On Jan 16, 2024, I observed two roe deer feeding on a snow-covered oil radish field by a road of rather intense traffic.
It might be relevant that it had been snowing very heavily in the morning (until about 8 am) and even during the day the temperatures had dropped to around -10 °C.
This could be the reason why these two individuals had ventured out to forage at about 12.00 – 12.30 pm.
The roe deer emerged from the riparian forest on the field side of the road but they came from the ‘wrong side’ where the forest was the narrowest and where the human infrastructure was very close (a restaurant-type facilities).
They also began feeding on the field in a spot where the road was very close and where they were poorly sheltered from wind.
Most local roe deer that reside in the riparian forest, firstly, emerge from other parts of that forest and, secondly, they feed slightly further where their foraging grounds are further from the road (although not by much, perhaps by 20 metres) and where the curve in the riparian forest/field edge serves as a buffer against wind.
It appeared to me that these two individuals were not locals and that they were perhaps unaware of better foraging grounds (granted that no other deer were in the vicinity and they could have foraged anywhere on the field) or they did not wish to intrude further into the local subpopulation foraging patches.
They did not belong to the other subpopulation that is sometimes observed feeding in that very spot because this group arrives from across the road while the two deer emerged from the forest on the field side of the road, as mentioned before.
They appeared adult. I believe on of them was male but I could not determine the sex of the other roe deer.
They were of contrasting colour.
One of the deer was slightly darker as is common in the local group but the other one was very light brown (almost beige).
The darker individual began foraging straight away, scraping snow off the soil very actively with its front leg.
This individual must have been living near roads because it only looked at the first car that passed by and ignored the following 4 – 5 cars.
The other individual (the lighter one which I think was male) did not get at the feeding at once.
It had noticed us (me and my dog) and it stood completely still watching us and assessing the situation.
We also froze, and I suppose that eventually the roe deer either believed our impersonation of inanimate objects or decided we were not a threat.
What I find interesting is that the individual deer was looking at us very intently for a very long time (longer than the ordinary, non-specific, overall-surveyance vigilance bouts).
The other deer was foraging vigorously very close to the vigilant deer (within 1.5 metres) and not once the foraging deer felt that it should, too, check out whatever its fellow was watching out for at such length and intensity.
This caused me to wonder over several hypotheses –
1
When moving around in groups, roe deer might split the vigilance duties whereby one individual is more responsible of watching out for threat while the other(s) can relax and feed.
Such system might be based on either equality (taking turns) or dominance (in this case, reliance on an authoritative individual who would monitor the situation and give alarm need it be).
2
Vigilance itself might not translate into alarm and anxiety in roe deer.
I find this potential explanation rather interesting because often we assume that animals that are vigilant are also worried.
Sometimes vigilance is thought of as stress level measure.
Perhaps it is not the truth of it.
Perhaps roe deer can tell the difference between individuals who are simply performing a random monitoring of the surroundings or even assessing some strange object/subject/occurrence vs. individuals who are worried over what they have seen.
These roe deer were too close for the non-vigilant individual to have been completely oblivious to the other deer’s prolonged watchfulness.
I would venture to guess that either this other individual trusted that unless the vigilant individual gave an explicit alarm, there was no cause to be concerned (and, in this case, it would be curious to understand how roe deer alarm one another if they do not deem the alarm from the others’ behaviour but rather expect for a specific signal), or the other individual knew (e.g., from scent) that their fellow was vigilant but not alarmed.
Perhaps the other individual would have acted, as well, by looking up at us if there had been some change in the vigilant individual’s psychological state that could be perceived as a shift in body posture or scent that the individual produces etc.
However, I believe that the latter possibility attests to the hypothesis that roe deer that are watching out for general or specific threats do not reach the psychological (and behavioural/hormonal) condition of being anxious.
If this were true, vigilance is not the same as stress.
When we, as humans, are looking around and inspecting the environment for danger, we are usually already worried because our social organization frequently creates conditions in which we do not have to be vigilant at all times.
We are vigilant in response to real or perceived threat.
Meanwhile, vigilance in animals might not be a response to actual or imagined stress and the actual stress reaction might be detached from behavioural vigilance and it might only become manifested if the individual estimated the observed circumstance as dangerous.
In such case, vigilance is simply observance and cognitive assessment of one’s environment.
Alternately, the observant individual might have been stressed all the while but the other individual might not have reacted unless a certain stress threshold has been surpassed.
The continued observation perhaps illustrates stress tolerance in roe deer and there might be very subtle changes in stress levels that the individuals respond or do not respond to.
When the vigilant individual had decided not to be concerned over us, it also began feeding.
Meanwhile, the traffic intensity was growing because it was close to the hour when most establishments observe the lunch break.
Around 11.00 am to 13.00 pm many more cars drive along that road than at other hours (expect, of course, the hours in morning and evening when people go work and return from work).
These roe deer had selected a bad time to forage on that particular field in that particular spot.
This further suggests that they might not have been familiar with the site (although they did not move around as individuals who were there for the very first time, either).
I had mentioned before that the actively foraging individual had already screened the first car that was passing and it had ignored some other 4 – 5 cars.
