- Email: [email protected]
Costs and Genetic Benefits of Various Sizes of Predator Populations in Sweden—A Comment
Journal of Environmental Management (1996) 48, 411–413
Comment Costs and Genetic Benefits of Various Sizes of Predator Populations in Sweden—A Comment Ivar Mysterud∗, Jerry T. Warren∗ and Leif J. Asheim† ∗Department of Biology, Division of Zoology, Post Box 1050, Blindern, University of Oslo, 0316 Oslo, Norway; †Norwegian Agricultural Economics Research Institute, Post Box 8024, Dep. Oslo 1, Norway Received 24 November 1995; accepted 20 December 1995
In attempting to conserve endangered species such as the brown bear (Ursus arctos), wolf (Canis lupus), wolverine (Gulo gulo) and lynx (Lynx lynx), the biological needs of each species must be addressed. Economic losses borne by traditional users of predator habitat (e.g. livestock owners, reindeer herders) must also be considered. Realized as well as potential losses must be addressed when deciding the degree of protection, in securing viable populations and when excessive livestock losses and subsequent compensation outlays mandate the evaluation of alternative conservation strategies. In a recent issue of the Journal, Boman (1995) attempts to estimate the costs associated with various population sizes of the four large predators in Sweden. Most of the incurred cost is in the form of compensation payments made to Sami reindeer owners, and Boman’s analysis is limited specifically to these costs. Two methods are used, whereby the second is used to check the plausibility of the first: (1) A regression analysis of government compensation payments (dependent variable) and predator populations (independent variables). Reindeer populations are in part also used as an independent variable. (2) An estimation of the maximum cost of the predators’ annual meat consumption, measured in terms of reindeer meat equivalents. Both methods are used to estimate the costs of maintaining an effective population of 500 individuals of each of the four species. Such effective populations equate to a total of 2600 bears, 1850 wolves, 2500 wolverines and 2500 lynx. Using regression analysis (method (1)), Boman arrives at a total cost of SEK 4771 310 000 for an effective population of 500 individuals of each predatory species. Estimation of the maximum annual reindeer meat consumption by these predators (method (2)) yields a cost of SEK 594 730 000 per year, still well above the total value 411 0301–4797/96/120411+03 $18.00/0
1996 Academic Press Limited
412
Predator populations in Sweden
of the Swedish reindeer meat production. Thus, some of the cost estimate based on the regression analysis is rejected and considered implausible. Boman’s estimates reveal that most of the costs (4·5 of the SEK 4·7 billion) obtained by using method (1) is attributed to wolverines. In addition, 175 million is due to wolves. Damage caused by bears and lynx (16·5 and 9·12 million, respectively) is minor by comparison, and more in line with estimated costs to Norwegian sheep farming based upon present and future predator populations (Asheim, 1995). Based on these figures, we suggest two reasons why Boman’s regression analysis failed: (1) The study fails to discuss or to take into account the damage due to surplus killing; the fact that some predators kill more animals than they consume. (2) The study apparently fails to consider that a portion of the damage observed in Sweden may be caused by predators from Norway and Finland. Boman’s second method should normally yield higher costs than the first, since all four predators also have sources of food other than domestic reindeer. The occurrence of surplus killing, which is well documented among bears (Mysterud, 1980), wolves (Miller et al., 1985) and especially wolverines (Lynnebakken, 1995), complicates the analysis, however. Indeed, it is reasonable to assume that actual consumption will not exceed a maximum conceivable quantity. However, Boman’s estimate based upon the regression analysis is lower than the estimated maximum cost of annual meat consumption for bears and lynx only. Closer scrutiny of the data suggests the possibility that the damage caused by the larger and often transient (into Sweden) populations of Norwegian wolverines and Finnish wolves may be greater than that caused by the smaller Swedish populations of these species. That is to say, the actual number of wolves and wolverines for which damage payments are made is likely greater than that used by Boman in his analysis (i.e. strictly Swedish predators). For example, the Norwegian wolverine population of approx. 