AMER. ZOOI.., 14:371-389 (1974).
Social Play in the American Black Bear: Its Similarity to Canid
Social Play and an Examination of its Identifying Characteristics
J. D. HENRY AND S. M. HERRERO
Department of Biology and Faculty of Environmental Design,
The University of Calgary, Calgary, Alberta, Canada, T2N 1N4
SYNOPSIS. Bears evolved from a canid stock at quite a recent date (early Miocene) .
j-'Cspitc tuis recent origin, ucsrs show substantial morphological, pliySiologiCai, and
ecological differences when compared to modern day canids. However, the display behaviors of Canidae and Ursidae have remained remarkably similar. In this paper, the
motor patterns of black bear social play are described in detail. Numerous similarities
between canid and ursid social play are pointed out. Agonistic displays common to
both families are also pointed out. These behavioral similarities support the principle
that social behavior, particularly display behavior, will frequently be conservative in
its evolution as compared to the evolution of morphology, anatomy, or ecological
adaptations.
Beach (1945) stressed the importance of identifying and testing the general characteristics of play. A large number of characteristics have been suggested as being
diagnostic of play, but these characteristics have received very little testing. Five characteristics of social play were tested in this study, and two were found to be only
partially valid for black bear social play. Extensive testing of the general characteristics of play on as wide a range of species as possible is definitely recommended for
future research.
show substantial differences (see Papez,
1929, and Davis, 1964, for reviews). For exBears evolved from a canid lineage at ample, Ursidae manifests expansion of cerquite a recent date. The ursid line is first tain areas in the cerebral cortex which apidentified in the fossil record during the pears to be related to the enhanced maniplower Miocene, and the modern day genus ulative abilities of the ursid forelimbs
Ursus did not appear until the upper Plio- (Davis, 1949, 1964). Regarding ecological difcene (Herrero, 1972). Colbert (1955) states ferences, many ursid species have adopted
that, along with Hyaenidae, the family an omnivorous niche. And in cold climates,
Ursidae is the youngest and most recent bears have evolved winter lethargy. Folk
family of carnivores to differentiate. De- et al. (1972) and Nelson et al. (1973) review
spite this recent origin, Ursidae exhibits the physiological adaptations that allow
many differences when compared with mod- bears to achieve this state of winter dormancy.
ern day canids.
Despite these morphological, ecological,
For example, regarding morphological
differences, bears show only a rudiment of and physiological differences, the social disthe large canid tail. Bears also exhibit a plays of Canidae and Ursidae have replantigrade condition and have evolved a mained remarkably similar. This is one of
bunodont dentition (Davis, 1964). Even the the main hypotheses examined in this rebrain morphologies of Canidae and Ursidae search. It is examined first by comparing
the social play of black bears with that of
canids. A subsequent article will look at
This research was supported by N. R. C. Grant
#69-0734, by the Killam Foundation, and by the agonistic behavior.
If the social displays of Canidae and
Environmental Sciences Centre (Kananaskis). The
co-operation of the National and Historic Parks Ursidae are indeed similar, it illustrates the
Branch of Canada and the Calgary Zoo made this principle that social behavior can be rather
research possible. We gratefully acknowledge the
conservative in its evolution when comfinancial support and co-operation received from
pared with the evolution of morphology,
these organizations.
INTRODUCTION
371
372
J. D. HENRY AND S. M. HERRERO
anatomy, or ecological adaptations. Hofer
(1972) and Geist (1974) discuss this principle. Hofer applies it to evolution among
the primates.
The preceding statements assume that
behavioral homologies exist between Canidae and Ursidae. Criteria indicating morphological homology were outlined by
Remaine and applied to behavioral homology, first, by Baerends (1958) and, more
recently, by Wickler (1967a). The conclusion that social behavioral homologies exist
between Canidae and Ursidae has been
made because several of these criteria can
be satisfied. First, homology is indicated
because of the criterion of relative position:
namely, many motor patterns occupy the
same relative position in the temporal sequencing of canid and ursid social behaviors. Secondly, the criterion of specific
quality is satisfied: There are extensive similarities in the external appearances of motor
patterns and displays in canid and ursid
social behaviors. Finally, the fact that the
same motor patterns and displays occur in
a large number of closely related canid and
ursid species indicates that these motor patterns are homologous. Numerous examples
illustrating the above three criteria will be
given in the descriptions of black bear social play.
Beach (1945) states that a definition of
play behavior must be based on its objective
characteristics which, when combined, set
off play behavior from non-play behavior.
Bekoff (1972) has offered an operational
definition of social play that is, in fact,
based on several of play's suggested identifying characteristics (see also Bekoff, 1974).
His definition of social play is used throughout this study. A large number of charafcteristics have been suggested as being diagnostic for solitary and social play (see MeyerHolzapfel, 1956; Tembrock, 1958; Marler,
1966; Loizos, 1967), but these characteristics
have received very little testing (MullerSchwarze, 1968, 1971). It is imperative that
objective descriptions of play exist from
as wide a range of species as possible and
that the suggested identifying characteristics of play be tested on this wide range of
species. If play is a valid, unitary category
of mammalian behavior, this testing should
lead to an objective and verifiable definition of play behavior.
The purpose of this paper, then, is twofold: first, to describe the social play behavior of black bears as part of an effort to
describe the social behavioral repertoire of
this species; and, second, to examine which
of the suggested characteristics of social
play are valid for black bear social play.
METHODS
Black bear social play was studied principally by observing black bear cubs (Ursus
arnericanus) under captivity conditions. At
the Calgary Zoo, three cubs (two females,
one male) were raised together from approximately 3 months of age in a 12- x 12yard arena. As a consequence of feeding and
cage cleaning, the cubs received approximately li/2 hr of close contact with humans
per day. All three cubs appeared healthy
and showed considerable growth over the
summer, but the male cub always remained
somewhat smaller than the two females.
The male cub did not, however, permanently occupy the lowest position in the
hierarchy.
Observations on social play began after
the bears had been housed together for over
a month. From mid-June to the end of July
1973 the cubs were observed and a total of
508 social play sequences were filmed using
8 mm cine film. For each filmed sequence,
pertinent notes were also taken regarding
the exact beginning and end of the sequence, the precise location of vocalizations
on the film, etc. In slow motion and occasionally frame by frame, these films were
analyzed for social play motor patterns, and
the films were tested for the identifying
characteristics of black bear social play.
Additionally, for several years, freeranging black bears have been observed in
several Canadian national parks. Bears were
frequently observed at or around sanitary
landfills where they congregated to feed on
refuse, but also were observed occasionally
in the backcountry, a number of miles away
from these landfills. Black bears were observed during the summer and fall of 1968
373
SOCIAL PLAY IN THE AMERICAN BLACK BEAR
at the Jasper Landfill in Jasper National
Park, Alberta, and during the summer and
fall of 1971 and 1972 at the Waskesiu Landfill in Prince Albert National Park, Saskatchewan. Aggressive behavior as well as
social play were thoroughly studied at these
times. Seventy-two social play sequences
were filmed in the cub, yearling, and subadult black bears that visited these landfills,
while numerous other social play sequences
were described, but not filmed. These data
from free-ranging black bears are used to
determine whether the descriptions and
conclusions made about the captive cubs
appear to be valid for the behavior of freeranging black bears.
THE CLASSIFICATION OF SOCIAL PLAY
Free-ranging black bears, from cubs as
young as 4 months old up to sub-adults
estimated to be 4 years old, commonly
exhibited social play. Social play usually
occurred in one of three social contexts:
(i) among litter mates, (ii) between a mother
and her offspring, and (ill) among sibling
or non-sibling sub-adults that have separated from their mothers (see also MeyerHolzapfel, 1957).
