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Sloth Bear Attack Behavior and a Behavioral Approach to Safety

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Sloth bears (Melursus ursinus) are known to behave aggressively toward humans, and are believed to be one of the most dangerous wild animals in India. Although several papers have documented sloth bear attacks, no attention has been given on how to behave in sloth bear country to avoid encounters, or how to react to a sloth bear attack to minimize injuries and the likelihood of death. Wildlife SOS field research teams interviewed a total of 342 people, including 180 that had either been attacked or that had witnessed an attack, and 162 people that have had encounters with wild sloth bears that did not result in an attack. Our research and investigation confirmed that all attacks were defensive-aggressive in nature; we found no evidence for predatorial motivations. Our findings also show that people who had been making noise while moving through sloth bear country were less likely to be attacked. Our data also reveal that 9% of individuals who fought back during an attack were killed, and 11% of people who attempted to run were killed, whereas there were no deaths among people who merely fell to the ground and did not fight back. However, the data also reveal that those who fell to the ground and did not fight back were more likely to sustain serious injuries than those who did fight back.
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Sloth Bear Attack Behavior and a
Behavioral Approach to Safety
Thomas R. Sharp, Shanmugavelu Swaminathan, Attur Shanmugam Arun,
Tom Smith, Kartick Satyanarayan, and Geeta Seshamani
March 2017
They [sloth bears] have a reputation for attacking people without apparent reason, provided that person
happens to pass too close, either while the bear is asleep or feeding, or just ambling along. So the natives
give bears a wide berth; together with the elephant, they command the greatest respect from jungle
dwelling folk.
Kenneth Anderson, Man-Eaters and Jungle Killers
[The sloth bear] is also more inclined to attack man unprovoked than almost any other animal, and
casualties inflicted by it are unfortunately very common, the victim being often terribly disfigured even
if not killed, as the bear strikes at the head and face. Blanford (author of The Fauna of British India,
Including Ceylon and Burma) was inclined to consider bears more dangerous than tigers.
Robert A. Sterndale, Natural History of the Mammalia of India
Suggested citation: T. R. Sharp1, S. Swaminathan2, A. S. Arun2, T. Smith3, K. Satyanarayan4, and G.
Seshamani4. 2017. Sloth Bear Attack Behavior and a Behavioral Approach to Safety. Final Report to
International Association for Bear Research and Management.
1. Wildlife SOS Salt Lake City, Utah, United States
2. Wildlife SOS – Bangalore, Karnataka, India
3. Brigham Young University – Provo, Utah, United States
4. Wildlife SOS New Delhi, India
Sloth Bear Attack Behavior and a Behavioral Approach to Safety
i
CONTENTS
Summary ............................................................................................................................................... 1
Introduction .......................................................................................................................................... 1
Objectives .............................................................................................................................................. 2
Study Area ............................................................................................................................................ 2
Methods ................................................................................................................................................. 2
Results ................................................................................................................................................... 3
Sloth Bear Attack Motivation ............................................................................................................. 3
Defensive Attacks: Circumstances ................................................................................................. 4
Defensive Behaviors....................................................................................................................... 5
Avoiding Encounters in the Wild ....................................................................................................... 7
Injuries and Responses to Attacks ...................................................................................................... 8
Fighting Back ................................................................................................................................. 8
Running .......................................................................................................................................... 8
Playing Dead (Falling to the Ground and Not Fighting Back) ........................................................ 9
Comparison to Other Bear Species ................................................................................................... 10
Discussion............................................................................................................................................ 11
Attack Motivation ............................................................................................................................ 11
Defensive Behaviors ........................................................................................................................ 12
Avoiding Encounters in the Wild ..................................................................................................... 13
How to React to a Sloth Bear Attack ................................................................................................ 13
Future Directions .............................................................................................................................. 13
Acknowledgments .............................................................................................................................. 14
Literature Cited .................................................................................................................................. 14
Sloth Bear Attack Behavior and a Behavioral Approach to Safety
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FIGURES
Figure 1. Sloth bear/tiger encounter demonstrating the appearance of a very large sloth bear head
(photograph by Aditya Dicky Singh). ........................................................................................... 6
Figure 2. Sloth bear/tiger interaction demonstrating a sloth bear’s aggressive stance toward a tiger;
the bear’s ears are not pulled back in a defensive posture (photograph by Julien Boulé). .............. 6
Figure 3. Sloth bear/tiger interaction demonstrating the sloth bear’s predilection to rise onto two
hind legs during a dangerous encounter (photograph by Aditya Dicky Singh). .............................. 7
Figure 4. Number of incidents (n=69) by injury type that resulted from fighting back with an
attacking sloth bear. ..................................................................................................................... 8
Figure 5. Number of incidents (n=64) by injury type that resulted from running from an attacking
sloth bear. ........................................................................................................................... 9
Figure 6. Number of incidents (n=23) by injury type that resulted from playing dead with an
attacking sloth bear. ................................................................................................................... 10
Sloth Bear Attack Behavior and a Behavioral Approach to Safety
1
SUMMARY
Sloth bears (Melursus ursinus) are known to behave aggressively toward humans, and are believed
to be one of the most dangerous wild animals in India. Although several papers have documented
sloth bear attacks, no attention has been given on how to behave in sloth bear country to avoid
encounters, or how to react to a sloth bear attack to minimize injuries and the likelihood of death.
