Many research publications have been dedicated to dispersal in grey wolves that are some of the nature’s most spectacular dispersers (with respect to distances, overcoming of obstacles, methods used, e.g., swimming rivers, swimming seas, travelling across ice bridges, conquering mountain ranges etc.).
A decent review of many of these dispersal studies (including references) can be found in ‘Patterns and determinants of dispersal in grey wolves (Canis lupus)’ by Morales-González, A. et al., 2021.
Few studies, however, have addressed the habitat use during dispersal which can determine dispersal speed, dispersal distance, tortuous vs. straight dispersal trajectories and other aspects of the important life stage process.
Most of these studies have not been dedicated to habitat use during dispersal specifically but in addition to the main research objective, anthropogenic habitat use during dispersal such as crossing of highways, traversing agricultural landscape and approaching human settlements (as well as the conflict rates it entitles) etc. has been discussed.
A study by Barry, T. et al., 2020, that has looked at these factors predominantly found that wolves were bolder during dispersal (taking higher risks with respect to anthropogenic habitat elements) and that the increased boldness rate was still observed after dispersal (compared to the boldness demonstrated in the natal habitat) even when the availability of anthropogenic / non-anthropogenic habitats had been accounted for.
Other studies address the important issue of habitat connectivity and the available migration routes.
My curiosity, meanwhile, lies with the use of habitats during dispersal when analyzed from two perspectives:
- landscape features that wolves tend to perhaps follow or keep notice of in order to ensure survival during dispersal and in order to evaluate the suitability of the lands travelled to a wolf’s purpose;
- travelling behaviour while on habitats similar vs. dissimilar to natal habitat.
Our knowledge regarding wolf decisions during migration is rather scarce.
It is known that wolves are likely looking for a new territory (suitable habitat), mates (local wolf population or at least an individual of the opposite sex) and that they have to adjust to resident wolf densities.
Also, it is known that wolves are impacted by some geographic elements relatively few of which are insurmountable to the great traveller that is the wolf.
However, high mountain ranges, very wide rivers, coastal areas etc. can stop wolf movement if not definitely then for a while resulting in a slower colonization rate in some areas.
Some of the wolves’ decisions during dispersal should be made from the perspective of the individual’s immediate survival (necessity to provide for himself/herself) and from the perspective of the likelihood that other wolves would be encountered at some point (including potential mate) and that the area is adapted to accommodate wolves.
I imagine that it might be easier to base some of these evaluations on what is already known to the wolf (and also – on what ‘feels right’ from the perspective of genetic traits not all of them might have been called for in the natal habitat and some of which might announce their influence upon encountering circumstance that is novel to the individual but that is perhaps not novel to the individual’s genetic inheritance or the individual’s ancestry; although this would be rather more difficult to study).
It might be interesting to study whether wolf use of habitats crossed during dispersal is different when the wolf traverses habitats that have resources, landscape elements, local climate, local weather etc. similar to those that the wolf grew up surrounded by and that the wolf already knows to exploit.
It is not easy to predict how such use might affect quantifiable aspects of wolf’s dispersal such as timing, distance, speed, trajectory.
For example, it is possible that ‘familiar-feeling’ habitats are utilized for a longer time because the wolf is more capable to navigate itself in this setting and therefore such habitats are more suitable for satisfying the basic needs of finding food, shelter etc.
Similarly, the wolf might estimate that habitats similar to its natal habitat can apparently be used by wolves because wolves are already making use of such habitats (i.e., the natal habitat) and a mate can therefore be found there as well as a territory established suited for a family’s requirements (just like the similar habitat/landscape once suited the needs of the wolf’s own natal pack that bred successfully).
Accordingly, habitats similar to wolf’s natal habitat might be explored for a longer while deviating from the straight trajectory and lowering the speed in order to determine the qualities and local wolf population status and to make the final judgement over staying or moving on.
On the other hand, ‘familiar-feeling’ habitats might speed up the travel if the wolf has not decided to ‘investigate’ or if the wolf is in no need to rest and to replenish after a longer journey through less accommodating areas.
The ‘ease of travel’ might arise out of faster prey acquisition rates in habitats that the wolf already knows how to hunt in.
Also, the wolf might be better capable of locating linear landscape elements (such as forest dirt roads, seismic lines, pipelines etc. – see, e.g., Dickie, M. et al., 2016) that facilitate travel.
Therefore, it cannot be claimed with confidence that the wolf would move slowly through more familiar landscapes, nor it can be claimed that the wolf would necessarily move faster.
It depends on the wolf’s former experience (e.g., need to rest, traumatic experiences in unfamiliar settings etc.), the wolf’s decisions on settling down or moving on (that can be impacted also by the finding or the not finding of a mate), the wolf’s character (resolve to explore or caution to dismiss ‘nice enough’ options) as well as other possible factors.
However, it would be interesting to track wolf’s decisions more closely during dispersal and to analyze the use of habitats the wolf encounters.
It might be curious to see how a wolf treats habitats that are very dissimilar to its native range and that might even lie on the border of the species’ range.
In such ‘unfamiliar-feeling’ places the wolf might also slow down to move cautiously, to explore, to find prey that might be very different from the prey that used to be hunted ‘back at parents’ home’, to assess whether the climate conditions are at all suitable and bearable etc.
On the other hand, the wolf might speed up the travel in order to avoid risks of starving or facing dangers that are new to the wolf.
