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Original Article
Polar Bear Attacks on Humans: Implications
of a Changing Climate
JAMES M. WILDER,
1
U.S. Fish and Wildlife Service, Marine Mammals Management, 1011 E. Tudor Road, Anchorage, AK 99503, USA
DAG VONGRAVEN, Norwegian Polar Institute, Fram Center, N-9296 Tromsø, Norway
TODD ATWOOD, U.S. Geological Survey, Alaska Science Center, 4210 University Road, Anchorage, AK 99508, USA
BOB HANSEN,
2
Government of Nunavut, Igloolik, NU X0A 0L0, Canada
AMALIE JESSEN, Government of Greenland, Department of Wildlife and Agriculture, P.O. Box 269, 3900 Nuuk, Greenland
ANATOLY KOCHNEV, Russian Academy of Sciences, Far East Branch, Institute of Biological Problems of the North, Mammals Ecology Lab, 18
Portovaya Street, 685000 Magadan, Russia
GEOFF YORK, Polar Bears International, PO Box 3008, Bozeman, MT 59772, USA
RACHEL VALLENDER, Canadian Wildlife Service, Environment Canada, 351 St. Joseph Boulevard, Gatineau, QC K1A 0H3, Canada
DARYLL HEDMAN, Manitoba Conservation and Water Stewardship, Northeast Region, Box 28, Thompson, MB R8N 1N2, Canada
MELISSA GIBBONS, Wapusk National Park and Manitoba North National Historic Sites, Parks Canada, Box 127, Churchill, MB R0B 0E0,
Canada
ABSTRACT Understanding causes of polar bear (Ursus maritimus) attacks on humans is critical to ensuring
both human safety and polar bear conservation. Although considerable attention has been focused on
understanding black (U. americanus) and grizzly (U. arctos) bear conflicts with humans, there have been few
attempts to systematically collect, analyze, and interpret available information on human-polar bear conflicts
across their range. To help fill this knowledge gap, a database was developed (Polar Bear-Human
Information Management System [PBHIMS]) to facilitate the range-wide collection and analysis of human-
polar bear conflict data. We populated the PBHIMS with data collected throughout the polar bear range,
analyzed polar bear attacks on people, and found that reported attacks have been extremely rare. From
1870–2014, we documented 73 attacks by wild polar bears, distributed among the 5 polar bear Range States
(Canada, Greenland, Norway, Russia, and United States), which resulted in 20 human fatalities and 63
human injuries. We found that nutritionally stressed adult male polar bears were the most likely to pose
threats to human safety. Attacks by adult females were rare, and most were attributed to defense of cubs. We
judged that bears acted as a predator in most attacks, and that nearly all attacks involved 2 people. Increased
concern for both human and bear safety is warranted in light of predictions of increased numbers of
nutritionally stressed bears spending longer amounts of time on land near people because of the loss of their
sea ice habitat. Improved conflict investigation is needed to collect accurate and relevant data and
communicate accurate bear safety messages and mitigation strategies to the public. With better information,
people can take proactive measures in polar bear habitat to ensure their safety and prevent conflicts with polar
bears. This work represents an important first step towards improving our understanding of factors
influencing human-polar bear conflicts. Continued collection and analysis of range-wide data on interactions
and conflicts will help increase human safety and ensure the conservation of polar bears for future generations.
Ó2017 The Wildlife Society.
KEY WORDS attacks, climate change, conflicts, conservation, management, PBHIMS, polar bear, predatory, Ursus
maritimus, wildlife.
Polar bears (Ursus maritimus) have evolved to exploit the
biologically productive Arctic sea ice niche by using it as a
platform to prey upon marine mammals (Amstrup 2003).
Before European exploration, this habitat specialization
likely kept them separated from most people, and thus
helped reduce human-bear conflicts. However, the extent
of human-polar bear interactions began to change in the
sixteenth century with the advent of widespread maritime
exploration. Historical records provide some insight
into the nexus between human and bear behavior and
help inform current efforts to reduce human-polar bear
conflict.
Received: 26 August 2016; Accepted: 22 May 2017
1
E-mail: james_wilder@fws.gov
2
Consultant, Living with Wildlife Specialist, PO Box 386, Tofino, BC
V0R 2Z0, Canada.
Wildlife Society Bulletin; DOI: 10.1002/wsb.783
Wilder et al. Polar Bear Attacks on Humans 1
Although the Arctic has been inhabited by Indigenous
people in relatively low numbers for thousands of years, the
first recorded polar bear attack we found dates to 1595 when
2 members of William Barent’s second expedition were
reportedly killed and eaten by a polar bear in the Russian
Arctic (de Veer 1876). The incident occurred on 6
September on an islet near Vaygach Island. Two men
were lying in a wind-free depression resting, when:
“a great leane white beare came sodainly stealing out,
and caught one of them fast by the necke, the beare at the
first faling vpon the man, bit his head in sunder.” The
ship’s crew rallied, and tried to drive the bear off of the
victim: “hauing charged their peeces and bent their pikes,
set vpon her, that still was deuouring the man, but
perceiuiug them to come towards her, fiercely and cruelly
ran at them, and gat another of them out from the
companie, which she tare in peeces, wherewith all the rest
ran away (de Veer 1876:63).”
Eventually the crew was able to again rally, and finally
killed the bear as it continued to devour its victims. The vivid
account provided by de Veer demonstrates the potential
danger of polar bears, and is consistent in many respects with
what we have learned from more recent attacks.
