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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 |
|
a Estimated |
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.
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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 $460,783 per year in depredation expenses.
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Table 3.
Average annual number of wolves and monetary costs per wolf for
maintaining wolves in Minnesota for 3 periods during 1979-2005. |
|
Factors |
Annual
for period |
|
1979-1989 |
1990-1998 |
2001-2005 |
|
No. wolvesa |
1,438 |
2,044 |
3,150 |
|
Control costs ($) |
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:
- the potential for wolf population increase is much higher than the
relatively low rate at which the Minnesota wolf population has been growing;
- the 1997 estimated wolf population may be lower than the actual
population;
- it will become more difficult and expensive per wolf to further control
the wolf population as it expands into a larger area; and
- 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).
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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.
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