Recently I wrote a post about possible ‘standing on watch’ behaviour in beavers observed under circumstances when one of the adult beavers are foraging in dangerous conditions and the other might have been patrolling or keeping guard in a more fixed-location capacity in order to warn the risky-foraging mate from danger (Beaver observations (Feb, 2024) – keeping watch / mate guarding behaviour?).
Today I observed two additional instances that suggested to me that beavers do not send the alarm signal (tail-slapping) randomly (as sort of a general obligation which is achieved irrespective of the particular situation) and that they might keep aware of their family’s foraging locations ensuring that the signal actually reaches them.
These observations also imply that beavers keep track of one another’s locations during foraging and they conform to my earlier observations that adult beavers do not seem to slap their tails unless other family members are nearby and that subordinate (subadult) beavers might slap their tails mostly when kits are nearby (Age and status group differences in beaver tail slapping behaviour).
On the first occasion, I was walking along a forest trail which is well-worn and allows for very little stealth.
Accordingly, I disturbed a beaver which had been either foraging or swimming nearby.
The beaver slapped its tail twice. First, it slapped its tail in a location where apparently the water was rather shallow. Then it swam perhaps 1 – 2 metres to its right (but both slaps were so near in space and time I am certain it was the same individual) and gave a decent splash.
I walked on and got out of the forest and onto a meadow.
There I sat down to generally observe what was happening (there can be some tawny owl sightings, fox sightings etc. nearby).
As I was sitting (not that far from the forest trail), another loud splash resounded some distance between the spot where I had encountered the beaver previously and my current location.
I should say it was about 10 – 15 metres from the upstream spot (where the beaver had already slapped its tail) and about 20 more metres to my observation spot.
As there are absolutely no trees within that sector (not even further inland), I could not help but assume that the same beaver had followed me.
If the beaver perceived me as a danger, it was strange for it to swim after me (although I do not suppose the local beavers think of me as a true threat but as I have not explicitly tried to befriend them, they give in to their natural behaviours without the level of tension which would be involved if I was entirely unfamiliar to them).
Also, the beaver probably had to return swimming upstream (in rather strong current) to its former foraging site or to swim at least 100 more metres downstream to a new foraging site.
I watched carefully to see if the beaver had swum up to investigate me (which also did not make much sense because if beavers do so, they (just like any expert naturalist) prefer to remain quiet not give out their presence).
I could not see the beaver swimming anywhere but I must admit it was very foggy and the visibility was poor.
Then as the silence was restored, I heard the typical beaver foraging munch downstream.
The beaver had been there all the while because it had already brought forage down to the shore and the other beaver was unlikely to have been so speedy at both covering the distance (although it was downstream in the aforementioned strong current) and already getting at a meal.
Thus, I concluded that the first beaver had wished to warn its family and as our encountered had occurred in the forest (at least 300 metres from where its buddy was foraging) and as I was headed right into the direction of its buddy, the first beaver had swum after me to give another splash (at a safe distance from me, however) with regard to the known location of its buddy.
Perhaps it is also noteworthy that the river turns slightly there and that the first alarm (and by ‘first alarm’ I mean the first two slaps one of which was weaker than the other) had been given in surroundings of tree and shrubs cover.
Accordingly, the first alarm would not have carried as far.
The sound would have been absorbed by the forest vegetation and it would have ‘bumped’ into the riverbank where the channel bent.
In fact, the second alarm was given out by the beaver in a strategic location where the channel was straight and where the surroundings were open.
I find it likely that the beaver had made these considerations in order to estimate how far it should swim out of the forest section of the river in order to ensure its signal carried off to its family.
And, indeed, when I stopped listening to the munching of the beaver downstream and when I resumed my path, the beaver downstream noticed me and also gave a splash.
Interestingly, there had been two beavers one of which was apparently a kit because it slapped its tail, too, but with a very faint vigour (and I saw it was rather small, comparatively speaking).
This confirmed that there had been family to warn.
Also, I wondered whether the first, feebler splash given by the individual upstream had been weaker due to the shallows or perhaps the beaver had been young and not as large in size.
If the subadults are responsible for the kits to some extent and if there had been a kit downstream known to this subadult, the subadult might have tried its best to account for the first two ‘unsuccessful alarms’ (the first due to the shallows and the individual’s size; the second due to the location of our encounter in the forest, before the river bend) and whether it had realized it had to compensate for these two half-failed warnings by adding the third warning.
***
The second observation concerns another beaver family which resides even farther downstream (although due to some behavioural traits I suspect these two families might be related and I hope to discuss this in another post soon).
This family forages either on the riparian growth that in one sector borders with a hayfield or, at times, they enter a ditch which is connected to the main river channel.
The ditch runs along a lush grove of willows.