These decisions might be impacted by the wolf’s boldness and curiosity but also by the degree of threat that the wolf thinks the novel habitat poses.
Possibly, the choices also depend on the wolf’s age and sense of purpose.
If the wolf has left the natal range as a subadult (not having reached sexual maturity yet), it is conceivable that lesser pressure is felt to settle down at once and to locate resources that are essential for breeding.
Also, the wolf’s physical condition (general fitness but also life history, injuries suffered back in the natal range or on the way etc.) might pose constraints or open up opportunities.
Another particular concerning wolf dispersal is the orientation by certain landscape features.
For example, the wolf must bear in mind that food will be needed and the wolf might orient itself with respect to landscape elements and habitat types that are utilized by the wolf’s prey and where encounters with prey are likely.
Thus, the wolf might actually follow features that are not necessary to a wolf directly but that are necessary for its known prey.
E.g., a wolf in winter wolves do not really need to have significant water intake from ice-free sources and wolves, in general, can satisfy much of their liquid requirements through the consumption of prey biomass which contains a high percentage of water content.
However, prey species might aggregate in the proximity of waterways due to the need to drink but also due to the vegetation associations with water.
It is possible that wolves, too, would stick closer to water bodies simply because of the probability of locating prey.
A side note – it would be interesting to trace wolf use of habitats during dispersal by comparing the general habitat use in prey species on wolf’s natal range vs. the habitat use in species on the new landscape (or random habitat use).
Perhaps prey species habitat use is not the most adequate measure because wolves do not follow prey densities per se but rather they travel along routes where prey species can be met and killed.
Regardless, these routes might vary between different prey species and there could be discrepancies if the wolf travelled through habitats that hosted white-tailed deer while the wolf was born on range where elk were predominant.
At some point, is is possible that the wolf learns the ‘new ways’ and adapts its ‘route-planning’.
These choices (by the wolf and the prey) might also be reflected in tree species composition or habitat types, e.g., if the wolf initially keeps closer to open grassland habitats (even if they are scarcer) while the local prey community is adapted to utilizing forested areas.
Of course, during dispersal, wolves might rely on more opportunistic and smaller prey that is easily acquired by a single individual (or by a pair on occasions when a couple roams together before settling down in a territory).
However, apart from livestock conflict potential, to my knowledge, prey selectivity and hunting strategies during dispersal have not been studied at all.
I believe it would be an interesting topic, especially, from the perspective of prey switching as adaptive behaviour and the quickness and readiness with which a wolf adapts to the new dietary resources.
This could manifest in changes in the wolf’s habitat use as the wolf grows familiar with the local conditions and the likeliest prey encounter/prey kill sites.
Diel activity patterns might also be of relevance both with respect to prey availability and with respect to shifts in latitudes.
In different areas, wolves acquire rather specific diel activity patterns and while prey usually adapts to the predator diel activity, a lone predator might be forced to take notice of prey diel activity patterns, as well, that could be dissimilar to those experienced on the natal range.
Generally, it would be curious to see how the dispersing wolf reacts if environmental variables in the new area become substantially different to those of the natal range.
For example, daylight hour changes with latitudes might be confusing to an individual who travels, e.g., from Oregon to California (like wolf OR-7 did).
Considerably higher or lower humidity/temperature levels or novel weather phenomena as well as altitudinal atmospheric conditions might be either avoided or explored by the dispersing wolf.
An individual might choose to spend a longer time in some area merely to determine whether it is liveable because, in some cases, it has to be determined over a period exceeding few days.
It has fascinated me why wolves sometimes settle in areas with no other wolves around.
Perhaps there is a ‘point of no return’.
Wolves do not always disperse once and forever.
They are known to travel back to their natal pack as, for example, in the case of the female wolf in study by Fritts, S.H & Mech, L.D., 1981 where the individual travelled at least 138 km (straight line distance) from her natal range but a traumatic experience (finding herself within an area of extensive wildlife) forced her to return to her natal pack in autumn (which she possibly left once more in the winter).
She had spent a approximately a couple of months travelling and she had covered a great distance but she returned (and other cases have been registered where wolves have returned even after a year or longer absences).
However, the ‘point of no return’ might constitute several conditions.
The aforementioned female left a range of increasing wolf population density which might have triggered her dispersal (scarce resources) and which might have caused her to disperse once more after the failed attempt.
If the wolf population density is too high or if the individual has dispersed after a pack break-up due to mortality or other factors, the return might not be an option.
Some distances (e.g., > 600 km) might be too great to be covered twice or appear too great for the individual, especially, if the journey has been arduous and the individual has exhausted some internal resources for exploration, curiosity and a will to keep going.
Thus, an individual might remain in some area despite lack of potential mates – in hopes that other wolves would arrive and that the newly formed couple would thereby prosper from the opportunity to carve out their range where no other wolves can interfere with their rule.
To resume the former line or reasoning, novel types of habitats that present new diel patterns, new climatic / weather conditions, new prey basis, new vegetation communities etc. hold the potential of providing abundant resources for a new family.
If the wolf has come from area with great competition pressure from other predators or scavengers, the individual might discover relief in an area that is very dissimilar to the natal range and that might even difficult to adapt to initially but that offers lower competitive pressure.
In some cases, personally, I believe that the wolf might be curious to explore its own physical capabilities and constraints or even to explore traits that have been dormant in the natal habitat but that are present through genetic inheritance.
I would enjoy studies dedicated to wolf resource use patterns and wolf hunting strategies during dispersal.
Notes by Ieva 