Predators and people: Conservation of large carnivores is possible at high human densities if management policy is favourable

Abstract

In a recent analysis Woodroffe (2000) found a positive relationship between historical patterns of large carnivore extinction probability and human population density. However, much of the data in this analysis came from a period when carnivore extermination was a management objective. In order to explore the hypothesis that large carnivores can persist at high human densities when the management regime is more favourable we have repeated the analysis using up-to-date data from North America and Europe. In North America we found that large carnivore populations have increased after favourable legislation was introduced, despite further increases in human population density. In Europe we found no clear relationship between present carnivore distribution and human population density. We therefore believe that the existence of effective wildlife management structures is more important than human density per se.

Full text

Predators and people: conservation of large carnivores is
possible at high human densities if management policy
is favourable
INTRODUCTION
In our modern and crowded world, large carnivores are
among the most challenging taxonomic groups to con-
serve (Mech, 1995). Their massive area requirements
and predatory behaviour (on both wild prey and live-
stock) lie at the core of the problem (Nowell & Jackson,
1996). In addition, their populations have been dramat-
ically reduced during the last 200 years. However, their
decline has not been uniform throughout the world, and
while some populations have been exterminated, others
have survived to a far greater degree. In a recent analy-
sis of historic trends, Woodroffe (2000) attempted to
explain some of this variation by examining the rela-
tionship between large carnivore extinction probability
and increasing human population density. For a variety
of species, Woodroffe found a clear positive relationship
between human density and extinction probability.
However, we believe that while being a fair analysis of
past processes her analysis does not present an accurate
picture of the ability for large carnivores to persist in the
modern world under favourable management regimes.
Instead, against a background of European experience
and an examination of more modern North American
data (which were not covered by Woodroffe), we pre-
sent the thesis that large carnivore persistence is more
adequately explained by management policy, and the
enforcement of this policy, than human population den-
sity per se.
RECENT TRENDS IN NORTH AMERICAN
LARGE CARNIVORE POPULATIONS
The North American extinction data used by Woodroffe
(2000) stem from the late 1800s and early 1900s. During
this entire period the widespread social agenda, and
politically sanctioned policy, was to eradicate large car-
nivores (Mech, 1970; Brown, 1983; chapters in Novak
et al., 1987). Bounties were offered at various times by
county, state and federal administrations. In addition,
large amounts of federal money were used to support
professional hunters who used all available methods (e.g.,
traps, poison, aerial hunting) to kill carnivores. During
the same time period, there was widespread conversion
of forest habitats to farmland, and decimation of the prey
base of native ungulates on which large carnivores
depend. As human population size also correlates with
time, the data analyzed by Woodroffe (2000) describe
the progressive success of this extermination policy, and
the temporal progression of immigrant expansion into
relatively unsettled territory, rather than a simple causal
density-dependent relationship between human density
and carnivore extinction. Woodroffe’s critical human
density appears to be a measure of the effort that humans
must make in order to exterminate large carnivores
when they are trying. Therefore we believe that it is not
Animal Conservation (2001) 4, 345–349 © 2001 The Zoological Society of London Printed in the United Kingdom
John D. C. Linnell1, Jon E. Swenson1,2 and Reidar Andersen1,3
1Norwegian Institute for Nature Research, Tungasletta 2, 7485 Trondheim, Norway
2Department of Biology and Nature Conservation, Agricultural University of Norway, PO Box 5014, 1432 Ås, Norway
3Zoology Department, Norwegian University of Science and Technology, 7491 Trondheim, Norway
(Received 12 September 2000; accepted 11 June 2001)
Abstract
In a recent analysis Woodroffe (2000) found a positive relationship between historical patterns of
large carnivore extinction probability and human population density. However, much of the data in
this analysis came from a period when carnivore extermination was a management objective. In order
to explore the hypothesis that large carnivores can persist at high human densities when the man-
agement regime is more favourable we have repeated the analysis using up-to-date data from North
America and Europe. In North America we found that large carnivore populations have increased
after favourable legislation was introduced, despite further increases in human population density. In
Europe we found no clear relationship between present carnivore distribution and human population
density. We therefore believe that the existence of effective wildlife management structures is more
important than human density per se.