The ditch cannot be inhabited permanently because it is too narrow and too shallow.
It is less than 1 metre wide in most places and (as I happen to know because I have tried to cross it a few time), it is barely 1 metre deep and during summer the water level can drop to 40 cm or less.
The beavers have constructed a small dam between the ditch and the main river channel.
This has not resulted in formation of a pond but it has stopped or slowed the outflow of the rainwater or meltwater from the ditch into the river.
However, I was not walking by the ditch. I am explaining the layout because it is important to understand that the beavers in the river and the ditch are family and that the ditch is another foraging area for this family.
I was walking along the river on the hayfield and I found my other observation post there.
I sat down and watched and listened quietly.
After some time, I got a terrible sneeze.
My sneeze was followed by a very loud and impressive splash right in front of me (almost gave me hiccups).
Then as I noticed the heads of the beavers sliding along the surface of the river, the other beaver that had been there, as well, also gave a very loud splash (less than half a minute after the first splash).
Apparently, these two beavers had been hanging out together and as they both seemed adult, I believe they were the dominant pair.
They obviously were not warning one another of my presence.
I looked intently to try and notice the third beaver but I could not.
I was somewhat startled at the exuberance of the display.
The splashes had been given right in front of me and at full might, investing all the body size into the effort.
I found this urgency a bit strange because normally the adult beavers would retreat some distance before giving these alarms (especially, if the second/third beaver was not in imminent danger) and I was not even getting up to walk off.
The beavers clearly saw that I could not threaten anybody anytime soon (apart from them as they were extremely close to me and as they had completely given up their location).
Curiously, I kept watching for a kit (I assumed such effort would be invested in the protection of the young).
There was no third beaver on sight.
Then I came by this inkling.
The ditch is rather long.
The first foraging site along the ditch is about 200 metres from the channel of the river.
The ditch is also shallow and if someone tried to catch a beaver there, it would be difficult for the beaver to escape or to even move unnoticed (now with the flood it could dive under but the commotion would probably be seen and the individual would be scented out by someone of the likes of a wolf or a dog).
The ditch is located right across the hayfield and beyond the willow grove (perhaps 500 metres in straight line from the spot where the adults had slapped their tails across the field to the ditch).
I wondered if these two adults had tried to warn their family who was foraging by the ditch because it took a long time to escape from the ditch and it was very dangerous to be found in the ditch.
The adults must have known that their slaps had to be very loud in order to carry over the entire hayfield and through the willows (at the same time it made little sense to swim upstream and to slap the tails in the spot where the ditch was adjoined to the river because, once more, the sound would not travel out in the open but it would be absorbed by the riparian forest which starts near the ditch and which borders the ditch for the first 100 metres).
From the perspective of the soundwave travel, the beavers had made the right choice where to give the alarm if their alarm had been intended for someone in the ditch.
Also, it would explain the sense of urgency because the foraging individual might gave been on the land (in the willows) and then they would have had to reach the ditch and to swim the additional 200 – 500 metres to the safety of the river.
I waited until the sense of alarm had faded out (at least in my view) and sneaked quietly to the willow grove in order to (from a safe distance – not to give the poor beaver a heart-attack at close quarters) listen in whether there was any foraging activity by the ditch.
And, indeed, there was a beaver foraging about 300 metres from the outflow.
I could not tell how large the beaver was etc. because I did not want to disturb it.
I simply wished to confirm that there had been someone there (because not always this family forages by the ditch).
***
These observations suggest to me that beavers are aware of one another’s foraging locations even if they are not foraging in immediate proximity to one another.
Also, beavers might adjust their alarm signalling with respect to the location of their family but also with respect to the sound travel conditions within the setting.
The beavers are capable of emphasizing with the other individual in order to predict how much time they might need to escape (judging by their own experience in the same location).
They might, additionally, take into account the direction that the threat/predator has taken (toward their family or not) and their sense of responsibility might be truly great as they might put themselves slightly at risk (approaching the threat or giving alarm very close to the threat which betrays their own location) in order to ensure the warning carries to their buddy.
I believe that beavers are enormously familiar with the landscape structure and qualities within their territory, and they take detailed account of elements such as river bends, forest vs. open areas, the distance to foraging sites (i.e., to their closest possible family foraging location) etc.
However, I will mention, once more, that these families have known me since some time and I had never caused any trouble.
In fact, every Sunday if I happen upon them, I give them out a Sunday greeting and I wish the best of times to their families on that blessed day.
I do not believe they perceive me as a threat and instead they probably are confused and think of me as a peculiarity.
Consequently, these behaviours might not have been exhibited under circumstances of grave perceived danger but rather under circumstances where the beavers can make choices more freely (unless we totally startle one another) because they are not overly perturbed.
Notes by Ieva 