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Sustainable Society:  A society that balances the environment, other life forms, and human interactions over an indefinite time period.

 

 

 

 

 

 

Estimated Costs of Maintaining
a Recovered Wolf Population in
Agricultural Regions of Minnesota


L. David Mech*
September 1999

 

Abstract
Introduction
Methods
Results and Discussion



Abstract:
The annual costs of maintaining Minnesota gray wolves (Canis lupus), now numbering about 2,500, under 2 plans are compared: (1) maintaining a population of about 1,400 primarily in the wilderness and semi-wilderness as recommended by the Eastern Timber Wolf Recovery Plan, and (2) allowing wolves to continue colonizing agricultural areas for 5 years after removal from the endangered species list, as recommended by a consensus of wolf stakeholders (Minnesota Wolf Management Roundtable). Under the first plan, each year an estimated 27 farms would suffer livestock losses; wolves would kill about 3 dogs; 36 wolves would be destroyed; and the cost per wolf in the total population would be $86. Under the second plan, conservative estimates are that by the year 2005, there would be an estimated 3,500 wolves; each year 94-171 farms would suffer damage; wolves would kill 8-52 dogs; 109-438 wolves would have to be killed for depredation control; and the annual cost averaged over the total population would be $86 for each of the 1,438 wolves living primarily in the wilderness and an additional $197 for each wolf outside the wilderness.

Introduction

Gray wolf (Canis lupus) populations in Minnesota, Wisconsin, and Michigan have increased and expanded their range considerably during the past 2 decades (Fuller et al. 1992, Wydeven et al. 1995, Mich. Dep. Nat. Resour. 1997, Wis. Dep. Nat. Resour. 1998) and are about to meet the recovery criteria of the Eastern Timber Wolf Recovery Plan (hereafter, Recovery Plan; U.S. Fish and Wildl. Serv. 1992). Consequently, the Minnesota Department of Natural Resources is developing a state wolf management plan to present to the 1999 State Legislature for approval. The Wisconsin and Michigan Departments of Natural Resources also have developed state plans. When the federal government is assured that the state plans are adequate to ensure wolf population survival in these states at or above recovery levels, it will propose de-listing the wolf from the endangered species list in these 3 states plus an undetermined number of adjacent states, and de-listing will probably occur by 2001 (R. Refsnider, U.S. Fish and Wildl. Serv., pers. commun.).

As states prepare to manage wolf populations, they must contend with a public that has been conditioned to view the wolf as an endangered animal (Mech 1970, 1995; Van Ballenberghe 1974) and a symbol of the wilderness (Theberge 1975). In addition, the animal rights movement has utilized this attitude to capitalize on public sentiment for the wolf (Mech 1995, Mech et al. 1998).

Concurrently, wolf recovery has resulted in increased wolf depredations on livestock in Minnesota (Fritts 1982, Fritts et al. 1992), and research has documented that, under certain circumstances when wolves begin losing fear of humans, they may be dangerous to people, especially children (Jhala and Sharma 1997; Mech 1998; R. D. Strickland, Algonquin Provincial Park, pers. commun.). Thus, wolf management has developed a sociopolitical dimension that extends beyond the primary biological concerns.

In Minnesota, these factors have translated into an approach to wolf management that has included public involvement. The Minnesota Department of Natural Resources held a series of public meetings followed by 8-day-long stakeholders' (Minnesota Wolf Management Roundtable) discussions that led to a consensus on wolf management recommendations. The Minnesota Department of Natural Resources had agreed to follow these recommendations as it develops a wolf management plan to present to the state legislature. There are no federal restrictions on state wolf management plans except that they must ensure the survival of the wolf at or above recovery levels.

The Roundtable consensus recommended, for the first 5 years of the Minnesota Wolf Management Plan, that no further wolf population control occur other than the wolf-depredation control program that has been in effect since 1978, when the wolf in Minnesota was downlisted to threatened (Fritts 1982, Fritts et al. 1992). Despite this depredation-control program, the Minnesota wolf population has increased, mostly by range expansion into agricultural areas, from an estimated 1,235 in 1979 to 1,500-1,750 in 1989, an average annual increase of 3% (Fuller et al. 1992). The winter 1997-1998 estimate was 2,445 (Berg and Benson 1999). At this level, the average annual increase from 1989 to 1998 would be 5%. Recent average annual increases in Wisconsin were 40% per year (Wisc. Dep. Nat. Resour. 1998) and in Michigan, 38% per year (Mich. Dep. Nat. Resour. 1997).

