Overview
Wolverines function primarily as scavengers, taking advantage of carcasses left by other predators. However, wolverines are also efficient predators themselves, preying on everything from small rodents and birds to larger ungulates. Because most predators will scavenge in addition to killing their own prey, this alters predation effects and implies that one cannot treat these as independent processes.
Prey:
In Scandinavia, prey species are more likely to face predation by wolverines in the summer, when vulnerable reindeer calves are abundant, and individual kill rates are negatively related to local reindeer body mass. This relationship is absent in winter. The probability of scavenging is higher in winter and increases with decreasing local reindeer body mass, likely as a response to increased carrion supply.
Semi-domestic reindeer comprise the majority of wolverines' diet in Sweden (whether through scavenging or predation). However, for the non-alpine forest-dwelling wolverine population in Sweden, reindeer comprise virtually 0% of wolverines' diet. Research into this population's food sources and feeding strategies is ongoing.
Northern wolverines' reliance on semidomestic reindeer within the Sámi reindeer husbandry area creates conflict, and in the past led to decimation of wolverine populations. Conservation performance payments to Sámi reindeer herders for wolverine reproductions has been instrumental to their recovery in Sweden. Adult female wolverines were significantly less exposed to illegal killing and this allowed the population to more than double in a decade.
Other Predators:
Scandinavian wolverines seem to have a special relationship to Eurasian lynx. Because wolverines rely on scavenging opportunities (particularly during the winter), predation events by lynx provide critical resources. This should not imply a cooperative relationship, however, as lynx and wolverines actively avoid each other, with the degree of avoidance being greater for simultaneous than time-delayed predator locations. This risk-avoidance strategy appears to be reactive (rather than predictive). This relationship is crucial to successful management and conservation of wolverines, particularly within reindeer husbandry areas.
Since wolverines have adapted to co-exist with lynx, exploiting lynx-killed reindeer carcasses while avoiding potential encounters, the combined presence of both predators may reduce wolverine kill rate and thus the total impact of these predators on semi-domestic reindeer in Scandinavia. But while the presence of lynx may reduce the kill-rate of wolverines on reindeer, the co-existence relationship does not appear to significantly increase lynx kill rate. This suggests that if the management goal is to maintain successful populations of both species while simultaneously minimizing predation events on reindeer, the kill rate will be lower if wolverine and lynx co-exist in the same areas, rather than attempting to maintain separated populations.
For the non-alpine, forest wolverine population, a similar sympatric relationship may exist between wolverines and wolfs. Research in this area is ongoing. This southern population also appears to rely on food sources from another predator, humans, as the wolverines scavenge from hunting remains.
Prey:
In Scandinavia, prey species are more likely to face predation by wolverines in the summer, when vulnerable reindeer calves are abundant, and individual kill rates are negatively related to local reindeer body mass. This relationship is absent in winter. The probability of scavenging is higher in winter and increases with decreasing local reindeer body mass, likely as a response to increased carrion supply.
Semi-domestic reindeer comprise the majority of wolverines' diet in Sweden (whether through scavenging or predation). However, for the non-alpine forest-dwelling wolverine population in Sweden, reindeer comprise virtually 0% of wolverines' diet. Research into this population's food sources and feeding strategies is ongoing.
Northern wolverines' reliance on semidomestic reindeer within the Sámi reindeer husbandry area creates conflict, and in the past led to decimation of wolverine populations. Conservation performance payments to Sámi reindeer herders for wolverine reproductions has been instrumental to their recovery in Sweden. Adult female wolverines were significantly less exposed to illegal killing and this allowed the population to more than double in a decade.
Other Predators:
Scandinavian wolverines seem to have a special relationship to Eurasian lynx. Because wolverines rely on scavenging opportunities (particularly during the winter), predation events by lynx provide critical resources. This should not imply a cooperative relationship, however, as lynx and wolverines actively avoid each other, with the degree of avoidance being greater for simultaneous than time-delayed predator locations. This risk-avoidance strategy appears to be reactive (rather than predictive). This relationship is crucial to successful management and conservation of wolverines, particularly within reindeer husbandry areas.
Since wolverines have adapted to co-exist with lynx, exploiting lynx-killed reindeer carcasses while avoiding potential encounters, the combined presence of both predators may reduce wolverine kill rate and thus the total impact of these predators on semi-domestic reindeer in Scandinavia. But while the presence of lynx may reduce the kill-rate of wolverines on reindeer, the co-existence relationship does not appear to significantly increase lynx kill rate. This suggests that if the management goal is to maintain successful populations of both species while simultaneously minimizing predation events on reindeer, the kill rate will be lower if wolverine and lynx co-exist in the same areas, rather than attempting to maintain separated populations.