Wildlife SOS field research teams interviewed a total of 342 people, including 180 that had either
been attacked or that had witnessed an attack, and 162 people that have had encounters with wild
sloth bears that did not result in an attack. Our research and investigation confirmed that all attacks
were defensive-aggressive in nature; we found no evidence for predatorial motivations. Our findings
also show that people who had been making noise while moving through sloth bear country were
less likely to be attacked. Our data also reveal that 9% of individuals who fought back during an
attack were killed, and 11% of people who attempted to run were killed, whereas there were no
deaths among people who merely fell to the ground and did not fight back. However, the data also
reveal that those who fell to the ground and did not fight back were more likely to sustain serious
injuries than those who did fight back.
INTRODUCTION
Sloth bears are known for their propensity to behave aggressively toward humans, and are believed to
be one of the most dangerous wild animals in India (Sterndale 1884, Pillarisett 1993). It is not known
exactly how many people are seriously injured or killed by sloth bears in India during a given year.
Nonetheless, in the state of Madhya Pradesh, there were 48 sloth bearrelated human deaths and 687
maulings between 1989 and 1994 (Rajpurohit and Krausman 2000) for an average of 6 deaths and 115
maulings per year. Compared to American black bears (Ursus americanus) in the United States and
Canada during the last 110 years (19002009), there have been 63 documented human deaths due to
predatory attacks (Herrero et.al. 2011). Additionally, Herrero (1985) estimates that during the past 100
years in the United States and Canada, roughly 100 people have been killed by brown bears (Ursus
arctos).
Most people working and living in sloth bear habitat do not possess firearms or have access to bear
(pepper) spray or other commonly used bear deterrents (e.g., flares, screamers, shotgun deterrent
rounds). Additionally, there is currently no messaging that emphasizes the importance of bear avoidance,
how to behave when encountering a sloth bear, or how to react to a charging sloth bear. Sloth bears are
considered very unpredictable and often aggressive. Given the number of attacks and the associated
human casualties, coupled with the lack of firearms and bear spray, a behavioral-based approach to
reducing bear encounters and associated attacks in the wild could be useful for saving human lives. Such
an approach has been very successful in Canada and the United States, and has helped people better
understand these mammals. This study is the first comprehensive effort to identify a behavioral approach
to reducing risk from sloth bears in India.
Sloth Bear Attack Behavior and a Behavioral Approach to Safety
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OBJECTIVES
1. Determine a sloth bear’s motivation(s) for attack: defensive or predatorial.
2. Determine the circumstances under which defensive attacks occur.
3. Determine defensive behaviors that sloth bears typically exhibit.
4. Determine the most effective ways for humans to avoid sloth bears in the wild.
5. Determine the best way to react when observing a wild sloth bear, based on its behavior.
6. Determine the best way to respond if attacked by a wild sloth bear, based on its attack motivation.
STUDY AREA
Sloth bears occupy mainly lowland habitats throughout India, extending south to Sri Lanka and north to
Nepal. However, Wildlife SOS works extensively in the southern Indian state of Karnataka, and so we
largely interviewed people from that region, namely in the districts of Ramnagaram, Arasikere, Tumkur,
Koppal and Ballary in Karnataka.