Continued European expansion into the Arctic led to
increased conflict with, and exploitation of, polar bears
(Conway et al. 1904). For example, a commercial expedition
to Svalbard in 1610 reported killing 27 polar bears and
catching 5 cubs (Lønø 1970). Commercial polar bear
hunting continued through the centuries. In the early
decades of the twentieth century, hundreds of bears were
harvested on Svalbard annually. In 1924 alone, at least 901
polar bears were harvested on Svalbard (Lønø 1970). The
widespread use of fossil fuels further accelerated human
access to remote areas of the Arctic, resulting in significant
hunting pressure on polar bears throughout their range after
World War II. As a result, by the 1960s, the most significant
threat facing polar bears was over-hunting, and populations
in some areas were considered to be substantially reduced
(Larsen 1975).
To address these and other conservation concerns, in 1973
the 5 polar bear countries (Canada, Denmark [on behalf of
Greenland], Norway, the former Soviet Union, and the
United States) signed the Agreement on the Conservation of
Polar Bears (1973 Agreement). The 1973 Agreement
requires the 5 signatory countries (the Range States) to
restrict the taking of polar bears and manage polar bear
subpopulations in accordance with sound conservation
practices based on the best available scientific data
(DeMaster and Stirling 1981, Prestrud and Sterling 1994,
Larsen and Stirling 2009). It also allows harvest by local
people using traditional methods in the exercise of their
traditional rights and in accordance with the laws of that
Party (1973 Agreement). Subsequent to 1973, measures
implemented by the Range States, such as increased research
and monitoring, cooperative harvest management programs,
and establishment of protected areas, were presumed to have
either stabilized, or led to the recovery of, subpopulations
that had experienced excessive unregulated harvest (Amstrup
et al. 1986, Prestrud and Sterling 1994). Today, polar bears
are legally harvested by Indigenous peoples in Alaska,
Canada, and Greenland, and harvest levels in most
subpopulations are well managed and occur at a rate that
does not have a negative effect on population viability
(Obbard et al. 2010, Regehr et al. 2015).
However, polar bears now face a new and unprecedented
threat due to the effects of climate change on their sea ice
habitat (Stirling and Derocher 1993, 2012; Derocher et al.
2004; U.S. Fish and Wildlife Service 2008; Atwood et al.
2016a). Although the current status of polar bear sub-
populations is variable, all polar bears depend on sea ice for
fundamental aspects of their life history (Amstrup et al.
2008), including access to their primary prey, ice seals
(Stirling 1974). Arctic sea ice extent and thickness have
declined over the last 4 decades (Stroeve et al. 2014, Stern
and Laidre 2016), leading some to conclude that the Arctic
Ocean in summer may be largely ice free (i.e.,
<1,000,000 km
2
) as early as 2020 (Overland and Wang
2013).
In some parts of the polar bear range, diminishing
summer sea ice has resulted in the increased use of
terrestrial habitat by polar bears (Stirling et al. 1999,
Schliebe et al. 2008, Gleason and Rode 2009, Cherry et al.
2013, Rode et al. 2015b). Longer ice-free periods (Stern
and Laidre 2016) shorten polar bear hunting opportunities
during the critical hyperphagic period of late spring and
early summer (Ramsay and Stirling 1988), when hunting
conditions are most favorable (Stirling and Øritsland
1995), and extend the duration of the on-land period
through which polar bears must survive on finite stores of
body fat (Cherry et al. 2013). The resultant increased
fasting has significant negative effects on polar bear body
condition (Stirling et al. 1999, Rode et al. 2010a)andthe
increasing ice-free period has been linked to declines in
survival (Stirling and Derocher 1993; Stirling et al. 1999;
Regehr et al. 2007, 2010; Bromaghin et al. 2015). Longer
periods of fasting and increased nutritional stress (Cherry
et al. 2009; Molnar et al. 2010, 2014; Rode et al. 2010a;
Regehr et al. 2010) have also been attributed to incidents
of infanticide, cannibalism, and starvation in some polar
bear subpopulations (Lunn and Stenhouse 1985, Derocher
and Wiig 1999, Amstrup et al. 2006, Stirling et al. 2008a),
although Taylor et al. (1985) suggested that cannibalism is
not an uncommon phenomenon in polar bear biology.
When on shore, some nutritionally stressed bears are
highly motivated to obtain food however they can, and
appear more willing to risk interacting with humans as a
result (e.g., Stirling and Derocher 1993, Derocher et al.
2004, Stirling and Parkinson 2006, Towns et al. 2009).
Increased frequency of hungry bears on land due to
retreating sea ice, coupled withexpandinghumanactivity
in the polar bear range, is expected to result in a greater risk
of human-polar bear interaction and conflict (Stirling and
Derocher 1993, Derocher et al. 2004, Stirling and
Parkinson 2006).
2 Wildlife Society Bulletin 9999()
To date, polar bear attacks on humans have been rare.
When they do occur, they evoke negative public reaction,
often to the detriment of polar bear conservation. In some
communities, those negative reactions can persist for decades
and result in less social tolerance for polar bears and increased
defense kills (L€oe and R€oskaft 2004, Voorhees et al. 2014).
Recurrent conflicts not only undermine the well-being of
people and wildlife (Madhusudan 2003), they also negatively
affect local support for conservation (Naughton-Treves et al.
2003). Therefore, the effective management of human-bear
conflict is an essential precondition for the coexistence of
bears and people across the Arctic (Madden 2004).