The entire play repertoire of the black
bear can be classified according to the following system (after Tembrock, 1958):
I. Solitary Play: Play with an inanimate
object or body part, (see Leyhausen,
1949; Meyer-Holzapfel, 1957).
TI. Social Play: Play with a social partner.
A. Intraspecific Social Play: The social
partner is a conspecific.
1. Play-fighting: Play that involves
physical contact and consists primarily of agonistic-like motor
patterns.
2. Locomotory Play: Play that consists mainly of chasing or climbing after another bear and involves little physical contact. Motor patterns resemble agonistic
motor patterns.
3. Sexual Play: Play that involves
physical contact and consists primarily of sexual-like motor patterns.
B. Interspecific Social Play: The play
partner is from a different species.
This paper analyzes intraspecifk social
play of the black bear which, by definition,
implies an interaction between two or more
black bears. An interaction is defined as any
behavioral situation where two or more
black bears react with each other in such a
way as to disrupt their ongoing patterns of
moving, feeding, or resting (Stonorov and
Stokes, 1972). Social play was analyzed in
terms of sequences. A sequence is simply
an interaction that takes place over time
(seconds or minutes). Social play among
black bears usually occurs in discrete sequences, that is, the bears approach, interact with each other, and then usually separate bringing the interaction to an end.
Sequences are made up of a series of motor
patterns. A motor pattern is defined as a
distinct and frequently repeated spatiotemporal pattern of muscular contractions
(Hinde, 1970).
The sequences of black bear social play
showed an intensity gradient. This gradient
was particularly conspicuous in play fighting. We tried only to divide this intensity
gradient approximately in half and to
classify sequences into either high or low
intensity. We did so according to the following criterion: if over 50% of the motor
patterns, as measured in seconds, were
judged to be performed in a high intensity
manner (fast running, vigorous clawing
actions, intense biting actions, etc.), the
play sequence was classified as a highintensity sequence. Otherwise, it was classified as a low-intensity sequence.
The 508 social play sequences from the
captive cubs are classified in Table 1. The
TABLE 1. Quantitative classification of the 508 social
play sequences from the captive cubs. In the third
column, the average time duration and its standard
deviation are listed for each type of social play.
n
428
Play-fighting
low intensity
high intensity
Locomotory play 68
12
Sexual play
Totals
508
%
Time duration
occurrence
(X ± SD)
84%
228
200
20.3 •+• 49.6 sec
18.2 ±13.1 sec
14%
2%
100%
9.3 •+• 10.5 sec
18.6+ 15.9 sec
374
J. D. HENRY AND S. M. HERRERO
table shows that black bear intraspecific
social play is predominantly play-fighting
(84% of the sequences). Only 14% of the
play sequences were locomotory play, and
only 2% were sexual play. These findings
correlate well with observations from freeranging bears. Among free-ranging cubs
and sub-adults, social play was predominantly play fighting, while locomotory play
and sexual play were only occasionally observed. Social play between a sow and her
cub usually took the form of low intensity
play fighting.
One way to test the adequacy of a behavioral classification system is to measure
the amount of overlap between categories
of that system. 86% of the filmed social play
sequences showed behavior from only one
category of play (either play-fighting, locomotory play, or sexual play). Only 14% of
HG. 1. The smaller cub shows the relaxed openmouth face and partially flattened ears. The larger
the sequences showed behavior that combined two different types of social play. Of
the four different combinations possible,
only two combinations appeared: locomotory play was combined with play-fighting,
and sexual play was combined with playfighting. In Table 1, these combination
sequences were classified according to which
type of play predominated in the sequence.
We conclude that play-fighting is by far the
predominant form of social play among
black bears and that the other two forms of
social play (locomotory play and sexual
play) frequently have at least some playfighting behavior associated with them.
THE EAR POSTURES, FACIAL EXPRESSIONS, AND
VOCALIZATIONS OF SOCIAL PLAY
Ear postures
The pinnas of the black bear are large
cub shows the alert face and frontal alert ears,
SOCIAL PLAY IN THE AMERICAN BLACK BEAR
375
FIG. 2. One cub exhibits crescent ears. The other cub is face-pawing.
and mobile. The pinnas appear especially
large in young black bears. Their conspicuity appears to be due to differential growth.
Using analysis of variance, Sauer (1966)
examined measurements from 129 black
bears of various ages and found that the
pinnas attain adult size when the black
bear is only 1 or 2 years old.
As with many canid species, the pinnas
of the black bear appear to be important
signals for social communication (Burghardt, 1972). Five distinct ear postures are
recognized in black bear social communications. All five ear postures are observed
during social play, and a description of each
follows.
Frontal alert: The pinnas stand erect on
the head and face forward (Fig. 1).
Laterad: The pinnas face laterad, halfway between erect and flat on the neck.
Laterad appears to be the relaxed ear
posture.
Crescent posture: The pinnas face ventrad or nearly so, and stand perpendicularly
out from the side of the head (Fig. 2). This
ear posture can be readily identified by the
crescent-like curve formed by the bear's
pinnas and forehead. In young black bears,
the crescent ear posture may have an exaggerated quality due to the special largeness
of the pinnas. The crescent ear posture is
observed during active submission, during
interactions between a sow and her cub,
and during social play.
Flattened posture: During aggressive behavior, the black bear flattens its ears on its
neck, and the pinnas disappear completely
from view. Flattening the ears appears to
be a strong sign stimuli in black bear social
communication. For example, in social play
if the physical contact becomes intense, one
of the bears may flatten its ears, and this
frequently leads to a quick termination of
the social play sequence.
376
J. D. HENRY AND S. M. HERRERO
\ A-J
FIG. 3. The darker subadult rears bipedally and
shows the puckered-lip face. The other subadult ex-
hibits partially flattened ears and the relaxed openmouth face.
Partially flattened posture: The pinnas
are partially flattened on the neck but are
still somewhat visible (Figs. 1, 3). Specifically, the pinnas are flattened to a point so
that an imaginary straight line can be
drawn from the nose through the eye of the
bear and along the exterior surface of the
pinna (Fig. 1). If the pinnas are flattened
below this imaginary line, the ear posture
is classified as flat. Above this line, the ears
are classified as laterad. In the black bear,
the partially flat posture is seen during
flight behavior and also during social play.
During social play, this ear posture can be
interpreted as a somewhat defensive, but
play-permitting signal. Since flattening the
ears tended to disrupt the social play sequence whereas partially flattened ears did
not, these two ear postures are interpreted
as distinct, although somewhat related, sig-
nals (see also Schenkel, 1947; Fox, 1970).
It is important to realize that these five
ear postures graded and changed into one
another, and that it was difficult to determine what was communicated by the many
intermediate ear postures observed. We did,
however, examine the hypothesis that
the ears were clearly crescent or clearly
partially flat at the beginning of the social
play sequence. This hypothesis was supported by 88% of the high intensity social
play sequences. The bear that initiated social play usually clearly exhibited crescent
ears. Its partner usually clearly exhibited
partially flattened ears.
Social communications by means of ear
postures is further supported by the exceptions during high intensity social play sequences. In 23 sequences, the bear being
approached either flattened its ears or
SOCIAL PLAY IN THE AMERICAN BLACK BEAR
showed frontal alert ears. The other bear,
instead of initiating social play, pivoted
and fled in all but two of these sequences.
Thus, from the ear postures alone we could
successfully predict whether or not the play
sequence would be initiated.
The ears of both bears were most clearly
crescent or partially flat at the beginning
of high intensity social play sequences.
However, black bears tend to exhibit these
two ear postures, although in more variable
forms, continuously during all social play.
These two ear postures, in conjunction with
other characteristics, are useful identifying
characteristics of black bear social play.
