The Return of Native Nordic Fauna

A research blog exploring animal reintroduction history by Dolly Jørgensen

Category: beaver (Page 1 of 7)

Beaver history on TV

I appeared on the NRK live broadcast television program Sommeråpent on 8 August 2017. The broadcast was at Nelaug train station in Åmli kommune. I’ve has worked on the history of beavers in Norway and Sweden and Åmli holds a special place in that history because all beavers in Scandinavia originate from there. I had the chance on the program to introduce this history, as well as the historical use of beaver products.

While I was waiting for the filming to begin, I got to sit with the taxidermied beaver on a picnic bench. I had lots of kids stop by so I got to give mini-talks about beavers and their history. The kids were very interested and some even brought their parents over after hearing about the beavers to show the parents what they learned. It was great!

So here’s the video of my part on the show, which was broadcast live on NRK 1 and is now available in the video archive:

This blog of course contains much more information about the beavers of Åmli for you to read, such as a post about my visit to Næs Ironworks, a post on the Beaver Whisper Peder Jensen, and a post inspired by my first visit to Elverheim museum on castoreum.

While I was in the area, I also had a meeting with Tonje Ramse Trædal of Elverheim Museum (who was kind enough to provide the beaver and castoreum sacs for the TV appearance). We are planning a museum exhibit to mark the 100 year anniversary of the beavers being sent in 1921 from Norway to Sweden for reintroduction. I’m excited about this opportunity to reach an even bigger Norwegian audience with this research.

Unexpected media blitz

Earlier this week the press department at my university published a write-up in Swedish about this project based on an interview with me: Utrotade arters återkomst väcker känslor. The university press contact Sofia Stridsman had seen that I had an article in The Washington Post and wanted to find out more about my research. I thought it was a nice gesture, so I quickly agreed to the interview.

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The tale of two castors

When two things get the same name, it is easy to get them confused. This has happened with two medicines with similar names that have cropped up in my research: castoreum and castor oil.

The display of medicine derived from beaver at Elvarheim museum, Norway. It should be showing castoreum but instead displays castor oil. Photo by D Jørgensen.

The display of medicine derived from beaver at Elvarheim museum, Norway. It should be showing castoreum but instead displays castor oil. Photo by D Jørgensen.

As I mentioned in my last post, the Elvarheim museum in Åmli, Norway, recently opened a new beaver exhibit. I was quite impressed with the set-up. I did, however, notice an error in the display case of beaver products. The case included a beaver felt hat and the beaver gall liquor I’ve tried, both of which are made from beaver parts. It also had a shelf of medicine that was supposed to be from beaver, but the bottles on display were castor oil.

Castor oil is not made from beavers. Instead it is the oil extracted from seeds of the plant Ricinus communis, the castor oil plant. The plant is indigenous to the Mediterranean, east Africa, and India, but cultivation has spread globally. Castor oil was a common 19th century and early 20th century household remedy. The seeds contain a toxin in the shell (called ricin) which is extremely toxic, but the pressed oil is not toxic.

A sick child in bed has his castor oil medicine poured for him. France. Photomechanical print after J. Geoffroy, 1894. Credit: Wellcome Library, London. Wellcome Images http://wellcomeimages.org

A sick child in bed has his castor oil poured for him. Photomechanical print after J. Geoffroy, 1894.
Credit: Wellcome Library, London. Wellcome Images

That doesn’t mean it tastes good. You’ve probably heard nightmarish stories about children being forced to take castor oil for any number of ailments. You can certainly see the look of trepidation on the young boy’s face in a photo from France in 1894 on the right.

Wood's castor oil. From collection of the Museum of Health Care at Kingston, Artifact 1977.12.20.

Woods’ castor oil. From collection of the Museum of Health Care at Kingston, Artifact 1977.12.20.

Companies selling castor oil tried to market their oil as palatable for all. The Woods company, for example, labelled its castor oil as ‘sweet’ — it had been ‘sweetened and flavored as to disguise the taste’. The company claimed, ‘Children like it’.

In the later 1900s, companies started packaging castor oil in capsules to avoid the taste problem all together. But as the bottles on display in Åmli show, liquid is still a common form.

