AMER. ZOOL.,
14:323-340
(1974).
Social Play and Play-Soliciting by Infant Canids
MARC BEKOFF
Department of Biology,
University of Missouri,
St. Louis, Missouri 63121
SYNOPSIS. The development of social interaction was studied in infant coyotes, beagles,
and wolves. In this paper, social play behavior is discussed. Social play may be characterized in a number of ways: (i) actions from various contexts are incorporated into labile
(unpredictable) temporal sequences; (ii) the "play bout" is typically preceded by a metacommunicative signal which indicates "what follows is play"; these signals are also
observed during the bout; (iii) certain actions may be repeated and performed in an
exaggerated manner; (iv) the activity appears "pleasurable" to the players.
By comparing these three species, some insight into the dynamics of social play may
be gained. Coyotes were the least successful in soliciting play. When they did play, 90%
of all bouts had been previously solicited. Coyotes also tended to use the most successful
signals most frequently. This trend was not observed in the beagles or the wolves. By
taking into account the fact that infant coyotes are significantly more aggressive than
either infant wolves or beagles, the differential ontogeny of social play can be explained.
Some of the functions of social play in canids are discussed, and it is concluded that
social play is a valid class of social behavior and lends itself nicely to quantitative study.
"By the very clarity and simplicity of its expression, the play of children is often an excellent
window through which an observer may look upon
a culture otherwise concealed by complexities, suspicion, and the barriers of language." (Gardner
and Heider, 1968, p. 63).
Although there have been many recent
reviews of social play behavior in various
mammals (e.g., Loizos, 1966, 1967; Millar,
1968; Berlyne, 1969; Dolhinow and Bishop,
1970; Muller-Schwarze, 1971; Bekoff, 1972a,
1974), few quantitative data have been
amassed concerning this important category
of social behavior. Many workers have concluded that "play" is not a valid class of
behavior (e.g., Schlosberg, 1947; Berlyne,
1969; Welker, 1971), because they lump
social play behavior together with inanimate object play and/or exploration. These
are not the same behaviors (Hutt, 1970;
I would like to thank Suzanne King for helping
me with observations. I am also grateful to Ms.
King and Professor Viktor Hamburger for help in
translating some papers. Thanks also to Ms. Carolyn Reynolds for typing the manuscript. At various
times our facility had support from PHS grants
GM-01900 and ES-00139 (the latter through the
Center for the Biology of Natural Systems, Washington University).
Muller-Schwarze, 1971). Social play must be
studied in its own right, as involving two
(or more) living organisms, capable of exchanging information about an on-going
interaction. The level of study may involve
the observation of gross movements (postures, gestures, facial expressions), the analysis of vocalizations, or the monitoring of
neuromuscular processes (e.g., Welker, 1971).
Another source of confusion stems from the
fact that definitions of social play range
from being totally uninformative (e.g., play
is "any socially directed play activity, including rough-and-tumble, approach-withdraw, and noncontact play"; Suomi, 1973,
p. 73) to being fairly comprehensive (e.g.,
Bertrand, 1967, p. 58ff; Muller-Schwarze,
1971; Bekoff, 1972a). Workers should make
every effort to indicate what they mean by
"social play behavior" in the organisms
that they are observing.
In canids, there have been few in-depth
studies of social play behavior (e.g., Tembrock, 1958; Ludwig, 1965; Zimen, 1971;
Bekoff, 1972a,&; Bekoff and Jamieson, unpublished). Social play in canids (and other
mammals) may be characterized as follows:
(i) actions from various contexts are incor-
323
324
MARC BEKOFF
porated into labile (unpredictable) temporal sequences; (ii) the "play bout" is
typically preceded by a metacommunicative
signal which indicates "what follows is
play" (Bateson, 1955); these signals are also
observed during the bout; (iii) certain actions may be repeated and performed in an
exaggerated manner; (iv) the activity appears "pleasurable" to the participants
(Bertrand, 1969; Csikszentmihalyi and Bennett, 1971; Csikszentmihalyi, personal communication;1 Bekoff, 1974; Reynolds, unpublished). There is usually an initial decrease in distance between the interactants
(Bekoff, 1972a), however, this distance may
decrease and then increase, such as during
chase and running play.