Facial expressions
Lorenz (1953) suggests that because bears
are solitary animals and have a thick skin
covering their head and face that they strike
without warning, that is, without first laying back their ears or giving an agonistic
facial expression. Our observations, however, suggest that black bears almost always
lay their ears back before attacking and that
facial expressions appear to be of great
importance for social communication (see
Meyer-Holzapfel, 1957).
There appear to be seven distinct facial
expressions in the black bear. Bolwig (1964)
and Fox (1970) have emphasized the similarity of facial expressions in primate and
canids, and ursids also show many of these
similarities. Because of these similarities,
we adapted our terminology and method of
study from van Hooff (1967) and Fox (1970)
whenever possible.
In the black bear, there are three closedmouth facial expressions which are listed in
order of increasing alertness: the relaxed
face, the alert face (Fig. 1), and the
puckered-lip face (Fig. 3). All three are
frequently seen during social play. In addition, there are four open-mouth facial expressions that are also listed in terms of
increasing alertness: the relaxed openmouth face (Fig. 1), the jaw-snapping face,
the jaw-gape face, and the biting face. Of
these four, only the relaxed open-mouth
face is commonly seen during social play.
The other three are observed during aggressive behavior.
377
Ear postures in the black bear appear to
be relatively independent of facial expressions. For example, the puckered-lip face is
associated with frontal alert ears during social investigation, crescent or partially flat
ears during social play, and flat ears during
serious aggression. Judged by the reactions
of the bear receiving the signals, the same
facial expression combined with different
ear postures appears to have a somewhat
different message content. A detailed description of the puckered-lip face and the
relaxed open-mouth face follows.1
The puckered-lip face (Fig. 3): The eyelids in this facial expression are usually
wide open. The skin on the forehead is
flexed and a furrow sometimes appears. The
eyebrow regions are usually raised. This
elevation of the eyebrow regions may be
emphasized by the brown eye patches that
are located above and mediad to the eyes
(see Fig. 2). Cubs, yearlings, and sub-adults
usually have these brown eye patches, although there are some exceptions; these eye
patches frequently disappear in adult boars.
The bear with a puckered-lip face alternates
between a quick short stare at the opponent
and a partial looking away. In this facial
expression, the mouth is held tightly shut.
The upper lip and the corners of the mouth
are puckered out. This puckering is especially conspicuous in front (see also MeyerHolzapfel, 1957; Burghardt, 1972). The
anterior black color of the upper lip may
help to emphasize this puckering (see Fig.
3). Vocalizations usually do not occur with
this facial expression, although moaning is
sometimes associated with it in cubs.
The puckered-lip face occurs in several
different social contexts. It is commonly observed during social investigation, during
active submission (Schenkel, 1967), during
the terminal phase of agonistic encounters,
and during the initiation and termination
of social play. During social play, the
puckered-lip face appears in a low intensity
form, that is, the forehead is usually not
furrowed, the eyebrow regions are fre1
In a subsequent article, the other five facial expressions will be described, and a diagram illustrating all the facial expressions and ear postures of the
black bear will be provided.
378
J. D. HENRY AND S. M. HERRERO
quently not raised, and the eyelids may appear partially closed.
The relaxed open-mouth face (Figs. 1, 3):
This facial expression is related to the
aggressive jaw-gape face, but the two are
distinct because of subtle differences in the
eyelids, forehead, and ears.
In the relaxed open-mouth face, the eyelids are partially closed, and the forehead
and eyebrow ridges are relaxed. The ears are
either crescent or partially flat. The mouth
is held open from 20° to 60°, and the corners
of the mouth are slightly elevated. The
upper lip is puckered out but not as extensively as in the puckered-lip face. The lower
lip is also puckered out and, along its sides,
hangs down away from the teeth. The lower
canines are usually clearly visible. No vocalizations except for breathing sounds are
normally associated with this facial expression. The relaxed open-mouth face is usually
observed during social play in the following
context: Prior to biting, one bear assumes
this facial expression and stares directly at
the opponent. This is quickly followed by
reaching to bite at the opponent, or by
head-ducking as the opponent bites or paws
first. Occasionally a bear will assume this
facial expression and maintain it for up to
30 sec without biting. During this time the
bears paw and play-wrestle with each other.
The aggressive jaw-gape differs from the
relaxed open-mouth face in a number of
subtle ways. In both, the mouth is held
open 20° to 60°. In the jaw-gape face, however, the eyelids are wide open, instead of
partially open; the eyebrow regions are
raised instead of relaxed; and the ears are
flat on the neck, instead of crescent or partially flat. The jaw-gape face is usually
associated with the aggressive body posture
of arching the back and strongly flexing the
head and neck down. This challenge posture is rarely observed during social play.
Thus, these two facial expressions can be
distinguished on the basis of subtle differences in their external appearances.
The relaxed open-mouth face is only observed during play behavior and can be
considered a "play face" in the black bear.
In the black bear this "play face" appears
more closely associated with biting actions
and biting intention movements than it
does in many canid and primate species (see
Bolwig, 1964; van Hooff, 1967; Fox, 1970).
The "play face" in bears is not observed
during locomotory play nor is it usually
observed during the play-soliciting approach (see below). In many canid and primate species, the "play face" is observed
during both of these contexts.
Vocalizations
Play in the black bear is distinguished by
its lack of vocalizations, that is, during solitary and social play no vocalizations are
given except for respiratory sounds, such as
panting and breathing sounds. Serious agonistic behaviour is the antithesis of social
play in that it is marked by numerous and
frequent vocalizations (Darwin, 1872).
Burghardt (1972) also observed that during black bear play silence was the rule and
stated that "this distinguishing characteristic
of true play was virtually without exception." Silence during play-fighting was observed in captive sloth bears (Mclursus
ursinus), Himalayan black bears (Selenarctos thibetanus), and polar bears (Ursus
maritimus) at the Calgary Zoo. Free-ranging
sub-adult grizzlies (Ursus arctos) in Banff
National Park were also observed to be silent during play-fighting. The rule of silence
may differentiate the social play of Ursidae
from that of Canidae. Bekoff (1972) reports
that in the domestic dog play-soliciting
gestures, such as the play bow, are often
accompanied by an attention-getting bark.
Although social play is silent, it may be
terminated by one of the bears moaning.
When physical contact in social play became
intense, one bear frequently oriented
towards the other bear and moaned. Moaning was followed by a quick termination of
social play in 22 out of the 34 sequences in
which moaning occurred. In those sequences
where contact play continued, the moaning
bear frequently flattened its ears and aggressively attacked its social partner.
In conclusion, social play in the black
bear can be identified by two constant accompanying features: (i) no vocalizations
are given except for respiratory sounds, and
379
SOCIAL PLAY IN THE AMERICAN BLACK BEAR
(ii) the ears are continuously either in the
crescent or partially flattened ear postures.
No other type of black bear social behavior
that we have observed shows these two features continuously during the behavioral
sequence.
THE MOTOR PATTERNS OF SOCIAL PLAY
Table 2 enumerates 30 different motor
patterns that are frequently observed during
black bear social play. Twenty-two of these
motor patterns are similar to motor patterns
observed in various canids (Tembrock,
1958; Fox, 1969, 1970, 1971; Bekoff, 1972).
This fact illustrates the extensive similarity
between canid and ursid social behaviors.
This section describes the motor patterns
characteristic of locomotory play, play fighting, and sexual play in that order.
Motor patterns of locomotory play
In the black bear, there are two types of
locomotory play. The first kind involves
chasing after a conspecific. The second type
involves seizing an object.