Wildlife SOS currently operates four sloth bear rescue centers across India. The Bannerghatta Bear
Rescue Center (BBRC) in the state of Karnataka houses roughly 80 bears. We collected video footage
of bear behavior at this facility to analyze sloth bear behavior.
METHODS
We employed the following four methods to determine the motivations behind sloth bear attacks, and
the best ways to avoid encounters and attacks.
1. Literature reviewWe conducted a thorough literature review of past sloth bear attacks and
other aspects of their ecology that could help predict wild sloth bear behavior when encountering
humans. This included sloth bear diet, behavioral details of attacks, and known behavioral
elements of inter- and intra-specific sloth bear interactions, including with tigers (Panthera
tigris).
2. Interviews We interviewed 342 people in their native language who have had a variety of
encounters or observations of sloth bear behavior, including the following:
a. People who had been attacked by sloth bears (n=180).
b. People who have had an encounter with a sloth bear in the wild that did not result in an
attack (n=162).
c. Veterinarians and biologists who have more than 10 years of experience working with
sloth bears at the Wildlife SOS sloth bear rehabilitation centers, and who have observed
sloth bear behavior toward humans as well as between sloth bears.
3. Video documentation of sloth bear behaviorWe recorded videos of intra-specific sloth bear
interactions and behavior at the Wildlife SOS bear facilities in Agra and Bangalore as well as
bear charge videos.
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4. Comparison of bear behaviorWe compared the behavior of sloth bears to that of bears with
better understood and documented human attack behavior, namely American black (Ursus
americanus) and grizzly (Ursus arctos) bears.
RESULTS
Sloth Bear Attack Motivation
We studied documented sloth bear attacks to assess motivation for attack. We initially posited that
attacks would be either predatorial or defensive in nature, as is the case with North American bears. If
an attack was deemed defensive, we attempted to assess whether the animal was protecting cubs, a food
cache, or was surprised and therefore defensive-aggressive. If the attack did not fit any of these criteria,
we set it aside for further analysis. We then looked at relationships between sloth bears and other species
that could be a threat to them, namely tigers, but also other predators or megafauna.
The analysis of the data gathered indicates that sloth bear attacks appear to be wholly defensive. We did
not find a single case that was clearly predatorial in nature when conducting our intensive literature
review or in the attacks we documented. However, we did find accounts, both historical and
contemporary, of sloth bears partially consuming human corpsesoccasionally including those they
had killed themselves. Our reasons for not labeling these attacks predatory is illustrated in the examples
that follow.
We studied two historical accounts of sloth bear maulings that included consumption of the victim. The
most famous is the “sloth bear of Mysore,” which was reported to not only have mauled 24 people and
killed another 12, but also partially consumed three of its victims (Anderson 1957). The second account
involves the “sloth bear and cubs of Chandra,” which threatened small villages for a six-week span,
reportedly consuming more than one victim. More recently, Bargali et al. (2005) reported two incidents
in which a bear that had killed a person remained in the area feeding on body parts. However, because
we do not know how this event unfolded, we cannot reasonably conclude what the bear’s initial
motivation was.
During our interviews, 4% (n=7) of victims claimed their attack to have been predatorial. It is important
to recognize that a non-predatorial attack could easily appear predatorial from the victim’s perspective,
especially if there seemed to be no other apparent motivation for the confrontation. Additionally, sloth
bear attacks tend to focus on the victim’s head region, leading some to believe the attack was predatorial;
however, focusing on the head and face does not appear to be linked to predatorial attacks in bears in
general (Smith et al. in review) but is indicative of the attack strategy. Herrero (1985) surmised that
bears attack the head and neck region largely because they perceive our teeth as a weapon threat, the
same as they would with conspecifics.