In this paper I would like to present data
which have been collected on pairs of
wolves, coyotes, and beagles, observed under
controlled conditions from 3 to 7 weeks of
age. This period of life is characterized by
important changes in the central nervous
system (Fuller and Fox, 1969), and it is also
during this period of time that the animals
form intraspecific (and interspecific) social
relations (Mills, 1898; Scott and Fuller,
1965). These three species of canids show
very different courses of social development
during early life (Fox, 1969; Bekoff, 1972&),
and by following the ontogeny of social play
under standardized conditions, a comparative analysis is possible.
METHODS
The animals observed in this study included four coyotes (Canis latrans), four
wolves (C. lupus), and four beagles (C. familiaris). The animals were hand-reared
from approximately 10 days of age and
were all treated similarly. Until they were
able to chew semi-solid food, all animals
were tube-fed liquified Esbilac (Borden's
bitch's milk supplement). In order to regulate social interaction, the animals were
housed separately, and allowed to interact
x
The interested reader may contact M. Csikszentmihalyi at the University of Chicago for a copy of
his paper entitled "Flowing: A general model of
intrinsically rewarding experiences."
for 15 min per day (at the same time each
day, 1 hr after feeding), from 21 to 50 days
of age with a similarly reared littermate in
a 1.5-mX 1-5-m four-wall arena. The animals were housed together in pairs (with
the same littermate with whom they had
had previous interaction) after dominance
relations were formed or on day 42 (whichever came first), in order to determine if any
changes in behavior would result due to cohabitation (e.g., food competition, increased
proximity).
Thirty-five discrete motor action patterns
(body postures, facial expressions, gestures)
were catalogued and coded (Bekoff, 1972a,
b). Coding the actions facilitated recording
the data. Detailed daily notes were also
taken. During all observation periods I and
the same co-observer were present.
DESCRIPTIONS OF ACTIONS USED TO
INITIATE SOCIAL PLAY
Bow (B): The soliciting animal crouches
on its forelegs and elevates its hind-end
(Fig. 1); from this position the animal is
able to perform a wide range of other movements such as leaping, dodging, and springing back-and-forth.
Exaggerated approach (EA): The soliciting animal approaches its prospective playmate in a "loose, bouncy" gait, at a speed
greater than that observed during normal
walking; this has also been called a "play
rush" and "gamboling" in the non-human
primate literature; during the approach,
the shoulders and head are frequently
moved from side-to-side in an exaggerated
fashion.
Approach /withdrawal (A/W): The soliciting animal approaches its prospective
playmate and then withdraws; withdrawal
may involve stepping away slowly, or running away for a few meters and then approaching (and withdrawing) once again;
it is not uncommon to observe the soliciting
animal approach, stop, and then rock backand-forth in one spot, making intention
movements of running away.
General movements (GM): These include
movements of the head and eyes, such as
head-tossing and eye-rolling, and also body
SOCIAL PLAY IN CANIDS
FIG. 1. A "bow" performed by the dog on the right.
(After Bekoff 1972a, with kind permission o£ the
Quarterly Review of Biology.)
movements such as shoulder swaying; stalking of the prospective playmate is also included—one animal slowly circles its
partner, and then slowly, stealthily approaches; the approach after a stalk may be
exaggerated, and may also involve rapid
approach/withdrawals.
Face-pawing (FP): This action involves
extension of one of the forelimbs toward
the face of the other animal (Fig. 2); it is
FIG. 2. Face-oriented pawing by the beagle on the right.
326
MARC BEKOFF
FIG. 3. High leaping during play soliciting by a red fox.
not uncommon to observe rapid extension
and flexion of the forelimb when the animals are at a few meters from one another
(in this case the action is called a "paw
intention").
Leap-heap (LL): This action involves
two high-amplitude leaps in which the forelimbs are lifted off the ground, and hit the
ground, simultaneously.
Barking (Bk): See below.
