Guest Essay by Kip Hansen — 16 November 2023
Once in a while one comes across a really good bit of research – research that tells us something we didn’t already know. Cara Giaimo, writing at the New York Times, reports clearly in a piece titled “Leave It to Beavers? Not if You’re a Wolf.” It is about a paper published in the Proceedings of the Royal Society B – Biological Sciences, 8 November 2023, Volume 290 Issue 2010. The paper is titled: “Wolves alter the trajectory of forests by shaping the central place foraging behaviour of an ecosystem engineer”.
The title uses a catchy phrase — “an ecosystem engineer” — in place of the simpler and more direct “beavers”. However, it isn’t used just as click-bait. The authors, from the University of Minnesota and the University of Manitoba (Canada), are studying something a little more complicated than wolves and beavers — they study how central place foragers and prolific ecosystem engineers (beavers) change the nature of their immediate environments differently under predation by wolves.
From the Abstract:
“Wolves (Canis lupus) and beavers co-occur across most boreal ecosystems in North America and Eurasia. Wolves are the primary predator of beavers wherever the two species co-occur, and beavers are important seasonal prey for wolves. Although wolves are primarily cursorial predators, they often use ambush strategies to hunt and kill beavers. Still, a substantial proportion of predation is the result of opportunistic encounters]. Because wolves are apex predators and beavers are ecosystem engineers, wolf predation on beavers can have outsized ecological effects. For example, by killing dispersing beavers, wolves alter the creation and recolonization of wetlands, and in turn, alter all of the ecological effects associated with beaver-created wetlands. Logically, wolf predation could also have indirect ecological effects by shaping beaver foraging behaviour.”
“Central place foragers” (CPF) – a term used in the title of the paper — are animals that forage for food from a central place, in a big circle around a central point. Many honeybees are CPFs – collecting nectar from flowers in a certain area surrounding their hive. Beavers cut trees and drag them back to their pond that contains/surrounds their lodge.
Thomas D. Gable and his co-authors study the predation of beavers by wolves and the effect that that predation (or the beaver’s fear of predation) on the forest environment in the immediate area of a beaver lodge.
“We searched 27 741 clusters of GPS locations from 51 wolves during 2015–2022. In doing so, we identified 543 wolf-killed beavers and 1909 instances where wolves attempted to ambush beavers. Of the 543 wolf-killed beavers, 135 (25%) were killed on feeding trails and we recorded the length of feeding trails at 128 of these kills. Of the 1909 ambushing attempts, 949 (50%) were at feeding trails. All other kills and ambush attempts occurred at other beaver features including beaver dams, scent-mounds, feeding canals and lodges.”
As you would suspect, the further a beaver travels from his lodge and home water, along established paths created by the dragging of this food supply back to the lake/pond, to forage food from a limited supply of appropriate trees, the more dangerous it becomes for the beaver in the presence of wolves. If the pond is close, the beaver can dash back into the protection of the water upon becoming aware of a wolf in the area. But at further distances, the researchers found that wolves tend to more successfully ambush the beaver along the path that leads back to safety.
Of particular interest is the elimination of beaver forage trees near the ponds. It appears that the beaver have eaten themselves out of house and home in panel (a). They dare not travel further than the white line in (c) and (d) for either fear of, or actual, predation by the wolves. The more wolves, the smaller the circle. You can see that the beavers do not cut the conifers (pines, fir, spruce). But they cut nearly everything else, almost denuding the shores of their ponds. That then gives conifers a chance to begin or continue to grow and eventually take over the shores of these current or ex-beaver ponds.
In (b), you can see stands of aspens, a preferred food for beavers, at the edge of the are they have already cleared. The distance to those aspens is between 20 and 30 meters – possibly representing the furthest distance a beaver feels safe to travel from the safety of that pond.
We already know that beavers create meadows by flooding areas. The trees in the new pond die (drown). The new pond then, over time, silts up, and eventually become a new meadow. Trees and bushes that are not shade-dependent then begin to sprout up in the meadow, and on it goes.
So, here we have the larger environmental situation: The beavers create ponds by flooding low lying areas through the damming of streams. Then the beavers begin harvesting preferred trees for food…but only up to a distance that is safe enough to limit the predation by wolves. After some time, the shores of the beaver pond become denuded of forage trees but not conifers which allows additional conifers to take root and grow in a “fairy ring” circling the pond. At some point, the pond is no longer tenable for the beavers – they have consumed all the appropriate trees within safe foraging distance and the beavers must move on to another area where forage is available. There they build dams, flood the area, and begin to forage the shores of the new pond and on it goes.
I have emailed the corresponding author asking if they see that last effect—multiple conifer-ringed abandoned beaver ponds—along streams and ponds.
I’ll let you know what he says.
# # # # #
Author’s Comment:
This little study was not so little, and depended on data kept by the Voyagers National Park rangers on beaver pond locations—17 years worth. And seven years of GPS collar location tracks for wolves in the area, follow up by physical inspections of suspected ambush sites. Add to that trail cams near beaver paths for two further years. Terrific field work.
Interesting to me is the data on attempted kills vs successful kills. The wolf seems to have gotten the beaver only about 1/5th of the time.
I like beavers – but then, they haven’t flooded my land. My wife visits the beavers every few days, counts pups, etc. from a convenient railroad bridge that spans their pond. But not everyone appreciates those busy little buggers. I have a neighbor that had beavers flood 5 acres of high value property – the state authorities forbade him to remove the dam or the beavers.
The featured image is by Derek Otway via unsplash.
Let’s hear your beaver Wows and Woes in comments.
Thanks for reading.
# # # # #
Both wolves and beavers are beasties that are preferably somewhere else, not on territory people are trying to use.