200 animals (Mysterud and Mysterud, 1995) is located in areas close to the border with Sweden. Many of these animals presumably reproduce and migrate across the border, probably preying on sheep in Norway and on reindeer on both sides of the border. Both the economic costs and the genetic benefits are subsequently shared by the two countries. As for Finnish wolves, the influence of emigrants may be less significant, though even a few wolves could have a significant influence as the Swedish/ Norwegian population is small. For lynx and especially bears, the situation may be reversed. Considerable losses are for example sustained by Norwegian sheep owners due to Swedish bears (Warren and Mysterud, 1995). Such losses are not reflected in Swedish compensation payments. Additional international data could yield quite different results and other regression functions that are perhaps more realistic. Since large predators often cross international borders, we suggest a more Nordic approach to such loss estimates and cost/benefit analysis. A more limited, single-country analysis seems more difficult to justify. Further, if 500 (effective) animals of each of the four large predators were to be realized in each of the Nordic countries, the damage would effectively preclude continued reindeer herding in Scandinavia. Boman’s estimated annual cost of SEK 594 million is considerably higher than the value of the Swedish reindeer meat production, probably rendering such outlays politically unfeasible. Even so, if such costs were tolerated, and measures based on compensation payments were implemented, though against the will of local herders/stock owners, additional social costs would certainly be incurred. Subsequently, a cheaper solution is therefore required. A Nordic solution, with for example effective populations of 500 individuals of
I. Mysterud et al.
413
each predator species, in all of Fennoscandia, seems more realistic. Such a solution would still be within the guidelines set by the Bern Convention. We encourage further discussion on the international and social cost and benefits of recovering predator populations, as well as new estimates based upon Nordic predator damage and population data. References Asheim, L. J. (1995). Økonomiske konsekvenser for sauenæringen (Economic consequences for the sheep industry). In Perspektiver pa˚ rovdyr, ressurser og utmarksnœringer i dagens- og framtidens Norge: En konsekvensutredning av rovviltforvaltningens betydning for sma˚fenœring, reindrift og viltinteresser. (Perspectives on predation, resources and range users in Norway—today and in the future. An environmental impact statement for sheep production, reindeer herding and ungulate hunting interests.) (I. Mysterud and I. Mysterud, eds). pp. 175–202. Final report, KUR-project Biological Institute, University of Oslo. (In Norwegian, English summary). Boman, M. (1995). Estimating costs and genetic benefit of various sizes of predator population: the case of bear, wolf, wolverine and lynx in Sweden. Journal of Environmental Management 43, 349–357. Lynnebakken, T. (1985). Tapsmonster og risikofaktorer for sau (Ovis aries) pa˚ fjellbeite i Ma˚lselv, Troms. (Loss patterns and risk factors for sheep (Ovis aries) on mountain pastures in Ma˚lselv, Troms). Hovedfagsoppgave i økologi til Cand. scient. eksamen ved Univ. i Oslo. 67p. [In Norwegian]. Miller, F. L., Gunn, A. and Groughton, E. (1985). Surplus killings as exemplified by wolf predation on newborn caribou. Canadian Journal of Zoology 63, 295–300. Mysterud, I. and Mysterud, I. (eds) (1995). Perspektiver pa˚ rovdyr, ressurser og utmarksnœringer i dagens- og framtidens Norge: En konsekvensutredning av rovviltforvaltningens betydning for sma˚fenœring, reindrift og viltinteresser. (Perspectives on predation, resources and range users in Norway—today and in the future. An environmental impact statement for sheep production, reindeer herding and ungulate hunting interests). Final report, KUR-project Biological Institute, University of Oslo. 336 p. (In Norwegian, English summary). Mysterud, I. (1980). Bear management and sheep husbandry in Norway with a discussion of predatory behavior significant for evaluation of livestock losses. In Bears: Their Biology and Management. (C. J. Martinka and K. L. McArthur, eds) pp. 233–241. Fourth International Conference on Bear Research and Management. Kalispell, Montana, February 1977. Warren, J. T. and Mysterud, I. (1995). Mortality of domestic sheep in free-ranging flocks in southeastern Norway. Journal Animal Science 73, 1012–1018.