We have also had the opportunity to
observe some red foxes {Vulpes vulpes) (Bekoff and Fox, personal observation). Some
actions which they perform to initiate social play, that are not observed in other
Canidae include high-leaping (Fig. 3), flattening out (the animal lies flat on the ground
and moves its head from side-to-side), and
"high-stepping" with the hind-legs.
RESULTS
Interobserver agreement was consistently
over 95%. The observed animals demonstrated large differences in the development
of social behavior (Fig. 4). Note the high
frequency of agonistic behavior observed in
the coyotes from days 21-28, and the low
frequency of play-soliciting during this same
time period. Coyotes typically form their
dominance relationships between 25 to 30
days of age (Fox and Clark, 1971; Bekoff,
19726; Bekoff and Jamieson, unpublished),
and with few exceptions, these social relations are the outcome of severe, unritualized
fights. The beagles show an early ontogeny
of play and play-soliciting and very low
327
SOCIAL PLAY IN CANIDS
levels of agonistic behavior. In fact, the
levels indicated on the graph represent very
mild threat behavior and absolutely no
fighting at all. Likewise, the wolves initially
show low levels of agonistic behavior and a
higher percentage of play-soliciting. As the
frequency of agonistic behavior by the
wolves decreased from days 43-50 (the ani-
mals were housed together in pairs on day
42), the incidence of play-soliciting increased. All agonistic behavior consisted of
threat, and there was no fighting at all.
Table 1 presents data concerning the relative success (P{P/S}) of each of the actions
used to initiate social play. The beagles
were successful greater than 56% of the
S-PLAY-SOLICITING
COYOTE
AGONISTIC
BEHAVIOR
21 29
28 35
36 43
42 50
21 29 36 43 21 29
28 35 42 50 28 35
t
t
DAYS
FIG. 4. The median frequency of occurrence (%)
of action patterns observed during both play soliciting and agonistic interactions, in relation to the
total number of actions performed during the
36 43
42 50
t
OF AGE
stated time periods, t = animals housed together
in pairs at the beginning of this time period; vertical bars z=. range.
328
MARC BEKOFF
TABLE 1. Play-soliciting by beagles, wolves, and coyotes (days 21-50).
Action
B
EA
A/W
GM
FP
LL
BK
S(#)a
67
70
77
54
32
37
29
Beagles
U(#) a P(P/S)a
42
17
35
13
2
9
33
.61
.80
.69
.81
.96
.80
.56
S(#)
29
11
29
11
7
Wolves
U(#)
P(P/S)
.52
27
31
111
4
10
.26
.21
.73
.41
S(#)
12
5
10
31
2
Coyotes
U(#)
P(P/S)
.36
27
.19
21
.26
29
51
8
.38
.20
—
—
.28
.09
—
—
.43
x — _ b.c
.05
S.D. = .12d
—.70
rho — _ . 4 8
+.87
* S = frequency of occurrence of successful play solicits.
U = frequency of occurrence of unsuccessful play solicits.
P(P/S) = given that there was a play-signal (S), what was the probability that social play (P)
resulted. In other words, P(P/S) is equal to the success of soliciting social play.
"Based
on first 5 actions; X for beagles based on all 7 actions = .75, S.D. = .13.
c
See figure 5 for "P" values (levels of significance).
a
Correlation between success of an action (P(P/S)) and the frequency of occurrence of that
action.
77
time, using any of the actions. In the wolves
and coyotes, general movements were most
successful, and bows, second-most. Figure 5
shows the total number of play bouts observed, the overall success (P{P/S}) rates,
the levels of significance for the differences
P (play/s oliciting) r
P(soliciting/play)
B
bouts: 480
163
w
69
FIG. 5. The success with which beagles (B), wolves
(W), and coyotes (C) initiated social play. P(play/
soliciting)—see Table 1 for explanation; P (soliciting/play)—see Table 6 for explanation. The small
numbers on the left-hand graph (e.g., .01) indicate
levels of significance (see text). The small numbers
on the right-hand graph indicate the individual
scores for each member of each pair of animals.
(1 applies to the first pair of animals and 2 to the
second pair—see Table 6). Rho = the correlation
between the success of a particular action and the
frequency with which it was used. Bouts — the
total number of play bouts observed.