Tom ==> A common sentiment. That said, beavers are usually good for the ecology of any area they are found, bringing changes that increase “biodiversity”, and create new conditions, particularly with the water cycle.
There is always some disagreement about top-tier predators. Many of us like to think of White Fang and the wolves of Alaska but get nervous when wolves are introduced in the areas where we live and raise our kids.
Beavers can be good in an appropriate location, but incredibly destructive in others. In an attempt to reintroduce beavers into areas of the UK, some misguided activists ignored all the advice they were given and released them into obviously unsuitable areas. They have compromised flood defences and other water control measures, not just increasing the risk of extensive shallow flooding but dangerous flooding. I’ve got a lot of affection for beavers but none whatsoever for ignorant fools who think they know better.
Interesting. I didn’t know that. Which locations was this attempted at?
Its become a sort of trophy species for eco-rewilding movement.
I think it was a couple of areas in Scotland. Some areas have been fine, others they’ve caused problems for Salmon fisheries resulting in huge losses there and then there were incidents where the beavers had burrowed into flood defence embankments, compromising their structure, potentially initiating a collapse, although I haven’t heard that things had got that bad. The message appears to be, from Poland, Lithuania and Latvia as well, that rewilding might be a good thing but only if it’s done in appropriate areas and only if the populations are controlled after they’ve established themselves. Simply letting them get on with it might be the activists dream but it don’t work in the real world.
And then the state goes after the private land owner in some cases.
Reintroductions of species- if they don’t happen on their own- really should be handled by wildlife experts. We have some good ones here in Wokeachusetts- not that I like to give any positive reviews of my state government, but this agency does good work. However, the state makes it very difficult to remove troublesome beavers. You’d better have a terrific justification. On a timber sale I was managing 30 years ago- the property had a string of beaver dams. The logger said that if one of the dams was removed, he’d have better access to some of the marked timber. I said no- you’ll have to go around. So one day when I didn’t check up- he knocked the dam out with his log skidder. I really didn’t mind as long as we didn’t get nailed by the state or local conservation commission- and that didn’t happen. The beavers had already left that pond. If we got caught- it would be easy to blame the logger since the contract specifically said to stay clear of the dams.
Joseph Zorzin ==> Pretty typical story — competing interests of conservationists, land owners, loggers, farmers, etc. Thanks for sharing
Kip, speaking of competing interests, alarmists are pushing to reduce anthro’ methane emissions. Yet, ‘beaver-huggers’ are also pushing to reintroduce beaver, which will increase wetlands, which will increase methane emissions. Personally, I think that restocking beaver should only be allowed if wolves are simultaneously reintroduced to control the beaver population.
It is like wildlife in Africa, where some poor farmer needs some good reason to tolerate potential crop destruction. Getting rights to paid hunts, as in payment from the hunters, and the rights to the meat, are the only thing I have ever heard of that worked.
Bambi environmentalists despise people.
Tom ==> The problem arises especially when the “farmer” is really a sustainence gardener, whose family depends on the food produced on rather small plot of land. One elephant coming in in the night to feed threatens the very lives of the farmer’s family.
Heck, here in central Indiana, i walk out and check around when I put my dogs out to do their business at night because of coyotes! If I lived in Wolf country I would go with my Glock 21. Coyotes wiped out my neighbors chicken coop.
And the problem needn’t be as large as a coyote. One of my earliest memories as a young boy, probably about 6 or 7 years of age, was driving out from northern Illinois to visit my paternal grandmother in Nebraska. Arriving after midnight, one of the first things my grandmother asked of my father was if he had brought his pistol because there was a skunk under the hen house. So, my father had to dispatch it before we could all go to bed.
Fully agree Kip. Across most of Canada we co-exist with beavers and wolves on the landscape, it’s not that difficult, at least in a forested landscape. I appreciate livestock and ranching can be a different story and perhaps the context Tom Halla is coming from. Beavers will cause some problems here with backing up water near roads and water crossing structures at times, but that’s just a reality you have to accept. Local trappers are usually pretty good at keeping the population stable but modest, and quick to remove “nuisance” beavers when they cause issues. Wolves are seldom seen, but definitely there, just too smart to allow a human to get close.
I live close to the center of a metro are with a population of 2.2 million. I am across the road from a park that is on the banks of a creek. I have seen beavers in the park. I have also seen them cross the freeway that crosses the stream.
Anecdotally not scientifically,
Our family farm, which has been in the family for 100 years now, has a nearby creek and geofeature we named “the Butte”. My grandfather talked about the small forest there. My father was unhappy with the beavers gnawing down the trees on “the Butte” which the creek passed alongside. The trees there were actually the only natural tall tree growth near our prairie farm. By my early youth in the 1960’s “The Butte” had no trees left, only pointy stumps….by my teenage years in the 70’s, the beaver dams were washed out by floods. Now some 50 years later, “the Butte” is again tree covered, probably awaiting discovery by an exploring beaver….Life goes on, seemly in about 60 year cycles….
DMac ==> Interesting story. That is the root of y question about beavers eating themselves out of house and home.
Kip, surely you aren’t suggesting that humans aren’t the only creature that defiles the land and makes significant land-use changes? 🙂
You will have to live a while longer to determine if your ‘seemly’ is fact… do it!
BTW I would be cool with wolves if they would cull the deer that destroy our flowers.
Deer are cute, but very destructive. I used to live in Cottonwood Shores, Texas, which was overrun with deer. The only bushes they would not eat were oleanders.
What- not enough good old boy deer hunters in Texas? Shocking.
It is semi-rural residential.
There’s plenty down there. In fact in Texas companies buy “deer leases” on privately owned property to bring their clients in to enjoy hunts. Their white tails don’t get nearly a big as we have up here in the midwest but they got plenty of them.