Comment Costs and Genetic Benefits of Various Sizes of Predator Populations in Sweden—A Comment Ivar Mysterud∗, Jerry T. Warren∗ and Leif J. Asheim† ∗Department of Biology, Division of Zoology, Post Box 1050, Blindern, University of Oslo, 0316 Oslo, Norway; †Norwegian Agricultural Economics Research Institute, Post Box 8024, Dep. Oslo 1, Norway Received 24 November 1995; accepted 20 December 1995
In attempting to conserve endangered species such as the brown bear (Ursus arctos), wolf (Canis lupus), wolverine (Gulo gulo) and lynx (Lynx lynx), the biological needs of each species must be addressed. Economic losses borne by traditional users of predator habitat (e.g. livestock owners, reindeer herders) must also be considered. Realized as well as potential losses must be addressed when deciding the degree of protection, in securing viable populations and when excessive livestock losses and subsequent compensation outlays mandate the evaluation of alternative conservation strategies. In a recent issue of the Journal, Boman (1995) attempts to estimate the costs associated with various population sizes of the four large predators in Sweden. Most of the incurred cost is in the form of compensation payments made to Sami reindeer owners, and Boman’s analysis is limited specifically to these costs. Two methods are used, whereby the second is used to check the plausibility of the first: (1) A regression analysis of government compensation payments (dependent variable) and predator populations (independent variables). Reindeer populations are in part also used as an independent variable. (2) An estimation of the maximum cost of the predators’ annual meat consumption, measured in terms of reindeer meat equivalents. Both methods are used to estimate the costs of maintaining an effective population of 500 individuals of each of the four species. Such effective populations equate to a total of 2600 bears, 1850 wolves, 2500 wolverines and 2500 lynx. Using regression analysis (method (1)), Boman arrives at a total cost of SEK 4771 310 000 for an effective population of 500 individuals of each predatory species. Estimation of the maximum annual reindeer meat consumption by these predators (method (2)) yields a cost of SEK 594 730 000 per year, still well above the total value 411 0301–4797/96/120411+03 $18.00/0
1996 Academic Press Limited
412
Predator populations in Sweden
of the Swedish reindeer meat production. Thus, some of the cost estimate based on the regression analysis is rejected and considered implausible. Boman’s estimates reveal that most of the costs (4·5 of the SEK 4·7 billion) obtained by using method (1) is attributed to wolverines. In addition, 175 million is due to wolves. Damage caused by bears and lynx (16·5 and 9·12 million, respectively) is minor by comparison, and more in line with estimated costs to Norwegian sheep farming based upon present and future predator populations (Asheim, 1995). Based on these figures, we suggest two reasons why Boman’s regression analysis failed: (1) The study fails to discuss or to take into account the damage due to surplus killing; the fact that some predators kill more animals than they consume. (2) The study apparently fails to consider that a portion of the damage observed in Sweden may be caused by predators from Norway and Finland. Boman’s second method should normally yield higher costs than the first, since all four predators also have sources of food other than domestic reindeer. The occurrence of surplus killing, which is well documented among bears (Mysterud, 1980), wolves (Miller et al., 1985) and especially wolverines (Lynnebakken, 1995), complicates the analysis, however. Indeed, it is reasonable to assume that actual consumption will not exceed a maximum conceivable quantity. However, Boman’s estimate based upon the regression analysis is lower than the estimated maximum cost of annual meat consumption for bears and lynx only. Closer scrutiny of the data suggests the possibility that the damage caused by the larger and often transient (into Sweden) populations of Norwegian wolverines and Finnish wolves may be greater than that caused by the smaller Swedish populations of these species. That is to say, the actual number of wolves and wolverines for which damage payments are made is likely greater than that used by Boman in his analysis (i.e. strictly Swedish predators). For example, the Norwegian wolverine population of approx. 