For the non-alpine, forest wolverine population, a similar sympatric relationship may exist between wolverines and wolfs. Research in this area is ongoing. This southern population also appears to rely on food sources from another predator, humans, as the wolverines scavenge from hunting remains.
Our Related Peer-Reviewed Research:
(For student theses, see here.)
(For student theses, see here.)
Scavenging vs. Predation (2016):
We examined the relative importance of predation vs. scavenging and the mechanisms driving the variation between the two, using data on 41 GPS-collared wolverines in four different Scandinavian sites. The most important factor affecting the relative extent of predation and scavenging was mean prey body mass. Predation was more pronounced in summer, when vulnerable reindeer calves are abundant and individual kill rates were negatively related to local reindeer body mass. The probability of scavenging was higher in winter and increased with decreasing local reindeer body mass, likely as a response to increased carrion supply. Wolverine feeding strategy was further influenced by predictable anthropogenic food resources and the presence of a top predator, Eurasian lynx, which provided a continuous carrion supply promoting scavenging. Our results suggest that wolverine feeding strategies are flexible and strongly influenced by seasonally-dependent responses to prey body condition in combination with carrion supply.
Mattisson, J., G. R. Rauset, J. Odden, H. Andrén, J. D. C. Linnell, and J. Persson. 2016. Predation or scavenging? Prey body condition influences decision-making in a facultative predator, the wolverine. Ecosphere 7(8):e01407. 10.1002/ecs2.1407 PDF
Wolverine & Lynx Use of Shared Resources (2016):
Using Eurasian lynx and wolverines, we tested the hypotheses that tracking among heterospecifics and reactive responses to potential risk decreases the probability of an agonistic encounter when predators access shared food resources, thus facilitating coexistence. Lynx and wolverines actively avoided each other, with the degree of avoidance being greater for simultaneous than time-delayed predator locations. In general, lynx stayed longer and were more stationary around reindeer carcasses than wolverines. However, when both predators were present at the same time around a carcass, lynx shortened their visits, while wolverine behavior did not change. Our results support the idea that risk avoidance is a reactive, rather than a predictive, process. Since wolverines have adapted to coexist with lynx, exploiting lynx-killed reindeer carcasses while avoiding potential encounters, the combined presence of both predators may reduce wolverine kill rate and thus the total impact of these predators on semi-domestic reindeer in Scandinavia. Consequently, population management directed at lynx may affect wolverine populations and human-wolverine conflicts.
Lopez-Bao, J, Mattisson, J., Persson, J., Aronsson, M. & Andrén, H. 2016. Tracking neighbours promotes large carnivores’ coexistence. Scientific Reports. doi:10.1038/srep23198. PDF
Improving Wolverine Conservation Through Performance Payments (2015):
We show that conservation performance payments to Sami reindeer herders for wolverine reproductions has been instrumental in the recovery of wolverines in Sweden. Adult female wolverines were significantly less exposed to illegal killing and this allowed the population to more than double in a decade. We argue that this program provides protection for adult female wolverines through a combination of direct monetary value and indirect protection because of monitoring activities. The program’s success, even in a system where livestock is the main prey for the predator, reveals an exceptional potential for future implementations in large carnivore conservation.
Persson, J., Rauset, G.R., and Chapron, G. 2015. Paying for an endangered predator leads to population recovery. Conservation Letters 8 (5): 345-350 doi:10.1111/conl.12171. PDF
We examined the relative importance of predation vs. scavenging and the mechanisms driving the variation between the two, using data on 41 GPS-collared wolverines in four different Scandinavian sites. The most important factor affecting the relative extent of predation and scavenging was mean prey body mass. Predation was more pronounced in summer, when vulnerable reindeer calves are abundant and individual kill rates were negatively related to local reindeer body mass. The probability of scavenging was higher in winter and increased with decreasing local reindeer body mass, likely as a response to increased carrion supply. Wolverine feeding strategy was further influenced by predictable anthropogenic food resources and the presence of a top predator, Eurasian lynx, which provided a continuous carrion supply promoting scavenging. Our results suggest that wolverine feeding strategies are flexible and strongly influenced by seasonally-dependent responses to prey body condition in combination with carrion supply.