One night driving a big truck I counted 100 of them feeding on the grass along the side US 90 in west Texas. There were more than that but I got tired of counting after 100. I’ll tell you that gets a drivers attention, but not one ran out in front of me. They just looked at me as I went by.
We live in the hilly boonies… two fairly large gardens… fenced… so we enjoy the deer (particularly watching the youngsters advance through the Seasons)… tho’ they do like the groundcover close around the house. Net Positive (for us).
Just understand that wolves don’t just attack and eat deer…
Then find me something that does.
Deer hunters are the only thing I can think of!
Chronic wasting disease
Just reported in Yellowstone.
Here in the UK there is a problem with deer, again not being properly managed, where they are overpopulating an area and destroying trees there. Someone has suggested, as a serious answer, reintroducing the European Lynx which I believe is a bit smaller and shyer than the North American one, is a predator of deer and would manage and control the numbers fairly well.
That’s what the reintroduction of wolves to Yellowstone has done, the pressure on the elk that had damaged the ecosystem has allowed the pressure on other species to change. Beavers have returned which has allowed the water table to change and other beneficial changes.
https://www.yellowstonepark.com/things-to-do/wildlife/wolf-reintroduction-changes-ecosystem/
And that is why hunters are important in areas where the natural high end predators have been eliminated. Back about 15 years ago, Indiana DNR did a “deer census”. They found there were more white tails than were reported in the first “deer census” in the 1890s. about 10 years ago, the state asked for hunters to cull the deer populations down in Brown and Morgan counties. The deer were starving and causing considerable damage to the flora in the state parks. The meat was donated to the food banks. PETA showed up and tried to make a stink about it. IDIOTS!
Common Sense solutions do not seem to be their bailiwick.
Like the grizzly bears that the Federal government wants to put back in the Northern Cascade range (Washington and Oregon, USA). There is a reason we hunted them out. They see us as slow and tasty.
ONLY if humans interfere with their ‘natural’ food sources (so I have read).
Have a friend who lived in Chantilly Virginia, a burb of DC. He lived in a built out, for 20 years, community of large houses on 1/2 acre lots. His house backed up to a small stream about 15 feet below his basement level. The nearest “forest” area was several miles away. A beaver began to build a dam behind his house. I noticed it when visiting, he mentioned that he saw the wood there but thought a recent storm had washed it in. When we saw the tracks and teeth marks, he knew what was up.
Somehow the beaver died.
Somehow.
Better not to ask permission to remove a beaver dam on your property. Best to pack it with Tannerite and give your teenage daughter target practice from a safe distance.
Milo ==> And such solution have been used by many — in NY State, the is New York State’s official mammal. There is allowance for the removal of Nuisance Beaver. But the beaver rules get complicated by freshwater protection rules…
There are hunting and trapping rules that vary by State in the USA.
I don’t think you’re supposed to give the game away like that! First rule of nuisance beaver club.
Used to have a dog that was great at destroying dams. Pick up a small pebble and flip it at the dam. He would then “chase” the pebble and grab the nearest stick from where he thought it landed, rinse and repeat. It would not take long to have a pile of sticks at your feet with a crumbling/draining dam without me actually touching it. Of course beavers being so busy this was an ongoing project but the dog loved it! He was a border collie mix so his passion to retrieve sticks was equal to the beavers desire to build dams.
DarrinB ==> Great story. Dog vs.Beaver
Thanks for the post.
When I first moved to the current location, beavers were on the creek that flows by the house (about 40 yards). Wolves and cougars were not around.
The creek is connected to, and part of, a long in-play irrigation system. Downstream irrigators, Department of Ecology, lawyers, and Fish & Game all have a say in activities affecting the creeks.
When the beavers were here, they would go as far as 150 yards across open horse pasture to obtain small trees, about 5 or 6 inches diameter. Closer to the stream, they cut much larger stuff.
A few local beavers were trapped and relocated because the dams caused water to flow across land with no water rights. Then, a massive melt one spring cleaned the creek of the dams and left piles of rock rubble.
There are now some wolves in the region north of me and more cougars (hunting with dogs was prohibited about 25 years ago).
Now there are no beavers and fewer coyotes.
A neat story.
Coz all the way through the article, we learn that beavers make a perfect proxy for ‘human settled civilisations – the ‘central point feeders‘
Then, a massive melt one spring cleaned the creek of the dams and left piles of rock rubble.
And that describes Soil Erosion to a T.
Maybe it wasn’t an especially big melt, but that there were sooo many beavers dams on the creek, that when one failed high upstream, it triggered a cascading domino-effect all the way down the stream
Just like ‘Derna’ in fact….
NB: The longest lasting human civilisations are, what’s left of, The Nomads
And ‘settled civilisation’ is Socialist innovation/requirement.
You can not ‘tax’ Nomads. If they don’t like being sucked dry by parasites, they just ‘up and leave‘
But it takes ‘guts’, self-confidence, strength of character and a good memory of accumulated knowledge to do that.
Consider: Does anyone really imagine/think that there is sufficient of the right sort of ‘knowledge’ out on the interweb to allow any modest group of individuals to ‘just up and leave‘
To become Nomads
There’s one more thing your kindergarten teacher lied about.
Might there be anything else the interweb is not telling us?
“just up and leave”…. and where would they go, and survive, without their TV and Cellphone (which would track them anyway).
John ==> The old old story of predator and prey. And natural events that re-arrange the local environment, with winners and losers.
How dare those beavers distribute water without government issued water rights!
Link below goes to the apparently real government cease and desist letter (and the classic response) for unpermitted beaver dams.
http://www.getipm.com/personal/dam.htm
Thank you, PI! It’s always good to reread the classics!
fbi swat alert in today’s environment! Good ol’ 1997.