A primary management goal of the Range States is to
ensure the safe coexistence of polar bears and people. In
2009, the Range States recognized the need to develop
comprehensive strategies to minimize human-bear conflicts
resulting from expanding human activities in the Arctic and a
continued increase of nutritionally stressed bears on land due
to reductions in sea ice (Directorate for Nature Management
2009). However, one of the difficulties in understanding and
managing human-polar bear conflicts is that they are often
poorly documented, particularly at the circumpolar level
(Vongraven et al. 2012). Although considerable attention
has been focused on understanding black (U. americanus)
and grizzly (U. arctos) bear-human conflicts (Herrero 2002),
there have been few attempts to systematically collect,
analyze, and interpret available information on human-polar
bear conflicts across their range (but see Fleck and Herrero
1988, Stenhouse et al. 1988, Gjertz and Scheie 1998, Dyck
2006, Towns et al. 2009). As a result, the public is left with
misconceptions and misinformation regarding polar bears
and their behavior, most of it driven by sensational media
coverage. For example, it is commonly asserted that polar
bears are the most aggressive of bears and polar bears are
the only large predator that will actively hunt people (e.g.,
The Daily Mail 2008). An important factor that fuels such
common folklore is that only a small fraction of the
interactions between polar bears and people are reported; the
exceptions are attacks that lead to human injuries or death.
To address these knowledge gaps and public mispercep-
tions, the Range States tasked the United States and Norway
with leading an effort, in collaboration with other polar bear
experts and managers, to develop a system to collect and
analyze data on human-polar bear conflicts (Directorate for
Nature Management 2009). The result was the Polar Bear-
Human Information Management System (PBHIMS), a
database designed to document, quantify, and help evaluate
human-bear interactions and other information relevant to
bear management. We analyzed data entered into PBHIMS
to characterize the occurrence of polar bear attacks on
humans. We used this information to suggest methods to
minimize the risk of future polar bear attacks to promote
both human safety and polar bear conservation. We also
identified data needed to best inform future management of
conflicts. Although the PBHIMS includes other types of
data that can be used to mitigate conflicts, we initially
focused on attacks because they are the most extreme and
undesirable encounters between humans and polar bears.
STUDY AREA
Our study area comprised the range of the polar bear,
including the frozen seas and coastal areas of Arctic Canada,
Greenland, Norway, Russia, and the United States.
METHODS
We compiled information on human-polar bear conflicts
from government records, published literature, biologists’
field notes, and news media for entry into PBHIMS. We
included some data that were previously reported (Gjertz and
Persen 1987, Fleck and Herrero 1988, Gjertz et al. 1993,
Gjertz and Scheie 1998), and augmented those data with
additional information, where available. To the extent
possible, we formulated data categories and variables of
interest in PBHIMS to be consistent with relevant literature
on human-bear conflicts (Fleck and Herrero 1988,
Stenhouse et al. 1988, Smith et al. 2008, Hopkins et al.
2010).
We limited this analysis to incidents in which polar bears
attacked people. A bear attack refers to intentional contact by
a bear resulting in human injury (Smith et al. 2005, Hopkins
et al. 2010). A predatory attack is one in which a bear preyed
upon, or attempted to prey upon, people (Herrero and
Higgins 2003, Hopkins et al. 2010). We considered wounds
to the head or neck and consumption of human flesh to be
indicative of a predatory attack. We also used behavioral
components such as stalking and rushing the victim (Herrero
and Higgins 2003), absence of vocalizing and stress
behaviors by the attacking bear (Fleck and Herrero 1988,
Herrero et al. 2011), and prolonged attacks despite sustained
attempts by onlookers to drive the bear off, to support the
identification of predatory events. The completeness of the
information reported here varied by period, data source, and
region. We acknowledge that this is not a complete dataset,
and additional attacks likely occurred that we are unaware of
because of incomplete reporting.
We classified independent bears from 3 to 4 years of age as
subadults, and bears older than 4 years as adults. When
information on bear body condition was available, we
assigned a condition score from 1 (skinny) to 5 (obese) using
the body condition index developed for polar bears (Stirling
et al. 2008b). When possible, we assigned a probable cause to
each attack after considering the totality of information
available. Probable cause is the main factor that initially
brought bears and humans into conflict.
A food-conditioned bear is one that has learned to associate
people (or the smell of people), human activities, or human-
use areas, with anthropogenic food (Hopkins et al. 2010).
We followed Stenhouse et al. (1988) and defined location
types where human-bear conflict occurred as follows: 1)
towns (communities of 50 people living long-term in
permanent buildings), 2) industry (permanent camps such as
mines, well sites, and exploration camps), 3) research
(associated with scientific expeditions and research activi-
ties), and 4) field areas (associated with camps and people
camping or traveling across the land). We defined encounter
group size as the number of people that initially encountered
Wilder et al. Polar Bear Attacks on Humans 3
the bear(s). This may be different than the total number of
people in the group. For example, in an incident where the
lead 2 hikers in a group of 5 strung out over several hundred
yards of a trail encounter a bear, the total group size is 5, but
the encounter group size is 2.
We summarized polar bears attacks on humans from 1870
to 2014. Because reported attacks in recent decades were
more accessible than were older records, we used records
since 1960 to investigate trends in attacks by decade. We
report spatial, temporal, and demographic characteristics of
attacks, and notable aspects of bear and human behavior that
may have influenced causation and outcome. We used a
linear regression to determine if there was a trend in the
number of attacks per decade from 1960–2014. We used
chi-square tests to determine if a relationship existed
between sex and age class of polar bears involved in attacks,
and if the incidence of attacks varied relative to the number of
people encountered by bears. Polar bear harvest is typically
male-biased, with upwards of 60–70% of the annual harvest
consisting of males (Derocher et al. 1997). However, there is
no harvest in Norway and Russia, so we used what we believe
to be a conservative ratio of 60 females:40 males for the
expected sex class proportions in chi-square tests. Age class
composition of harvest varies between populations and years
but is close to a ratio of 50:50 for subadults to adults (Lee and
Taylor 1994), which we used for the expected age class
proportions. We accepted statistical significance at a¼0.05.