All correspondence to: John Linnell. Tel: ++ 47 73 801 442;
Fax: ++ 47 73 801 401; E-mail: john.linnell@ninatrd.ninaniku.no

directly relevant to the discussion about how to conserve
large carnivores when we actually try.
If our hypothesis on the role of management policy is
correct, large carnivore populations should have stabi-
lized or recovered once policy objectives changed,
despite the fact that human density remained stable or
increased further. Official policy towards all predators,
including large carnivores, began changing after the
1940s, but the most dramatic changes occurred during
the early 1970s (Novak et al., 1987, and references
therein). The indiscriminate use of toxicants for carni-
vore control was banned in the United States in 1972,
and wolves (Canis lupus) and grizzly bears (Ursus arc-
tos) were placed on the endangered species list (in
the lower 48 states) in 1974 and 1975, respectively.
Similarly, bounties were removed from wolves in
the various Canadian provinces between 1949
(Saskatchewan) and 1975 (Northwest Territories). By
the mid-1970s wolves, grizzly bears and cougars (Puma
concolor) were all either protected or managed as har-
vestable game species (game or furbearer designations)
throughout Canada and the United States (Novak et al.,
1987, and references therein).
In the subsequent 25 years, there have been no fur-
ther extinctions of these three species in their range
states/provinces (Table 1). Although there have been
some local declines, these either have been due to
planned population reductions, or were reversed after the
decline was detected. In fact, most populations have
expanded. Wolves have naturally expanded from north-
eastern Minnesota (the only area where they persisted in
the lower 48 states) to recolonize central Minnesota,
upper Michigan and parts of Wisconsin and North
Dakota. In addition, northern Montana has been recolo-
nized from Alberta (Mech, 1995). In addition, the delib-
erate reintroduction of wolves into formerly occupied
habitats in Idaho and the Greater Yellowstone ecosys-
tem has been a success (Bangs et al., 1998), and a new
reintroduction is underway in the southwestern states
(Parsons, 1998). Grizzly bear populations in Alaska and
Canada remain secure, and even the five remnant pop-
ulations in the lower 48 states have generally held their
own (Servheen, Herrero & Peyton, 1999). Augmentation
of the grizzly bear population in the Cabinet–Yaak area
of Montana has been carried out, and a reintroduction
into the Selway–Bitteroot area on the Idaho–Montana
border is being planned (Servheen et al., 1999). Wildlife
managers in 15 states and provinces have reported that
their cougar populations are either stable or increasing,
including the isolated population of cougars in Florida
(reports in Paldey, 1997). This is all despite the fact that
the human population of North America has almost
quadrupled since 1900 (Woodroffe’s survey date) and
has increased by 25% since 1975 when the modern era
of conservation-orientated large carnivore management
began. Many of these states (Table 1) have human pop-
ulations well above Woodroffe’s cut-off densities (4–14
people km–2), and wolf recovery plans are being seriously
evaluated for northeastern states like New York which
has 148 people per km2 (Mladenoff & Sickley, 1998).
CARNIVORE PERSISTENCE IN EUROPE AT
HIGH HUMAN DENSITY
If large carnivore persistence is simply linked to human
population density per se, we should expect to find a sim-
ilar relationship between carnivore persistence and
human population density in an area not considered by
Woodroffe. To examine this issue we collated data on
the past distribution and present status of brown bear
(Ursus arctos), wolf and Eurasian lynx (Lynx lynx, the
ecological equivalent of a cougar) in Europe from a series
of action plans, recently published by the Council of
Europe (Boitani, 2000; Breitenmoser et al., 2000;
Swenson et al., 2000) and the IUCN (Nowell & Jackson,
1996; Servheen et al., 1999). Additional status updates
presented at a meeting of the ‘Group of Experts on Large
Carnivores to the Council of Europe’s Bern Convention’
in Oslo in June 2000 were included in some cases. We
considered countries to be former-range states if large
carnivore populations had persisted into the early 1800s
(this excludes cases like wolf extinction from Britain and
Ireland that occurred in the 1600s for example).
