Co-author Irina Rotenko
Every May we continue our long-term study on behaviour and ecology of denning wolves. Since 2004 the terrain of Naliboki Forest (the central-western part of Belarus) has been the main study area for the question. Since 2018 the brown bear has become more or less common there. It appears possible to investigate the interspecific interactions of brown bears and wolves and particularly during denning period in wolves.
In this post we would like to describe the video-documented attack of a brown bear on a wolf den. However, first of all we will tell some preliminary stories on the question in Naliboki Forest. In the second half of May 2019 in Naliboki Forest we registered very plausible killing of small wolf pups by a brown bear. Two brown bears (mating couple) frequently followed the wolf couple at denning, they inspected their dens, and finally the wolf litter disappeared (See another post).
Also, in May-June of 2018 in Naliboki Forest we registered similar behaviour of another adult male bear in relation to other wolf breeders, but that case was less documented.
Moreover, in July-September of 2018 in Naliboki Forest we documented regular visiting of homesite of another wolf family with relatively small pups by another male bear. The bear marked that place a lot in three points. Interestingly, that in May-July of 2019 the bear was present at that place again, but did not mark all the three points, when there was no regular stay of breeding wolves in the place.
However, still a direct attack of a brown bear on a wolf den was not photo- or video-documented.
Recently i.e. during May of 2021 one of the discovered wolf dens was situated in an enlarged red fox earth. Six pups of about 10-12 days old were in a burrow chamber of 1.5 meters deep. In a few days after this finding, being already convinced that the pups are normally nursed by their mother, we carefully set a camera-trap on a big pine at a distance of about 10 meters from the entrance of the burrow-den and the height of about 4 meters.
When we came there in two weeks, the den was destroyed by a brown bear. The video we could take from that distance (part of the event appeared out of the camera shooting) you can see below.
The brown bear discovered the wolf den and began destroying it. Extirpation of that by the bear took half an hour. It looks like the parent wolves were observing the bear’s action from aside, but they were afraid to approach the bear and attack it. Right after the bear has gone the parent wolves came to the extirpated den. They looked scared. After some shy and careful inspection of the den-site, the parent wolves left the place and came back there only at night. Also, they returned to the den-site few more nights, tried to dig and investigated the burrow-den inside and searched for their pups. Plausibly, the pups were killed and, perhaps, eaten by the bear.
During a week we (together with Gerard Oonk) traced the location and behavioural traits of the wolf couple with their tracks. Our preliminary, but very plausible inference is that the wolf couple lost the pups. The wolf couple began to range within almost the former winter home range, marked forest roads a lot and showed slow manner of walking on forest roads. All these traits did not match with usual behaviour for parent wolves. Conversely, they are rather opposite to the behavioural features of wolf parents having small pups.
You can support the research on large carnivores in Naliboki Forest by buying just a coffee. It will help to keep the study going.
Zoology by Vadim Sidorovich 
Sad story but part of nature , thanks again for your interesting posts
Interesting that the camera was set up near the wolf den, then a bear just happens to find it….Makes you think was any kind of scent put out, like meat so that the bear could find the den……makes for a good video!!
Thanks. Just bears know all the burrows in their home ranges and dig for cubs and adults of beavers, badgers, red foxes and in that case for wolf pups.
Would the bear have found the wolf den if no human scent was near the opening of the den?
Thanks for the question. My answer on that will be in several theses.
First, in this forested area we live and work there are quite many people the terrain-wide particularly in the warm season. It was especially common presence of human in that place with the wolf burrow has been, because it was situated about 150 meters from a forestry road and about 1 km from a hamlet.
Second, in Belarus bears being stressed by human all the time (hunters, antler searchers, tourists, forestry workers, collectors of berries and mushrooms etc.) are strongly afraid of people and avoid places recently visited by human.
Third, here bears know all the burrows in their home ranges and they regularly inspect them by trying to steal up cubs of badgers or red foxes or their parents at a burrow or catch wolf pups. So, it was nothing surprising that the bear appeared at that wolf burrow-den.
Forth, that bear came to the wolf burrow-den in a week after we carefully visited the burrow surrounding and almost in two weeks after we filmed the pups. So, there was no any our smell definitely.
Great video! Unique!
Another example of Vadim Sidirovich´s unmatched skills in documenting big predators behaviour in Naliboki forest.
Thank you Vadim for sharing this with us!
Great video! Thanks.
Thanks for sharing. Very interesting interaction.
Amazing video to watch Vadim! fascinating to see actual behaviour I have only read about being captured in the forest. Great credits to you both. You must have had a lot of responses and it must have been quite some experience returning to the site to see such a scene of sign before you. Spring is turning into summer here and I am still monitoring the female wolf, she has a new companion from the pack in the northern territory. A 2 year old male that dispersed in April. So hopefully it is the start of 2 teriitories located either side of our main motorway the A1. Still the monitoring procedure here is slow with much red tape to jump through. We do have DNA sampling on a 2 month delay but it does help build a definite database of individuals. Travel restrictions are starting to ease a little this side of Europe as the vaccination programs near completion. I wanted to organise a trip to Naliboki with a group around the same time of year that we went last year. Is this a possibility with you both? end of september/beginning of August Hope you are all well and that the spring denning season in total provided sufficient and interesting data for you to work with.All the bestKristian
End of September / beginning of August??? Does he mean the End of August/ beginning of September?? or do your months run backwards???
Don’t worry, we understood each other
A very interesting video and analysis. Had no idea bears posed a threat to wolf cubs with such an intent! What I would really like to know is whether bears – and wolves – are a threat to the rural (human) poulation of Belarus – any documented cases/incidents of attacks on humans.
Thank you. Still we did not face with direct aggressive behaviour of brown bears to human. Of course, bears destroy beehives. It is fairly common.
Put the entire video up.
That is all we took by a camera-trap. Sorry. The bear, while it was destroying the wolf den, got out of the camera working distance.
I think it’s time to start thinning out the brown bear population. Is this another place that wolves were hunted to extinction levels and now you’re trying to increase their numbers through conservation through observation efforts? Usually the brown bears haven’t suffered such devastation as the wolves and any assistance they could receive from the human population to ensure their survival so they can once again thrive is never a bad idea. We usually were the reason for their dwindling numbers so why couldn’t we help them achieve their once great numbers as well, until they reestablish their rightful place amongst the hierarchy of the forest.
It seems that thinning the human population would be, and is a much better method of protecting both the bear and wolf population, as well as the environment in general
I agree
Very sad. I don’t know why though. They would eat my dog, as in China! I only eat hot dogs.
Has the photographer taken responsibility for leaving so much human scent at the location to attract the brown bar to the area so that it found and terminated the wolf den?
Thanks for the question. I will reply in theses, from which you will understand all questioned. First, in our case when we photographed a bear destroying a wolf burrow-den with pups, the bear came to the den in a week after our finding of the den. There was much rain that time. We were very careful at the den (no sitting, only walking with rubber boots, nothing left etc.) So, in a few days there was no any our smell anymore, even in a day afterwards. Even the parent-wolves did not detect our being there, and they did not relocate the pups.
Second, Naliboki Forest situated on the distance of 40-90 km from Minsk city with two million people and one million cars. So, in these forest with relatively good roads there are many people all the time and the destroyed den was located only about 300 meters from used forest road. So, people around was everyday.
Third, in our country it is allowed to search for wolf den and even kill the pups. Moreover, many game husbandries pay a honorarium for that to our regret.
What kind of Cam did you use? Brand / Model? Very nice doku! Thanks.
this video was captured by some old model of browning dark ops