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Response of moose hunters to predation following wolf return in Sweden.

Wikenros C, Sand H, Bergström R, Liberg O, Chapron G - PLoS ONE (2015)

Bottom Line: However, the reduction in hunter harvest was stronger within wolf territories compared to control areas without wolves.The reduction in harvest was larger in small (500-800 km2) compared to large (1,200-1,800 km2) wolf territories.We show that the re-colonization of wolves may result in an almost instant functional response by another large predator-humans-that reduced the potential for a direct numerical effect on the density of wolves' main prey, the moose.

View Article: PubMed Central - PubMed

Affiliation: Grimsö Wildlife Research Station, Department of Ecology, Swedish University of Agricultural Sciences, Riddarhyttan, Sweden.

ABSTRACT

Background: Predation and hunter harvest constitute the main mortality factors affecting the size and dynamics of many exploited populations. The re-colonization by wolves (Canis lupus) of the Scandinavian Peninsula may therefore substantially reduce hunter harvest of moose (Alces alces), the main prey of wolves.

Methodology/principal findings: We examined possible effects of wolf presence on hunter harvest in areas where we had data before and after wolf establishment (n = 25), and in additional areas that had been continuously exposed to wolf predation during at least ten years (n = 43). There was a general reduction in the total number of moose harvested (n = 31,827) during the ten year study period in all areas irrespective of presence of wolves or not. However, the reduction in hunter harvest was stronger within wolf territories compared to control areas without wolves. The reduction in harvest was larger in small (500-800 km2) compared to large (1,200-1,800 km2) wolf territories. In areas with newly established wolf territories moose management appeared to be adaptive with regard to both managers (hunting quotas) and to hunters (actual harvest). In these areas an instant reduction in moose harvest over-compensated the estimated number of moose killed annually by wolves and the composition of the hunted animals changed towards a lower proportion of adult females.

Conclusions/significance: We show that the re-colonization of wolves may result in an almost instant functional response by another large predator-humans-that reduced the potential for a direct numerical effect on the density of wolves' main prey, the moose. Because most of the worlds' habitat that will be available for future colonization by large predators are likely to be strongly influenced by humans, human behavioural responses may constitute a key trait that govern the impact of large predators on their prey.

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Simulated and realized changes of moose harvest within wolf territories compared to control areas.The x axis indicates the proportion of females harvested and the y axis indicates the total number of moose harvested. The continuous bands indicate values of harvest rates and proportions of females in harvest (light grey: without wolves, dark grey: with wolves) calculated assuming a moose density that would make sustainable the first year harvest. The arrows indicate the yearly averages of annual total harvest and the proportion of females in this harvest in a) 5+5 year wolf areas, b) 5+5 year control areas, c) 10-year wolf areas, and d) 10-year control areas. The dotted line in a) shows the year when wolves returned and in b) the comparison if wolves had established.
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pone.0119957.g005: Simulated and realized changes of moose harvest within wolf territories compared to control areas.The x axis indicates the proportion of females harvested and the y axis indicates the total number of moose harvested. The continuous bands indicate values of harvest rates and proportions of females in harvest (light grey: without wolves, dark grey: with wolves) calculated assuming a moose density that would make sustainable the first year harvest. The arrows indicate the yearly averages of annual total harvest and the proportion of females in this harvest in a) 5+5 year wolf areas, b) 5+5 year control areas, c) 10-year wolf areas, and d) 10-year control areas. The dotted line in a) shows the year when wolves returned and in b) the comparison if wolves had established.

Mentions: Data showed that hunters reduced the total number of harvested moose (Fig. 5). In the 5+5 year wolf areas the actual average reduction in the total number of moose harvested was 2.1 moose 10 km-2 during the first five years after wolf establishment including a reduction of 1/3 of the proportion of females. This reduction was higher than the estimated reduction needed to compensate for wolf predation (Fig. 5a). Harvest in the 5+5 year control areas also declined but not to an extent that would match the amount theoretically required compensating fully for wolf predation (Fig. 5b), suggesting that the decline in the 5+5 wolf areas was mainly driven by wolf establishment. In the 10-year areas, harvest declined both within wolf territories (Fig. 5c) and in the control areas (Fig. 5d), with the former experiencing a much larger decline.