Details for some variables of interest were not always
available for each incident analyzed. In those cases, we report
the number of incidents for which we had adequate data.
RESULTS
We analyzed 73 confirmed attacks in which 20 people
were killed and 63 were injured by wild polar bears. Of
theattacks,38occurredinCanada,4inGreenland,10in
Norway, 15 in Russia, and 6 in the United States. Seven
other probable fatalities and 5 injuries occurred in Russia
and Norway during this same period but are not included in
our analyses because we could not confirm them (i.e., those
attacks were referenced in other literature, but the details
could not be confirmed or there were no witnesses to the
incidents to confirm that they were actually attacks, even
though all evidence indicated that as the most likely
explanation).
Probable Cause of Attacks
Based on the criteria described in our methods, we judged
that the bear involved acted as a predator in 59% (37 of 63) of
attacks on people (Fig. 1). Sixty-four percent (7 of 11) of
attacks by females with cubs resulted from defense of cubs; 2
of these occurred at den sites. Where probable cause could be
determined, 100% (5 of 5) of attacks by single females were
predatory in nature, 4 of which were by subadults and 1 by
an adult (Table 1). Only 1 attack could be attributed to
a bear defending a carcass. In 38% (14 of 37) of attacks,
anthropogenic attractants were present. There was no
indication that natural attractants (e.g., whale carcass)
were present in any polar bear attacks on people.
Demographic Characteristics and Body Condition of
Attacking Bears
For attacks in which sex of the bear was known (n¼45;
Table 1), the observed percentages of male (62%) and female
(38%) polar bears involved differed from hypothesized
percentages (x
21
¼9.26, P¼0.002). Ninety-one percent (11
of 12; Table 1) of attacks by adult females involved those with
cubs (cubs of the year, yearlings, or 2-year-olds; x
21
¼8.33,
P¼0.004). Incidence of attacks also varied by age class
(x
22
¼12.33, P¼0.002), with adults involved in 52%
(n¼28), subadults in 35% (n¼19), and independent
2-year-olds and yearlings in 13% (n¼7) of attacks in which
age class was known. Fifty-four percent (7 of 13) of attacks in
towns were by subadult and yearling polar bears.
The incidence of predatory attacks (n¼25) differed
among sex classes (x
21
¼10.67, P¼0.001). Seventy-two
percent (18 of 25) of predatory attacks involved male bears,
20% (5 of 25) involved single female bears, and 8% (2 of 25)
were committed by females with cubs (Table 1). Incidence of
predatory attacks also varied between age classes (x
22
¼5.87,
P¼0.05) with 42% (13 of 31) committed by adults, 45% (14
of 31) committed by subadults, and 13% (4 of 31) by
independent yearlings or 2-year-olds. Where reported, polar
bears vocalized before attacking in only 13% (4 of 30) of
attacks.
Sixty-one percent (19 of 31) of bears that attacked humans
were in below-average body condition, meaning they were
skinny or thin (Figs. 2 and 3). Only 6% (2 of 31) were
considered fat (Fig. 3); none were considered obese. Sixty-
five percent (13 of 20) of bears involved in predatory attacks
on people were in below-average body condition; none were
in above-average body condition. Fifty-six percent (5 of 9)
of the bears that attacked people in towns were in below-
average body condition; none were in above-average body
condition.
Sixty-four percent (7 of 11) of bears involved in fatal attacks
on humans were in below-average body condition; none were
in above-average body condition. We judged that the bear
involved acted as a predator in 88% (14 of 16) of fatal attacks.
Figure 1. Probable cause of polar bear attacks on humans in Canada,
Greenland, Norway, Russia, and the United States, 1870–2014. The
predatory on human category includes predatory attacks on people in tents
and buildings (9) and predatory investigations (2).
4 Wildlife Society Bulletin 9999()
Where reported, 100% (10 of 10) of the people killed by polar
bears received major wounds to the head and neck. In 83%
(10 of 12) of fatal incidents, the bear consumed part of the
human; in 1 clearly predatory incident the bear was killed
before feeding on the human. Only single bears were
involved in fatal attacks on people: 93% (13 of 14) were
committed by males, 7% (1 of 14) by females, 64% (9 of 14)
by adults, 21% (3 of 14) by subadults, and 14% (2 of 14) by
yearlings.
Spatial and Temporal Patterns of Attacks
Between 1960 and 2009, 47 attacks by polar bears on people
were reported, ranging between 7 and 12 per decade, though
we note that the partial decade of 2010–2014 had the most
number of attacks (n¼15). There was no trend in the
number of attacks by decade from 1960–2014 (r
2
¼0.21,
b¼0.08, P¼0.36; Fig. 4). Between 1870 and 2014, attacks
occurred in every month, with 68% (44 of 65) occurring
between July and December. Since 2000, 88% (22 of 25) of
attacks have occurred between July and December.
The majority of attacks (53%, 35 of 66) occurred in
association with field camps and people traveling across the
landscape; 27% (18 of 66) occurred in towns; 8% (5 of 66)
occurred in association with research activities; and 6% (4 of
66) occurred at industrial sites. Eleven percent (7 of 63) of
attacks were on people in their tent. Two attacks involved a
Table 1. Attacks by independent polar bears on humans in Canada, Greenland, Norway, Russia, and the United States by bear demographic class, 1870–
2014, for all attacks and for predatory attacks.