329
SOCIAL PLAY IN CANIDS
TABLE 2. Frequency of occurrence of mounting (M),
clasping (CL), and pelvic thrusting (PT) by beagles
during play.'
Males
CL
PT
21-35
36-50
3
3
6
7
12
19
2
5
7
M
Females
CL P T
1
3
ol o o
M
o|oo
Days
T
" No mounts, clasps, or thrusts were observed in
the coyotes; on day 45, one female wol£ mounted
her brother.
observed, the Spearman rank-order correlation (rho) for the relationship between the
success of a particular action and the frequency of its occurrence, and the frequency
with which bouts were solicited (P{S/P})>
The beagles were significantly more successful than either the wolves (df = 8, t =
3.42, P < .01) or the coyotes (df = 8, t =
6.7, P < .001), and the wolves more successful than the coyotes (df = 8, t = 2.20, P <
.05). Exaggerated approaches and face-pawing were least successful in the coyotes. The
low success of approach/withdrawals in the
wolves was due to the inactivity and lack
of "playfulness" on the part of one of the
animals (see below). It is also interesting
that the correlations between success of a
particular action and the frequency of occurrence of that action was negative in both
the beagles and the wolves, and highly positive in the coyotes. That is, coyotes tended
to use the most successful actions most frequently.
Table 2 shows the frequency of occurrence of "sexual" behaviors during play
bouts. The male beagles performed more
of these actions than did the females; mounting and thrusting were first observed on day
TABLE 3. Frequency
of occurrence
Hsh«
Beagles
126
Coyotes
229
Wolves
319
(26)-
(59)
(i
(68)
* Hsh =
FP =
FB =
SB z=
GB =
'Median
27. No "sexual" behaviors were observed
in any of the coyotes, and one female wolf
mounted her brother on day 45.
Table 3 shows the frequency of occurrence of head-shaking (side-to-side shaking
of the head while biting), face-pawing and
also the frequency of occurrence of biting
directed to various parts of the body. The
beagles did more face-pawing (it was very
successful in soliciting play) and this action
persisted throughout" the course of observations. In the coyotes and the wolves, the
frequency of face-pawing began to decrease
on approximately day 35. The wolves performed more head-shaking and also more
scruff-biting, while the beagles bit more at
the face and the body (legs, flank, and back).
Individual differences
Coyote pair 1. In this pair there was a
severe, unritualized fight (uninhibited biting accompanied by vigorous head-shaking)
on day 25, U female emerging dominant.
On this day there was no play-soliciting by
either animal, and there was a large increase
in self-directed play (tail-chasing) by the
subordinate male (Fig. 6). There was a further increase on self-directed play on day
26. Similarly, on days 45 and 46, when there
was an increase in aggression by the dominant female, there was an increase in selfdirected play by her subordinate brother.
Overall, the subordinate male (C) performed
significantly more self-directed play behavior than his dominant sister (135:33; P <
.005, sign-test). Usually this behavior either
followed an unsuccessful play-solicit (28%)
or occurred in the absence of any play-
of various actions and bite orientation
FP
389
^90)
61
(16)
158
(35)
(days
21-50).
FB
SB
GB
1182
193
1141
(46)
i
(287)
237
3255
(67)
5444
side-to-side head-shaking accompanying a bite
face-pawing
face-biting
scruff-biting
general biting (flank, body, tail)
(130)
i(57)
502'
(115)
881
(246)
©
TABLE 4. Day of first occurrence of actions used to initiate social play.
Coyotes
Beagles
(1)
Action
CU
Male
b
28
(27)
EA
—
A/W
28
GM
30
(24)
FP
(27)
(26)
(2)
Female'
49
(30)
CU
Male
31
24
32
30
(26)
34
(35)
(31)
30
(29)
(46)
41
(29)
(25)
BW
Male
25
23
J
9(28)
(29)
32
2
(27)
—
—
B
—
—
37
29
29
(26)
* Dominant animal.
b
Day of first success.
( ) = day of first failure.
c
See text for code.