Extinction was defined if a given species did not occur
in a consistently reproducing status for a period of at least
some decades (Table 2). In order to test for the ability
of large carnivores to persist under modern manage-
ment regimes we repeated the analysis using present
346 J. D. C. L
INNELL ET AL
.
Table 1. Present trends in wolf and cougar populations in North
American states in relation to present human population density.
Human population densities are for the year 2000 (US Census
Bureau). Carnivore population trends are indicated by arrow symbols
("= increasing, #= stable, $= decreasing)
State/province Human density Cougar1Wolf2
Alaska 0.4 #
Alberta 4.1 "#
Arizona 16.2 #
BC 3.9 ""
California 82.1 "
Colorado 15.1 "
Florida 108.1 #
Idaho 5.8 "
Labrador 1.4 #
Manitoba 1.7 #
Michigan 67.0 "
Minnesota 23.2 "
Montana 2.3 ""
Nevada 6.4 "
New Mexico 5.5 "
NWT30.02 #
Ontario 10.0 "
Oregon 13.3 "
Quebec 4.6 "
Saskatchewan 1.5 #
Texas 29.6 "
Utah 10.0 "
Washington 33.4 "
Wisconsin 37.3 "
Wyoming 1.9 "
Yukon 0.06 #
1Source = state-by-state survey from fifth mountain lion workshop
in 1996 (Paldey, 1997).
2Source = Hayes & Gunson, 1995; Stephenson et al., 1995; Thiel &
Ream, 1995; figures generally include up to 1992.
3Trend does not include High Arctic areas where data are lacking.

distributions of reproductive populations (including the
results of both natural recolonization and reintroduction).
There was some subjectivity associated with classify-
ing a population within a national border as simply
present or extinct, because many populations straddle
international borders and are in a dynamic state. This
was especially true for Norway, as wolves only recolo-
nized in 1998 (represented by only three packs that use
Norwegian territory exclusively in 2000) and no repro-
ducing female bears exclusively use Norwegian territory
(Swenson, Sandegren & Söderberg, 1998). As Norway
has by far the lowest human population density in main-
land Europe, the classification of its wolf and bear pop-
ulations can have a dramatic effect on the analysis.
Therefore, we carried out separate analyses where these
populations were considered as either present or extinct,
respectively. Human population densities were taken
from the estimated present densities (year 2000) by the
United States Census Bureau. Although some countries’
populations may have grown at slightly different rates
during the last two centuries, we believe that the rela-
tive rankings should be unchanged, and present human
density is directly relevant to the analysis for persistence
at the present time.
The only species showing a significant relationship
between human population density and historical extinc-
tion since the early 1800s was the Eurasian lynx (Tables
2 and 3). This probably reflects the greater vulnerabil-
ity of lynx to human influences on their ungulate prey
base rather than disproportionate human persecution.
Lynx are strictly carnivorous and therefore cannot sur-
vive in the absence of prey species; wolves and bears
are better able to survive on garbage and plants, respec-
tively. With regard to present coexistence with humans,
lynx showed no relationship to human density, owing to
their successful reintroduction and recolonization in
many countries in central Europe. Although the present
status of both wolves and bears appeared to show a rela-
tionship with human density, this was due to the influ-
ence of Norway as an outlying data point (Table 3). If
Norwegian wolf and bear populations were included in
the analysis as functionally extinct, then there was no
significant relationship between human density and car-
nivore presence.