Needless to say, castor oil is not the same thing as castoreum.

Jars in the Riga Pharmacy Museum. Photo from D Jørgensen.

Castoreum is the secretion of the castor sac of the beaver. Beavers of both sexes have two sacs near the base of the tail. The secretion is used for marking territory. To make castoreum as a medicine, the sacs are removed, dried, and ground up. Most often the castoreum was administered in small doses as a tincture prepared with alcohol. Almost every historical apothecary collection from the 1700s to mid-1900s has a jar for castoreum. Most often these would have had castoreum from North American beavers since the beavers in Europe were extremely rare. The source of the beaver is apparent on the jar labels in several examples in the Riga Pharmacy Museum which say ‘Castor. Canadens.’

Castor sacs on display at the Elvarheim museum, Åmli. Photo by D Jørgensen.

Castor sacs on display at the Elvarheim museum, Åmli. Photo by D Jørgensen.

The Elvarheim museum has a very good example of the beaver’s castor sacs on hand in the exhibit. The sacs had previously been kept out, but they exuded such a strong smell that the museum staff decided to encase them. A small hole has been made in the case and a stick sitting in the hole touches the sac. The stick is then removed so the visitor can smell it. The castoreum scent is overwhelming and brought back memories of my earlier castoreum consumption encounter.

I encouraged the museum staff to replace the castor oil jars with old apothecary jars of castoreum in the display. Of course the castor sacs are also a wonderful supplement to the medicinal section.

The moral of the story is that the same name does not equal the same source. Castor oil and castoreum may sound similar but they are not related at all.

A historian walks through the beaver’s homeland

In historical work, we are called on to imagine ourselves in another time and another place. We try to see the world as the people (or animals) in our stories would have seen it. That’s not always an easy task. But because I was lucky enough to spend the last two days in southern Norway in the homeland of the Scandinavian beaver, it’s now a little easier for me as I write the beaver reintroduction story.

Næs Ironworks. Photo by D Jørgensen.

Yesterday I walked around the property at Næs Ironworks, which is now a museum featuring the double blast furnace, water-powered hammering shop, and templates for cast iron stoves. It was a lovely clear day for a stroll with my guide Gunnar Molden. Gunnar told me all about the Aall family who became the mill’s proprietors after Jacob Aall purchased it in 1799. Jacob was supposed to become a priest, but opted instead to travel around Europe to learn the iron working trade. When his father (who had been the one pushing him into church service) died, Jacob decided to purchase this iron mill in the Norwegian countryside. Jacob would go on to become well-known for his involvement in Norwegian independence from Denmark in 1814.

View of the pond on the Næs property. Photo by D Jørgensen.

Unlike most mill owners who continued to live in the big cities, Jacob and his wife Lovisa moved to a stately home on the Næs property. Lovisa worked to create a gentile estate, including making a romantic park in the English garden style with an artificial pond and gazebo. The pond was on some line between wild and tame, natural and artificial. Walking through the grounds let get a sense of what it would have been like to have this as my backyard, which is what it would have been for Nicolai, the oldest son of Jacob and Lovisa.

The setting matters because Nicolai Aall would go on to become the owner of the ironworks in 1844, and some time after that, he banned all hunting of beavers on Næs property. At this point, I have not found a concrete reason why he did it, but several things about his background give us hints. Growing up on this property would have certainly encouraged him to appreciate nature. Although he formally studied mineralogy at the university, he developed a passion for zoology. He collected zoological books and amassed an impressive collection of insects and birds, as well as mammals. He was also an avid hunter and employed a taxidermist on his staff. So at some point he decided that beavers were getting too rare as hunted prey and they needed protection. It is said that this protection is the only thing that kept the beaver in Norway from going extinct like the beaver in Sweden.

Along Telemarksvegen. Photo by D Jørgensen.

Along Telemarksvegen. Photo by D Jørgensen.

