I have encountered several publications dedicated to the use of carcasses (mortality due to predation, starvation etc.) by scavengers (e.g., Selva, N. et al., 2003, Wenting, E. et al., 2022).
There are also publications evaluating these carcass sites as potential hotspots where the localized concentrations of nutrients benefit plant communities and habitat heterogeneity is enhanced (Johnson-Bice, S.M. et al., 2023).
I became interested in two additional issues.
1
Do prey species of the scavengers (and also predators who produced the carcass) alter they behaviour with respect to the distribution of large, durable carcasses on the landscape?
Some apex predators, for example, wolves are known to kill very large ungulates (e.g., moose or even bison).
The carcasses of the large ungulates can become more permanent landscape features that are visited and revisited by scavengers on a long-term basis (especially, during winter when snowpack as well as freeze and thaw cycles bear influence on the accessibility of carcass resource).
These sites could turn into places where predation risk is higher due to an increased probability of predator (scavenger) use.
If such places endure over longer periods, prey species might learn to adapt their distribution and movement accounting for the higher risk patches.
Thus, the lush vegetation might be also the result of reduced herbivory pressure (in addition to nutrient deposits).
I have seen videos where herbivores actually attend to carcass sites and even scavenge on the carcasses (in order to obtain such limited nutrients as minerals that can be obtained from bones).
However, the overall visitation rate might attest to slight or moderate avoidance.
If this were the case, these scavenger-frequented sites could assist in regeneration of some faster-growing species (outgrowing herbivory level or approaching the level where safety is reached soon) or establishment of vulnerable species.
It would be interesting to determine whether carcass sites are included in landscape of fear elements (in addition to poor-visibility high-bank riparian zones or coarse woody debris).
It would also be interesting to determine whether habitat and microhabitat types that can be considered typical kill sites (not prey encountering sites), i.e., sites where large carcasses are likelier to occur, represent more successful regeneration of vegetation that is vulnerable to herbivory not by the main prey species (because kill sites could also be sites that are avoided due to ‘everyday’ predation risk) but by herbivores that are the prey of other scavengers (such as smaller herbivores that are not hunted, e.g., by wolves but by foxes or coyotes).
2
If scavengers tend to modify their own routes in order to visit and revisit carcass sites, their distribution in the landscape might become more predictable over the period which is necessary to consume the carcass fully.
The ability by scavenger prey species to adjust their behaviour to the distribution of carcasses (and their predators) depends on the size of the carcass.
Thus, in places where such predators as wolves provide large carcasses that are more ‘durable’ and where these carcasses are provided more evenly throughout the season (not merely the end of the winter where larger die-offs can be expected due to weakened state of large mammals), the prey species of scavengers might be better able to prognosticate the movements of their predators on the landscape.
Thus, wolves could indirectly benefit the prey species of mesopredators-scavengers through creating a route of carcasses along which the scavengers might travel and which the prey species can learn to avoid.
If this avoidance is possible not merely during one month but during the entire winter period, the general survival of the prey species might be improved.
Similarly, if mesopredators-scavengers track wolves anticipating fresh carcasses (behaviour observed in, e.g., coyotes and wolverines who also predate on smaller mammals), their prey species might learn to avoid wolves despite the wolves themselves posing little risk to them.
In order to assess the profitability of avoiding wolves (followed by mesopredators), it would be important to know whether wolves demonstrate a more predictable pattern of habitat use than mesopredators (when they do not follow wolves).
Some studies suggest that wolves can have a rather regular use of travel routes and their territory (e.g., revisiting the same territorial boundary every 6 – 8 days in a clockwise pattern, Hillborg, P. 2006).
I am not aware of such studies regarding the regularity of space use in mesocarnivores but it might be possible that the predictability of wolf space use in combination with their association with mesopredators might facilitate survival of some mesopredator prey species who could learn to avoid: 1. long-us carcass sites; 2. wolf-frequented areas that are also frequented by mesopredators.
Notes by Ieva 