Bow hunter reported to have shot a mountain lion in self defense in Wisconsin.
Gee, only took 17 years – these researchers have a keen grasp of the obvious – although I will admit the aerial imagery is cool. Not sure which state disallowed beaver control, to my knowledge beaver trapping is legal throughout most of the US. Failing that, it seems to me the installation of a Clemson Leveler would have been an option, just causing a leak in the dam that the beavers can’t figure out, so eventually they move on. Beavers are in no way endangered. The state is participating in a “taking” of private property, so the landowner should have some redress. Otherwise, he is living in a police state where private property rights are routinely trampled.
Beavers do clearly prefer aspen (Populus tremuloides and P. grandidentata), but not uncommonly they get confused. I well recall while taking the Forest Management class while matriculating through the University of Maine in the mid-1970’s, completing a management plan for a private landowner in southwestern Maine. Along a stream that bordered the property there grew a stand of mixed hardwoods, which included some very nice northern red oak (Quercus rubra). About 6 feet from the streambank grew probably the nicest red oak in the stand, a tree that was already a small sawlog and growing vigorously. That is, until beavers girdled it.
LKMiller ==> “Not sure which state disallowed beaver control, to my knowledge beaver trapping is legal throughout most of the US.” Trapping is legal in NY State too…but with sharp limits and a season. But those trapping laws run into conflicting and confusing laws about beaver dams themselves …. one can get a permit to remove a nuisance beaver, such a thing is allowed, but the State is under no obligation to issue the permit – either to have a beaver removed or to remove a beaver dam. This goes to your “Otherwise, he is living in a police state where private property rights are routinely trampled.”
No one said beavers were smart — just busy.
Ice age beavers were up to 6′ long and 600 pounds, or so I’ve read- part of the megafauna. I’d love to go back in a time machine and see that fauna.
Nice to see another forester here- or at least you took some forestry courses. Foresters tend to not be very talkative on the internet, at least those here in Wokeachusetts. Been trying to get them to speak up about issues for half a century – so far with little luck.
Wait a minute…
They gathered data over an extended time period and did an analysis before publishing their findings and it’s not blamed on CO2?
Who do they think they are? Scientists?
Redge ==> I’m sure someone will call for a correction for failing to find the obvious cause of conifer fairy circles – increasing CO2.
likely
Surprised and pleased that there is a contribution of Scientists from Manitoba, as most of my Relatives are there, and are still advancing the benefits of the “jabs”, and their Gov’t.’s Control.
[way off topic ~mod]
This study is typical of Kuhn’s “normal science” operating under a flawed paradigm. The flaw in the paradigm, and this study, are that they fail to include or consider human influence.
In the real world, in Canada and elsewhere, for the last 12,000+ years both wolf and beaver populations have been controlled by humans, who also managed the vegetation.
The current paradigm is deeply anti-human: their mantra is Nature abhors all people. Historical human influence is denied or grudgingly noted as an aberration or worse, the destabilizing pollution of pristine ecosystems. They seek to model Nature in the ideal, the ideal being with humans removed.
The outcome of defective paradigms is crappy science and theory contradicted by inexplicable outliers and anomalies in the real world. The flawed narrative also fits neatly with a sociopolitical trend, dysanthropy, that seeks to dehumanize the world or large portions of it.
forestermike ==> Gee, I didn’t get any of that from the published study. The study was quite focused in the central place forager concept and the affect that wolf predation has on the pattern of beaver foraging in a specific place.
Exactly. And because the conditions, time, and place are specific, no general conclusions may be drawn that are applicable to anywhere or anywhen else. It’s a study in a snow globe. And that snow globe lacks the pelt-clothed apex predator who has dominated the population dynamics of flora and fauna here for millennia. Therefore, the study is flawed and unreliable.
I don’t know what the “central place forager concept” is, but it’s something that lacks human influences. It takes humans out of the model. That’s the flaw in the paradigm, right in the heart of the foundational axioms.
As such, studies like these are easy to spot, commonplace, and useless. Pretty myths with no relationship to reality.
forestermike ==> “central place forager concept”” I gave a link in the essay. They were not studying the effects of humans on wolves or beavers, but only their effect on one another as relates to the forest around them.
I suspect that you have not read the study and are not aware of its conclusion at all. Come back when you have read it. Let me know what part of their conclusion you disagree with.
Another anaccounted factor is that the fur trade has virtually come to an end. In the 1980s it was still possible to earn a few bucks between freeze-up and Christmas by trapping all kinds of fur bearers. Not anymore. The pseudo-environmentalists have made trapping into an unmitigated evil and thrown paint on ladies with fur coats. At this time the only market for wild fur is South Korea, or at least it was a few years ago. It may be gone by now, too. So a very significant element in the beaver/wolf relationship no longer exists.
It’s also the case that beaver don’t congregate in herds. A beaver lodge will consist of the two parent animals and their kits. Upon maturation the kits leave and find homes of their own, probably where other beaver have been taken by predators or trapped because they’ve become a nuisance.
The lodges are located in the same spots they have been for many centuries unless man makes physical changes that eliminate them. A family of beaver can’t denude the surroundings of all aspen and other edible trees in the time that it takes those fast-growing trees to grow back. In many situations they travel far upstream, gather food and float it down to their lodge.
Wolves don’t lie in wait for a beaver to wander away from water. They are constant travelers in packs and they need enough food for everyone on a daily basis. Depending on local conditions their range will cover hundreds of square miles.While they won’t pass up a rabbit or a grouse if one crosses their path, their main objective is larger mammals, basically moose, deer and caribou. If there are none of these in an area there won’t be any wolves, either.