(33)
u
c
Female
Male
Female
21
22
(29)
27
23
23
40
28
23
27
26
(40)
(26)
—
(25)
(28)
(30)
(26)
(31)
21
21
26
37
30
34
25
23^
27
25 ( 2 3 )
(28)
28
26
(23)
22
27
(27)
V)
5(24)
5
(24)
32
(37)
(34)
(35)
I
(24)
u
26
Male
28
-
(27)
(39)
4C
24
29
s (34)
45
(26)
28 C
26
24 (26)
27
(38)
o(26)
40
9 (4 3 )
29
(27)
(41)
(42)
37
(43)
(26)
(43)
26
48
(28)
24
(27)
(2)
c
30
(30)
(28)
(30)
(1)
23
(42)
35
(28)
Male
23
(26)
(2)
BW
Female
23
24
(23)
X
25
(30)
(27)
27
Female
(25)
LL
—
Female*
30
(32)
28
Wolves
(1)
30
(25)
30
(29)
30
(31)
36
(38)
n
W
331
SOCIAL PLAY IN CANIDS
T
24
FIG. 6. The relationship between self-directed play
and play-soliciting by the subordinate male in coyote pair 1. The star indicates that on day 25, dominance relations were formed (see text).
soliciting (in vacuo) (67%). On a number
of occasions, tail-chasing occurred, and then
the male briefly stopped and looked at his
sister, and then commenced chasing once
again. Between days 21-42 there were only
17 bouts of play, and between days 45-50,
there were 23 bouts. The animals did not
get more successful in soliciting play as
length of time with social experience increased.
The subordinate male first successfully
solicited social play on day 28 after having
been unsuccessful on days 24, 26, and 27
(Table 4). The dominant female first successfully solicited social play on day 28. On
day 32 there was an increase in social play
by the female, and on day 33, the longest
fight of all was observed. Overall, playsoliciting resulted in an aggressive response
only four times, the remainder of the unsuccessful solicitations being responded to
with "indifference" by the recipient On
day 45, when there was an increase in aggressive behavior by the female, the male
approached her after play soliciting and she
did not respond. Ten seconds later, he approached once again without previously signalling a "play intention," and she responded aggressively. It is also important
to point out that of 40 attempts to initiate
chase play by the dominant female, only
1 was successful, and this was the only one
which was preceded by a play signal (general movements) (Table 5).
Table 6 presents the data dealing with
the success (P{P/S}) of play-soliciting and
also the probability that a bout had been
previously solicited (P{S/P}. The dominant
female of this pair was both less successful
and less solicitous than her brother, and
when play did occur, the probability that
the subordinate male had previously solicited playful interaction was higher than
that observed for his sister. A total of 90%
of all bouts were signalled by either animal
(see also Fig. 5).
Play bouts typically consisted of wrestling, jaw-wrestling, and inhibited biting.
"Role reversals" were also observed, the
dominant female allowing her subordinate
brother to "dominate" her. On a few occasions, play fighting did lead to real fighting.
On day 40, for example, the animals were
engaged in a reciprocal bout of wrestling
and play-fighting, when all of a sudden the
dominant female aggressively vocalized and
began attacking her brother. He rolled over
into a passive-submissive posture (Bekoff,
19726) and remained motionless until she
TABLE 5. Chase sequences in coyotes.
Turning-away
Chase
20
Response by subordinate male
Rolling-over
Def. threat
No reaction
14
y
5dominant
•
female
* The only instance in which chase was preceded by a play-signal.
Play
Total
40
332
MARC BEKOFF
TABLE 6. Play-soliciting by individual animals observed in pairs."
S(#)b
U(#)b
P(P/S)b
# Bouts
(P(S/P)b
40
26
36
.65
.42
Coyote 1: C Male
10
30
.25
.25
40
U Female"
19
37
.66
.34
29
Coyote 2: C Female
7
34
.24
.17
29
U Female"
86
40
.35
.68
243
Beagle 1: B Male
76
17
.31
243
W Female
.82
127
51
.54
237
Beagle 2: B Male
.71
237
95
33
.40
W Female
.74
.21
15
56
.18
85
Wolf 1:
C Female
.23
13
44
85
.15
U Male
.42
78
56
79
Wolf 2:
.72
C Female
.46
78
6
7
.08
U Male
•b Based on the total frequency of play-soliciting actions
See Table 1 for legend concerning S, U, and P(P/S); P(S/P) = given that there was play (P),
what was the probability that it was preceded by a play-signal(s). In other words, P(S/P) is equal
to cthe % of solicited play bouts.
