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Are there beavers in Cantabria?

Watercolour of four beavers in blue, pink and purple

Good, beaver, best

The Eurasian beaver (Castor fiber) is one of the most fascinating of Europe’s native mammals. Its dam-building behaviour makes it a “keystone species”. Beaver-constructed wetlands help to prevent soil erosion and flooding by slowing the flow of water through river catchments. By the same token, they improve water quality in rivers as well as helping to mitigate the effects of drought. They also create a diverse habitat for hundreds of other species, including amphibians, mammals, birds, insects and plants.

So beavers bring a host of benefits to an ecosystem, as a powerful natural agent of rewilding. But not everyone sees it like that: some consider them a pest because they damage trees and inundate areas of land (although these issues can be remediated with, for instance, appropriate tree guards.) As a result, some countries have tried to eradicate beavers.  

In 2020, I organised an art-action called 87 Beavers: In Memoriam which aimed to protect Scotland’s beavers from legalised slaughter. Over a hundred artists contributed artworks that were then auctioned in support of beaver conservation. (At the link, you can hear a poem of mine and see a selection of the artworks submitted to the project.)

Beavers in Spain: extinction and return

From the Middle Ages to the 19th century, beavers were hunted almost to extinction in Europe for their fur, oil and meat. By 1900, the beaver population of Eurasia had been reduced to some 1200 individuals in eight relict populations. But since then, thanks to a combination of public awareness, legal protection, and a drop in their economic value, beavers have bounced back.

In the Iberian Peninsula, beavers were driven to extinction sometime in the 19th century. Until quite recently, I assumed that this continued to be the case. Not so! In 2003, some unknown “beaver smugglers” released 18 individuals (originally from Bavaria) on the Ebro river in northern Spain, somewhere near the border between the regions of Navarra and La Rioja. (As an aside, I wonder how they know that exactly 18 beavers were released? Did the smugglers leave a note?)

Despite being protected as a native species since 1982, their reintroduction was deemed illegal, and the authorities lost no time in trying to make them extinct again. From 2008–2017, 102 beavers were trapped by regional authorities in La Rioja, 83 in Navarra and 31 in Aragon (totalling 216). But, given the huge amount of suitable beaver territory in the area—not to mention the fact that the authorities in the Basque Country, to which they had also spread, never joined in the cull—their eradication proved impossible, and in 2018 the EU ruled that the beavers were indeed protected in law.

According to a 2020 population survey,  there are now at least 1000 individuals in Spain, and they have spread at least 100km both up- and downriver along the Ebro from the introduction site, as well as to most of the tributaries.

Map of the Ebro watershed, showing (in red) the estimated range of beavers in 2018. At the time of writing, it is probable that they have already spread upriver as far as the Embalse del Ebro (the blue area at top left).

But are there beavers in Cantabria?

According to Dr Duncan Halley, lead author of the cited survey, “I would expect that beavers are now probably established as far up as the [Embalse del Ebro] and possibly on the side streams downstream from it, given usual expansion rates.” (personal communication). So in the extreme south of Cantabria, around Polientes, it’s very likely that beavers will be present within a few years, if they aren’t already.

So how soon can we hope to see beavers on the Atlantic side of the Cantabria Cordillera, in the beautiful streams and rivers near Abrazo House? Sadly, this could take a while longer. As Dr Halley adds, “It’s unlikely as yet that they are established… north of the watershed divide between the Ebro and smaller rivers running into the Bay of Biscay… Watershed divides, especially in mountains, are significant barriers to spread.” 

It looks like we’ll be waiting for some time before beavers are again seen near Abrazo House. Unless, of course, some enterprising beavers smugglers get to work. 

Images by Charlotte O’Niell, Sue Creech, and P. Poitras-Jarrett from the 87 Beavers: In Memoriam project.

Postscript

Since posting this, I’ve been informed that the source for the figure of 18 beavers introduced in 2003 is “an individual who identified himself in confidence as being in on the release”. 

Even so, the figures of 18 beavers introduced in 2003, and 216 captured between 2007 and 2018, with more than 1000 living wild at the latter date, really don’t add up—even if those 18 Bavarian beavers were Olympic champions at reproduction. Could there have been an/other release/s that we don’t know about?

I’ve also learned that beavers have now spread from the Ebro to the Duero watershed in the province of Soria—which suggests that they will be able to spread downriver and perhaps before long reappear in Portugal, one of the few European countries where they have not yet reappeared. 

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