200 animals (Mysterud and Mysterud, 1995) is located in areas close to the border with Sweden. Many of these animals presumably reproduce and migrate across the border, probably preying on sheep in Norway and on reindeer on both sides of the border. Both the economic costs and the genetic benefits are subsequently shared by the two countries. As for Finnish wolves, the influence of emigrants may be less significant, though even a few wolves could have a significant influence as the Swedish/ Norwegian population is small. For lynx and especially bears, the situation may be reversed. Considerable losses are for example sustained by Norwegian sheep owners due to Swedish bears (Warren and Mysterud, 1995). Such losses are not reflected in Swedish compensation payments. Additional international data could yield quite different results and other regression functions that are perhaps more realistic. Since large predators often cross international borders, we suggest a more Nordic approach to such loss estimates and cost/benefit analysis. A more limited, single-country analysis seems more difficult to justify. Further, if 500 (effective) animals of each of the four large predators were to be realized in each of the Nordic countries, the damage would effectively preclude continued reindeer herding in Scandinavia. Boman’s estimated annual cost of SEK 594 million is considerably higher than the value of the Swedish reindeer meat production, probably rendering such outlays politically unfeasible. Even so, if such costs were tolerated, and measures based on compensation payments were implemented, though against the will of local herders/stock owners, additional social costs would certainly be incurred. Subsequently, a cheaper solution is therefore required. A Nordic solution, with for example effective populations of 500 individuals of
I. Mysterud et al.
413
each predator species, in all of Fennoscandia, seems more realistic. Such a solution would still be within the guidelines set by the Bern Convention. We encourage further discussion on the international and social cost and benefits of recovering predator populations, as well as new estimates based upon Nordic predator damage and population data. References Asheim, L. J. (1995). Økonomiske konsekvenser for sauenæringen (Economic consequences for the sheep industry). In Perspektiver pa˚ rovdyr, ressurser og utmarksnœringer i dagens- og framtidens Norge: En konsekvensutredning av rovviltforvaltningens betydning for sma˚fenœring, reindrift og viltinteresser. (Perspectives on predation, resources and range users in Norway—today and in the future. An environmental impact statement for sheep production, reindeer herding and ungulate hunting interests.) (I. Mysterud and I. Mysterud, eds). pp. 175–202. Final report, KUR-project Biological Institute, University of Oslo. (In Norwegian, English summary). Boman, M. (1995). Estimating costs and genetic benefit of various sizes of predator population: the case of bear, wolf, wolverine and lynx in Sweden. Journal of Environmental Management 43, 349–357. Lynnebakken, T. (1985). Tapsmonster og risikofaktorer for sau (Ovis aries) pa˚ fjellbeite i Ma˚lselv, Troms. (Loss patterns and risk factors for sheep (Ovis aries) on mountain pastures in Ma˚lselv, Troms). Hovedfagsoppgave i økologi til Cand. scient. eksamen ved Univ. i Oslo. 67p. [In Norwegian]. Miller, F. L., Gunn, A. and Groughton, E. (1985). Surplus killings as exemplified by wolf predation on newborn caribou. Canadian Journal of Zoology 63, 295–300. Mysterud, I. and Mysterud, I. (eds) (1995). Perspektiver pa˚ rovdyr, ressurser og utmarksnœringer i dagens- og framtidens Norge: En konsekvensutredning av rovviltforvaltningens betydning for sma˚fenœring, reindrift og viltinteresser. (Perspectives on predation, resources and range users in Norway—today and in the future. An environmental impact statement for sheep production, reindeer herding and ungulate hunting interests). Final report, KUR-project Biological Institute, University of Oslo. 336 p. (In Norwegian, English summary). Mysterud, I. (1980). Bear management and sheep husbandry in Norway with a discussion of predatory behavior significant for evaluation of livestock losses. In Bears: Their Biology and Management. (C. J. Martinka and K. L. McArthur, eds) pp. 233–241. Fourth International Conference on Bear Research and Management. Kalispell, Montana, February 1977. Warren, J. T. and Mysterud, I. (1995). Mortality of domestic sheep in free-ranging flocks in southeastern Norway. Journal Animal Science 73, 1012–1018.