Dominant animal
stopped attacking. Eye-contact by the fe- individual animals did not display indimale was sufficient to induce flight and vidual differences as large as those observed
turning away by the male (Fig. 7).
in the coyotes or the wolves. In both dyads,
Coyote pair 2. In this pair of coyotes, C
appeared to be dominant over her sister
Typical
Sequences
(U) between 26 and 30 days of age. There
was no fight and the relationship was not
BEAGL ES:
as clear-cut as had been observed in coyote
pair 1. On day 30, U began asserting domiday 29nance over C and controlling their interplay bow.
actions from then on. Of the 24 periods in
which there appeared to be an assertion of
dominance by one of the animals, U was
clearly dominant during 20 (83%).
From 3 to 4 weeks of age, there was little
pelvicwrestling
difference in their success of soliciting play
thrusts
and their "playfulness," C attempting to solicit play eight times, and U attempting to
solicit play six times. After U began asserting dominance on day 30, C became more COYOTES:
successful in soliciting social play. The aniday 32:
mals were housed together on day 35, and
between days 36-42, there were no bouts of
AIW
play, as U became more aggressive. On day
42 there was a dominance fight, U clearly
dominant over C. Between days 43-50, C
eye-con ta c t
was clearly more solicitous, attempting to
initiate social play 21 times to her sister's 8. FIG. 7. Some typical sequences of social play in the
and coyotes. EA = exaggerated approach;
U was less successful overall, and more bouts beagles
TA = turning away; CH — chase; GB = general
were preceded by a play signal sent by her body biting; hsh = side-to-side head shaking acsubordinate sister (Table 6). A total of 90% companying the biting; RO = rolling over; A =
of all play bouts were preceded by a play approach; CR = chin rest; NR = no response;
ISO = incomplete stand-over; A/W = approach/
signal sent by either animal (Table 6).
withdrawal; PS == play solicitations. For pictoral
Beagle pairs 1 and 2. It is not misleading representations and full descriptions of these acto clump the data for the beagles, since the tions see Bekoff, 19726.)
SOCIAL PLAY IN CANIDS
FIG. 8. This sequence of photos shows a play sequence between two 30-day old beagles. The beagle
on the right performs a bow (A) and his littermate
approaches (B). As she approaches he makes direct
eye-contact and she turns her head away for a brief
3S3
moment (C). D, the female (on the left) rears and
leaps off the ground; E, the male responds by moving closer. A play bout consisting of wrestling, rolling, and inhibited face-biting occurred (f).
334
MARC BEKOFF
no dominance relations were formed, and
there was a lot of reciprocal interaction.
The beagles were the most solicitous and
playful of the animals (engaging in 483
bouts of play) and successfully solicited play
earlier than their congeners (Table 4). The
frequency of occurrence of play bouts for
any seven-day period (e.g., 21 to 28, 29 to
35 days of age) ranged from 45 to 69. In
the first pair, when W female was inactive
between days 29-35, B male engaged in selfdirected play 112 times. Typical sequences
of beagle play are illustrated in Figures 7
and 8. During play bouts, more "sexual"
actions were noted in the beagles. Also, the
beagles were the only animals which barked
during the solicitation of social play. (We
also observed barking at inanimate objects
such as the food bowl and water bucket.)
None of the beagles were as successful as
the subordinate coyotes (Table 6).
Play consisted of reciprocal chase, wrestling, inhibited biting, and rearing and
pushing with the forepaws.
A breed-typical action pattern, the leapleap, was performed in its highest frequency
by the beagles (mean = 165), and it was
highly successful in the initiation of social
play (Table 1). It was never observed in
the coyotes and very rarely in the wolves
(mean = 9). When it occurred in the wolves,
the leaps were of lesser amplitude.