The Minnesota Wolf Management Roundtable consensus recommendations contrast sharply with those of the Eastern Timber Wolf Recovery Plan (U.S. Fish and Wildl. Serv. 1992), which recommended an optimal population of 1,250-1,400 wolves inhabiting primarily wilderness and semi-wilderness. The rationale for that recommendation was to maintain a viable wolf population that would continue to produce a large number of dispersers to help repopulate adjacent states, but at the same time minimize wolf-human conflicts.

Since 1989, when the Minnesota wolf population began increasing above the estimated 1,500-1,750 that inhabited primarily wilderness and semi-wilderness (Fuller et al. 1992) and proliferating into regions with more agriculture, wolf depredations on livestock have increased considerably (Table 1). This increase reflects the increased colonization of agricultural land. Wolves inhabiting wilderness cost little to society except for the dispersers they generate that pass through or colonize agricultural land.

Table 1. Wolf depredations in Minnesota from 1979 to 1998 (Fritts 1982; Fritts et. al. 1992; W.J. Paul, Wildl. Services, U.S. Dep. Agric., pers. commun.)

Year

Farms
affected

Wolf-killed
dogs

Wolves
destroyed

Compensation
paid ($)

Control program
cost (x $1,000)

1979

12

1

6

20,800

 

1980

17

1

21

20,500

 

1981

38

3

29

38,600

 

1982

27

2

20

19,000

 

1983

28

4

42

24,900

 

1984

19

6

36

19,500

 

1985

27

2

31

23,600

 

1986

25

1

31

14,400

60

1987

30

2

43

24,200

64

1988

35

3

59

28,100

68

1989

41

10

81

43,700

116

1990

55

11

91

42,700

148

1991

42

9

54

32,200

126

1992

62

6

118

23,200

175

1993

57

6

139

31,100

155

1994

74

8

172

31,200

158

1995

64

8

78

34,100

160

1996

69

10

154

43,600

200

1997

93

12

216

46,500

255

1998

99

25

161

50,000a

300

aEstimated



Because Minnesota's wilderness and semi-wilderness are saturated with wolves, the only remaining areas of the state left for the wolf population to colonize are primarily agricultural. Thus, it is likely that the increase in rate of depredations on livestock will continue and even accelerate. The following may be expected to increase similarly: costs of wolf-depredation control, compensation payments by the Minnesota State Department of Agriculture for livestock killed by wolves, number of wolves killed by the depredation-control program, and potential wolf-human interactions.

These increased costs have not been estimated, and they may or may not be politically or socially acceptable. Herein I attempt to compare the costs of maintaining a wolf population in Minnesota at about the level recommended by the Eastern Timber Wolf Recovery Team (U.S. Fish and Wildl. Serv. 1992) with the level recommended by the Minnesota Wolf Management Roundtable.

Methods

My starting point was the mean annual cost of the Minnesota wolf population from 1979 to 1989, because the numbers and distribution of wolves during that period approximate those recommended by the Recovery Plan.

I used data on the Minnesota wolf population and its increase rate (Fuller et al. 1992; Berg and Benson 1999), statistics on wolf depredations on livestock and dogs, costs of the U.S. Department of Agriculture Wolf Depredation Control Program, and of the Minnesota Department of Agriculture compensation payments (Table 1, Table 2) to calculate annual per-wolf costs of these programs for 3 periods: 1979-1989, 1989-1998, and 2001-2005. Costs that I considered included monetary outlays as well as social costs in terms of numbers of farms affected, number of dogs killed by wolves, and number of wolves destroyed. Dog losses were considered because pet loss is especially disturbing to humans (Fritts and Paul 1989), and wolves destroyed were considered because they are important to animal rights advocates.

Table 2. Number of wolves and overall costs of maintaining the wolf population in Minnesota for 3 periods during 1979-2005.

