It is undeniable that wolves, like many other species, rely on scent in order to identify kin, specific individuals, neighbours, unrelated strangers and so on.
Scent-recognition might also be a mechanism behind such important strategies as, for example, inbreeding avoidance where the ability to identify kin can prevent mating among two closely related individuals.
While it is easy to identify relatives while living on the same range, it might be trickier if the related individual is encountered during dispersal (outside of natal range and maybe even very far from it), if considerable time has elapsed since the individuals last saw one another and if perhaps the individuals are related but they have never even met before (e.g., siblings of different litters one of whom has dispersed before the other was born).
It is not know to what extent wolves are capable of identifying their relatives under these confounding conditions.
It is known that packmates can welcome back individuals after months or years of separation but it is not clear to what extent the place of reunion contributes to recognition.
Young wolves keep developing and maturing, i.e., growing in size and probably developing a new scent pattern.
If sexual maturity is onset around two years of age, the hormonal production could alter the individual scent.
Thus, if the two individuals last met as pups, it might be more difficult for them to recognize one another as siblings after, for example, a year or two years because they would gave grown up, commenced hormonal production and otherwise altered their appearance and scent-pattern.
If they meet outside of their natal home, they might be less able to recognize one another without the assistance of the cue that indicates – hereabouts my kin resides.
If at least one of such individuals was older and mature upon separation, the subsequent recognition might be facilitated.
These issues have not been studied that much but they are rather important because they can either promote selection of unrelated mates or reduce the efficiency of inbreeding avoidance.
In this post, however, I wished to discuss another aspect that I believe might be pertinent with these matters and that is the impact of local environment on the scent identity of the individuals inhabiting it.
Scent is formed through different mechanisms but essentially microorganisms (e.g., bacterias) are involved and bacterial fauna might be dissimilar between places.
Also, close proximity to one’s social group would expose the individual to microorganisms of the rest of the group members and the social interactions that the individuals engage in might lead to a more uniform scent through exchange of bacteria.
Thus, it is possible that individuals who share habitat and who interact with one another in close physical contact might develop a scent-identity that is also somewhat similar (more similar than that of their neighbours).
Species such as European badgers even actively create a ‘group scent’ through directly exchanging microorganisms during the allo-marking (pressing their bottoms together).
It is not know to what extent the scent identity is shared in species like wolves who do not actively allo-mark although some marking might occur indirectly (through rolling in another wolf’s urine, secretions etc. as well as through the aforementioned pack socializing, e.g., play which is very intense and implies a lot of body contact in wolves).
The reason why I am curious regarding the degree of environmental and social impact on the individual’s scent-identity is related to the subsequent recognition of individuals as related or not-related.
For example, if wolves disperse and they spend a lot of time outside of their natal range, their scent identity might, as well, become altered due to lack of exposure to social interactions with their kin and also due to exposure with environment that is different from the conditions (microorganism communities) found on their natal range.
Thus, it might be more difficult for an individual to recognize their sibling as such if both wolves have spent a lot of time away from their home (they do not ‘smell like family’ because they no longer ‘smell like home’).
This effect could be exacerbated if the environmental and social ‘inputs’ modify the individual’s own particular microorganism assembly and chemical constitution.
That is to say, if environmental contribution interacts with the individual’s specific ‘scent identity’ through chemical and biological pathways, even the individual’s own body microflora, microfauna and chemistry might become different with respect to the microorganisms and chemicals it is exposed to.
Interestingly, I also wonder if this scent-identity that is perhaps partly derived from environmental influence could be a confounding factor with respect to mate selection among direct neighbours.
I have stated elsewhere (Some thoughts on Isle Royale wolf inbreeding and dispersal/neighbour relations) that it, subjectively, seems to me that wolves do not pick mates out of their immediate neighbouring groups and that the prospective mate has to travel (or the pack individual itself has to travel) over at least a few pack ranges to be accepted as a mate).
I have not quantified this assumption but I wonder if the relationships with neighbours are at all impacted by the relative similarity of scent that these groups might produce due to the fact that they largely share the same habitat and its conditions.
If two wolf packs live in the same habitat type and if they are exposed to very similar microorganisms and chemicals, they might also develop a similar scent-identity which then interferes with mating selection because wolves are averse to inbreeding but this aversion is likely founded on scent identity.