Sex class
Age class Male Female Female with cubs Unknown Total
All attacks
Adult 14 1 11 2 28
Sub-adult 8 4 NA
a
719
Two-year old 1 1 NA 0 2
Yearling 3 0 NA 2 5
Cub 0 0 NA 0 0
Unknown 2 0 NA 17 19
Total 28 6 11 28 73
Predatory attacks
Adult 9 1 2 1 13
Sub-adult 5 4 NA 5 14
Two-year old 1 0 NA 0 1
Yearling 2 0 NA 1 3
Cub 0 0 NA 0 0
Unknown 1 0 NA 5 6
Total 18 5 2 12 37
a
Not applicable.
Figure 2. Representative body condition of polar bears: skinny (A) and
average (B). Photos by D. Hedman, Daniel J. Cox Natural Exposures.
Figure 3. Body condition of polar bears that attacked humans in Canada,
Greenland, Norway, Russia, and the United States, 1870–2014.
Wilder et al. Polar Bear Attacks on Humans 5
bear attacking a person inside a building. Sixty percent (9 of
15) of attacks in towns were predatory.
Human Behavior
The incidence of attacks varied with the number of people a
bear encountered (x
22
¼19.34, P<0.001). Encounter group
size was available for 56 attacks, 61% (34) of which involved 1
person, 27% (15) involved 2 people, and 12% (7) involved 3
or more people (i.e., 2 attacks involved 5 people and 2
involved 8 people). The encounter group size was known in
16 fatal attacks; 75% (12) involved 1 person, 19% (3) involved
2 people, and 6% (1) involved 5 people.
In 59% (30 of 51) of attacks, the person’s behavior
contributed to the attack (e.g., the person shot and wounded
the bear or its cub, got too close or provoked the bear, fed the
bear, slept on the ice, ran from the bear, was unarmed, carried
inadequate firearms, or was inexperienced with the firearms
carried). In 38% (24 of 63) of attacks, firearms were used to
end the attack. In 84% (31 of 37) of nonfatal attacks, either
the victim or a nearby bystander had firearms in their
possession. In 57% (8 of 14) of fatal attacks, no firearms were
in possession. In 25% (9 of 36) of attacks where a firearm was
in possession, victims and bystanders mishandled firearms
because of inexperience or the stress of the incident
(sometimes multiple times by multiple people). In all cases
this contributed to further human injury or death.
In 56% (29 of 52) of attacks, the person was surprised and
had no chance to deter the bear before the attack. Thirty-
nine percent (11 of 28) of attacks in which the person was
aware of the bear before the attack were predatory in nature.
In 7 attacks, multiple attempts to scare the bear off before the
attack were unsuccessful. Bear spray was in possession of the
person in only 1 of 36 polar bear attacks since 1986 (when
bear spray became available in some regions). However, the
spray was not used in that incident because the victim was
attacked, reportedly without warning, and dragged from his
tent in the middle of the night.
In 51% (32 of 63) of attacks, other people who witnessed
or were involved in the attack were able to save victims by
driving off or killing the attacking bear. Victims successfully
fought off or killed the attacking bear in only 9% (6 of 63) of
attacks. In the attacks in which the bear did not kill a person,
fatalities and further injuries were prevented by killing the
bear (n¼22), by the bear ending the attack on its own
(n¼9), and by hitting the bear in the head with a tool
(n¼2); single observations of wounding the bear with a
firearm, using a helicopter, poking the bear in the eye with a
thumb, firing flares at the bear, running into a building, using
a cellphone light, stabbing the bear, scaring the bear away
with snowmachines, throwing stones and shouting, a dog
chasing the bear away, and shooting at the bear were
recorded.
DISCUSSION
This research offers the first comprehensive assessment of
polar bear attacks on people, the frequency of which has
historically been low. For example, between 1960 and 1998,
black and grizzly bears caused 42 serious or fatal human
injuries in Alberta, Canada (Herrero and Higgins 2003).
Herrero et al. (2011) documented 63 fatal attacks by black
bears from 1900 to 2009 throughout North America.
Conversely, over the 145-year period we investigated, we
found records of only 73 confirmed polar bear attacks that
resulted in 20 human fatalities and 63 human injuries. We
acknowledge that we likely have not discovered or had access
to information on all the attacks that occurred during
the period investigated, and some attacks occurred that
were likely never recorded. Regardless, under historical sea
ice conditions and human population levels in the Arctic,
the odds of being killed or injured by a polar bear were low.
Although the risk of a polar bear attacking a person remains
low, it does exist, particularly when bears are nutritionally
stressed and in poor body condition, which was characteristic
of bears involved in the majority of attacks we analyzed. It is
reasonable to postulate that polar bears (which are obligate
carnivores) in poor body condition represent a greater threat
to people than polar bears in above-average body condition.
Indeed, those living near polar bears commonly report that
bears in poor nutritional body condition are much more
dangerous and aggressive than bears in good condition
(Voorhees et al. 2014). This is supported by data presented
here, which indicates that the body condition of polar bears is
a significant factor contributing to their attacking people.
Further, historical conditions are increasingly rare as the
availability of sea ice is dramatically and rapidly changing
throughout the polar bear range (Stroeve et al. 2014, Stern
and Laidre 2016). These changes will likely influence how
polar bears interact with people. For example, the greatest
number of polar bear attacks occurred in the partial decade of
2010–2014, which was characterized by historically low
summer sea ice extent and long ice-free periods (i.e., the
period of time when 15% concentration sea ice is absent;
Stroeve et al. 2014) that have been linked to increased land
use in a number of subpopulations (Rode et al. 2015b,
Atwood et al. 2016b).