The lack of evidence for sloth bear predatorial attacks is consistent with their diet (Joshi et al. 1997,
Garshelis et al. 2008). These studies indicate that red meat is only rarely a component in the normal diet
of a sloth bear. Although the occasional small rodent or reptile has been found in sloth bear scat, even
these food types are likely ingested incidentally while foraging for insects and grubs. Similarly, T. Smith
(personal communication) has found bees (Bombus spp.) in brown bear scat, incidentally ingested while
Sloth Bear Attack Behavior and a Behavioral Approach to Safety
4
foraging on the inflorescences of cow parsnip (Heracleum lanatum). There is no evidence to suggest
that sloth bears purposely forage for even small mammals. However, sloth bears are known to
occasionally scavenge on larger mammals, including humans. In 1995, Kartick Satyanarayan found a
human index finger in a sloth bear scat during a tiger-scat collection drive on a research project in Central
India. It was later confirmed that a tribal burial site was nearby, and the bear scavenged on a human
corpse that had been excavated by other scavengers.
Perhaps Kenneth Anderson said it best roughly 60 years ago (Anderson 1957) when he wrote the
following about the famous sloth bear of Mysore case:
Local rumors had it that the bear had taken to eating its victims, the last three of whom
had been partly devoured. I had no opportunity to verify the truth of these rumors but
felt that they might be true to some extent as the Indian sloth bear is a known devourer
of carrion at times, although generally he is entirely vegetarian, restricting himself to
roots, fruit, honey, white ants [termites] and similar delicacies. So fresh meat, even
human meat, might not be unwelcome.
It is possible that scavenging on the remains of humans, especially those that the bears themselves
killed, has led to the belief that sloth bears prey on people. Consuming a victim initially attacked for
defensive reasons is not unique to sloth bears; it has also been described in grizzly bear literature
(Herrero 1985). It is likely that the bear is simply being an opportunistic omnivore by feeding on
human flesh.
Defensive Attacks: Circumstances
Grizzly bear defensive attacks can be subdivided into four categories 1) a mother protecting her young,
2) a bear protecting its food cache, 3) a surprise encounter, and 4) a harassed bear. Our data and the
literature suggest that defensive sloth bear attacks are motivated by three of these four categoriesthe
protection of young, surprise encounters, and harassed bears. We have found no cases of a sloth bear
attacking to protect a food cache.
The “harassed bear” category refers to attacks provoked by human harassment (often chronic) that leads
to a bear charge and physical contact. For sloth bears, this category varies a bit from how it is used for
grizzly bears. This type of harassment in the case of sloth bears often includes people throwing objects
and yelling at the bear. This situation can also escalate into what is termed an “attack spree.” These are
cases in which a harassed bear kills multiple people in what appears to be self-defense, usually because
the bear appears unable to escape, or is motivated to become aggressive by the overall threat of the
situation. It therefore feels forced to confront one person after another. Attack sprees have been
documented between brown bears and humans in Alaska (T. Smith, personal observation), though sloth
bear attack sprees last longer and appear, at least superficially, to put the animal in more of a frenzied
state.
During our interviews with 181 sloth bear attack victims, almost half of the attacks (n=84, 46%) involved
a female with dependent young. These cases fall under the mother protecting her young” category. Of
the 161 encounters that were reported and did not end in an attack, 40% (n=65) involved a female with
dependent young.
Sloth Bear Attack Behavior and a Behavioral Approach to Safety
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Of the 181 attacks, 52% (n=94) involved single bears. The motivation for these attacks was most likely
due to surprise encounters. Single bears accounted for 60% (n=96) of the encounters that did not result
in an attack. The remaining 2% (n=3) of attacks involved a pair of bears.