Today as I drove from Arendal on the coast up into the mountains to visit the Elvarheim museum in Åmli, I understood why beaver would have survived in Åmli long enough to be protected by Nicolai Aall. With mixed deciduous-coniferous forest rising up on the hills, there were small, still lakes around every bend — the perfect kind of lakes for beavers. I’m sure plenty of beavers now inhabit the waters I drove by, and I’m sure they did 100 years ago as well.

I met Tonje Ramse Trædal at the Elvarheim museum, which was founded from a hunter’s huge collection of taxidermy specimens and hunting/trapping gear. Just this June they opened a brand new beaver exhibit, which includes both fabulous displays about beaver ecosystems and some local information about the role of Åmli in populating the beavers of Europe. All of the beavers reintroduced to Sweden in the 1920s and 1930s came from this little town.

The view from P-M Jensen Tveit's farm toward Sigvald Salvesen's farm (in distance on left). The beaver pen likely stood just past the rocks in the foreground. Photo by D Jørgensen.

The view from P-M Jensen Tveit’s farm toward Sigvald Salvesen’s farm (in distance on left). The beaver pen likely stood just past the rocks in the foreground. Photo by D Jørgensen.

More specifically they went through the hands of Peder Martinius Jensen Tveit, “Bever Jensen”. So it was a treat to take a car ride with Tonje to Tveit, a few kilometers up the hill from Åmli, to see the Jensen farm. What was fascinating was that Jensen’s property, called Austigard, is adjacent to a farm named Bakkane, which was owned by Sigvald Salvesen. Sigvald was the Jensen’s main competitor in the live beaver business and from the tone of some documents I saw today, there was no love lost between them. Looking out past Jensen’s property to Salvesen’s, which would be no more than a few minutes to walk, it made the language in the documents all the more real. I could ‘hear’ the men complaining about each other.

Historians often work behind a desk. It might be in an archive, a library, or an office. It might be looking at digital files, hand written letters, or artwork. But more often than not it is divorced from the place of the history. This trip reminded me that it’s both insightful and refreshing to get out in the fresh air and see where history took place.

Beavering away in Västerbotten

Yesterday evening I went on my second beaver safari. This time I was near home–only 36 km away in Vännäs on the Vindel river. We had great luck and saw several beavers right away.

Beaver on beaver safari in Vännäs, Västerbotten country, Sweden. Photo by D Jørgensen

Beaver on beaver safari in Vännäs, Västerbotten country, Sweden. Photo by D Jørgensen

Beaver were first brought back to the county of Västerbotten very early in the reintroduction process. In 1924, the second beaver reintroduction in Sweden took place in Västerbotten on the Tärnaån further inland. But no more reintroductions happened in the area until after World War II. In the 1950s and 60s beavers were set out intentionally and more animals migrated in from the neighbouring Jämtland reintroductions.

According to an article from 1984 in the journal Från hav till fjäll, an inventory in 1961-62 counted 39 animals in Västerbotten county. By 1969, the number had grown in 63, and by 1976 it had jumped to an estimated 500. By 1983, the estimate was 5600 to 7000 animals and it’s gone up significantly since then. The beavers have been beavering away in Västerbotten.

Beaver skins on the benches on beaver safari, Vännäs, Sweden. Photo by D Jørgensen.

Beaver skins on the benches on beaver safari, Vännäs, Sweden. Photo by D Jørgensen.

Like my previous research object safari experiences, this was also a sensory tour. We started out around a fire to have a cup of newly open-fire cooked coffee while sitting on wooden benches draped with beaver skins. The skins were soft and warm. And our guide, Stefan Lindgren of By the River, explained that it is the soft underfur which has thousands of follicles per square cm that keeps the beavers fur waterproof (and soft). Stefan said that he had acquired them from a retired beaver trapper, who had originally kept them in order to make a beaver coat for his wife, but she refused to have it! So he bought the skins and now uses them on tours to allow the guests to get closer to beavers.

It was also a physical tour — we were in a rubber boat and each guest had to do some paddling along the ride. Luckily the wind was blowing upstream, so we had it pretty easy with the wind’s help. There was a stillness out on the Vindel river. You have to be quiet to not scare off the beavers, so it was just the sound of the paddles, the wind in the trees, a fish splash here and there, and the slap of a beaver tail when one dove out of sight.