Given projected further declines in summer sea ice extent
and lengthening of the open-water period, polar bears will
likely become increasingly reliant on land during summer
(Atwood et al. 2016a). The interplay between the amount
of time spent onshore, fat reserves accumulated prior to
arrival, and available terrestrial food will determine where
Figure 4. Number of polar bear attacks on humans by decade (e.g.,
1960–1969) from 1960–2014.
6 Wildlife Society Bulletin 9999()
over-summering is possible (Douglas and Atwood 2017).
The presence of anthropogenic food attractants is likely to
draw the increasing number of nutritionally stressed land-
based bears into close proximity to human activities,
escalating the risk of conflict and the potential for lethal
outcomes.
We suggest the range-wide adoption of comprehensive
protocols for conflict investigation and that thorough
investigations and analyses be completed for all polar bear
attacks and aggressive bears that are killed. Furthermore,
rigorous analyses of spatio-temporal patterns of human-
polar bear interactions are warranted to identify risk factors
and geographic hot spots for conflict. For the safety of people
and conservation of polar bears, it is essential that managers
craft both site-specific and range-wide management strate-
gies through a data-driven assessment of human-polar bear
conflicts, and tailor bear safety recommendations to specific
user groups throughout the polar bear’s range.
To gain a more comprehensive understanding of human-
polar bear interactions and place them in proper perspective,
it is necessary to also analyze incidents that do not result in
human injury or death (Herrero 2002). For example, we do
not have records of all the times that bears were successfully
deterred, and more importantly, how. This limits our ability
to determine what factors can prevent human-polar bear
incidents from escalating to more dangerous levels. Where
government agencies have the authority (e.g., when issuing
permits), they should consider requiring that permittees
report the details of all human-polar bear interactions to the
appropriate authorities.
To help accomplish these objectives, polar bear managers
should continue to populate and refine the PBHIMS with
conflict data, and other data of interest. These include
observations of natural bear mortalities (e.g., drowning,
starvation, cannibalism), taking of alternative prey, and
unusual movements, which could all be indicators of local
or regional changes in the ecology and the welfare of polar
bears (Vongraven et al. 2012). The long-term value of
the PBHIMS database is that it standardizes how such
observations are recorded, which will be important to
estimating whether the rate of occurrence of such events
changes over time.
Characteristics of Attacking Bears
Male bears were responsible for the majority of predatory
attacks on people, and have been implicated in most serious
and aggressive polar bear-human interactions throughout
Canada and Norway (Lunn and Stirling 1985, Fleck and
Herrero 1988, Stenhouse et al. 1988, Gjertz et al. 1993,
Gjertz and Scheie 1998). Rather than being defensive, our
data suggest that the intent of a male polar bear during an
attack is to kill the person. Our results also indicate that
independent immature bears (subadults, 2-year-olds, and
yearlings), irrespective of sex, were more prone to be
predatory towards humans. Males tend to be more aggressive
than females (Tate and Pelton 1983, Ramsay and Stirling
1986, Dyck 2006), and immature bears may be less cautious,
more easily habituated to humans, more nutritionally
stressed than adults, and more aggressive towards people
(Stirling and Latour 1978, McArthur Jope 1983, Dyck 2006,
Towns et al. 2009). Furthermore, independent young bears
are not yet adept at catching their natural prey (ice seals) and
thus more prone to being in below-average body condition
than are older, more experienced animals (Lunn and Stirling
1985, Towns et al. 2009). In addition, immature bears, with
their smaller absolute fat stores, are likely to be among the
first affected by prolonged fasting periods (Cherry et al.
2013, Pilfold et al. 2016). Nutritional stress associated with
the lengthening ice-free season has been linked to increases
in conflicts involving subadult bears in the western Hudson
Bay region (Stirling and Parkinson 2006, Towns et al. 2009).
Fleck and Herrero (1988) reported that, in contrast to male
polar bears, females with offspring that attacked people were
not exhibiting predatory behavior but rather were defending
their cubs. Our results differ in that we found that some
attacks by female polar bears with offspring were predatory.
However, we do not know of any reports of a female polar
bear with cubs killing a person.
Seasonality of Attacks
Historically, polar bear attacks have occurred in every month
of the year. Inuit in Northern Hudson Bay and northwest
Greenland told early explorers that polar bears were generally
very hungry in the spring and there were many instances of
them breaking into tents and sometimes killing women or
children (Perry 1966). However, our data indicate that since
2000, 88% of polar bear attacks on people have occurred
between July and December, which includes the period of
time when sea ice is at its minimum extent. Towns et al.
(2009) found that the date of sea ice freeze-up was the best
predictor explaining the annual occurrence of problem bears,
which is cause for concern in light of a lengthening open-
water season and the consequent effects on polar bear body
condition (Stern and Laidre 2016).
Without the sea ice substrate, prey are largely unavailable to
polar bears (Stirling and Derocher 1993, Rode et al. 2015a);
the result is increased fasting, which leads to declines in body
condition and survival (Atkinson and Ramsay 1995,
Derocher and Stirling 1995, Cherry et al. 2009, Robbins
et al. 2012, Derocher et al. 2013). These adverse
consequences become increasingly dire as the ice-free period
lengthens beyond 4 months (Molnar et al. 2010, 2014;
Robbins et al. 2012; Pilfold et al. 2016). By the end of this
century, ice-free conditions in the Arctic are likely to persist
for 5 to 11 months out of the year (Amstrup et al. 2008). This
is well beyond the point (i.e., 5 to 6 months) at which
extended fasting will likely lead to increased starvation in
polar bears (Molnar et al. 2010, 2014; Robbins et al. 2012;
Pilfold et al. 2016). This, combined with the evidence that
bears in below-average body condition are more prone to
attack people, should be a serious concern for all who live,
work, or recreate in polar bear habitat, as well as for the
agencies responsible for managing polar bears.