Chasing usually begins by one animal
walking up to another animal from behind
and play nipping that animal. The play nip
is a quick, painful bite usually delivered to
the flank, rump, or hindlimb of the opponent (see Table 3). The attacking bear
immediately flees. The bear that was bitten
usually pivots around, obviously aroused by
the bite and makes high intensity biting or
clawing actions at the fleeing bear. About
25% of the time, it chases after the attacker.
Alternately, chasing was initiated by one
bear running at a second bear who fled before physical contact was made. The first
bear then simply continued to chase after
the fleeing bear. During chasing behavior,
both bears exhibit the alert or puckered-lip
face. The fleeing bear usually has partially
flat ears while the chasing bear usually has
crescent ears. Chasing sequences among
free-ranging sub-adults have been observed
to last for over 2 min. Infrequently, a climbing chase was observed while both bears
were in a tree.
TABLE 2. The motor patterns of black bear social play.
Motor patterns of play-fighting:
Playful approach
Rearing
Head butting
Pawing
Face-pawing
Lunging
Clawing
Inhibited clawing
Hind-leg-clawing
Rolling over
Play bites
Biting intention movement
Inhibited bite
Neck-bite-hold
Head shake
Muzzle seizure
Standing over
Looking away
Licking-cut-off
Head and neck extension
Motor patterns of locomotory play:
Play nip
Running chase
Climbing chase
Seizing the object
Motor patterns of sexual play:
Vulva stimulation
Shoulder-scruff-bite
Clasping with forepaws
Pelvic thrusts
Mounting
Inguinal presentation
*
*
*
*
* Indicates that motor pattern is also observed in
canid species (see text).
The second type of locomotory play involves seizing an object. This type of locomotory play has been described in several
other carnivore species. Chrisler (1958) described it among young semi-captive wolves,
and Schaller (1972) described it between a
lioness and two cubs. In the captive bear
cubs, the object seized was usually a new
object in the arena. It was usually chewable,
but not edible, for example, a bone, a
branch, or a feather. Specifically, one cub
approached another cub that was chewing
on a new object. The cub approached at a
walk and then gently pawed or smelled at
the object in the other bear's mouth. The
object was seized when it dropped to the
ground, or it was seized directly from the
mouth of the other bear. The bear then
fled with the object and began to chew on
it. The second bear usually did not immediately chase after the fleeing bear, but
within a few minutes it approached and
380
J. D. HENRY AND S. M. HERRERO
seized the object back in a similar manner.
During one occurrence involving a feather,
reciprocal seizing of the object continued
off and on between the three captive cubs
for over 20 min.
Motor patterns of play-fighting
Play-fighting sequences started with one
bear approaching another bear, usually in a
walk (80% of the sequences), infrequently
in a run (20%). This bear exhibited a
puckered-lip face with ears usually crescent
(63%), infrequently partially flat (37%).
The bear approached and, when close to
the other bear, pawed, bit, head butted, or
reared bipedally. The other bear, almost
simultaneously, reared, bit, or pawed back
at the initiator.
The playful approach followed by pawing, biting, head butting, or rearing appears
to be the play soliciting gesture of the black
bear. The black bear does not show the play
bow, exaggerated approach, or play dance
that are play-soliciting behaviors in canids
(Fox, 1970; Bekoff, 1972).
Play-fighting sequences ended with both
bears shutting their mouths, assuming a low
intensity puckered-lip face, and walking or
running away from each other. In 50% of
the play-fighting sequences, this moving
apart was preceded or accompanied by a
cut-off or submissive display, for example,
looking away, licking cut-off, head and, neck
extension, or shrugging away (see Fox, 1970,
for a description of these behaviors in
canids).
The 20 different motor patterns commonly observed during play-fighting are
described under two headings. These headings relate to the double weapon system of
the black bear. Canid species use only the
teeth to inflict injuries during social combat
(Fox, 1969, 1970). Ursid species, on the other
hand, are equipped with two weapon systems for social combat, the teeth and the
claws. This dual weapon system of the bears
has influenced the appearance of both serious agonistic behavior and play-fighting.
The dual weapon system has apparently led
to the development of new motor patterns
while modifying the external forms of
others.
Motor patterns associated with biting actions. During play-fighting, different kinds
of biting actions were observed. The neckbite-hold was the most intense type of biting
observed and differs from the ordinary playbite in a number of features. During the
neck-bite-hold, the opponent's neck was bitten and held for up to 10 sec, instead of
being immediately released as in the playbite. Pawing actions, attempting to pin the
opponent to the ground, were observed with
neck-bite-holds, but not with ordinary playbites. Vigorous head shaking was often observed just prior to the release of the neckbite-hold. Head shaking was only infrequently associated with ordinary play-bites.
Also the orientation of the neck-bite-hold
was quite regular: 74% weie oriented
towards the lateral neck surface of the opponent (Table 3). The orientation of the
play-bite was more variable: 14 different
body parts were bitten in 146 different playbites (Table 3).
Biting attempts are complete biting actions where the animal missed or had its
head blocked by the opponent. Biting attempts are to be distinguished from biting
intention movements. Biting intention
movements are incomplete biting actions,
performed once or repeatedly, but always in
an incomplete manner. They usually consisted of one bear opening its mouth and
orienting it towards, without reaching to
bite, the other bear. At their highest degree
of completion, biting intention movements
take the form of the inhibited bite. In the
inhibited bite, the jaws are placed around
the opponent's neck or limb but are not
shut or are shut very gently. The jaws are
held there for 1 to 2 sec, and then withdrawn. Inhibited biting is also observed
during serious agonistic encounters in the
black bear. Bekoff (1972) suggests that in
canids inhibited biting appears to be a partially learned response as a result of a conflict situation: the animal wishes to bite but
fears a counter-attack (see also Poole, 1966;
Fox, 1971).
During play-fighting, young black bears
also show muzzle seizure behavior (Fig. 4).
During this behavior, two bears come to-
SOCIAL PLAY IN THE AMERICAN BLACK BEAR
581
FIG. 4. Two of the captive cubs engage in muzzle seizure behavior.
gether in a face-to-face orientation, interlock their jaws, and hold them interlocked
for up to 15 sec. Gentle squeezing actions
are frequently observed.
Muzzle seizure is observed in the wolf and
coyote (Fox, 1970, 1971). In the wolf, it
serves a number of different functions, for
example, a greeting behavior, a dominance
display, a play activity among young wolves,
and a form of "ritualized aggression" (Fox,
1971). In the black bear, muzzle seizure has
never been observed to form a type of "ritualized aggression." It is usually observed
only during low intensity play-fighting
a m n g cubs and sub-adults, or infrequently
as a greeting behavior between a sow and
her cub.
Motor patterns associated with pawing
and clawing actions. Davis (1949, 1964)
states that bears, as compared to canids,
show an increased manipulative ability of
the forequarter and forepaws. He supports
this statement by describing in detail the
morphological adaptations exhibited by
bears for this increased manipulation of the
forepaws.
During play-fighting, increased manipulative ability of the forepaws is evident in
both pawing and clawing actions. Pawing
actions are variable, low intensity arm movements that are often aimed at knocking the
opponent's head or arm out of the way and
thus blocking an attack. Figure 2 shows
face-pawing, a type of pawing frequently
observed during black bear social play, and
often used to initiate the social play
sequence.
Pawing actions also occur during lunging
when one bear extends his forelimbs and
lunges at the opponent's shoulder region in
an attempt to knock the social partner over.
Knocking the social partner over is also
382
J. D. HENRY AND S. M. HERRERO
accomplished by head butting. In this motor pattern, one bear walks into the other
bear with its forehead and gives a quick
head lift movement trying to knock the
other bear off balance. Head butting is frequently observed at the initiation of the
social play sequence.
Clawing actions as compared to pawing
actions are vigorous swiping movements
aimed at various parts of the opponent's
body (Table 3). Observations support that
clawing actions can inflict serious injuries.