Factors examined

Periods

1979-1989
(annual )

1998

Projected 2005

Wolf population

1,438a

2,520b

3,546b

Farms affected

27

99

94-171c

Wolves killed

36

161

109-438d

Dogs killed by wolves

3

25

8-52e

Compensation payments ($)

25,209

50,000

75,002-182,074f

Control costs ($)

77,000

255,000

245,060-512,610g

Total costs ($)

102,209

301,413

320,062-694,684

a Based on 3% mean annual increase (Fuller et al. 1992).
b
Based on 5% mean annual increase, 1989-1997 (Berg and Benson 1999).
c
Projection of linear regression of 1990-1998 data (r2=0.48; P=0.04).
d
Projection of linear regression of 1990-1998 data (r2=0.77; P< 0.01).
e
Projection of linear regression of 1990-1998 data, with 1990 removed as outlier; (r2=0.053; P=0.04).
f
Projection of linear regression of 1990-1997 data with 1990 removed as outlier (r2=0.70; P= 0.02).
g
Projection of linear regression of 1990-1998 data (r2=0.72; P< 0.01)


For the first 2 periods, I calculated the mean number of wolves in Minnesota per year assuming a mean annual increase of 5% (Berg and Benson 1999). I also calculated annual averages for the number of depredations and the depredation costs. For the first period, I divided the annual costs by the average number of wolves. For the second period, I subtracted the mean annual number of wolves during 1979-1989 from the mean number during 1990-1998 to yield the mean annual number of wolves over that of the first period. I referred to these wolves as "extra" because they were the number above that recommended by the Recovery Team.

I also subtracted the annual means of depredation control and compensation costs for the first period from those for the second period. Dividing the results by the mean difference in number of wolves for the 2 periods yielded a mean cost per wolf for the extra wolves.

Because wolves had saturated the wilderness and semi-wilderness areas and had begun to spread into agricultural land by 1989 (Fuller et al. 1992), I assumed that the depredation-control cost data from 1990 to 1998 would constitute a reasonable basis for projecting the future costs of wolves colonizing additional agricultural regions. Similarly, I assumed that the number of farms where wolf depredations were verified, the number of dogs killed by wolves, the amount of compensation, and the number of wolves killed by controllers would also continue to increase at the same rate.

Thus I used simple linear regression of 1990-1998 data to determine trends for these factors and projected these trends (95% CL) for the third period, 2001-2005. I chose the years 2001-2005 because that is the best estimate of the period when Minnesota will have regained management responsibility while continuing to allow the wolf population to expand. I then averaged the projected costs per year for 2001-2005.

I also projected that the wolf population trend would continue to increase at an average annual rate of 5% per year, the rate of increase for both the previous periods. I then calculated the mean number of wolves per year during 2001-2005.

I subtracted the mean annual number of wolves for the first period from this number to yield the mean annual number of extra wolves for 2001-2005. I subtracted the mean annual costs for the first period from the projected mean annual costs. I then divided the difference in mean annual costs by the mean annual extra wolves to derive a mean annual cost per extra wolf.

Because the Minnesota State Legislature increased the maximum compensation payment per animal killed by wolves from $400 to $750, an increase of 87.5%, I multiplied all compensation figures for the third period by 1.875 (although this approach does not yield a completely accurate measure of the total increase in compensation payments, it is the best approximation that can be made without knowing precisely how many of each kind of livestock will be killed). I similarly adjusted the mean annual cost for the first period before subtracting from the projected costs, because this cost represents the cost for maintaining the basic number of wolves in the wilderness and semi-wilderness and thus would also increase. I did not consider inflation in any calculation because it is not considered in the payments except as the legislature changes the payment rate.

To estimate the number of wolves it would be necessary to kill annually for depredation control at various population levels, I performed a regression analysis using the 1990-1998 depredation-control take as the dependent variable and the estimated annual populations, assuming a mean annual increase of 5% (Benson and Berg 1999) as the independent variable. Then, I projected the regression line.

 

Results and Discussion

The results indicate that the average annual monetary cost per wolf in the population during 1979-1989 was $71; based on the 1997 compensation rates, this increased to $86. From 1990 to 1998, each wolf above the 1979-1989 average number of wolves per year (1,438) cost $202 per year; and for 2001-2005, each extra wolf would cost an estimated $197 per year (Table 3). The total population from 2001-2005 would cost a projected $460,783 per year in depredation expenses.

Table 3. Average annual number of wolves and monetary costs per wolf for maintaining wolves in Minnesota for 3 periods during 1979-2005.