Defensive Behaviors
Grizzly bear defensive behavior such as laying their ears back, slapping the ground, jaw popping,
and huffing are well documented. Sloth bear defensive behaviors have not been explicitly
documented. The ears being drawn or pinned back is a common defensive reaction among bears
and many other species of wildlife (e.g., felids and canids). However, this behavior is rarely, if ever,
exhibited by sloth bears. Sloth bear charge videos taken by Wildlife SOS and other wildlife
videographers show that sloth bear ears are not laid back during a charge. Additionally, sloth bear
ears do not appear pulled back during tiger encounters (http://www.arkive.org/tiger/panthera-
tigris/video-ti11b.html). Aditya Dicky Singh’s 10-photograph series of a tiger/sloth bear interaction
(http://www.dickysingh.com/2011/04/10/bear-tiger-confrontation-10-pics-that-tell-a-story/)
provides several interesting details. One photograph (Figure 1) clearly shows the heads of each
animal during the most intense moments of the confrontation. The contrast is remarkable; while the
tiger clearly has its ears pulled back, the sloth bear does not; in fact, the bear’s head appears larger
than usual. The sloth bear’s shaggy head potentially conceals drawn-back ears, rendering them
useless as a means for communicating stress. Additionally, it seems possible that the fur on the head
makes the bear appear larger and thus more intimidating. Pulling back the ears would potentially
make the head look smaller. Another tiger/sloth bear confrontation photographed by Julien Boulé
shows a sloth bear aggressively squaring off with a tiger and holding its ground (Figure 2). Once
again, the tiger’s ears are pulled back while the sloth bear’s are not.
Sloth Bear Attack Behavior and a Behavioral Approach to Safety
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Figure 1. Sloth bear/tiger encounter demonstrating the appearance of a very large sloth bear
head (photograph by Aditya Dicky Singh).
Figure 2. Sloth bear/tiger interaction demonstrating a sloth bear’s aggressive stance toward a
tiger; the bear’s ears are not pulled back in a defensive posture (photograph by Julien Boulé).
Sloth Bear Attack Behavior and a Behavioral Approach to Safety
7
Sloth bears may also attempt to look larger by getting up on their two hind legs during attacks on humans
or in encounters with tigers. A bear on two hind legs will appear larger and more intimidating (Figure
3). A bipedal bear also brings all three weapons, two paws and its teeth, into play simultaneously,
presenting a formidable threat to would-be attackers.
Figure 3. Sloth bear/tiger interaction demonstrating the sloth bear’s predilection to rise onto
two hind legs during a dangerous encounter (photograph by Aditya Dicky Singh).
Sloth bears, unlike most other bear species, are very vocal, and will actively voice their uncertainty and
discomfort with a situation. However, only 4% of the attack victims (n=7) noted that the bear vocalized
before it charged and made physical contact. Yet it is clear in video of sloth bear charges and sloth
bear/tiger interactions that bears are markedly vocal during such encounters. A Wildlife SOS video from
the BBRC captured a vocalization that sounds more reminiscent of a gorilla’s charge than a bear’s. It
seems clear that these vocalizations add a startling and intimidating element to the charge.
Overall, sloth bears appear to forego the subtle defensive/stress displays that grizzly bears and American
black bears make when warning people or other animals that their stress level is rising. However, sloth
bears do use several methods to intimidate a potential threat, after which an attack may or may not occur.
Avoiding Encounters in the Wild
We asked the interviewees involved in 181 bear attacks if they had been making noise before the
encounter. Roughly two-thirds (n=111, 67%) stated that they had not been. We also analyzed sloth bear
encounters that did not result in an attack or physical contact. Of the 126 interviewees who experienced
Sloth Bear Attack Behavior and a Behavioral Approach to Safety
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a sloth bear encounter without an attack, and could recall if they were making noise, 78% (n=98) claimed
to have been making noise, whereas 22% (n=28) had not been.
Injuries and Responses to Attacks
To identify potential patterns, we assessed the severity of bear-attack injuries based on how the victim
reacted to the confrontation. Our intent was to identify responses that resulted in the least amount of
bodily injury. We paid particular attention to the three most common responses to an attack: 1) fighting
back, 2) running, and 3) falling to the ground and not fighting back.
Fighting Back
We interviewed 69 individuals involved in separate incidents who fought back when attacked (or who
had witnessed it). Approximately 9% of these people were killed, 12% were severely injured, and 50%
suffered minor injuries (Figures 4 and 5).
Figure 4. Number of incidents (n=69) by injury type that resulted from fighting back
with an attacking sloth bear.
Running
We interviewed 64 individuals who were attacked by a sloth bear (or witnessed an attack) when
attempting to run away. In all, 11% that ran were ultimately attacked and killed. Another 9% were
severely injured, and 42% suffered moderate injuries (Figures 6 and 7).