Carrying out the study may have been an interesting and fun way to spend some time but the correct information could have been easily obtained in a tavern in Alaska, the Yukon Territory, most of the Canadian provinces, or a northern tier US state.
nailed it!
general custer ==> anecdotal information is useful, but does not trump actual careful on-the-ground field study data.
Wolves ambushing beaver is established as a fact — at least at that place and during those years. The authors acknowledge your viewpoint, but find that the wolves, at least there in Voyagers National Park, do wait and ambush.
Read the study — you might learn something outside of a tavern.
A person that makes a significant portion of his income in the bush, hunting and trapping the animals that live there, must learn the habits of their lives. Those that live among them must, as they have for many centuries, observe them in order to survive. No studies by grad students have shown them how animals in the wild behave. I doubt if Tom Gable, for instance, has ever been in a serious enough situation in the bush to make the eating of a wolverine a necessity. This person has.
general ==> No one is questioning your woodscraft.
Did you read the study? If so,what portion of the methodology or the conclusion are you objecting to?
I don’t quite get it.
As the article I posted about Yellowstone showed the primary impact of wolves was on the overpopulation of elk. Once the behavior and overpopulation of the elk was modified by the wolves other changes such as the return of beavers occurred.
Another anaccounted factor is that the fur trade has virtually come to an end.
The November issue of Fur-Fish-Game has the prices of the fur market listed
on page 52. Looks like rug quality wolves quoted at $600-$800,
but most of the others quoted are not very encouraging like muskrats, beaver and coyotes
not worth the effort. Lynx cats being the exception $1,000 to $1.500.
One point that has not been mentioned here is that bears will open a beaver lodge
and kill and eat them. Just do a google for *grizzly bear beaver lodge*. and
take a look at the images. I’ve seen what a beaver lodge looks like after a grizzly
rips it apart, not much left.
That’s actually hilarious. If you and your family were lounging around in the house watching “Dancing With The Stars” and Godzilla showed up and began tearing the roof off the building would you all just sit there in front of the TV munching popcorn? The entrance to a beaver house is under water. Long before the exposed portion is demolished the beavers will have departed. They don’t know from Google and wouldn’t wait for the show to end.
Lynx are cyclical in population, which is probably related to the snowshoe hare numbers, their main food.. They might be in a down cycle right now which would account for the fur price being as high as it is. As with everything else inflation is a factor. They’re also generally solitary creatures. When their prices reach a certain point northwestern coyotes are dyed with lynx-like spots and sold as the real deal.
A high price for a good wolf pelt is an indication of either a smaller population or less trapping effort, fewer available pelts than the demand. They’re one of the most difficult animals to trap.
Recall in grade school how we leaned that after the ice age there were beavers 6 ft tall? WOAH! They must have had lots of acreage flooded to their liking. Canoe please!
They lived during the Pleistocene glaciations and survived its many interglacials until humans entered North America before the Holocene.
I agree with the article about the formation of the “fairy rings”.
However, IMO they are wrong about the beavers “moving on” only after depleting the food supply.
Young male beavers are ALWAYS moving on to a create a new colony – usually when they are about 2 years old.
The creek on our property is colonized by a smallish male every 2-4 years. Sometimes I believe he is single for an entire year, before finding a mate. Sometimes I spot two beavers shortly after I find new beaver activity.
We don’t trap the beavers since their creek pools are a benefit, and they otherwise don’t interfere with any of the other game management or farming projects. However, our creek has a very large watershed. The beavers get their dam blown out by a big flood in either the first or second full year.
I have never had fresh beaver sign immediately after a dam-blowing flood. I don’t know if the flood kills them, or if the beavers are like, “WTH just happened? I am moving to a safer place!”
(Just one guy’s longitudinal observations.)
P.S. Our top predators are coyotes and bobcats. I don’t think a single coyote could take a large male beaver all by itself. However, a pack probably could if they could keep him from reaching water.
pillageidiot ==> The study authors did not speak to the “moving on” idea — that was my observation, about which I have emailed the authors.
And, of course, the young males always move on — like with many other species. But, see the aerial photos from Voyager National Park — when a pond and surrounds look like that — where do the resident beavers find forage?
Thanks, Kip… I find your ‘responses’ astute, if I may say so. I SO enjoy this site, its articles, AND the responses… I imagine that this is what going to a good, solid University would have been like (had I gone).
When I was in middle school in the 1960’s, our eighth grade home room class had a student teacher for a time who was exceptional in every way.
When his student teaching stint ended, we got him a going away card which featured a group of beavers wearing hard hats and constuction garb; holding picks, shovels, and jack hammers; and standing on a beaver dam.
The caption read this. “Best wishes from the whole dam crew”.
BB ==> Cute!
I once came across a tree that a beaver had manage to get down- but it landed on the beaver and he was lying there dead under the tree.
Joseph ==> I have seen my sons come close to doing the same for themselves!
Kip,
Would you call that a family tree?
Geoff S
sherro01 ==> Well, it would be an anti-family tree, I guess. My youngest looked up and said: “Ha! Missed me!”
Yep.. one HAS TO BE very careful… I find the dead trees most unpredictable… at 88+ I don’t move quite as quickly as 30 years ago.
Fun story. My Wisconsin dairy farm is up a side valley from Otter Creek near where it runs into the Wisconsin River. When we bought the farm over 40 years ago there were no beavers and no otters. All trapped out when the the Uplands first was settled in the 1870s. About 20 years ago, the beavers came back and eventually built several beaver dams up and down the creek. They apparently like the aspens and birch that line Otter Creek. About 10 years ago, the otters had come back because the beaver dams filled with fish. Now it really is Otter Creek again.
