This morning I observed two roe deer on a harvested, snow-covered field.
One of the deer had been standing on the field, possibly foraging before I arrived but then demonstrating some vigilance as it tried to figure out if I was there or not (it was very dark – several hours before civil twilight, not to mention dawn).
The other deer was perhaps a bit smaller and it came out of a small grove of trees.
These deer had not been able to see one another prior to the second deer’s emergence out in the open (but it is, of course, possible that they had only separated briefly, e.g., minutes or half an hour ago and thus the return of the smaller deer was not unexpected).
It was very… well, not really as much dark as it was grey 🙂 A very grey weather (new moon, overcast sky). Therefore, I cannot say if either of these deer had antlers.
My guess would be that they did not but I could be wrong.
That summer, I had frequently observed a roe deer mother and her fawn in that same spot and these could have been the same individuals but they are not the only deer in the particular area.
As the smaller deer walked across the field (it was very clear that this smaller deer knew the larger deer very well as it headed straight toward it and I would even venture to claim the smaller deer had been vigilant of the larger deer all the while from the grove – keeping it in sight perhaps for the purpose of feeling more secure in the ‘distant company’ of the adult), the larger deer turned to face it.
The larger deer made a few steps toward the smaller deer but there was no greeting ritual.
I do not know if roe deer even have greeting rituals. I should pay attention to this phenomenon while watching trail camera recordings.
However, it seemed to me that the larger deer was deliberately trying to visually make out the smaller deer’s identity.
It was also more difficult for the larger deer because the smaller deer was approaching at an angle which resulted in the trees and shrubs constituting the background.
Meanwhile, from the perspective of the smaller deer, the larger deer was far more clearly discernible on the snowy field.
There did not appear to be any anxiety and I do not suppose that the larger deer was worried that it was being approached by a stranger.
I simply think that the larger deer was trying to identify the smaller deer as a particular individual out of its winter group.
Then the two deer (without having touched and having only neared one another as close as 1 metre) departed together (in the same direction, at the same pace).
This observation made me wonder about roe deer greeting rituals and also about the mechanisms through which roe deer identify familiar individuals vs. strangers and particular familiar individuals out of the local herd.
It appeared to me that the larger deer was using sight and visual identification might be prevalent in roe deer unlike in many other species where individuals identify one another by scent and therefore they approach one another more closely and frequently engage in rituals that involve touching (e.g., sniffing body parts or touching noses etc.).
This might be consistent with my supposition that roe deer have evolved less pronounced scent due to their predator avoidance strategy (see Scent of roe deer vs. red deer).
Evolution of less pronounced scent might be an anti-predator strategy which then also impacts social processes.
Also, if I am correct, the larger deer identified the smaller deer from its frontal features (as the smaller deer was headed straight at the larger deer and the larger deer turned around to face it frontally).
On the other hand, roe deer are not predators and therefore their vision is not fully frontal.
Still, the eyes are located more frontally than, e.g., in red deer or bison.
Mostly, I have not noticed that roe deer would try to spot things by turning their head slightly from the side in order to take in the lateral perspective.
Perhaps this adaptation is also somehow related to roe deer life strategies but I have not yet read any research on the field of vision in roe deer compared to other ungulates.
For example, if roe deer tend to freeze in order to let danger pass by, they still would prefer to keep an eye (eyes) on the threat.
But, under these conditions, moving the head or only using the scope of one eye might expose the deer to danger (the individual would be spotted by predator as it moves its head) or it might reduce the efficiency of keeping things in check (only one eye is available for vigilance if the head cannot be moved).
It might be interesting to study how roe deer identify one another and whether frontal vision is more efficient in this species than in other ungulates..
While roe deer do not form maternal herds where identification of her offspring by mother is crucial, they tend to aggregate in groups in winter where they probably discriminate between familiar individuals and strangers.
Notes by Ieva 