0
5
10
15
20
25
30
35
No Injury Slight I njury Moderate Injury Severe Injury Fatal Injury
Number of Incidents
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Figure 5. Number of incidents (n=64) by injury type that resulted from running from an
attacking sloth bear.
Playing Dead (Falling to the Ground and Not Fighting Back)
We interviewed 23 individuals who played dead (i.e., fell to the ground and did not fight back) when
attacked. No individuals who played dead suffered fatal injuries. However, 18% of those playing dead
suffered severe injuries, while 65% incurred moderate injuries (Figures 8 and 9).
0
5
10
15
20
25
30
No Injury Slight Injury Moderate Injury Severe Injury Fatal Injury
Number of Incidents
Sloth Bear Attack Behavior and a Behavioral Approach to Safety
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Figure 6. Number of incidents (n=23) by injury type that resulted from playing dead with an
attacking sloth bear.
Comparison to Other Bear Species
Although anecdotal reports of bear attacks on humans exist for the polar bear (Ursus maritimus), Asiatic
black bear (Ursus thibetanus), Andean bear (Tremarctos ornatus), panda bear (Ailuropoda
melanoleuca), and sun bear (Ursus malayanus), American black bear and grizzly/brown bear attacks
have been the most studied and best understood. Importantly, the grizzly bear accounts for more than
80% of all bear attacks in North America (Herrero 1985, Smith et al. in review), even though they are
far outnumbered by black bears. Smith et al. (in review) report that grizzly bears are 26 times more
likely to engage in conflict with humans than are black bears, and 6 times more likely than polar bears.
Nonetheless, bear attacks in North America have averaged 7.6 attacks/year in the last decade (Smith et
al. in review). This level of human-bear conflict pales in comparison to that of humansloth bear conflict
in India. Although data are lacking for the entire country of India, human-bear conflict statistics from a
single Indian state prove this point. Rajpurohit and Krausman (2000) documented sloth bear attacks in
the state of Madhya Pradesh from 1989 to 1994. They found that sloth bears inflicted 48 fatalities and
687 maulings during a 6-year period, for an average of 123 attacks/year, 16 times more than the entire
state of Alaska for the same time. From this perspective, the sloth bear appears to be a far greater threat
to human safety than any bear species on the North American continent. However, differential contact
rates with humans clearly play a role in these statistics. Whereas the human density in North America is
roughly 22.9/km2, it is reported to be 389.9/km2 for India, or approximately 17 times greater. Just as this
differential population density correlates highly with the difference in bear attack frequency between
0
2
4
6
8
10
12
14
16
No Injury Slight Injury Moderate Injury Severe Injury
Number of Incidents
Sloth Bear Attack Behavior and a Behavioral Approach to Safety
11
North America and India, Smith et al. (in review) demonstrated that population growth in Alaska over
130 years accounts for 87% of the variation in bear attacks during the same period. Indeed, the more
people enter bear habitat and commingle with them, the more likely are human-bear encounters and risk
of subsequent injury and/or death, whether grizzly or sloth bear. We do not conclude, therefore, that
sloth bears are more dangerous than grizzlies, but rather that they are quite similar in their intolerance
of human incursions into their habitat.
DISCUSSION
Attack Motivation
Historical data and recent interviews with attack victims and witnesses all support the premise that the
motivations of sloth bear attacks are exclusively defensive in nature, not predatorial. In fact, we were
unable to document or find documentation for a single sloth bear predatorial attack. Occasionally a
victim reported an attack as predatorial, and though these attacks do not appear predatorial when
independently analyzed, we understand how they could appear as such. Attack victims have reported
feeling ambushed by an animal lying in wait because the bear appeared to be hidden and therefore could
have likely left the area without ever being detected. It then follows that people might conclude that the
motivation for attack was predatory. Other victims reported seeing a sloth bear hiding behind a tree,
only to attack after detection. Again, this appeared to the victim as predatorial. However, video footage
of a stressed bear at the BBRC shows it running behind a tree, only to charge again at people outside its
fenced area. The attack might look predatorial because it seems logical that a non-predatorial bear would
either stay hidden or run off rather than attack.