Factors

Annual for period

1979-1989

1990-1998

2001-2005

No. wolvesa

1,438

2,044

3,150

Control costs ($)

77,000b

186,333

342,830

Compensation ($)

25,209

37,990

116,953

Total costs/yr ($)

102,209

224,323

460,783

Cost/wolf/yr ($)

71 (1989);
86 (1997)c

110

146

Cost/wolf/yr for wolves
above the 1,438 in wilderness

 

202

197

a Based on 5% mean annual rate of increase, 1989-1997 (Berg and Benson 1999).
b Mean of 1986-1989 (only years for which data available), courtesy of U.S. Department of Agriculture.
c Increase in 1997 because of legislative increase in compensation payments.


Wolves not only incur costs; they also bring a strong positive value to Minnesota in the form of ecotourism by way of the International Wolf Center, which contributes an estimated $3 million annually to the local economy (Schaller 1996). However, this value would be little impaired if the wolf population were excluded from agricultural land, because the International Wolf Center is located in the heart of the wilderness wolf range. Other positive values of the wolf include the traditional consumptive and nonconsumptive uses, which are difficult to evaluate in monetary terms.

In addition to the monetary costs of extra wolves, the projected number of farms that might be affected annually by 2005 ranged from 94-171; the number of dogs killed by wolves, 8-52 per year; and the number of wolves killed for depredation control per year, 109-438 (Table 2). Although the number of farms affected is a small percentage of the total number in wolf range (Fritts et al. 1992), any increase in number of farms affected greatly increases rural resentment towards the wolf and its supporters.

The Minnesota wolf estimates are considered conservative, and the Roundtable consensus recommends allowing the population to continue to increase for another 5 years. Because deer densities are high in Minnesota agricultural areas, and because wolves have shown considerable adaptability to living around areas of human disturbance, there is reason to believe the wolf population will continue to increase by range expansion during the next several years.

The estimated costs in all currencies for an increased wolf population in agricultural parts of Minnesota should be considered conservative for several reasons:

  1. the potential for wolf population increase is much higher than the relatively low rate at which the Minnesota wolf population has been growing;
  2. the 1997 estimated wolf population may be lower than the actual population;
  3. it will become more difficult and expensive per wolf to further control the wolf population as it expands into a larger area; and
  4. the projections for population growth, depredation control, and compensation payments were linear, whereas trends of establishing populations often accelerate, as shown in Wisconsin and Michigan (Wydeven et al. 1995, Wisc. Dep. Nat. Resour. 1998, Mich. Dep. Nat. Resour 1997).

Most of the increase in the Minnesota wolf population has been, and will continue to be, through range expansion. Minnesota wolves are dispersing long distances through and into agricultural areas (Licht and Fritts 1994, Mech et al. 1995), and they are learning to tolerate high human disturbance even around dens and rendezvous sites (Thiel et al. 1998). As the wolf range expands, the cost of killing each depredating wolf becomes higher, because controllers cannot continue to operate from a central headquarters, and a reverse economy of scale results. Thus more headquarters, personnel, vehicles, and equipment are needed.

In most areas of the world, wolf populations are controlled (Mech 1970, 1995; Cluff and Murray 1995) except where their numbers are very low and are being nurtured. Therefore, it is reasonable to expect that Minnesota, too, will someday attempt to control its wolf population. If, after 5 years, wolf population control is implemented, as the Roundtable consensus may allow, it will be very difficult and expensive. To control wolf populations, some 28-53% of the population would have to be taken each year (Mech 1970, Peterson et al. 1984, Fuller 1989, Ballard et al. 1997). In 2005 that would require the removal of 730-1,382 wolves just to limit the population, not to reduce it. Alternatively, when the population reaches 3,000, it would be necessary to kill up to 1,830 wolves per year to reduce it (Table 4).

Table 4. Estimated number of wolf kills required under various types of control in Minnesota.

Wolf Population

Annual take required

Depredation control

Population limitationa

Population reductionb

2,500

73-293c

700-1,325

1,000-1,525

3,000

100-393c

840-1,590

1,200-1,830

3,500

115-504c

980-1,855

1,400-2,135

a Based on the required rates of 28-53% (Fuller 1989, Ballard et al. 1997).
b Based on the required rates of 40-61% (Gasaway et al. 1983, Potvin et al. 1992).
c Based on regression of 1990-1998 control data versus estimated annual wolf population (r2=0.48; P=0.04).