Our guide Stefan with the freshly gnawed off branches dropped by the beaver. Photo by D. Jørgensen.

Our guide Stefan with the freshly gnawed off branches dropped by the beaver. Photo by D. Jørgensen.

We got to see the entrance to the beaver’s den with branches piled up as protection and the beaver trails from the water into the woodlands. At one point, we saw a beaver dragging some freshly cut willow branches through the water. Unfortunately, when the animal saw us, he/she dropped the newly acquired prize and swam away. Stefan then guided the boat over to the branches and picked them up for us to see the beaver’s handiwork. We each got a piece of beaver gnawed branch to take home.

Although beavers make significant changes to their landscape, they are in many ways invisible. Few people have ever seen a beaver, even if they live in an area well-inhabited by the critters. Like most wildlife, they do a good job of hiding themselves. This of course makes wildlife tourism like beaver safaris challenging. In this case, there are typically one or two beaver families in this particular area which is a protected little island near one side of the river downstream from a rapids. It is perfect beaver spot, so Stefan knows that most of the time, beavers will be there, but nothing is guaranteed. So I feel privileged to have been able to see beavers at work in Västerbotten.

The power of legend

I was thinking this weekend about the repetition of stories. There was some discussion on twitter about whether or not the history of the conservation movement is the same thing as the history of the environmental movement (which came up in the context of an article in the New Yorker, “Environmentalism’s racist history”). While I can sympathise with the desire to make a distinction, I think it matters more how the histories are invoked by people as foundation legends. As humans reflect on themselves, they tell stories to make sense of the world. It seems to me that there is a tendency for people today to judge the past by whether the story turned out to be ‘true’ or not, rather than on what the story did for the people of the past (or people of the present, for that matter). Yet even untrue stories may hold truths of a kind.

The legend of the beaver is a case in point. One of the most influential encyclopaedic natural history texts ever written was penned by Pliny the Elder (AD23-79) during the last two years of his life. Book VIII is dedicated to terrestrial animals, with Chapter 47 dealing with beavers and other amphibious animals. He begins with the later oft-repeated legend of the beaver’s testicles:

The beavers of the Euxine, when they are closely pressed by danger, themselves cut off the same part [the testes], as they know that it is for this that they are pursued. The substance is called castoreum by the physicians.

A stuffed beaver showing off his massive teeth at the Skogsmuseum in Lycksele, Sweden. Photo by D Jørgensen.

A stuffed beaver showing off his massive teeth at the Skogsmuseum in Lycksele, Sweden. Photo by D Jørgensen.

This legend became the standard story about beavers until the early modern period. You might just chalk up Pliny’s story to the uninformed ancient Romans, but few have thought about the context of this story in the Natural History. Immediately after the section about biting off the testicles Pliny goes on for several sentences about the beaver’s teeth and how dangerous they could be because of their bite. When read together, the story about the beaver biting off his testicles becomes a tale about the danger of the animal’s sharp teeth. The teeth, not the castoreum, are the point of the story. And for anyone who has seen beaver teeth, they can understand Pliny’s obsession with the teeth.

Pliny in fact had information contradicting the testicle-biting tale. In Book XXXII, Chapter 13, Pliny takes up the uses of castoreum within a broader discussion of medicines extracted from amphibious animals. In this chapter he writes:

Sextius, a most careful enquirer into the nature and history of medicinal substances, assures us that it is not the truth that this animal, when on the point of being taken, bites off its testes: he informs us, also, that these substances are small, tightly knit, and attached to the back-bone, and that it is impossible to remove them without taking the animal’s life.

Sextius clearly knew his castoreum. He even rightly noted that true castoreum is contained in two pouches attached by a single ligament – so anything else is false. Pliny’s use of Sextius as expert testimony reveals that Pliny was not oblivious to castoreum’s true source. In this section on medicine, Pliny may have been trying to be as accurate possible in order to have people avoid being duped by false castoreum, but in the section on animals, the key attribute of each animal was in focus.

Beaver chase. British Library, Harley MS 4751 fol. 97.  Image in public domain, provided by BL.