During several aggressive encounters, we
observed an adult bear inflict 4- to 6-inchlong cuts in the side or rump of a rival bear.
During play fighting, the black bear appears to use a form of inhibited clawing.
In this clawing, the claws are not flexed
down, and the opponent (or the observer's
hand) is consistently hit with the foot pad
instead of with the claws.
We have described the neck-bite-hold
observed during play-fighting. In order to
break the neck-bite-hold the bear frequently
rolls over. Hip slamming which many canids
use to break neck-bite-holds (Fox, 1970,
1971) has not been observed in the black
bear. If rolling over does not break the
hold, hind-leg-clawing is frequently observed. Specifically, the bear that has rolled
over lifts its hind feet and alternately claws
at the forehead of the opponent. Hind-legclawing is similar to a motor pattern seen
in the domestic cat (Leyhausen, 1973), but
this claw-related motor pattern has never
been described in canid species.
Burghardt and Burghardt (1972) describe
rolling over as a play-invitation behavior
in black bears. We observed rolling over
used in the context of breaking neck-biteholds. We also infrequently observed it
when a larger bear playing with a smaller
bear rolled over apparently to assume a
subordinate role. In both of these contexts,
rolling over did not occur until well after
the play sequence had begun. In less than
1% of the sequences (3 out of 508) was
rolling over observed at the initiation of
the social play sequence.
In many play-fighting sequences, reamig
initiates the sequence but it may also appear repeatedly throughout the sequence.
Rearing occurs when the bear lifts its forepaws off the ground, and while standing
on its hind legs, or sitting, holds its forepaws free of the ground for up to 20 sec
(see Fig. 3). Rearing frees the forepaws for
manipulative actions, and rearing and pawing are closely associated in many playfighting sequences. For example, repeatedly
during a sequence, both bears may rear
and paw at each other trying to knock
each other over (Meyer-Holzapfel, 1957).
These extended rearing-pawing matches are
one of the most common activities during
play-fighting, but they have never been
observed during serious agonistic encounters.
Rearing also frequently precedes standing over. Standing over occurs when a bear
approaches a conspecific from the side,
rears, and places its paws on the conspecific's shoulder or back. Fox (1971) describes
standing over in various canids. Among
the captive black bear cubs, standing over
usually preceded play fighting, but in four
sequences standing over led to sexual play.
By way of summary, the typical playfighting sequence usually exhibits four
phases: initiation, pushing-pulling, bitingclawing, and finally, termination. One bear
approaches another bear and initiates play
by rearing, pawing, biting, head butting,
or, infrequently, lunging at that animal.
Frequently, both animals rear and an extended pawing match follows. The purpose
of pawing appears to be to knock the social
partner off balance so that a biting or clawing action can be delivered. Biting intention movements and face-pawing actions
are repeatedly observed during these extended rearing-pawing matches. Once the
social partner is pushed or pulled into
a vulnerable position, a play-bite or neckbite-hold is frequently delivered. The bitten
animal then rolls over and may hind-legclaw in order to break the neck-bite hold.
Once freed, both bears frequently return
to the rearing-pushing-pulling phase until
one of the bears once again becomes vulnerable to a bite or clawing action. This
alternation between the pushing-pulling
and biting-clawing phases continues on the
average for about 20 sec (see Table 1) until
383
SOCIAL PLAY IN THE AMERICAN BLACK BEAR
TABLE 3. The orientation of 200 biting actions and 200 clawing actions during black bear play
fighting. Number in parentheses is percentage of actions oriented towards that specific body region.
Play bites
Lateral face
Forehead
Lateral neck
Shoulder
Ear
Ventral neck
Chest
Foieliiu'u
Abdomen
Lateral body
Dorsal body
Rump
Hindlimb
Foot
45
9
19
4
5
5
(31%)
(6)
(13)
(3)
29
3
(74)
(8)
4
2
9
3
9
11
23
18
1
1
(2)
(3)
(3)
(6)
(8)
(16)
146
(100%)
39
(100%)
one of the bears closes its mouth, frequently
gives a cut-off display, pivots, and flees.
Flight behavior by one of the bears usually
terminates the play-fighting sequence. The
initiation and termination phases of the
play-fighting sequences are comparatively
regular. The pushing-pulling phase alternating with the biting-clawing phase shows
a great amount of variability in the temporal sequencing of motor patterns.
Many of the canid motor patterns that
black bears do not show are highly cursorial ones, for example, hip slamming, the
play dance, the play bow, and the exaggerated approach (Fox, 1970; Bekoff, 1972).
These may represent motor patterns of
more recent origins that evolved in Canidae
after the ursid line had differentiated (see
Lorenz, 1941, for an evolutionary study of
motor patterns in Anatinae).
Table 3 examines the orientation of 200
TABLE 4. The orientation of 129 biting actions and
42 clawing actions during adult black bear aggressive behavior. Number in parentheses is percentage
of actions oriented towards that body region.
Biting
actions
Lateral face
Lateral neck
Shoulder
Forelimb
Lateral body
Rump
Hindlimb
Foot
Total
90
28
2
2
3
4
(70%)
(21)
(2)
Clawing
actions
4
3
22
(10%)
( 7)
(52)
(2)
(2)
(3)
4
8
1
129
1
1
(7%)
(100%)
42
(10)
(19)
(2)
(100%)
56
52
28
50
(28%)
(26)
(14)
(25)
(7)
( 1)
( 1)
( 3)
2
Clawings
Play nips
(12%)
(3)
1
Total
Bite-and-holds
6
/
9\
\ *V
2
(13)
5
(3)
5
4
2
(33)
(27)
(13)
3
< 1)
15
(100%)
200
(100%)
biting actions and 200 clawing actions observed during play-fighting in the captive
cubs. Table 4 examines the orientation of
129 biting actions and 42 clawing actions
observed during aggressive behavior in
adult black bears. Adult aggressive behavior was identified by the complete flattening of the ears and numerous vocalizations that accompanied it. Complete biting
actions are relatively rare in adult black
bear aggressive behavior. Thus, the biting
actions contained in Table 4, are composed
of 100 high intensity biting intention
movements, 17 inhibited bites, and 12 complete, uninhibited bites.
In the black bear, there appears to be a
strong tendency to bite at the side of the
face or the lateral neck surface of the opponent. In play-fighting 49% of the biting
actions (98 out of 200) were directed towards these two regions. The remaining
biting actions in play-fighting were distributed among 12 other body regions.
Within the limitations of the comparison,
Table 4 suggests that this tendency to bite
at the side of the face or lateral neck surface
appears even stronger in adult aggressive
behavior; 91% of the biting actions in aggression were oriented towards these two
body regions. Biting actions during adult
aggressive behavior, therefore, appear to be
less variable in their orientation than biting
actions during social play.
In play-fighting, there appears to be a
strong tendency to claw at the side of the
384
J. D. HENRY AND S. M. HERRERO
face, forehead, or shoulder region of the
social partner. These three body regions
account for 79% of the clawing actions observed during play-fighting. Four other
body regions received the remainder of the
clawing actions. In adult aggressive behavior, one body region of the opponent,
the shoulder region, received 52% of the
aggressive clawing actions. Thus, as with
biting actions, clawing during adult aggressive behavior appears less variable in its
orientation than it does during social play.
Fox (1969) suggests that canid aggressive
behavior is ritualized because the attacker
tends to bite at certain, restricted body regions of the opponent. The above data suggest that this may also be true for black
bear aggressive behavior. Also the data suggest that the side of the face, forehead,
lateral neck, and shoulder regions of the
black bear should be examined for defense
mechanisms against aggressive clawing and
biting.
