This is a wonderful ten-minute BBC Earth summary of the life of the beaver, narrated by David Attenborough. There are two species of this rodent: the North American beaver (Castor canadensis) and the Eurasian beaver (C. fiber).
This is about the North American beaver, as European beavers are very rare, and almost went extinct. One of the best parts of the video is the footage from the first installation of infrared cameras inside the beaver lodge, showing them being active in winter (they also have some muskrat freeloaders). I also like their underwater “refrigerator” where they store their food (in winter: tree bark and cambium, the growth layer inside the bark). In general, they’re herbivores, but they store trees in winter for food by sticking them into the lake bed.
Beavers have so many diverse adaptations that they’re worth marveling at, and also wondering about their whole lifestyle got started. After all, their famous behavior is the creation of lakes and ponds by damming up streams with wood, and how the hell did that get started? And their complicated dams! (I suppose Eric Hedin, unable to figure it out, would say that beavers are proof of God.)
There must be hypothetical scenarios for the gradual evolution of beavers and their behaviors from other rodents (their closest living relatives are gophers and kangaroo rats), but I don’t have time to look it up. (A kindly reader can oblige).
13 thoughts on “The marvelous beaver”
“This is about the North American beaver, as European beavers are very rare, and almost went extinct” – the European ones are s-l-o-w-l-y making a comeback despite some being culled in the UK (bastards!): “Wild beaver numbers surge to 1,000 across Scotland’s southern Highlands” https://www.theguardian.com/uk-news/2021/aug/10/wild-beaver-numbers-surge-to-1000-across-scotlands-southern-highlands
Here is a link to a poster (from a student project) that helps explain why the beavers native to Europe and Asia have become so rare:
A great poster by Jonas Beinder!
The BBC video was great – I wonder if the saintly Sir David and his team sprung the leak in the dam deliberately so that they could film the repair?
The Eurasian beaver is also becoming more and more numerous in Germany from year to years thanks to strict nature conservation measures. It is estimated that in the meantime more than 30000 beavers live in the federal states again.
Much to my delight, I saw one of the Scottish Beavers near to Blairgowrie last month. I have also seen American Beavers in Tierra del Fuego where they were introduced.
I would put beavers with bees in the category of most interesting behaviors.
Check out Hölldobler and Wilson. “Journey to the Ants”
I use to watch the beavers work all the time on our farm in Iowa. We had the lake, a bayou and a river that made a perfect place for them to operate. Cutting down trees and building dams is their main thing. The trees were Willow, Cottonwood and Maple. The willow were the primary source of food. Most of the work is done at night.
These folks thought that dam building was the result of adaption in response to a cooling world, stemming from previous adaptations to swimming and a diet of woody plants.
From the abstract; “We propose that the behavioural complex (swimming, woodcutting, and consuming woody plants) preceded and facilitated the evolution of dam building. Dam building and food caching behaviours appear to be specializations for cold winter survival and may have evolved in response to late Neogene northern cooling.”
Seems plausible and has some evidence in support.
I have always found them fascinating and remember taking my young daughters to a pond to watch them one evening. I had binoculars, spotting scope, and camera ready to share the experience. After a minute my youngest turned to me and said “Okay dad we’ve seen the beavers, now can we go.” Teenagers can be a tough crowd.
There were a number of beaver species in the Pliocene and Pleistocene, including a giant one (about SmartCar size). Most of them were burrowers. Haven’t heard a good hypothesis for how they went from burrowing to dam building, but we can all work on coming up with one!
Saw beavers at work in Frankfurt (in a pond left over after a river regulation) in 2011, but never again after that.
In the 20th century in Germany, beavers were killed precisely because they create “riverine landscapes”, farmers didn’t like it when their fields got flooded -our part of Europe is a little crowded.
I see from Jonas Beinder’s poster that some survived in Eastern Germany (Elbe). Unknown to most, communist Eastern Germany was much better at nature conservation than Western Germany. They had white-tailed eagles, too. Part of their success was due to the lower population density, but they were also pretty good at getting the essentials of conservation right (like: No hunting).