Too far south in Wisconsin for its many wolves, although a few years ago we had a wolf pack visit the farm during deer hunting season. Wolves howl at night. Coyotes yap. Once you have heard both, you never forget the difference.
Rud ==> The interdependence of species…beavers make the creek suitable for otters. And, yes,aspens and birch are beaver food
And it was elk feeding on aspens that drove the beavers out of Yellowstone.
There is a wonderful conservation book of ‘short allegorical stories’ written by Wisconsin naturalist Aldus Leopold. Title is ‘Sand Hill Almanac’ (which is what locals call sandy central Wisconsin, just like my farm’s Uplands is Sw Wisconsin never glaciated steep limestone hills). His essays cover much more than Wisconsin.
One is titled ‘The Mountain Wept’ (Wisconsin has hills but no mountains). The mountain wept because humans killed its wolves that kept the elk in check from eating the mountain’s forest cover. So the mountain was now eroding and would eventually die as a mountain. So it wept.
Aldo Leopold. I found the story about the last grizzly in Arizona to be particularly poignant.
Oh my!
Kevin ==> Thank you! (knew someone would get the title)
Oh were we supposed to say something? Sorry Kip, I wasn’t aware of that.
Richard ==> I like the interaction with readers….the good, the bad and the ugly.
I studied beaver for many years, which led me to a formulation of a theory of cognition, namely that a complex instinct is an inherited body of expert knowledge. I ultimately wrote that theory up as a series of blog articles here:
http://horsecognition.blogspot.com/ A warning: it runs about 30,000 words. Lots of critters are considered besides beaver, from horses to baby birds.
As for beaver, those I studied never had “feeding trails” nor did they forage. They built lots of dams in one place, using wood from a nearby aspen grove that they felled and cut into proper lengths. The paths were from the wood supply to the construction site. They eat the bark from their building materials so never have to forage. They also lay in an underwater food supply in the one pond that includes their house.
For example one pair built 36 small dams on a small stream. Another pair built 9 dams in a row on a large stream, each 6 feet high. This many-dam behavior obviously greatly increases the risk of predation so why do they do it? The standard answer was they cannot stop building, which is evolutionarily absurd.
My conjecture is they do it to drown the conifers which they cannot eat and which are replaced by fast growing aspen, their food supply. Mind you the ones that build the dams are not likely to be the ones that later eat the aspens, so they are tree farming for future generations. Nomadic tree farming for the good of the species, at great risk to themselves.
In fact if you fly over the boreal forest the only gaps in the conifer blanket are beaver ponds and meadows, including aspen groves.
I should add that beaver dams take a lot of wood. Our earth dams are just piles of compacted dirt, but a beaver dam is a lattice of wood pieces with an impervious mud face on the upstream side. Structurally it is a wood dam.
Backcountry horse riders are warned not to ride over old beaver dams because if a horses legs punch into that lattice it will be hell getting them out. It is very hard to dismantle.
David Wojick ==> I think you are just using different words to describe the normal beaver behavoirs described in the paper.
I am not so sure that building bigger higher dams increases predation.
Read the paper which discusses the behaviors they found in Voyagers National Park and the evidence that had for them.
I don’t think he’s saying that bigger dams increase predatation; bigger dams means more work done, which means more trips along the trails which gives predators much more opportunity to ambush the beaver. Which ties in with the research in the article.
Indeed. The beaver could build just one dam with their house in the pond, then go out just for food as needed. Instead they build lots of dams which requires a great deal of time out of the water hence subject to predation. The difference in risk is enormous.
I have no problem with their findings. The question is why they are doing what they do? Feeding and building are very different behaviors.
David ==> Ah, I see some a differing research question emerging…”WHY? why do beavers keep building dams when what they have already built seems sufficient for their purpose?”
Easy answer based on my personal observations of Otter Creek beaver repopulation. Each dam shelters a single mated pair, and it’s lodge also houses their kits. When the kits reach maturity, they are forced out of the lodge and must find their own. That almost always requires a new dam and lodge.Thus was Otter Creek slowly repopulated up and down by beavers and then the otters enjoying the several soon fish filled beaver ponds.
(River Otters are easy to spot. They build underground burrows in the beaver pond banks above the water table. But then they create otter slides where they exit the burrow ‘back door’ on high ground with a muddy slide back into the beaver pond and their watery ‘front door’. Easy to see them on the slides.) Easy to know they are there just from the obvious slides.
Beaver teeth never stop growing, and grow rapidly. If they stop gnawing, their teeth are apt to get too long to be effective and result in their death.
Interest article. I have experience trapping beaver and predators like coyotes on our
farm. It wasn’t about the fur but to control the damage from the dams and
the predation to our fiber flock, but I did process the pelts and sell them. Trapping
and hunting are a big deal in this area. An old friend worked his way through collage
trapping beaver.
We also have wolf coyote hybrids, !/2 wolf and 1/2 coyote, 80-90 lb killing
machines. The government agency guys never talk about those at all but they exist.
We also have a high deer auto collision rate in this area and the government uses mt lions to control
the deer with them. They do this by limiting the quota of lions by the houndsmen. At the present
there are no hounds allowed due to the reintroduction of Grizzly bears. They also don’t allow
snares for wolves only foothold traps and the quota is something like 5. I friend of mine
quotas out in this area every year.
The lions come around after dark and kill the deer and eat their fill
and move on leaving the remains. This is in grizzly country. A deer carcass on your property
in a brushy creek bottom is not a good thing. I’ve removed a few. I pack a shotgun
with buckshot in the chamber and slugs in the magazine. When the stench of the carcass is
strong I walk very slowly, gun on low ready, finger on the trigger, safety off.