There is no doubt that Europe’s large carnivores have
been greatly reduced owing to human activities during
past centuries. Direct persecution, destruction of their
prey base and deforestation have all led to dramatic
reductions in distribution and numbers (Boitani, 1995;
Breitenmoser, 1998). Large carnivores were driven to
extinction in many countries, often early in historic or
even prehistoric times. However, the results from our
analysis show that, in general, there are few consistent
relationships between human population density and
large carnivore extinction in Europe. In addition, the crit-
ical densities are far higher than those found by
Woodroffe for North American large carnivores. Why is
this?
We believe that it is due to two factors. First, it is
important to remember that Europeans have shared their
continent with large carnivores for around 30,000 years.
347Large carnivores, human density and management policy
Table 2. Present trends in large carnivore populations in European
countries in relation to present human population density. P? = repro-
ducing population present but trend is uncertain; T = only transient
individuals present; E = extinct; NP = never present. Human popu-
lation densities are for the year 2000 (US Census Bureau). Carnivore
population trends are indicated by arrow symbols ("= increasing,
#= stable, $= decreasing)
Country Human Lynx1Bear2Wolf3
density (km–2)
Albania 121.40 ?P? #"
Austria 96.97 T "E
Bosnia 75.02 ?P? ?P? $
Bulgaria 70.30 E $#
Croatia 75.73 ## "
Czech Republic 130.30 #T "
Estonia 31.73 ## #
Finland 15.33 """
France 107.98 "#"
Germany 232.12 "E T
Greece 80.35 ?P? $#
Hungary 108.99 T E #T#
Italy 191.33 T #"
Latvia 37.76 ###
Lithuania 55.54 #T "
Macedonia (FYROM) 79.37 ?P? #"
Moldova 131.48 E E #
Norway 13.82 #" "
Poland 123.59 ## "
Portugal 109.12 NP E #
Romania 94.36 #($)4"
Slovakia 110.29 $"#
Slovenia 95.21 ## "
Spain 79.24 NP $"
Sweden 19.73 """
Switzerland 175.89 #E #T"
Ukraine 81.42 ?P? $#
Yugoslavia 104.36 ?P? ?P? ?P?
1Source = Breitenmoser et al., 2000; figures are for 1998.
2Source = Swenson et al., 2000; figures are for 1998.
3Source = Boitani, 2000; figures are for 1998.
4Reducing the brown bear population is currently a management goal
in Romania.
Table 3. Logistic regression analysis of large carnivore extinction in
European countries with respect to human population density. ‘Past
extinction’ includes countries where the species became extinct for a
period of at least several decades after 1800. ‘Present status’ is based
on the data in Table 2, and includes the results of population persis-
tence, recolonization and reintroduction. The later analysis has been
presented with and without Norway, as the country’s low population
density gives it a strong effect on the analysis, and the status of wolves
and bears is undergoing rapid change
N c2PMean human Mean human
density at density at
extinction persistence
Lynx
Past extinction 26 9.0 0.003
Present status 26 0.2 0.677 94.0 ± 32.8 94.7 ± 55.1
Brown bear
Past extinction 28 1.1 0.3
Present status 28 4.8 0.03 135.5 ± 61.2 83.4 ± 42.4
Present status 28 0.4 0.52
(Norway set as extinct)
Wolf
Past extinction 28 0.01 0.904
Present status 28 6.7 0.01 168.3 ± 67.9 85.8 ± 41.7
Present status 28 0.08 0.773
(Norway set as extinct)

This long-term overlap has led to a relatively high degree
of coexistence, for example with wolves exploiting
anthropomorphic food sources when wild prey are
absent (Vos, 2000), and with shepherds adopting effec-
tive methods of guarding their livestock (Coppinger &
Schneider, 1995). The second factor is clearly one of tra-
dition, which is expressed through management regula-
tion (Boitani, 1995). Royal decrees to regulate hunting
of bears date back to the 1600s in some cases, and most
countries were managing bears as game species by the
early- to mid-1900s. There is no doubt that the concept
of hunting large carnivores as game species is far older
in Europe than in North America and contributed greatly
to their persistence. In addition, despite the very high
human densities in Europe today (Table 2), the historic
declines in large carnivore numbers appear to have been
reversed with only a few exceptions. Large carnivore
population trends in most countries are stable or increas-
ing, and intensive conservation efforts are underway to
reverse the slow declines occurring in a few areas.