Defense mechanisms may take the form
of thick dermal shields (see Geist, 1964),
or long, thick protective coats of hair (see
Schallar, 1972). The long thick fur on the
dorsal and lateral surfaces of the bear's
neck may function as such a defense mechanism.
Motor patterns of sexual play
In the black bear, as in many species,
sexually immature animals on occasion
exhibit sexual behavior, and this type of
behavior has been termed sexual play. We
may validly ask if sexual play is really play
behavior; and, if so, by what criteria and
characteristics is it identified as such. We
will examine this question by comparing
the sexual behavior shown by black bear
cubs with the sexual behavior as shown by
adult black bears.
Sexual play was infrequently observed in
the social play of black bear cubs and subadults (see, for example, Table 1). During
the sexual play of captive and free-ranging
cubs, a male cub usually tried to mount a
male or female littermate. The male cub
approached, ears crescent, giving no vocalization. The male cub then reared and fre-
quently showed standing over by placing
his forepaws on the littermate's back. Next,
the male cub moved into mounting position, bit the littermate's shoulder scruffskin, and, finally, clasped the littermate
bilaterally with his forepaws. At this point,
the littermate usually rolled over on its
back and initiated play-fighting by pawing
and biting at the male cub's face. Infrequently, pelvic thrusts were seen during
sexual play. Since the baculum of cubs is
short and weighs appi'oximately half a
gram (Rausch, 1961), it is doubtful that
intromission ever takes place.
Vulva stimulation was also observed during sexual play. The male cub usually
approached a female littermate from behind and smelled the base of her tail and
rump without touching them. Then the
male cub moved his nose ventrad and
smelled and gently bit and licked the vulva
region of the female. Frequently, the female cub was lying on her side and, when
the male cub touched her vulva, the female
cub inguinal presented, that is, she rolled
one leg laterad exposing the inguinal region (see Fox, 1971, for a description of
inguinal presentation in canids). In adult
sexual behavior, vulva stimulation has always been observed to precede the first
mounting attempt. In sexual play, mounting was often attempted without vulva
stimulation preceding it.
Littermates usually responded to mounting and vulva stimulation by initiating
play-fighting. They frequently sat or rolled
over on their backs in order to break the
mounting attempt. Then they pawed and
bit at the male cub's face in a low intensity
manner. Rolling over and pawing at the
male's face are also observed in non-receptive adult females in response to the serious
mounting attempts of adult boars. The
non-receptive adult female during this reaction frequently shows partially flat ears,
a lack of vocalizations, and the relaxed
open-mouth face. It is one of the few consistent occurrences of play-like behavior in
the behavioral repertoire of adult black
bears.
From the above descriptions, it is apparent that the sexual behavior shown by
SOCIAL PLAY IN THE AMERICAN BLACK BEAR
cubs exhibits a number of features only
observed in other types of social play. For
example, the male cub in approaching a
littermate gives no vocalization and his ears
are usually clearly crescent. During adult
sexual behavior, the boar approaching a
female frequently makes a throat-clunking
vocalization and his ears, although variable,
are frequently frontal or laterad. Furthermore, during sexual play the male cub
usually performs only part of the normal
adult sexual sequence; for example, mounting is frequently attempted without vulva
stimulation preceding it. Marler (1966)
states that partially performed sequences
are frequently a characteristic of social play.
These characteristics support the conclusion that the sexual behavior shown by
cubs is indeed a form of social play.
HYPOTHESIS TESTING AND DISCUSSION
Beach (1945) stresses that play must be
defined according to its general, objective
characteristics. A number of researchers
have speculated about what the general
characteristics of play might be (see MeyerHolzapfel, 1956; Tembrock, 1958; Marler,
1966; Loizos, 1967). Muller-Schwarze (1968)
showed the value of testing this speculation. He found that several of the characteristics as put forth by Meyer-Holzapfel
(1956) were not valid for the social play of
blacktailed deer (Odocoileus hemionus columbianns). Extensive testing of this speculation over a wide range of species is necessary if the valid diagnostic characteristics
of play are to be identified. In this section,
five suggested characteristics are tested for
their validity in black bear social play.
Hypothesis about the characteristics of
social play can be grouped under two headings: (i) characteristics about the motor
patterns of social play, and (ii) characteristics about the sequencing of social play.
The following five hypotheses are examined
under these two headings.
Characteristics of the motor patterns of
social play
Hypotheses about the motor patterns of
social play compare the appearance of the
motor patterns during social play to the
385
same motor patterns as they appear in nonplayful behavior. We will discuss three of
these hypotheses.
Hypothesis 1: Motor patterns during
play often have an incomplete appearance
when compared to their appearance during
non-playful behavior. For example, during
play-fighting, in dogs, snarling may be dissociated from the piloerection which inevitably accompanies it during true fighting (Marler, 1966).
This hypothesis appears valid for much
of black bear social play. The following
examples illustrate this point. First, the
above example about piloerection appears
valid for black bear social play. In black
bears, piloerection of the dorsal and lateral
neck fur is occasionally observed during
real fighting but has never been observed
during play-fighting. Second, during black
bear social play many behaviors lack the
vocalizations that normally accompany
these behaviors during non-playful behavior (see p. 378). Third, many threat
displays are omitted from play-fighting.
For example, in an adult agonistic encounter, an approaching bear frequently
stops abruptly and paw swats the ground
(see also Jonkel and Cowan, 1971). Later
in the encounter, both bears usually display
the challenge postiure (see p. 378). At the
end of the encounter, a bear moving away
frequently jaw snaps repeatedly at the opponent. These three threat displays are
rarely observed during play-fighting. Poole
(1966) also observed that in the play-fighting of polecats (Putorius putorins) most
agonistic behaviors were present except
four threat behaviors which were omitted.
Thus, in at least two species of Carnivora,
certain threat displays appear to be selectively omitted from play-fighting behavior.
The above examples serve to illustrate
that the first hypothesis appears valid for
much of black bear social play: many motor
patterns are given in an incomplete manner
when compared to their appearance during
non-playful behavior.
Hypothesis 2: Social play may be identified by certain motor patterns which are
observed only during social play (Marler,
386
J. D. HENRY AND S. M. HERRERO
1966).
In the black bear there are several motor
patterns that are observed almost exclusively during social play. These are head
butting, muzzle seizure, the play nip, and
hind-leg-clawing. These four motor patterns which are frequently observed during
black bear play-fighting are extremely rare
in the agonistic behavior of cubs, subadults, or adult black bears. Marler (1966)
gives several examples of motor patterns
unique to social play, and all of the examples are play-soliciting behaviors. In the
black bear, only head butting and the play
nip appear to serve as play-soliciting behaviors (see p. 380). The other two motor
patterns unique to black bear social play
usually do not occur until well after the
social play sequence has begun.
Hypothesis 3: Social play is characterized by the exaggerated and uneconomical
quality of the motor patterns involved
(Loizos, 1967). Loizos states that this exaggerated and uneconomical quality of the
motor patterns is "what all playful activity
has in common."
There is an important need to state more
objectively what "exaggerated" and "uneconomical" mean in terms of observable
behavior. These terms are vague and somewhat subjective, and, therefore, difficult to
test (Beach, 1945). We interpreted "uneconomical" to mean that motor patterns during social play are more variable in their
orientation than they are during non-playful behavior. We interpreted "exaggerated"
to mean that social play motor patterns are
performed in an enlarged or prolonged
manner as compared to non-playful motor
patterns. From this enlarged or prolonged
quality, we would expect social play motor
patterns to exhibit an increased time duration as compared to non-playful motor patterns.
Tables 3 and 4 offer evidence that during
social play biting and clawing actions are
more variable in their orientation than
are adult aggressive bitings and clawings
(see p. 383). Mounting also appears more
variable in its orientation during sexual
play than during adult sexual behavior.