Mattisson, J., G. R. Rauset, J. Odden, H. Andrén, J. D. C. Linnell, and J. Persson. 2016. Predation or scavenging? Prey body condition influences decision-making in a facultative predator, the wolverine. Ecosphere 7(8):e01407. 10.1002/ecs2.1407 PDF
Wolverine & Lynx Use of Shared Resources (2016):
Using Eurasian lynx and wolverines, we tested the hypotheses that tracking among heterospecifics and reactive responses to potential risk decreases the probability of an agonistic encounter when predators access shared food resources, thus facilitating coexistence. Lynx and wolverines actively avoided each other, with the degree of avoidance being greater for simultaneous than time-delayed predator locations. In general, lynx stayed longer and were more stationary around reindeer carcasses than wolverines. However, when both predators were present at the same time around a carcass, lynx shortened their visits, while wolverine behavior did not change. Our results support the idea that risk avoidance is a reactive, rather than a predictive, process. Since wolverines have adapted to coexist with lynx, exploiting lynx-killed reindeer carcasses while avoiding potential encounters, the combined presence of both predators may reduce wolverine kill rate and thus the total impact of these predators on semi-domestic reindeer in Scandinavia. Consequently, population management directed at lynx may affect wolverine populations and human-wolverine conflicts.
Lopez-Bao, J, Mattisson, J., Persson, J., Aronsson, M. & Andrén, H. 2016. Tracking neighbours promotes large carnivores’ coexistence. Scientific Reports. doi:10.1038/srep23198. PDF
Improving Wolverine Conservation Through Performance Payments (2015):
We show that conservation performance payments to Sami reindeer herders for wolverine reproductions has been instrumental in the recovery of wolverines in Sweden. Adult female wolverines were significantly less exposed to illegal killing and this allowed the population to more than double in a decade. We argue that this program provides protection for adult female wolverines through a combination of direct monetary value and indirect protection because of monitoring activities. The program’s success, even in a system where livestock is the main prey for the predator, reveals an exceptional potential for future implementations in large carnivore conservation.
Persson, J., Rauset, G.R., and Chapron, G. 2015. Paying for an endangered predator leads to population recovery. Conservation Letters 8 (5): 345-350 doi:10.1111/conl.12171. PDF
Estimated Annual Predation on Reindeer (2012):
We used a long-term, large-scale database and Bayesian models to estimate the impacts of Eurasian lynx, wolverine, and brown bear on harvest of semi-domesticated reindeer by Sámi pastoralists in Sweden. The average annual harvest of reindeer averaged 25% of the population. Annual harvest declined by 96.6 reindeer for each lynx family group in a management unit and by 94.3 for each wolverine reproduction. We failed to detect effects of predation by brown bear. The mechanism for effects of predation on harvest was reduced population growth rate. The rate of increase of reindeer populations declined with increasing abundance of lynx and wolverine. The density of reindeer, latitude, and weather indexed by the North Atlantic Oscillation also influenced reindeer population growth rate. We conclude that there is a biological basis for compensating the Sámi reindeer herders for predation on reindeer.
Hobbs, T., Andrén, H., Persson, J., Aronsson, M. & Chapron, G. 2012. Native predators reduce harvest of reindeer by Sámi pastoralists. Ecological Applications 22 (5): 1640-1654. PDF
Importance of Lynx-killed Reindeer, and Kill Rates (2011):
We examined the composition and use of food resources by wolverines and in particular the relative importance of lynx-killed reindeer in wolverine diet in northern Sweden. We also examined the influence of wolverine scavenging on lynx kill rate. We found that 52% of carcasses visited by wolverines were lynx-killed reindeer, but only 11% were wolverine-killed reindeer. Of all wolverine locations at carcasses, 28% were on lynx-killed and 24% on wolverine-killed reindeer. Lynx predation rate on reindeer was nine times higher than that of wolverines. Wolverines scavenged 68% of available lynx-killed reindeer, 29% of which were still being used by lynx at wolverine arrival. Still, wolverine scavenging had a limited influence on lynx kill rate. Wolverines appear to benefit from coexistence with lynx through increased scavenging opportunities. We suspect that lynx presence reduces wolverine predation on reindeer due to increased scavenging opportunities. These results may have important implications for carnivore management in reindeer husbandry areas.