Another contributor to the belief that sloth bears may be predatorial is the existence of documented
cases, both recent and historical, of sloth bears partially consuming their victims’ corpses. However,
upon closer inspection, it appears that the initial bear attacks in these cases were defensive in nature (or
at the very least the motivation is unknown), and that the bears began consuming the corpse(s)
opportunistically. As we mentioned, sloth bears do occasionally scavenge larger mammals (Schaller
1984). Additionally, other bears (specifically, grizzlies [Herrero 1985]) have been documented feeding
on victims killed during defensive attacks.
The known ecology and diet of the sloth bear seems to corroborate the lack of predatorial attacks. It is
clear from studies (e.g., Laurie and Seidensticker 1977, Gopal 1991, etc.) that red meat plays nearly no
role in the diet of this species. Red meat is generally limited to the occasional rodent, which was likely
consumed inadvertently while the bear foraged for insects. Even scavenging on wildlife carcasses
appears rare for this species.
The sloth bear’s defensive nature appears to be the result of co-evolving with large predators, namely
tigers, which are known to occasionally kill and eat sloth bears. However, it is instructive to compare
the sloth bear’s survival strategy to that of the American black bear. Although the sloth bear behaves
defensively aggressive, the American black bear almost never attacks defensively. Even a female with
cubs will run in the face of danger, while the cubs climb trees. Sloth bear cubs do not climb trees when
threatened, but rather cling to their mother’s back for the first 9 months of their lives. Mother sloth bears
Sloth Bear Attack Behavior and a Behavioral Approach to Safety
12
with cubs have been documented fighting off tigers by charging them with cubs clinging to their backs.
The reasons for this difference in strategies between black and sloth bears may be explained by
differences in their respective habitats and the other species of wildlife occupying them. American black
bears are largely restricted to forested habitats, whereas sloth bears are often found in grasslands and
scrub jungle, where the opportunity to climb a tree is not always present. Additionally, though sloth
bears occasionally climb trees for honey and other foods, they are not nearly the climbers that American
black bears are. This may be partly due to the sloth bear’s very long claws, which are adapted to digging
rather than climbing trees. The tendency of sloth bears to attack without much provocation could have
evolved as a way to mitigate threats in their environment. Bouskila and Blumstein (1992) state that
“animals rarely have perfect information, and generally are expected to maximize fitness by
overestimating rather than underestimating risk. Overestimation costs, such as lost feeding
opportunities, have milder fitness consequences than the cost of underestimating danger, which might
be immediate death.” Frid and Dill (2002) concur with this assessment, stating that underestimating a
potential risk has much harsher consequences than overestimating a perceived threat. Sloth bears are
mid- to small-sized bears that coexist with many predatorial species such as tigers and leopards
(Panthera pardus) as well as megafauna such as the Asian elephant (Elephas maximus) and Indian
rhinoceros (Rhinoceros unicornis). Although sloth bears flee potential danger when given the chance,
they often use the strategy of “the best defense is a good offense,” and charge the putative threat.
North American bear species (black, brown/grizzly, and polar) have been known to see humans as
potential prey. We did not find predation to be a motivation for sloth bear attacks in India; most are the
result of surprise encounters. This is important because it suggests the solution to sloth bear-human
conflict lies in human behavior modification rather than arming people with expensive deterrents (e.g.,
firearms, bear spray, shotgun deterrent rounds), an economic impossibility for most. If a person acts
appropriately in sloth bear habitat, making noise and telegraphing their presence as they move about,
our research suggests that most bear encounters will be avoided. When avoidance measures (i.e., making
noise appropriately, hiking in groups, etc.) are the focus of bear safety messaging, the nuances of how
to best defend oneself during an attack (e.g., fight or flight) become much less important.
Defensive Behaviors
Sloth bears do not appear to display signs of stress before charging. This may be related to the species’
predilection to charge with less provocation than bear species such as grizzlies or American black bears.
Sloth bears do appear to incorporate several actions meant to intimidate, including vocalizing and raising
up on their hind legs. Sloth bears may also use their shaggy fur to appear larger to potential predators.