Response of moose hunters to predation following wolf return in Sweden.

Wikenros C, Sand H, Bergström R, Liberg O, Chapron G - PLoS ONE (2015)

Simulated and realized changes of moose harvest within wolf territories compared to control areas.The x axis indicates the proportion of females harvested and the y axis indicates the total number of moose harvested. The continuous bands indicate values of harvest rates and proportions of females in harvest (light grey: without wolves, dark grey: with wolves) calculated assuming a moose density that would make sustainable the first year harvest. The arrows indicate the yearly averages of annual total harvest and the proportion of females in this harvest in a) 5+5 year wolf areas, b) 5+5 year control areas, c) 10-year wolf areas, and d) 10-year control areas. The dotted line in a) shows the year when wolves returned and in b) the comparison if wolves had established.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4390345&req=5

pone.0119957.g005: Simulated and realized changes of moose harvest within wolf territories compared to control areas.The x axis indicates the proportion of females harvested and the y axis indicates the total number of moose harvested. The continuous bands indicate values of harvest rates and proportions of females in harvest (light grey: without wolves, dark grey: with wolves) calculated assuming a moose density that would make sustainable the first year harvest. The arrows indicate the yearly averages of annual total harvest and the proportion of females in this harvest in a) 5+5 year wolf areas, b) 5+5 year control areas, c) 10-year wolf areas, and d) 10-year control areas. The dotted line in a) shows the year when wolves returned and in b) the comparison if wolves had established.
Mentions: Data showed that hunters reduced the total number of harvested moose (Fig. 5). In the 5+5 year wolf areas the actual average reduction in the total number of moose harvested was 2.1 moose 10 km-2 during the first five years after wolf establishment including a reduction of 1/3 of the proportion of females. This reduction was higher than the estimated reduction needed to compensate for wolf predation (Fig. 5a). Harvest in the 5+5 year control areas also declined but not to an extent that would match the amount theoretically required compensating fully for wolf predation (Fig. 5b), suggesting that the decline in the 5+5 wolf areas was mainly driven by wolf establishment. In the 10-year areas, harvest declined both within wolf territories (Fig. 5c) and in the control areas (Fig. 5d), with the former experiencing a much larger decline.

Bottom Line: However, the reduction in hunter harvest was stronger within wolf territories compared to control areas without wolves.The reduction in harvest was larger in small (500-800 km2) compared to large (1,200-1,800 km2) wolf territories.We show that the re-colonization of wolves may result in an almost instant functional response by another large predator-humans-that reduced the potential for a direct numerical effect on the density of wolves' main prey, the moose.

View Article: PubMed Central - PubMed

Affiliation: Grimsö Wildlife Research Station, Department of Ecology, Swedish University of Agricultural Sciences, Riddarhyttan, Sweden.

ABSTRACT

Background: Predation and hunter harvest constitute the main mortality factors affecting the size and dynamics of many exploited populations. The re-colonization by wolves (Canis lupus) of the Scandinavian Peninsula may therefore substantially reduce hunter harvest of moose (Alces alces), the main prey of wolves.

Methodology/principal findings: We examined possible effects of wolf presence on hunter harvest in areas where we had data before and after wolf establishment (n = 25), and in additional areas that had been continuously exposed to wolf predation during at least ten years (n = 43). There was a general reduction in the total number of moose harvested (n = 31,827) during the ten year study period in all areas irrespective of presence of wolves or not. However, the reduction in hunter harvest was stronger within wolf territories compared to control areas without wolves. The reduction in harvest was larger in small (500-800 km2) compared to large (1,200-1,800 km2) wolf territories. In areas with newly established wolf territories moose management appeared to be adaptive with regard to both managers (hunting quotas) and to hunters (actual harvest). In these areas an instant reduction in moose harvest over-compensated the estimated number of moose killed annually by wolves and the composition of the hunted animals changed towards a lower proportion of adult females.

Conclusions/significance: We show that the re-colonization of wolves may result in an almost instant functional response by another large predator-humans-that reduced the potential for a direct numerical effect on the density of wolves' main prey, the moose. Because most of the worlds' habitat that will be available for future colonization by large predators are likely to be strongly influenced by humans, human behavioural responses may constitute a key trait that govern the impact of large predators on their prey.

Show MeSH