Beaver chase. British Library, Harley MS 4751 fol. 97. Image in public domain, provided by BL.

I’ve also read medieval bestiaries chided for their ‘silly’ stories of beaver behaviour, but these too have a purpose. In the bestiaries such as the Aberdeen Bestiary, the beaver is pursued by hunters, so he bites off his testicles and throws them to the hunter who then calls off the chase. Every image of the beaver shows some part of this story. Sometimes, there is even a beaver who has been a previous victim who lays on his back to prove to the hunter that he no longer has the precious jewels. The legend repeated over a thousand years before in Pliny was clearly still alive and kicking in the late Middle Ages.

But we have to remember that these texts were not just natural histories, but also moral histories. Immediately following the explanation of the beaver’s tactics, the application to a good Christian life is drawn:

Thus every man who heeds God’s commandment and wishes to live chastely should cut off all his vices and shameless acts, and cast them from him into the face of the devil.

So stories aren’t always what they seem. The person telling the story has a goal in mind. A legend or myth holds truth as well. If we analyse those stories we can find out what the people of the past valued—what they thought was important about their world.

Beaver Price Wars

Money may not be able to buy happiness or love, but it can buy beavers.

The first pair of beavers bought by Eric Festin in 1921 for reintroduction in Jämtland cost over 3000 Swedish kroner (SEK) for the beavers plus transport. The two pairs bought in 1925 cost 2500 SEK total — but Festin estimated it should have been 4000 SEK if extra expenses were accounted for and the exchange rate between Norwegian and Swedish kroner hadn’t been so favorable (in 1925, 75 SEK bought 100 NOK but by 1927 they had almost equal value and would stay that way until after WWII). This was still significantly cheaper than the first pair. And the price had kept falling. Festin noted that in 1934 two pairs of beavers could be bought for 800 SEK. “So one must now say that the price is reasonable,” he wrote.

P. M. Jenssen-Tveit was the main supplier of beavers from Norway to Sweden (and a host of other European countries), but he wasn’t alone in the beaver market. Because of competition, there was a question of what price should be used for exported beavers. Jenssen-Tveit asked the Agriculture Department (Landbruksdepartement) what the fixed price per pair should be in 1933. While I did not find a direct answer to the letter in the correspondence in the Norwegian National Archives, the archive documents reveal an ongoing struggle with pricing beavers.

In November 1934, Jenssen-Tveit corresponded with the consul from Latvia about beavers they wanted for reintroduction. In his letter he wrote, “Since the [Agriculture] Department has not told them a price, it is obvious that I can also deliver them for the same price per pair that other sellers have offered them for, namely 200 kr.” He noted that the box with water holder and lock would be an extra 15 kr. After writing the reply, Jenssen-Tveit sent a copy to the Agricultural Department along with a letter explaining that the Latvian consul had gotten bids from four beaver dealers who each delivered a bid for delivering the animals. One of the dealers said they could deliver the beavers for 200 kr per pair, so he was going to match that price. In this letter, we see that competition appears to have been driving the price sharply downward. Festin had written earlier in 1934 that beavers cost 400 kr per pair, so something was going on.

Back in March 1934, the animal exporter Sverre Holmboe wrote to the Agriculture Department complaining about slow beaver sales. He had sent letter to about 50 different individuals offering beavers for sale, but had gotten only two orders, “which shows how difficult it is to sell beavers when the price is high.” “However,” he continued, “I am in agreement that the price should be maintained up. The price which the Department established last year was 400 kr per pair adults.” The reason he was writing was to see if the price was supposed to be the same in 1934. If he didn’t hear anything back, he was going to assume that 400 kr per pair was the right price.

In December 1934, Jenssen-Tveit offered Eric Festin three pairs of beavers for 1000 kr, which was a reduction off the regular 400 kr per pair price but not down as far as 200 per pair. In a letter from July 1935, Holmboe noted again that the price that the Agriculture Department had set on a pair of living beavers was a minimum of 400 kr, delivered to a Norwegian port. It is not clear if Holmboe knew about the other price offers, but his letter implies that he wants to make sure that everyone is using the same “fair” price.