The individual watching us had ignored all cars (this individual seemed older, for some reason, or more experienced) and I believe it knew that cars do not drive on fields and that traffic itself was irrelevant to its safety.
I forgot to mention that the road was only about 20 – 30 metres from the spot where the roe deer were feeding.
At that point, however, traffic intensified and now there was a car passing almost every 20 seconds.
The roe deer looked not at the cars specifically but at the road and it appeared they were evaluating the situation.
They apparently decided that this was too much and they moved much closer to the forest edge.
They did not flee, however. They kept feeding close by the forest.
The entire episode made me believe that the roe deer were not aggravated by the cars as such (they were aware that, under such circumstances, passing cars were not a threat) but that they reacted to the noise and the unpleasant sensation that intense traffic causes.
They moved closer to the forest perhaps to retreat from the disturbance but maybe also because the impression of the traffic was too overwhelming and being near their natural environment made them feel at home in a sort of a ‘security blanket’ functional context.
Namely, I do not think that these individuals moved closer to the forest in order to be able to run in case some car drove right at them (although they might have been aware that cars can stop and that humans can emerge out of them and then danger ensues).
I believe that the experience of traffic noise and stench and the sensation of many unnaturally fast objects passing by, is unpleasant to wild animals and it might cause some state of loss of touch with reality.
For example, when we find ourselves in some loud and otherwise overbearing circumstances with intense sensory stimuli, it might be difficult to keep in touch with how we are feeling in our bodies (a type of ‘out of body’ experience) which can cause some unwanted consequences, e.g., consuming too great amounts of alcoholic beverages or making irrational purchases in supermarkets.
I think that the roe deer moved close to the forest not to be overwhelmed by the traffic and to keep their connection with some familiar environmental stimuli.
It is easily seen that this observation leads to several interesting assumptions regarding roe deer behaviour and threat/stress assessments.
The roe deer might not have a polarity of not being worried or being worried.
They might experience a subtle gradient of stress being very aware of how different degree of disturbance affect their state and choosing behaviours to mitigate stress.
I find it difficult to deduce where these individuals had travelled from.
It did not seem they were locals (in the sense that they came there every day because the roe deer subpopulations live very closely to one another and they can be separated by a few metres, e.g., by a river or a road) but they did not arrive from the typically observed neighbouring population, either.
They appeared to represent some third group.
I do not believe they were dispersing individuals because I do not think that roe deer would disperse in groups.
Dispersal is so low in roe deer that hardly they would evolve group dispersing behaviour.
I think they were individuals who were perhaps exploring new habitats and this was not the first time but perhaps third or fourth time they had visited there.
They also apparently lived in a similar habitat because they were equipped to handle the local disturbances.
It is simply curious where they lived because on this side of the road there is not much of a habitat.
The other potential subpopulation they might have arrived from (judging by the direction whence they emerged) is found over the river.
The temperatures have been freezing and the ice is rather thick on the river but mostly on the sides.
The water level was very high during late autumn and the stream was rather turbulent and in most areas the river has not frozen over thoroughly.
There are segments of the river that I cannot access (private property) and there is a possibility that the roe deer have found a passage across the river in one of the few spots where ice cover is contiguous.
I find it difficult to believe that they would have ventured to swim across because the water is now very deep and being wet during winter is no fun (although red deer still wade across).
If these two individuals were, indeed, from the neighbouring population and they had found a way across the river, I have an explanation of their ‘origin’.
As I mentioned, one of the individuals was darker in colouring, similar to the subpopulation which lives on this side of the river and forages on that field frequently.
Accordingly, this individual might be the descendant of the subpopulation on this side of the river or this individual might have dispersed from this side of the river to the opposite side (which is just a few tens of metres from its natal range).
If the individual had dispersed from this side of the river, it might have led the other individual (from the subpopulation on the other side of the river) across to explore and to forage in its natal range.
On the other hand, the two individuals did not enter the best foraging grounds that a dispersing individual would have been familiar with.
As I ventured to guess, the lighter-coloured individual seemed older or at least more experienced.
If it were so, the darker individual – while ‘on its former turf’ – might not have been as knowledgeable as to how to act in a situation where this individual is no longer the resident on that range but a visitor from another range.
The darker individual might have followed the lead of its more experienced companion under the circumstances of changed social relationships between the darker individual and its former subpopulation despite the darker individual’s familiarity with the terrain.
If the lighter individual was a male, the other, darker individual would most likely have been a female and if she led the male across to explore the habitat which was new to the male, it would be suggestive of leadership and initiative relationships between sexes in roe deer.
In fact, on several occasions, I have noticed the male keeping vigilance while the females (and their young) are feeding.
Perhaps there is some labour division between sexes in group situations.
***
On Jan 19, 2024, I went to inspect the ice bridge condition over the river in the section where the roe deer should have crossed to reach that field.
I could not access the very sector but apparently during the last week when temperatures, once more, dropped to about -10°C in several spots the river has frozen all over without the streaming water gap in the middle.
I also saw several roe deer tracks crossing the river in those spots.
Accordingly, it is very likely these two roe deer had arrived from the ‘roe deer neighbourhood’ from the other side of the river.
Notes by Ieva 