My wife backs me up. She packs pepper spray, a 357 and has a couple of dogs on heel.
It’s a very surreal experience smelling something dead walking along a creek bottom looking for the carcass in the evening. Living life in the west.
Mr. Ed ==> Great story — thanks. We have had black bear problems at our home in the last few springs. One of my sons brought me a marine pump action 12 ga loaded with slugs to deal with the problem if the bears got in the chicken coop or decided to raid the kitchen.
We just watch the beavers which live in a wooded semi-wetland nearby. There was a beaver lodge in a side creek that feeds the Hudson River, almost directly under the Rip Van Winkle Bridge. I was so surprised to see lodge in such an unlikely place that my wife and I kayaked out to verify that it was a lodge and not just a driftwood pile….and lodge it was.
I spent some time with an uncle who lived in the mountains in SW MT. He was a notable
hunting guide in his younger days and had some impressive trophy mounts in his house.
But no bear rugs, so I asked him one day if he ever hunted bears. He replied no he never hunted bears, just dealing with the ones that came around causing trouble was enough.
On our mt property we leave the beaver alone as their activities are not a problem. On the
valley property we don’t tolerate any beaver for a number of reason, most notably is
their activities destabilize the bank causing severe erosion during spring runoff when their
dams wash out. I remember seeing some beaver art work in a NYC subway station related to beaver pelt trading by John Jacob Astor aka Hudson Bay Company.
There was a Hudson Bay Trading Post to the west of here that was very famous. My wife found a old liquor bottle that dated to the 1840’s on this property that she was told that came from that post. Some interest history related to the beaver and their fur.
Mr. Ed ==> The history of the beaver in North America is fascinating, heartbreaking, inspiring and all of that too.
You can’t work in mineral exploration in the Canadian Shield without coming across the work of beavers wherever you go. But I never really thought much about beavers, other than to curse them whenever they used a culvert on an old logging road that we wanted to use to get to a work place. Culverts are perfect to start a pond, then they will build a dam on top of the roadway and the nice road you picked off an air photo is useless… aargh!
So learned two of things from this post that explained a couple of counter-intuitive things I’d seen. Thanks to Kip for posting it. Very interesting read.
If you do have a beaver problem (or a potential problem) with a culvert, you should try the beavercone – human ingenuity beats beaver industriousness! They can’t jam sticks in it because the openings get wider downstream and the water flow carries them away. Good Canadian invention.
Wow. Genius.
Smart Roick ==> Thanks for the stories and the link to Beavercone. Looks good!
A device that is used for issues related to beaver dams in this area is the “beaver deceiver”.
The local conservation group has used that a few times around here and it seems to work well.
Is that the inventor with the cane?
Interesting. The last few Colorado wolves were hunted down and killed in 1945, one poisoned, the other shot. There have been a few sightings recently, likely from dispersed members of Wyoming packs that have been travelling.
For better or for worse, Gray Wolves are schaeduled for re-introduction on the western slopes before the end of this year, so we’ll soon see how they interact, but a small poling of beavers in the area revealed that they are “not eager.”
https://biologicaldiversity.org/w/news/press-releases/us-agency-moves-forward-on-reintroducing-wolves-to-colorado-2023-09-15/
I imagine beavers and their geo engineering have long been a net benefit to humans. Consider that modern beavers are just the latest claimants to slow moving stretches of streams and creeks that have been “engineered” over the millennia. Modern dams are just the latest iteration. The gradual tree clearances and expansion of flat land with its silty deposits, rich with decomposing matter are the result. In the resulting lush “bottom land” it is possible to reap two harvests of hay per year.
In the Middle Ages meadows seem to have been prized highly among the various classes of land: garden, vineyard, ploughland (wheat, oats, barley and vetches), or open grassland. It was so valuable that it ultimately wound up in the hands of wealthy and powerful lords who would lease the rights to graze stock and harvest hay.
A little Obama humility for beavers: “You didn’t build that…”
I live in west central Colorado. Five years ago getting home shortly after dawn, I saw a ‘dog’ sitting at the top of my driveway. I stopped some 50′ away, while the canine rose and ambled down my driveway. It was a wolf, or a 100lb coyote. It made it down to the creek at the bottom of my drive and leapt 12′ across the creek and went into the woods. I lived with an Arctic wolf for over a dozen years, she was about 70 lbs. I called DOW to report the sighting, but they didn’t believe me. I’ve spoken with a few ranchers some 30-40 miles south of here and they have always seen wolves. No need to introduce them since they are here already. Same thing happened circa ’95 when I reported a lynx. It seems odd to have departments of concern for arenas that they are clueless about.
Steve ==> In the Catskills of New York state, I have a friend that has documented mountain lion on his property. Even with photographic and scat evidence, the state dept of Environmental Protection refuses to acknowledge their existence.
One possible explanation for this is the scenario: “If we, the DEP, say their are mountain lions, a thousand hunters will descend on the area to kill them, They are safer if we deny their existence.”
Bill ==> I am uncertain about re-introduction of wolves…opinions vary.
You are right as to why we value beavers —
The early day wolves that were wiped out were the Buffalo Wolf and they are now
extinct. The reintroduced wolf are the Timber Wolf from up north. Two completely
different animals. The book Jordan by Arthur J Jordan is a good read on the subject,
he was a wolfer and the town Jordan in MT is named after him
One thing I noticed after they were brought in was the hybrid crosses. Some call them
coywolves or coydogs. They have a different vocalization that starts with a howl and
ends with a yodel. Try and pin down a government agency guy about them and are they
considered a “endangered species” sometime. When the ADC trappers catch a problem
wolf they take a hair sample and it’s DNA tested. There was a hybrid trapped in WA state
a few years ago that was killing livestock and it was collared and released. It ended up
in central MT and a rancher shot it for livestock depredation. The coyote here in MT
is not protected but the wolf is. I’ve pointed the hybrid situation out to different agency
types and have not gotten a honest response..