One example that clearly shows the importance of
management policy is that of brown bears in Scandinavia
(Swenson et al., 1995). Both countries have low human
population densities (14 km–2 in Norway, 20 km–2 in
Sweden). Bounties on bears were introduced early (1733
in Norway, 1647 in Sweden). As a result, bear popula-
tions were rapidly reduced in both countries. However,
management policy diverged in the late 1800s. Bounties
were removed in Sweden in 1893, and increasing levels
of protection were phased in from 1909. This led to such
an increase that managed hunting could begin in 1943.
Today there is a population of about 1000 bears, that is
still increasing despite providing an annual harvest of 50
bears (Sandegren & Swenson, 1997). In contrast, despite
phasing out the state bounty in 1930 in Norway, unreg-
ulated killing was still permitted up until 1972, when
bears were finally given protection. By this time they
were functionally extinct (Swenson et al., 1995, 1998).
Recolonization from Sweden, Russia and Finland is
presently allowing a slow recovery of the Norwegian
population.
CONCLUSIONS
In conclusion, the data support our hypothesis that pat-
terns of large carnivore extinction and persistence in
Europe and North America are more adequately
explained by management policy and its enforcement
than by human population density. We therefore predict
that human density and carnivore density interact dif-
ferently in two phases of the development of wildlife
management structures. First, where there is no effec-
tive regulation of human behaviour, weapons (and poi-
son) are available, and a rapid period of human
expansion occurs into areas where resource exploitation
is not controlled, large carnivore extinction should be
related positively to human density (the ‘frontier’ phase).
This is mediated by a combination of habitat change,
destruction of prey base and direct persecution. This sit-
uation broadly corresponds to North America up until
the mid-1900s, and much of the developing world today.
Woodroffe’s (2000) analysis of North American data has
clearly shown how large carnivore extermination can be
achieved (if desired) even at very low human densities.
Second, where there is effective regulation of human
behaviour and established human populations in areas
where resource exploitation is regulated, there should be
no strong correlation between human density and carni-
vore extinction (the ‘stabilised’ or ‘wildlife manage-
ment’ phase). This corresponds to most of Europe and
North America today. In this phase, large carnivore
recovery into remaining habitat can occur, through either
natural recolonization or planned reintroduction. The
European experience shows how brown bears, lynx and
wolves can survive at high human densities.
The important implication of our results is that large
carnivore conservation requires the rapid establishment
of effective wildlife management and enforcement struc-
tures that either make protection effective or regulate
harvest of both large carnivores and their prey at sus-
tainable levels. Of course, achieving this in the devel-
oping world requires a whole range of measures, like
slowing human population growth, and fostering sus-
tainable socio-economic development. The point is that
large carnivore conservation is possible at high human
density, and that even wilderness protection is no guar-
antee of persistence (Woodroffe & Ginsberg, 1998).
European and North American experience clearly shows
that large carnivores and their prey can persist within
many heavily modified habitats (though not all) at high
human densities and even where both predators and their
prey are being harvested. In the face of the pressures on
wilderness areas today, this is extremely good news for
large carnivores (Linnell, Swenson & Andersen, 2000).
Implementation of such a policy requires an urgent
building of bridges between the academic field of con-
servation biology and the hands-on field of wildlife man-
agement.
Acknowledgements
We would like to thank Hans C. Pedersen, Henrik
Brøseth, John Odden and Erling J. Solberg for con-
structive input into this discussion.
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349Large carnivores, human density and management policy