Notably sloth bears do not pull their ears back during a tiger encounter. Since tiger attack sites are
typically the back of the neck, pulling one’s ears back is not particularly useful. Work by Walther (1969)
and Ghalambor and Martin (2000) suggests that prey have evolved predator-specific antipredator
behaviors. This may be the case here: no need to pull ears back for tigers whereas they may do so with
other sloth bears. Further observation of sloth bear-sloth bear aggression is required to determine if sloth
bears behave differently to different types of threats. Bear-bear attacks in North America are generally
frontal attacks of the head and face, and as such laying the ears flat makes more sense.
Sloth Bear Attack Behavior and a Behavioral Approach to Safety
13
Avoiding Encounters in the Wild
Our data strongly suggest that making noise while moving through sloth bear habitat helps to avoid
sloth bear encounters and attacks, and that encounters are less likely to turn into attacks. This suggests
that if the bear is not startled in close quarters, its preference is to leave the area without incident. This
is not surprising, and is similar to findings with other bear species, namely the grizzly and American
black bear.
How to React to a Sloth Bear Attack
The results of our interviews aimed at determining a behavioral approach to sloth bear attacks yielded
some mixed messages. Fighting an attacking sloth bear resulted in approximately 9% fatalities, while
running from an attacking sloth bear resulted in 11% fatalities. Playing dead when confronted by an
attacking sloth bear resulted in no fatalities. Therefore, if the goal is simply to survive the encounter,
falling to the ground and covering up in some fashion seems advisable. However, if we combine
fatalities with serious injuries, all three courses of action result in approximately 20% of individuals
being killed or severely injured. Further, a higher percentage of people who played dead and covered up
in some fashion suffered a higher rate of moderate injuries (65%) than did those who fought back (30%)
or those who ran (42%). The reasons for this are difficult to interpret; however, a partial explanation
may be that those who played dead did not cover up in the most protective manner. In fact, what many
of the victims reported doing while playing dead does not constitute effective protection. Therefore, it
is at least possible that if people were taught how to properly protect their head and neck regions from
injury, the severity of the injuries would lessen.
Those who fought back and did not die faired relatively well, as only 46% suffered minor injuries.
However, 9% were fatally injured and another 12% were severely injured. We are unable to ascertain
why nearly half of the victims escaped with minimal injuries while 21% were killed or severely injured.
The differences in injury may have to do with some unreported action on the victim’s part that resulted
in greater injury. It may also merely reflect the odds of an injury being severe or fatal. When a bear’s
jaws encompass the head, injuries are most often fatal, whereas when canines slip off the curvature of
the skull, severe injuries result but the brain remains protected. With this in mind, one can see how under
the same attack scenario, one individual may die while another might survive.
Finally, those who attempted to run from the attacking bear fared worst, with a higher percentage dying
than in the other response scenarios (11%). There is little doubt that running triggers a chase response
in sloth bears, just as it does in grizzly bears (Herrero 1985). There have been many cases of sloth bears
chasing, catching, and mauling human victims (Sharp and Sonone 2011).
Future Directions
Further follow-up studies on sloth bear attacks and responses to victim behavior will help confirm if
reacting to a sloth bear attack in the same manner as to a defensive grizzly bear attack would be most
beneficial for the victim. Additionally, outreach to communities in sloth bear habitat can educate them
on them how to avoid encounters with sloth bears, or what to do if they are charged and attacked.
Sloth Bear Attack Behavior and a Behavioral Approach to Safety
14
ACKNOWLEDGMENTS
We appreciate the funding from the International Association of Bear Research and Management. We
would also like to thank the Forest Department of the State of Karnataka for sharing their sloth-bear
attack records, which were instrumental in allowing us to conduct a number of interviews with bear
attack victims. We acknowledge the Wildlife SOS Field Research Team of Reagan, Balasubramaniam,
and Yogaraj for the persistent and extensive data gathering to make this publication possible. We thank
the Wildlife SOS BBRC team who extended their support for gathering photo and video documentation.
Finally, we extend a special thank you to Aditya Dicky Singh and Julien Boulé, who allowed us to use
their sloth bear/tiger encounter photographs for this report.
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