I sat through all the local reintroduction hearings back in the ’90’s
and the enviros pushing the reintroduction were not telling the truth in any way.
Total BS
But the real fun is with the grizzly bears. There is a lady out on the prairie,
Lisa Schmidt who wrote about their “adventures” with the wildlife for a local
paper and now is in print. Prairie Ponderings —Adventures in Raising Your Food–
She has a nice way with words and tells some interesting storys.
I hear and know things about what goes on in that area but won’t share those
on a forum like this…
Two great quotes from you in this post: “not eager” and “You didn’t build that”. Thanks for the humour.
Based on what happened in Yellowstone I’d expect the early effect to be a reduction in the Elk and coyote populations which will be favorable for beaver, foxes and willows.
I work in forest policy in Ontario Canada. For a long time we left uncut buffers around all waterbodies, including smaller lakes and ponds, to ‘protect’ the water feature. Starting in 2010 we permitted cutting to shoreline (with proper care to not introduce sediment into water, etc.) in part to avoid creating unnatural patterns, but specifically to provide early successional growth of deciduous trees (birch, aspen, etc.) and shrubs (willow, dogwood, etc.) as forage for beavers and other animals near water. Instead of rings we call the uncut buffers donuts. Thanks for bringing this study to my attention.
MJB ==> To be clear, you allow/encourage cutting to the shoreline to take out the trees that are not forage for the beavers and to encourage aspen, birch, etc – which the beavers will then begin to eliminate?
Good point, and no mention was made as to what species they were cutting out… conifers?
Replied to Kip above, it varies from pure hardwood, pure conifer, and varying mixes. It only takes a small amount of pre-harvest aspen to have a strong suckering response post-harvest when soil temperatures are increased from increased sunlight. Willows, dogwoods, and other deciduous shrubs seed in quite proficiently if given even half a chance. Our future forest goal is not necessarily to replace the pre-harvest forest type in each and every case at the same location. We recognize the forest is dynamic, that some conditions are successional events that do not originate with a large disturbance, and strategically manage the amount of different forest types at the landscape scale.
HI Kip, apologies for the delay, missed this question. In the boreal forest the majority of harvest in Ontario is clearcut with residual retention, so they would be cutting most of the large stems, including aspen and birch if present, leaving a relatively low density of residual stems in general, and specifically residual stems along the edge of the water body to provide a source of future downed trees falling into the water (and important substrate in some smaller ponds/lakes). Pre-harvest condition would range from pure hardwoods, to pure conifer, to varying mixes. The goal is to create nearly full sunlight conditions to encourage growth of early successional trees like aspen and jack pine that need close to full sunlight to grow well. In addition to needing sufficient light, aspen regenerates predominantly from root suckers and it’s necessary to remove the parent tree as there is a chemical suppression of root suckering if the parent stem remains. As an overall strategy we are emulating a fire, as a silviculture strategy we are providing the growing conditions necessary for a young successional forest to regenerate. Similar story for willow shrubs and white birch, providing the right conditions, although they can tolerate slightly more shade than aspen. Willow will both seed in and expand from existing growth, birch can seed in if there is a good seedbed (e.g. exposed mineral soil) but can also sprout prolifically from cut stumps, similar to after a fire. We do not promote hardwood and shrubs next to all water bodies, in some cases we target conifer dominated as well, but typically on the path to getting conifer dominated there would be a brief phase (~5-10 yrs) with shrubs and hardwoods as well. The relative mix of hardwood, mixedwood, and conifer is determined through development of forest management plans at the local level, with some guidance from policies on natural landscape composition.
MJB ==> Thanks for the thorough answer!
Kip – Thanks for a very interesting and enjoyable thread. We have a small stream run alongside our property here in NE Wales – no beavers only lambs and bullocks on the farm hill over the stream depending on the time of year, pheasants and the very occasional fox. We have, a couple of times, found several bullocks in the garden however!
Dave ==> Oh bollocks! (on the bullocks being in the garden, that is).
20 miles East of Boston, busy beaver, Department of Public Works like to keep the water table high here in the swamp for the water supply. Add Conservation Department. Professional beaver “handler” on the way to the fever swamp.
This is a good discussion talking about the re-introduction of wildlife to areas they previously occupied. Generally I am in favor of this even to the point of a little destruction and even deaths.
Having recently seen the Ken Burns documentary on Buffalo/Bison I wonder why/when we will see an effort to restore them to much larger areas. You obviously don’t want them on the highways, roads and in cities but couldn’t large portions of the various National Parks and Forests be fenced and opened to buffalo. Put in man gates for trails and grated openings for cars with a notice that you are responsible for your actions. And as I previously stated there would be destruction and even some deaths.
Removing buffalo changed a lot of the natural world.
The major issue is the livestock disease Brucellosis, which some states are free of
and the Bison are not.
There are some bison being moved around.
Brucellosis thread ==> This issue is a scientific controversy — with strong opinions (backed by “studies”) on all sides.
One opinions is : “Wildlife reservoir hosts are important in the U.S., where B. abortus has been eradicated from domesticated animals but is still maintained in bison and elk in the Yellowstone area. These animals may transmit brucellosis to livestock, especially cattle grazed on open ranges.” Iowa State University and the USDA
The opposite opinion is : “There has never been a documented transmission of brucellosis from wild bison to livestock. Even if buffalo were capable of spreading the disease, there are no cattle on these lands from mid-October to mid-June, making brucellosis transmission impossible.” from the Buffalo Field Campaign