There is evidence, therefore, to conclude
that certain motor patterns during social
play are less economical in their orientation
than they are during adult non-playful
behavior.
Regarding the enlarged or prolonged
quality of motor patterns, our observations
suggested that the majority of social play
motor patterns were not performed in an
enlarged manner when compared to the
same motor pattern in adult non-playful
behavior. We tested this point by timing
the filmed motor patterns. We selected and
timed six motor patterns that appear in
both high intensity adult aggressive behavior and in high intensity play-fighting
(Table 5). Filmed sequences were selected
by random numbers, and 30 timings for
each motor pattern were obtained. The
means and standard deviations for each
motor pattern are reported in Table 5. Differences between means were tested for
using the Student's t test (2 tail test,
a = .05). From these tests (see Table 5.),
we conclude that motor patterns in play
fighting do not show a consistent increased
duration when compared to their adult aggressive counterparts.
Loizos' hypothesis, therefore, appears
only partially valid for black bear social
play. Certain motor patterns appear more
variable in their orientation during social
play, but our tests and observations suggest
that motor patterns are not performed in
an enlarged or prolonged manner in social
play when compared to the same motor
patterns in adult non-playful behavior.
TABLE 5. The duration of motor patterns in black
bear play fighting and aggressive behavior (in sec).
Play
fighting
Biting
Clawing
Rearing
Lookingaway
Lickingcut-off
Bitingintentionmovement
Conclusion
a = 0.05
1.47 -t- 1.00 1.16 -i- 0.38 P.F. = Agg.
0.58 •+• 0.16 0.59 •+• 0.18 P.F. = Agg.
3.16 ± 2.42 2.13 ± 1.49 P.F. > Agg.
Aggression
1.76 ± 0.65 2.03 ± 1.01 P.F. = Agg.
1.35 ± 0.90 1.98 ± 1.28 P.F. < Agg.
1.27 ± 0.26 2.34 ±1.29 P.F. < Agg.
387
SOCIAL PLAY IN THE AMERICAN BLACK BEAR
Characteristics of social play sequences
We have examined three hypotheses concerning the motor patterns of social play.
A number of other hypotheses concerning
the sequences of social play have also been
advanced. We will examine two of these
hypotheses.
Hypothesis 4: A characteristic of play is
that certain motor patterns are repeated
more frequently in the play sequences than
during the non-play sequences (Meyer-Holzapfel, 1956; Loizos, 1967).
We tested this hypothesis in the following way: Motor patterns that occur more
than once in either a play-fighting sequence
or in an adult aggressive sequence are listed
in Table 6. Biting and clawing actions in
this table include both inhibited and uninhibited types of biting and clawing. Filmed
sequences were chosen at random and used
once. This included both play sequences
from cubs and aggressive sequences from
adult black bears. For each sequence, one
of the motor patterns from Table 6 was
chosen and the frequency of it in the sequence was counted. For each motor pattern 30 non-zero frequencies were obtained
(with 3 exceptions for adult aggressive behavior; see Table 6). The means and standard deviations of these frequencies are
presented in Table 6. Using a Student's t
test (Li, 1961), we tested for differences between means (2 tail test, a = .05). We conclude that four of the six motor patterns
examined are repeated significantly more
frequently during play-fighting than during adult aggression.
Greater frequency of a motor pattern per
sequence may result simply because playfighting sequences last longer than aggressive sequences. To test this point, we
recorded the time duration of each play
and aggressive sequence used. Using a t
test (2 tail test, a = .05), we found that in
five out of the six tests play-fighting sequences did not last significantly longer
than sequences of adult aggression. The one
exception involved the looking away behavior: Play-fighting sequences that showed
looking away last significantly longer than
adult aggressive sequences that showed this
TABLE 6. The frequency of motor patterns in black
bear play fighting and aggressive behavior. The
number in the parentheses indicates that the sample size was different from 30.
Biting
Clawing
Rearing
Lookingaway
Lickingcut-off
Bitingintentionmoveraent
Play
fighting
Aggression
3.87 ± 3.08 1.64 ± 0.93
(n - 19)
3.77 ±3.80 1.71 ±1.61
(n = 23)
2.53 ± 2.31 1.70 ± 1.40
(n = 23)
Conclusion
a = 0.05
P.F. > Agg.
P.F. > Agg.
F.F. = Agg.
2.30 ± 1.66 2.07 ±1.11 P.F. = Agg.
1.68 ±0.49
1.33 ±0.76 P.F. > Agg.
6.27 ± 6.64 2.75 ±2.11 P.F. > Agg.
display. It appears that greater repetition
of the motor patterns was not due to the
play-fighting sequences lasting longer than
the adult aggressive sequences. We conclude, therefore, that, within the limitations of the test, greater repetition of certain
motor patterns appears to be a valid characteristic of black bear social play.
Hypothesis 5: In play, normal temporal
groupings of functionally related motor
patterns break down, so that different kinds
of behaviors intermingle in the same sequence; for example, prey capture behavior
and sexual behavior may be combined in
the same play sequence (Meyer-Holzapfel,
1956).
Predatory behavior is rarely observed in
adult black bears, and it also appears to be
rare in black bear social play. Thus, there
is only one possible way that black bears
could manifest this characteristic, namely,
by combining sexual motor patterns with
agonistic motor patterns. We examined the
filmed sequences from the captive cubs and
from adult black bears for this combination.
Regarding sexual behavior, the sample
size is small, but a general trend appears
to be indicated. Three-fourths of the sexual
play sequence (9 out of 12) combined sexual
motor patterns with agonistic motor patterns. However, about three-fourths of the
adult sexual sequences (10 out of 12) also
showed this combination. As mentioned
earlier, this is because both cubs and nonreceptive adult females respond to courting
388
J. D. HENRY AND S. M. HERRERO
males by initiating play-fighting. Thus, the and social play are to be known. Beach
combination of sexual with agonistic motor (1945) and Marler (1966) have correctly
patterns cannot be used to differentiate stressed the need for this type of research.
sexual play in cubs from sexual behavior in
Repeatedly during this paper we have
adult black bears.
pointed out similarities between canid and
Regarding agonistic behavior, only 0.4% ursid social behavior. Geist (1974), among
of adult black bear agonistic sequences others, has stated that social behavior, and
(1 out of 247) showed sexual motor patterns particularly display behavior, can be excombined with agonistic motor patterns. pected to be rather conservative in its evoThe one sequence that showed this combi- lution. The conservatism of black bear
nation involved an agonistic encounter display behavior is illustrated by the folbetween an adult male and an adult female lowing example. Black bear and canids
black bear. The male emerged from the en- share the following active submissive discounter dominant, and immediately after plays: face-pawing, licking intention movethe encounter, tried to mount the female. ments, and nose-stab movements oriented
His attempt was unsuccessful because the towards the dominant animal's mouth (Fox,
female fled. Since only 1 out of 247 se- 1971). These displays in Canidae have been
quences showed sexual behavior combined derived from soliciting behaviors, that is,
with agonistic behavior, we may conclude from when young canids beg food from
that this combination is almost non-existent their parents (Fox, 1971). Bears have rein adult black bear agonistic behavior. It tained these active submissive displays even
also appears that black bears do not use a though the regurgitation response of Caniritualized mounting behavior as a domi- dae has been lost from the bear's behavioral
nance display. This type of dominance dis- repertoire.
play is frequently observed in primate speThe extensive similarities between canid
cies (see Wickler, 19676).
and ursid displays tend to support the prinIn black bear cubs, 3.9% of the play- ciple of the evolutionary conservatism of
fighting sequences (17 out of 428) showed social behavior. This principle has imagonistic behavior combined with sexual portant implications for behavioral research
behavior. We, therefore, conclude as fol- and ultimately for our understanding of
lows: Agonistic motor patterns combined man's future societies. The principle dewith sexual motor patterns is almost non- serves to be thoroughly tested.
existent in adult black bear agonistic beREFERENCES
havior. In cub play-fighting, the vast majority of the sequences (411 out of 428) show Baercnds, G. P. 1958. Comparative methods and the
only agonistic motor patterns; however, a
concept of homology in the study of behavior.
small percentage (3.9%) show agonistic beArch. Neer. Zool. 13:401-417.
havior combined with sexual behavior. In Beach, F. A. 1945. Current concepts of play. Amer.