The 400kr price does appear to have been communicated to the beaver dealers. Jenssen-Tveit referenced the price of 400 kr per pair in August 1937, noting that “your honourable department has earlier said that one should see to it that the price for Norwegian beaver is held as high as possible, therefore I have held my price at 400 kr per pair, as was offered to the Swedish State.” When Jenssen-Tveit offered to take beavers to Latvia in 1939, he also used the 400 kr per pair price as a reference, although he made sure to point out that his travel and accommodation expenses for delivery were on top of that amount.

In the 1930s and 1940s, you could send a telegram to BeverJensson at Åmli to order beavers for export.

In the 1930s and 1940s, you could send a telegram to Beverjensson at Åmli to order beavers for export.

During the German occupation of Norway, it appears that the price sank down to the 200 kr per pair level and afterwards the same price cropped up. When a request was received by Dr. O. Olstad, the State Veterinarian, from the Agriculture Department for 4 to 6 beavers to be sent to Austria in 1947, he recommended Jensen-Tveit as the supplier. In his letter dated 1 Sept 1947, Olstad noted that Jensen-Tveit had access to a large number of animals and would charge a reasonable price. Olstad indicated that a price of around 200 kr per animal would be sufficient.

When Jenssen-Tveit got this information, he was not pleased. He countered offered a pair for 2400 kr including transportation. According to Jenssen-Tveit, his biggest concern was that during the German occupation of Norway, many beaver were killed, hunted with leg traps, sold to Germans for between 200 and 300 kroner, and used as food for fox farms. The result was a severe reduction in the beaver population. He noted that only one beaver family was still around his family’s home property of 18,500 hectares, and on a neighbouring property of 30,000 hectares there were none. “This is extremely discouraging,” he wrote in a letter dated 18 November 1948. “And I have heard that it is not much better general.” I did not see a final decision about the beavers for Austria in the file, so I’m not sure what price they finally agreed upon.

The archival record shows an ongoing struggle with setting the price for beavers. The price for a pair had swung from 3000 kr down to a low of 200 kr, stabilized at 400 kr for a decade, and then dropped back down to 200 kr during WWII. After the war, the main beaver supplier expressed serious concerns about the beaver population in Norway and wanted to raise the price.

This whole episode should remind us that 1) animals for conservation and reintroduction projects are commodities which are bought and sold, 2) somebody is making a living off of capturing the animals to be moved, and 3) everything has its price.

Beavers are back in England

England has now reintroduced its first ‘official’ wild beavers.

Video documentation of a beaver colony in Devon in southwestern England had first surfaced in January 2014. Although reports of these beavers had been made since at least 2013, the British authorities could not ignore the new proof of beavers living wild in England.

The governmental agencies became concerned that the beavers might pose a risk since the animals had been released there illegally, i.e. no one had gotten a permit for the release and gone through the veterinarian and risk assessment protocols. The early statements by the Department for Environment, Food and Rural Affairs (DEFRA) indicated that there were concerns about the genetic background of the animals (Were they from Bavaria instead of Scandinavia like the beavers in the Scotland trial? Or even from Canada?) as well as their potential to carry the Echinococcus multilocularis parasite. DEFRA’s position was that the beavers should be caught and killed.

As you can imagine, a public outcry ensued about the potential beaver cull. In January 2015, Natural England issued a permit to the Devon Wildlife Trust to conduct a 5-year reintroduction trial with the wild beavers. DWT was still required to capture the beavers and run veterinarian checks on them. Five beavers were captured in March and tests showed that (1) they are Castor fiber (rather than the North American beaver Castor canadensis) and (2) were free from Tularaemia, Echinococcus multilocularis and bovine TB. With these confirmations, the beavers meet the Natural England permit requirements. The beavers were released back into the wild on 24-25 March 2015.

The beavers will now be monitored by DWT as part of an official reintroduction program, the first for beavers in England. The Scottish Beaver Trial just ended its 5 year monitoring program in Knapdale and is still awaiting a decision about the long-term status of its beavers. Now a 5-year trial in England has begun. With both projects together, beavers are poised to make a strong return to the UK.