Bear Behavior
As with black bears (Herrero et al. 2011), our data indicate
that polar bears acted as predators in most fatal attacks on
Wilder et al. Polar Bear Attacks on Humans 7
people. All humans killed by polar bears had major wounds
to their head and neck, similar to the method polar bears use
to kill ice seals (Stirling 1974). Predatory behavior typically
involves silent stalking, direct approaches with no sign of
curiosity or hesitation, followed by a fast head down rush
(Fleck and Herrero 1988). Polar bears hunting their normal
prey (seals) do not vocalize (Herrero and Fleck 1990); neither
did the majority of polar bears that attacked people in our
analysis. The lack of any warning noises or other directed,
investigatory behaviors by the bears that attacked people
suggests that they were hunting (Fleck and Herrero 1988).
Lack of warning, however, is not always related to predatory
intentions. For example, female polar bears will act
aggressively to protect their offspring, particularly during
sudden encounters.
The Role of Human Behavior in Attacks
Our findings suggest certain human behavior may influence
the potential for negative interactions with polar bears. For
example, it is likely important to not act like prey. Data in the
PBHIMS includes 3 incidents where bears stalked people
with predatory intentions but appeared to realize their
mistake at the last minute and emitted a puff of air (Stirling
2011) or a hiss (Stefansson 1923) just before aborting their
attack. This suggests that, because the bears were hunting
something different than their normal prey, they used their
sense of smell to give themselves additional information just
before attacking (Stirling 2011). Submissive human behavior
can cause an interaction with a cautious, curious bear to
escalate into something far more dangerous by encouraging
the bear’s natural predatory instincts. Conversely, there are
several cases where predatory polar bear behavior was
effectively deterred by people’s aggressive action, such as
shouting, throwing hot water or wax in the bear’s face,
rushing the bear with a vehicle, firing flares, using bear spray,
or striking the bear with rocks, fists, or sticks.
Furthermore, humans often exacerbate the potential for
negative interactions with polar bears by not properly
managing aromatic attractants such as garbage, harvested
animals, meat caches, and dog yards. In the absence of
attractants, polar bears are generally cautious during initial
encounters with people and more susceptible to being scared
away (Fleck and Herrero 1988). This may help to explain the
low number of attacks at industrial sites, which typically
implement strict mitigation policies that address attractant
management, building security, and hazing and deterrent
actions.
When attractants are present, nutritionally stressed or
food-conditioned bears can quickly lose their sense of
caution around people (Fleck and Herrero 1988, Herrero
2002). Some of these bears can become quite dangerous, and
may view humans as prey. We found that the majority of
attacks that occurred in towns involved subadult and yearling
bears, were predatory in nature, and most of the bears
involved were in below-average body condition, meaning
they were hungry and likely motivated to procure food
however they could, including by preying on people. We also
found that anthropogenic attractants were present at 80% of
attacks that occurred in towns. These findings support the
idea that the combination of anthropogenic attractants and
polar bears in poor body condition increases the risk for
negative and potentially lethal interactions.
In over half of the attacks we analyzed, other people who
witnessed or were involved in the attack were able to save the
victim(s) by driving off or killing the attacking bear.
Although we documented the use of firearms to successfully
end attacks by polar bears, we also found that in 25% of
attacks where a firearm was in possession, victims and
bystanders mishandled firearms because of inexperience or
the stress of the incident.
Many people do not believe that bear spray is effective
against polar bears. However, Fleck and Herrero (1988)
suggested that bears that have experienced an unpleasant
interaction with people are more likely to avoid them in the
future. We have records of 16 incidents in which bear spray
was used successfully to deter polar bears, including incidents
where other deterrents failed. Although bear spray was not
used in any attacks reported here, it was used successfully to
stop 3 attempted attacks by polar bears. In 3 other incidents
in which bears exhibited persistent aggressive behavior, bear
spray successfully altered the bear’s behavior after other
deterrent efforts failed. Importantly, no humans or bears
were killed or injured in the 16 incidents in which bear spray
was used to deter polar bears. Other researchers have also
found bear spray to be an effective deterrent against other
bear species (Herrero and Higgins 1998, Smith et al. 2008).
Bear spray is currently illegal in Norway and Greenland, and
unavailable, though legal, in much of the Canadian and
Russian Arctic.
Difference in Attacks by North American Bear Species
The nature of attacks by polar bears appears to differ from
attacks by grizzly and black bears. For example, a substantial
proportion of fatal attacks by grizzly bears are defensive and
carried out by females with young (Herrero 1970; Herrero
and Higgins 1999, 2003). We did not find a single case where
a female polar bear with cubs had killed a person. However,
in one clearly predatory attack, a female with a yearling
attacked and dragged off a worker at an exploration camp in
Canada’s Norwegian Bay in the dark of the Arctic night. The
victim was saved from being killed by a co-worker, who,
when alerted, tracked down the bear and drove it off the
victim with a front-end loader.
We also documented a substantial proportion of attacks by
polar bears in towns, which are relatively rare for grizzly and
black bears (Herrero and Higgins 2003), although some
exceptions exist, such as Anchorage, Alaska, USA (Coltrane
and Sinnott 2015). It is unclear why polar bears may be more
likely to attack people in and around human settlements.
However, increased nutritional stress experienced by some
polar bears may compel them to take greater risks by
venturing into settlements to seek food (Towns et al. 2009).