Wolf dyad 1. The wolves in this pair behaved very much alike and there was a good
deal of reciprocal play interaction. No dominance relations were formed. Between days
21-28 and days 29-35, there were 33 bouts
of play during each period. The frequency
of occurrence of social play precipitously
decreased between days 36-42 to 9, and between days 43-50 to 10. Play consisted of
chase and wrestling.
Wolf dyad 2. As in pair 1, no dominance
relations were formed during the course of
observation. Although both animals were
approximately equally successful in soliciting play (P{P/S}) (Table 6), there were
large individual differences in "playfulness,"
U male attempting to solicit social play
only 13 times. Unlike pair 1, there was a
great deal of play from days 35-50, there
being 28 bouts from days 36-42 and 29 bouts
from days 43-50. The large difference in
P(S/P) was due to U's inactivity. C female
performed significantly more self-directed
play when U was inactive and unresponsive
(38:8; P < .05, sign-test).
DISCUSSION
In canids, play may be characterized as
indicated in the introduction to this paper
(see Tembrock, 1958; Ludwig, 1965; Eisfeld,
1966; Altmann and Recker, 1971; Bekoff,
1972a,6). To an observer familiar with the
species or individuals under study, it is usually not difficult to differentiate social play
from other categories of social behavior.
Miller (1973) has correctly written that an
". . . observer who 'knows' he sees play,
even if he doesn't know what it 'is', is not
necessarily talking off the top of his head"
(p. 89).
By observing pairs of animals, much may
be learned about the dynamics of social interaction in a particular species (Kalmus,
1969; Poole, 1972). In order to gain insight
into social ontogeny, conditions of captivity
provide a good setting, since individuals
may be identified at an early age. In canids
in the wild, much behavior occurs inside
the den during the first weeks of life, and
in coyotes in particular, many valuable
data would be lost. Recent observations of
an intact litter of coyotes, reared in captivity with their mother, indicated that between days 18 and 35, 85-90% of all social
activity took place within the nest box, or
directly in front of it (Bekoff and Jamieson,
unpublished).
A most difficult aspect of the analysis of social play is the study of the temporal sequencing of the actions which are incorporated
into a play bout. Most of these actions originate in other contexts. Preliminary analysis (Bekoff, in progress) indicates that the
probability that an action will occur during
a bout is very little dependent on the nature of the preceding event. The sequences
appear more random and less predictable
than those observed during actual fighting,
courtship, or prey-killing. This is especially
true for the beagles and wolves. In mathematical terminology, it appears that most
SOCIAL PLAY IN CANIDS
play sequences would be categorized as
zeroth-order Markov chains (Slater, 1973).
That is, after one animal delivers a bite to
the rear leg of another animal, side-to-side
head-shaking occurs as frequently as biting
the other leg, scruff-biting, or rapid withdrawal. This lability of temporal sequencing has also been observed in free-roaming
dogs (Ludwig, 1965; Bekoff et al., in progress), and in wolves (Zimen, 1971). Slater
(personal communication) has suggested
that perhaps different rules apply at different points in the play bout, and that the
analysis of temporal sequences is complicated by the fact that two interacting organisms are involved. I do not agree with
Lazar and Beckhorn (1974) that ". . . play
activities are seen to be exaggerated, out of
sequence, incomplete . . . only when viewed
with respect to adult behavior patterns."
Fox (1969) and this author have observed
infant coyotes perform normal species-typical predatory sequences as well as engage in
true agonistic encounters. When these actions are performed by the same animals
during social play, there is exaggeration,
lack of sequencing, and incompleteness of
action. Thus, play need not be characterized only by reference to adult behavior.
Furthermore, I do not agree with Tobach
and Schneirla (1968) that "play is a term
for immature undifferentiated behavior patterns in the process of organization . . ." for
the above reasons, and for the more obvious
reason that adult animals do engage in social play.