Natur. 79:523-541.
only this very restricted sense is MeyerBekoff, M. 1972. The development of social interacHolzapfel's hypothesis a valid identifying
tion, play, and metacommunication in mammals:
characteristic of black bear social play.
an ethological perspective. Quart. Rev. Biol. 47:
CONCLUSIONS
The preceding tests show that several of
the suggested characteristics of social play
are only partially valid for black bear social
play. Extensive testing of the suggested
characteristics of play on as wide a range
of species as possible is definitely indicated
for future research. These tests are crucial
if the valid diagnostic characteristics of play
412-434.
Bekoff, M. 1974. Social play and play-soliciting by
infant canids. Amer. Zool. 14:323-340.
Bolwig, N. 1964. Facial expressions with remarks on
parallel development in certain carnivores. Behaviour 22:167-192.
Burghardt, G. M., and L. S. Burghardt. 1972. Notes
on the behavioral development of two black bear
cubs: the first eight months, p. 207-220. In S. M.
Herrero [ed.], Bears—their biology and management. IUCN Publ. No. 23. Morges, Switzerland.
Colbert, E. H. 1955. Evolution of the vertebrates.
John Wiley and Sons, Inc., New York.
SOCIAL PLAY IN THE AMERICAN BLACK BEAR
Crisler, L. 1958. Artie wild. Balantine Books, New
York.
Darwin, C. 1872. The expression of emotions in man
and the animals. 1965 reprint. Univ. Chicago
Press, Chicago.
Davis, D. D. 1949. The shoulder architecture of
bears and other carnivores. Fieldiana Zool. 31:285305.
Davis, D. D. 1964. The giant panda: a morphological
study of evolutionary mechanisms. Fieldiana Zool.
Mem. Vol. 3. Chicago Natural History Museum.
Folk, G. E., M. A. Folk, and J. J. Minor. 1972. Physiological conditions of three species of bears in
winter dens, p. 107-124. In S. M. Herrero [ed.],
Bears—their biology and management. IUCN
Publ. No. 23. Morges, Switzerland.
Fox, M. W. 1969. The anatomy of aggression and
its ritualization in canids. Behaviour 35:242-258.
Fox, M. W. 1970. A comparative study of the development of facial expressions in canids: wolf, coyote and foxes. Behaviour 36:49-73.
Fox, M. W. 1971. Behaviour of wolves, dogs, and related canids. Jonathan Cape, Ltd., London.
Geist, V. 1964. On the rutting behavior of the mountain goat. J. Mammalogy 45:551-568.
Geist, V. 1974. On the relationship of social evolution and ecology in ungulates. Amer. Zool.
14:205-220.
Herrero, S. M. 1972. Aspects of evolution and adaptation in American black bears (Ursus americanus
Pallas) and brown and grizzly bears (£/. arctos
Linne) of North America, p. 221-231. In S. M.
Herrero [ed.], Bears—their biology and management. IUCN Publ. No. 23. Morges, Switzerland.
Hinde, R. A. 1970. Animal Behaviour. 2nd ed.
McGraw-Hill Book Co., San Francisco.
Hofer, H. 1972. Prolegomena primatologiae, p. 3146. In H. Hofer and G. Altner [ed.], Die Soderstellung des Menschen. G. Fischer Verlag. Stuttgart.
Jonkel, C. J., and I. McT. Cowan. 1971. The black
bear in the spruce-fir forest. Wildlife Monogr. 27:
1-57.
Leyhausen, P. 1949. Beobachtungen aneinem jungen
Schwarzbaren (Ursus americanus Pall.). Z. Tierpsychol. 6:433-444.
Leyhausen, P. 1973. Vcrhaltensstudien an Katzen.
Beiheft 2 der Z. Tierpsychologie. 3rd ed.
Li, J. C. R. 1961. Introduction to statistical inference. J. W. Edwards Inc., Ann Arbor, Michigan.
Loizos, C. 1967. Play behaviour in higher primates:
a review, p. 226-282. In D. Morris [ed.], Primate
ethology. Aldine, Inc., Chicago.
Lorenz, K. 1941. Vergleichende Bewegungsstudien an
Anatinen. J. Ornithol. 89:194-294.
389
Lorenz, K. 1953. Man meets dog. Methuen, London.
Marler, P. 1966. The characteristics of play behavior, p. 192-195. In P. Marler and W. J. Hamilton,
Mechanisms of animal behavior. John Wiley and
Sons, Inc., New York.
Meyer-Holzapfel, M. 1956. Uber die bereitschaft zu
spiel- und Instinkthandlungen. Z. Tierpsychol.
13:442-462.
Meyer-Holzapfel, M. 1957. Das Verhalten der Baren
(Ursidae). Handb. Zool. VIII, Part 10 (17): 1-28.
Muller-Schwarze, D. 1968. Play deprivation in deer.
Behaviour 31:144-162.
Muller-Schwarze, D. 1971. Ludic behavior in young
mammals, p. 229-249. In M. B. Sterman, D. J.
McGinty, and A. M. Adinolfi [ed.], Brain development and behavior. Academic Press, New York.
Nelson, R. A., H. W. Wahner, and J. D. Jones. 1973.
Metabolism of bears before, during, and after
winter sleep. Amer. J. Physiol. 224:491-496.
Papez, J. W. 1929. Comparative neurology. Crowell,
Inc., New York.
Poole, T. B. 1966. Aggressive play in polecats. Symp.
Zool. Soc. London 18:23-44.
Rausch, R. L. 1961. Notes on the black bear, Ursus
americanus Pallas, in Alaska, with particular reference to dentition and growth. Z. Saugetierk. 26:
65-128.
Sauer, P. R. 1966. Growth of black bears from the
Adirondacks. Proc. N.E. Sect. Wildlife Soc. 33 p.
Mimeo.
Schaller, G. B. 1972. The Serengeti lion. Univ. Chicago Press. Chicago.
Schenkel, R. 1947. Ausdrucksstudien an Wolfen.
Behaviour 1:81-129.
Schenkel, R. 1967. Submission: its features and functions in the wolf and dog. Amer. Zool. 7:319-329.
Stonorov, D., and A. W. Stokes. 1972. Social behavior of the Alaska brown bear, p. 232-242. In S. M.
Herrero [ed.], Bears—their biology and management. IUCN Publ. No. 23. Morges, Switzerland.
Tembrock, G. 1958. Spielverhalten beim Rotfuchs.
Zool. Beitr. Berlin 3:423-496.
van Hooff, J. A. R. A. M. 1967. The facial displays
of the Catarrhine monkeys and apes, p. 9-88. In
D. Morris [ed.], Primate ethology. Aldine, Inc.,
Chicago.
Wickler, W. 1967a. Vergleichende Verhaltensforschung und Phylogenetik, p. 420-508. In G. Heberer
[ed.]. Die Evolution der Organismen I. 3rd ed.
G. Fischer. Stuttgart.
Wickler, W. 19676. Socio-sexual signals and their
intraspecific imitation among primates, p. 89-189.
In D. Morris [ed.], Primate ethology. Aldine, Inc.,
Chicago.