The interest in beaver reintroduction in the UK has come from the bottom up: local nature conservationists and organisations. The central agencies have tended to be conservative, finding ways to stick to the status quo and not attempt reintroduction. This is remarkably similar to the beaver reintroductions in Sweden in the 1920s and 30s, which were also organised and financed by people with local interests. What this shows is that even in a world dominated by technocratic and bureaucratic thinking, local conservation interests can make a difference — in this case, to the survival of the beavers on the River Otter in Devon.

On the origins of the beaver

Yesterday was International Darwin Day to mark the celebration of Charles Darwin’s birthday on February 12, 1809. In honor of ol’ Darwin, I wanted to write a bit about beaver evolution.

Most people think there is one kind of beaver globally. Actually, the beaver of Eurasia (Castor fiber) and the beaver of North America (Castor canadensis) are different species. In fact, they are very different species. Many of the species Darwin used when developing his Origins of Species theory, both domestic animals like dogs and pigeons (he was a pigeon fancier) and wild animals like his famous finches, technically could breed together in many cases even though they either can’t because of isolation or don’t because of preferences. Castor fiber and Castor canadensis, however, are even more distant as species than Darwin’s examples: they have a different number of  chromosomes (48 in the European and 40 in the North American). There is no known hybridization between the two species and it is assumed that they cannot produce viable offspring.

They did, of course, have a common ancestry. A study of beaver mitochondrial genomes showed that Castor canadensis branched off of Castor fiber about 7.5 million years ago when the animal migrated into the North American continent from Asia. It makes since that speciation would have occurred when the populations became geographically isolated à la Darwin.

Horne et al., Mitochondrial Genomes Reveal Slow Rates of Molecular Evolution and the Timing of Speciation in Beavers (Castor), One of the Largest Rodent Species. PLOS One. DOI: 10.1371/journal.pone.0014622

Timetree of rodent speciation in Horne et al., ‘Mitochondrial Genomes Reveal Slow Rates of Molecular Evolution and the Timing of Speciation in Beavers (Castor), One of the Largest Rodent Species’, PLOS One. DOI: 10.1371/journal.pone.0014622

As the figure shows there are also several recognised subspecies of the European beaver based on geographical isolation (the number varies in different publications from 5 to 8). The kind in Norway, which is the one involved in the reintroductions I study, is C. fiber fiber on the main branch.

Castor fiber specimen in the Zoology Museum of University of Aberdeen

Castor fiber specimen in the Zoology Museum of University of Aberdeen

I find it amazing–and disappointing–when I see misinformation about beaver species appearing even within the walls of natural history museums. When I visited the Zoology Museum at University of Aberdeen in Scotland last year, I noticed that the cute little Castor fiber specimen (at least it was tagged as such on its foot) had an informational card with a glaring error. It read:

FAMILY CASTORIDAE
There is one species, which is to be found in rivers and lakes in Europe, Asia and North America. The beaver is a water dwelling rodent…
BEAVER Castor fiber

Yikes! To see this museum sign claim that there is only one species of beaver globally is a huge error. And considering this museum is in Scotland where beaver reintroduction is an ongoing effort (and has been heavily), the museum really should make a point of saying that the species are not the same. I’ve noticed that the opponent discourse often references studies of C. canadensis to claim that salmon stocks will be damaged by the beavers, so a clear delineation between the two is imperative.

Giant beaver at the Field Museum, Chicago. Photo by D Jørgensen.

Giant beaver at the Field Museum, Chicago. Photo by D Jørgensen.

What’s not captured on the above genetic tree is the other, now extinct, branches of the Castoridae family. This included the awesome giant beaver of Pleistocene North America, castoroides. These beavers were probably twice as big as current C. canadensis, weighing in somewhere around 100 kg. I got to see the skeleton of castoroides at the Field Museum in Chicago. Beavers can bite if they feel threatened, so I can imagine that early humans 10,000 years ago were cautious around this guy (although I think the giant beaver is not nearly as scary as Zombeavers!).