Mattisson, J., Andrén, H., Persson, J. & Segerström, P. 2011. Influence of intraguild interactions on resource use by wolverines and Eurasian lynx. Journal of Mammalogy 92 (6): 1321-1330. PDF
Effect of Predator Co-Existence on Reindeer (2011):
Predators often interact with one another in different ways (e.g. interspecific competition, intra guild predation and kleptoparasitism) that may influence the total predation on a common prey. We estimated the total number of semidomestic reindeer killed by Eurasian lynx and wolverine at different relative abundances of the two species using a model based on diet, food requirements of lynx and wolverine and amount of food available on a reindeer. Our model suggests that total predation decreases by approximately 7.9% if wolverines scavenge on lynx-killed reindeer, compared to a model without scavenging. If the management goal is a constant number of predators, the model suggests that the total kill rate will be lowest in areas with only wolverines, as the estimated wolverine kill rate is much lower than the lynx kill rate. Our model showed that it is unlikely that the lowest number of reindeer killed per predator individual will be at a certain lynx-wolverine ratio, which would appear if lynx consumption of killed reindeer is low and wolverines are very efficient finding lynx-killed reindeer. However, if the management goal is a constant number of lynx and wolverines, the model suggests that the total predation is lower, if lynx and wolverines coexist in the same area compared to existing separately in different areas.
Andren, H., Persson, J., Mattisson, J. & Danell, A. 2011. Modelling the combined effect of an obligate predator and a facultative predator on a common prey – lynx and wolverine predation on reindeer. Wildlife Biology 17(1): 33-41. PDF
We used a long-term, large-scale database and Bayesian models to estimate the impacts of Eurasian lynx, wolverine, and brown bear on harvest of semi-domesticated reindeer by Sámi pastoralists in Sweden. The average annual harvest of reindeer averaged 25% of the population. Annual harvest declined by 96.6 reindeer for each lynx family group in a management unit and by 94.3 for each wolverine reproduction. We failed to detect effects of predation by brown bear. The mechanism for effects of predation on harvest was reduced population growth rate. The rate of increase of reindeer populations declined with increasing abundance of lynx and wolverine. The density of reindeer, latitude, and weather indexed by the North Atlantic Oscillation also influenced reindeer population growth rate. We conclude that there is a biological basis for compensating the Sámi reindeer herders for predation on reindeer.
Hobbs, T., Andrén, H., Persson, J., Aronsson, M. & Chapron, G. 2012. Native predators reduce harvest of reindeer by Sámi pastoralists. Ecological Applications 22 (5): 1640-1654. PDF
Importance of Lynx-killed Reindeer, and Kill Rates (2011):
We examined the composition and use of food resources by wolverines and in particular the relative importance of lynx-killed reindeer in wolverine diet in northern Sweden. We also examined the influence of wolverine scavenging on lynx kill rate. We found that 52% of carcasses visited by wolverines were lynx-killed reindeer, but only 11% were wolverine-killed reindeer. Of all wolverine locations at carcasses, 28% were on lynx-killed and 24% on wolverine-killed reindeer. Lynx predation rate on reindeer was nine times higher than that of wolverines. Wolverines scavenged 68% of available lynx-killed reindeer, 29% of which were still being used by lynx at wolverine arrival. Still, wolverine scavenging had a limited influence on lynx kill rate. Wolverines appear to benefit from coexistence with lynx through increased scavenging opportunities. We suspect that lynx presence reduces wolverine predation on reindeer due to increased scavenging opportunities. These results may have important implications for carnivore management in reindeer husbandry areas.
Mattisson, J., Andrén, H., Persson, J. & Segerström, P. 2011. Influence of intraguild interactions on resource use by wolverines and Eurasian lynx. Journal of Mammalogy 92 (6): 1321-1330. PDF
Effect of Predator Co-Existence on Reindeer (2011):
Predators often interact with one another in different ways (e.g. interspecific competition, intra guild predation and kleptoparasitism) that may influence the total predation on a common prey. We estimated the total number of semidomestic reindeer killed by Eurasian lynx and wolverine at different relative abundances of the two species using a model based on diet, food requirements of lynx and wolverine and amount of food available on a reindeer. Our model suggests that total predation decreases by approximately 7.9% if wolverines scavenge on lynx-killed reindeer, compared to a model without scavenging. If the management goal is a constant number of predators, the model suggests that the total kill rate will be lowest in areas with only wolverines, as the estimated wolverine kill rate is much lower than the lynx kill rate. Our model showed that it is unlikely that the lowest number of reindeer killed per predator individual will be at a certain lynx-wolverine ratio, which would appear if lynx consumption of killed reindeer is low and wolverines are very efficient finding lynx-killed reindeer. However, if the management goal is a constant number of lynx and wolverines, the model suggests that the total predation is lower, if lynx and wolverines coexist in the same area compared to existing separately in different areas.
Andren, H., Persson, J., Mattisson, J. & Danell, A. 2011. Modelling the combined effect of an obligate predator and a facultative predator on a common prey – lynx and wolverine predation on reindeer. Wildlife Biology 17(1): 33-41. PDF