Before wolves were protected by the Endangered Species Act of 1973, the Minnesota wolf population of about 650 wolves (Fuller et al. 1992) was controlled with bounties, a year-around open season, snaring, liberal trap-checking regulations, and the existence of several experienced wolf trappers. Most of the traditional wolf trappers have since died, and, except for government trappers, few people could or would catch enough wolves throughout their range to control the population.

Considering the difficulty of capturing wolves (Mech 1974), fur prices and trapping success may be too low to attract many trappers. Furthermore, trappers tend to capture primarily young-of-the-year and yearling wolves, because these animals are the least wary (L. D. Mech, unpubl. data).

There is almost no tradition of deliberate hunting of wolves in Minnesota, and, although there are methods that work, few if any hunters know them. Most wolves that are shot are taken incidental to other activities such as farming and hunting for deer (Odocoileus virginianus) or small-game.

Thus, a serious question exists about whether, without using poison or substantial financial incentives, the Minnesota wolf population would be controllable in 2005, or, for that matter, is controllable even at present. In any case, the sooner control is begun, the easier and less costly it will be.

The above comparisons of the costs of 2 wolf management plans indicate that the wolf population and range recommendations of the Recovery Plan (U.S. Fish and Wildl. Serv. 1992) are far less expensive in monetary costs, number of wolves killed for depredation control, and other social costs. In addition, it would be necessary to kill far fewer wolves, both at first and annually, if an attempt to control the wolf population were made as soon as possible rather than if population control is instituted in 5 years.

Acknowledgements

This study was supported by the Biological Resources Division of the U.S. Geological Survey and the U.S. Department of Agriculture, North Central Forest Experiment Station.

Literature Cited

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Berg, W. and S. Benson. 1999. Updated wolf population estimate for Minnesota, 1997-1998. Minnesota Department of Natural Resources. Grand Rapids, Minnesota.
Cluff, H. D., and D. L. Murray. 1995. Review of wolf control methods in North America. Pages 491-504 in L. N. Carbyn, S. H. Fritts, and D. R. Seip, editors. Ecology and Conservation of Wolves in a Changing World. Canadian Circumpolar Institute, Occasional Publication 35.
Fritts, S. H. 1982. Wolf depredation on livestock in Minnesota. U.S. Department of the Interior, Fish and Wildlife Service, Resource Publication 145.
Fritts, S. H., and W. J. Paul. 1989. Interactions of wolves and dogs in Minnesota. Wildlife Society Bulletin 17:121-123.
Fritts, S. H., W. J. Paul, L. D. Mech, and D. P. Scott. 1992. Trends and management of wolf-livestock conflicts in Minnesota. U.S. Department of the Interior, Fish and Wildlife Service, Resource Publication 181.
Fuller, T. K. 1989. Population dynamics of wolves in north-central Minnesota. Wildlife Monographs 105.
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Schaller, D. T. 1996. The ecocenter as a tourist attraction: Ely and the International Wolf Center. Thesis, University of Minnesota, Minneapolis.
Theberge, J. B. 1975. Wolves and wilderness. J. M. Dent and Sons, Toronto, Canada.
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U.S. Fish and Wildlife Service. 1992. Recovery plan for the eastern timber wolf. U.S. Fish and Wildlife Service, Twin Cities, Minnesota.
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Wydeven, A. P., R. N. Schultz, and R. P. Thiel. 1995. Monitoring of a recovering gray wolf population in Wisconsin, 1979-1991. Pages 147-156 in L. N. Carbyn, S. H. Fritts, and D. R. Seip, editors. Ecology and Conservation of Wolves in a Changing World. Canadian Circumpolar Institute, Occasional Publication 35.
_____
*
Mech, L. David. 1999. Estimated Costs of Maintaining a Recovered Wolf Population in Agricultural Regions of Minnesota. Wildlife Society Bulletin 26(4):817-822. Northern Prairie Wildlife Research Center Jamestown, ND. Northern Prairie Publication #1052. September 16, 1999. See at < http://www.npwrc.usgs.gov/resource/1999/wpop/wpop.htm >.

 

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