Grizzly bears occasionally attack or even kill people in
defense of, or to claim, a carcass (Herrero and Higgins 1999,
2003). In contrast to grizzly bears, we found only one polar
bear attack that could be attributed to a polar bear’s defense
8 Wildlife Society Bulletin 9999()
of a carcass; in this case a female with 2-year-old cubs
apparently defended fermented walrus (Odobenus rosmarus)
meat (igunaq) at a cache site.
Although polar bears are the apex predator in their
environment and therefore seem to have little fear of
anything save other bears, as obligate carnivores they must
maintain their physical capacity to hunt seals; any serious
injury they suffer could prove fatal. Unlike grizzly and black
bears, which are able to survive on vegetative diets, polar
bears must hunt seals to survive (Rode et al. 2010b). As
a result, polar bears may be more averse to physical
confrontations than grizzly bears, contrary to the common
assertion that they are the most aggressive of bears (Miller
et al. 2015). This is likely because, throughout their
evolution, the presence of other large terrestrial Pleistocene
predators (such as short-faced bears [Arctodus spp.] and
several species of large wolves and cats; Matheus 1995,
Leonard et al. 2007) selected for aggression in grizzly bears
(Herrero 1972, 2002). Conversely, polar bears evolved to
exploit a rich marine niche, largely in the absence of
competitive influences from the suite of terrestrial Pleisto-
cene predators that influenced grizzly bear evolution.
Another key difference in the nature of attacks between
North American ursids is that, unlike grizzly and black
bears, most predatory attacks by polar bears have been
committed by independent immature bears (subadults,
2-year-olds, and yearlings; Herrero 2002, Herrero and
Higgins 2003). Although most fatal attacks by polar bears
were caused by adults, the fact that even independent
yearlings have killed people is a striking difference from
other North American bear species (Herrero and Higgins
2003, Herrero et al. 2011). However, for polar bears the
proportion of fatalities to the total number of injured
persons, 24% (20 of 83 people injured by a polar bear died),
is relatively low. For comparison, Herrero and Higgins
(2003) reported a fatality rate for attacks by black and
grizzly bears of 42% and 32%, respectively. Furthermore,
contrary to popular opinion we found that the proportion
of fatal attacks by polar bears that were predatory (88%)
was almost identical to that of black bears (87%; Herrero
et al. 2011). In other words, to date polar bears have been
no more likely to actively hunt and kill people than black
bears.
Similar to findings for grizzly bears and black bears,
groups of 1 or 2 people are more likely to be attacked by a
polar bear than are larger groups (Herrero 2002, Herrero
et al. 2011). Numerically larger parties are probably louder,
more intimidating, and better able to fight off a bear attack
(Herrero et al. 2011). However, in stark contrast to those
species, we also found that in rare cases, polar bears were
willing to attack groups of 10 or more people. This
difference may be explained by some polar bears’ willingness
to attack large herds of prey (e.g., walrus; Calvert and
Stirling 1990). Finally, contrary to grizzly and black bears,
bluff charges directed at people have rarely been observed
in polar bears (Fleck and Herrero 1988). A charging polar
bear should be interpreted as a bear intent on injuring a
person.
MANAGEMENT IMPLICATIONS
Key to minimizing the potential for conflict between humans
and polar bears is proactive management of attractants,
encounter group size, evaluation of the behavior and body
condition of bears encountered, and proper use of deterrent
tools and techniques, which collectively can mitigate most
human-polar bear conflicts. All group members should be
knowledgeable and proficient with the firearms and other
deterrent tools carried. In anticipation of continued climate
change impacts, we suggest that wildlife managers prepare
for more human-polar bear encounters throughout their
range. Finally, the Polar Bear Range States would be well
served to support applied research into effective polar bear
warning and deterrent systems, such as use of biologically
relevant perimeter alarm systems (Wooldridge and Belton
1980), electric fences (Wooldridge 1983, McMullen 1999),
and bear spray. Our findings underscore the need for
managers to implement plans to address the stranding of
unprecedented numbers of nutritionally stressed bears on
coastlines throughout their range in close proximity to
human activities (Peacock et al. 2011, Derocher et al. 2013).
ACKNOWLEDGMENTS
We thank the many agencies and individuals who
contributed data and insights, particularly the members of
the Range States Human-Polar Bear Conflict Working
Group. In particular we thank T. DeBruyn, former Polar
Bear Project Leader, United States Fish and Wildlife
Service, and T. Punsvik, former Environmental Advisor,
Office of The Governor of Svalbard, Norway, for their vision
in initiating this collaborative approach to human-polar bear
conflict mitigation at the 2009 Polar Bear Range States’
meeting in Tromso, Norway. We thank M. Colligan, E.
Regehr, K. Simac, and H. Voorhees for thoughtful reviews
of early drafts of this manuscript. The World Wildlife Fund
has been very active in their support of this Range States’
initiative, in addition to their other work around the Arctic
helping to address polar bear conflicts. K. Dobelbower of
Cirrus North has provided crucial technical support to this
project. We thank A. Southwould of the United States
National Park Service, Alaska Region, for her technical
assistance in creating the original conflict database from
which the PBHIMS evolved. Finally, we thank the Associate
Editor, Dr. Betsy Glenn, and 3 anonymous reviewers for
their help improving this manuscript. Major funding for
this initiative was provided by the United States Fish and
Wildlife Service and the World Wildlife Fund. Any use of
trade, firm, or product names is for descriptive purposes only
and does not imply endorsement by the United States
Government. The findings and conclusions in this article are
those of the authors and do not necessarily represent the
views of the United States Fish and Wildlife Service.
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Associate Editor: Glenn.
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