will evaluate the information Rewilding sent this Tuesday, request additional information, and compare it with the ICNF's own monitoring", reported Expresso (June 12).

In May 2019, the Institute for Nature Conservation and Forests (ICNF) confirmed the presence of a brown bear in Portugal, the last recorded bear being shot in the Gerês Mountains in 1843, reported Expresso (May 8, 2019). The bear was sighted in Montesinho Nature Park, in the municipality of Bragança, near the Spanish border. However, since then there have been no more sightings, reported Expresso (June 12).

Again, as with the brown bear, there has been the confirmation of only one individual of the European beaver species.

Planning Coexistence

However, Rewilding Portugal, which was founded in 2019 in Guarda, is taking a proactive rather than a reactive approach.

According to More than 500 years later, the beaver is back in Portugal:

"Monitoring has continued, the beaver is officially back, and we still have time to support its return in a planned manner and in harmony with what already exists. Rewilding Portugal is once again open to participating in this process.

"For this same reason, the second congress dedicated to rewilding, which will take place in October/November in the Douro region, will have a large section dedicated to the return of the beaver and planning coexistence."