Similarities in scent identity caused by environmental sympatry might lead to aversion also to mating with non-related individuals who live nearby and whose scent identity has been formed by the same environmental conditions.
Personally, I think that wolves can be very effective at tracing any changes in scent-identity and I believe that they follow their neighbours’ fitness status through inspecting the scent-marks left on the boundaries and through determining whether their neighbours are healthy enough to keep the claim on their range.
Perhaps there is something of the sorts of an environmental baseline that the wolves recognize and they compare their own scent responses to this baseline to those of their neighbours.
If their own scent responses to the dynamic environmental conditions seem healthier than the scent modifications of their neighbours, these wolves might be aware that they are better adapted to their environment and its challenges at the time.
One of the reasons why I believe that wolves consider the environmental impacts (and perhaps social impacts) on scent identity is that:
- wolves sometimes pair up with one another and then split up without having produced pups while there is no apparent reason why the mate ‘was the wrong choice’;
- wolves sometimes pair up with close relatives even when they are perhaps quite aware of the kinship while, at other times, they go to extreme lengths in order to avoid inbreeding.
Perhaps before settling (choosing a mate permanently or even choosing a territory permanently), wolves spend some time with the potential partner and in the potential future home in order to evaluate their compatibility.
And maybe this is achieved through observing how their scent (the individual wolf’s own scent as well as that of their partner) changes under the influence of exposure to the local environment and to social interactions.
If the scent changes unfavourably, wolves might decide that they are not compatible either with the partner or the home they were to choose.
One of the objectives of the active scent-marking observed during courtship (alongside a closer bodily contact) in newly formed wolf pairs might be to follow these changes and to determine whether exposure to the habitat and to one another (environmental and social influence) would lead to favourable or unfavourable responses in the scent identities that inform the individuals on their prospective fitness if they stay together and if they stay in this location.
This might be even how wolves choose habitats if they can make the choice at all (because, frequently, in our times, wolves probably cannot be as selective, especially, in densely recolonized areas).
On similar notes, this could be the reason why wolves sometimes seem to make ‘the wrong choice’ by selecting a close relative rather than non-kin to mate with.
Perhaps wolves sense that this individual is more compatible with themselves or with their new habitat than other individuals are, and the wolf then makes the choice not based on their subjective perception (aversion) but on the compatibility for the sake of their pups or even for the sake of their future home.
It might appear strange that inbreeding would be selected over mating with a non-relative but if compatibility is higher (health outlook is greater) with the closer kin, the wolf might overcome the aversion.
Sometimes, indeed, inbreeding has not led to adverse fitness effects and who is to say that, rarely, it might be the better choice (over the rest of the options)?
I should like to repeat that (as in our societies we condemn inbreeding not merely as unhealthy but as sinful) I think it is not a choice the wolf makes out of its own subjective fancy but rather a choice the wolf makes for the benefit of all parties involved (including the home range) regardless of their personal feelings.
I would like to conclude the post with a belief of mine, i.e., that wolves do not consider their home limited to their territory.
I, personally, believe that wolves think of their homes as the vaster region that is inhabited both by themselves and their neighbours.
And I do not suppose that all territorial conflicts are based on personal interest of the involved wolf packs.
I hold to faith that wolves are attempting to provide the best care for their environment, their home, and if they are the better carers of if their neighbours, through some mishap, are no longer fit for caring for this vaster home, wolves might feel obliged to either improve the health of their neighbours (e.g., by posing a threat that encourages the neighbours to take notice of their deteriorating status) or to take over, or, perhaps, to let their own range be taken over.
I think that the ‘open and honest competition’ ensured by leaving scent-marks and inspecting them is not as much about the advertising of defensive intents as it is about advertising the pack’s ability to be the best carers (and their neighbours are then judges over this proficiency who can take gentler or harsher measures if one pack fails).
Perhaps some day I might be able to substantiate my claim but, for now, I let it remain as a folkloric or even mythological assertion.
In some respects, it could be regarded as adaptation to and compatibility with one’s land and one’s nation (within the term of ‘nation’ I include the neighbouring packs).
Notes by Ieva 