The ancient speciation of beavers matters even in contemporary reintroduction projects. There were debates, for example, about which Castor fiber subspecies was best to choose for the Scottish reintroduction project. And in the latest decision about the free-living beavers in Devon, they will be allowed to stay if free from targeted parasites/disease and if they are European beavers (rather than C. canadensis). Finland has certainly had problems with its population of introduced North American beavers, so this is a wise precaution. George Monbiot mentions the loss of castoroides in his plea for rewilding the world, so its only a matter of time before someone gets to working on backbreeding it like the aurochs. Of course considering the objections many still make to regular beaver reintroduction, I can’t imagine many welcoming the giant beaver with open arms.

Darwin’s On the Origin of Species By Means of Natural Selection was a concerted effort to work out the mechanics of speciation. His insights have repercussions today in our understandings of what a species is and which species belong where. A beaver is not just a beaver. Time and space result in shifts in the population that split beavers into different things. Even ancient history matters for contemporary conservation.

Internal colonisation of Norway

Beavers had survived in a small pocket near Aamli, Norway, longer than any other place in northern Europe. Even though Aamli had this remnant, the rest of the country had lost all of its beaver populations, just like Sweden, Finland, and the Baltic countries. Norwegians, just like the Swedes, would start reintroducing the animals to their lost ranges in the 1920s. Although the beaver population was naturally expanding in the southern counties, reintroduction projects allowed quick starts for northern communities where beavers would not have reached for many decades. Beaver reintroductions to the north would continue through at least the 1960s.

In 1925, three years after beavers had been released in Jämtland, Sweden, six beavers were released in Sørvassdalen in the municipality of Vefsn in northern Norway. The release happened on the property of the lumber processing company Nesbruket, but it is not clear from my sources who instigated the reintroduction. All of the animals had been caught in Aamli by Peder Jensen-Tveit, the beaver whisperer. They included a pair of adults, a pair of young adults, and a pair of kits. Unfortunately, the adults didn’t stay put and in the spring 1926, the female was shot. The younger pair remained in the release area two years but afterward they and/or their offspring moved to new waters — beavers were found in several nearby streams in 1933.

Release of beavers on the Sognli Jaktklubb property, August 1926. Picture was published in Aftenposten newspaper, 9 October 1926. Now in the DigitaltMuseum.

Release of beavers on the Sognli Jaktklubb property, August 1926. Picture was published in Aftenposten newspaper, 9 October 1926. Available in the DigitaltMuseum.

In 1926, another intra-country reintroduction of beavers in Norway took place in Sør-Trøndelag. The Norwegian industrialist Christian Thams, whose family fortune was based in mining, had established a hunting club called Sognli jaktklubb in 1907. Just like the hunters involved in reintroducing beavers in northern Sweden, Thoms and the other hunting club members were interested in wildlife conservation. One pair of beavers was released on the hunting club property in 1926 and another two pairs joined them in 1929. The reintroduced population appears to have built two beaver dens by 1935, but then most of the animals moved on to other nearby water courses according to O. Olstad writing in 1937.

While these beaver reintroduction projects had a conservation element, they should also be placed within the framework of making the countryside productive. Just as muskoxen were envisioned as potential meat and wool sources, beavers were potentially economic assets. This comes across in a newspaper article from October 1926, “De energiske kolonister i avsidesliggende dalfører” (The energetic colonists in remote valleys). The forest manager interviewed in the article was not particularly pleased with the recent spread of beavers because of potential damage to hardwoods, but he admitted that there were many international requests for beavers, especially from Sweden for reintroduction, so increasing the beaver population might pay. The beaver’s potential use as a pelt animal was also mentioned several times by the journalist who wrote the article. The journalist made one additional comment worth considering closer:

Here an experiment is underway with the setting out of beavers in districts where it has not been before — one tries to establish colonies in different places with the same amount of enthusiasm as the Danish government has when they send eskimos to Scoresby Sund and other places.

Two things strike me about this statement. The first is that the journalist doesn’t really know his history, since it is known that the beaver’s range extended through all of Norway in the past. The second is that beavers are being treated like nationalist colonists. They are being put to work, if you will, on behalf of the State as a way of claiming territory and making it productive. This is a reminder that reintroduction is always tangled up with understandings of what nature is for.

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