Species and individual differences
The early ontogeny of agonistic behavior
in coyotes which results in clear-cut dominance relations (Fox and Clark, 1971; Bekoff, 19726; Bekoff and Jamieson, unpublished) clearly differentiates coyotes from beagles and wolves. Overall, the beagles were
seven times as playful as the coyotes and
three times as playful as the wolves. (In the
domestic dog, breed differences are also evident [Ludwig, 1965; Scott and Fuller, 1965]
and whether or not these breed differences
are reflected in early ontogeny would be
interesting to study [Ewer, 1968].) There
335
were virtually no instances in which we
were unable to differentiate play-fighting
from real fighting, and I feel that rather
than labeling play-fighting as "quasi-agonistic" (McGrew, 1972), I would retain the
label "play-fighting." This is because, at
least in canids, both the sequencing of the
actions and the outcome of the interaction
differ from that observed during true fighting. Poole (1973) has recently differentiated
true fighting from play-fighting in polecats.
Recent data collected on a litter of coyotes (Bekoff and Jamieson, unpublished)
suggest that the differences in ontogeny
which are evident in the early life of canids,
may be useful in understanding later adult
social organization. And, as has been suggested for various mammals (Etkin, 1963;
Baldwin and Baldwin, 1974), it appears
that "animals which play together, tend to
stay together." Animals which play less appear to have weaker social ties to their
group.
Play-soliciting
Animals have to be able to differentiate
play from "not play." Before the play bout
commences, one organism may "metacommunicate" (Bateson, 1955) its intention to
play by using various signals. These signals
are usually clear and unambiguous, and
some appear to be specific to the context of
social play (Bekoff, 1972a; Sade, 1973). Furthermore, when two seemingly contradictory
signals are given, one of which is a playsoliciting action, priority is most usually
given to the play signal (Loizos, 1966; Bekoff, 1972a). In a previous paper I have discussed metacommunication in more depth
(Bekoff, 1972a), and I also suggested that
some of the play-signals in canids were specifically used to initiate social play. I was
referring to the "bow." It still appears that
although the bow and other movements are
also observed in other contexts (during
courtship for example) "play intention"
cannot be ignored. Christie and Bell (1972)
present quantitative data showing that
there is an increase in male-female play
during both pre-estrous and estrous in domestic dogs. We have observed courtship
between a male malemute and a female
336
MARC BEKOFF
wolf (Lockwood, Shideler, Bekoff, and Fox,
unpublished) and observed numerous bows,
along with other actions used to initiate
play. Perhaps play serves to strengthen the
bond between the courting animals and reduces flight tendencies.
After the bout is underway, there is continual feedback between the interactants,
and it appears possible that the animals
"know" that they are playing because of the
changes in the temporal sequencing (Chevalier-Skolnikoff, 1973). Therefore, when an
observer does not perceive a play signal, he
does not have to feel that he has necessarily
missed something, for the "signal" may be
in the sequencing itself. On the other hand,
a signal may be given which is so subtle as
to be almost undetectable to the human observer. By doing frame-by-frame analysis of
movie film shot at the "eye level" of the
interacting animals, we have observed very
slight eye and head movements directed toward the prospective playmate, and at the
moment, can only assume that they are of
some import to the animals (Bekoff and
Jamieson, in progress).
The coyotes were significantly less successful than the beagles or the wolves in
initiating play. However, when play did
occur, 90% of the time it was preceded by
a play invitation signal. The subordinate
animals were more playful than their dominant partners. Furthermore, in the coyotes,
there was a high positive correlation (rho)
between the success of a particular action
and the frequency with which it was used.
That is, coyotes showed a strong tendency
to use the more successful signals more frequently, while in the beagles and the wolves
there were negative correlations. (In an ongoing study of free-roaming domestic dogs,
we have found a correlation of rho = —.04.)
These facts fit in nicely with what has already been discussed concerning the differences in social development between these
three species. Since in the coyote there is an
"aggressive atmosphere" prevailing, and
during social play the actions observed are
usually those otherwise seen in true aggression, it would be important for an animal
to communicate its intention to engage in
social play and that this intention be per-
ceived and shared by the recipient. In the
coyotes, the least ambiguous signals (at
least to the observers) were the most successful. The importance of the signal in
coyotes is also indicated by the fact that if
play did occur after a signal was sent, it
was most usually the subordinate who had
solicited the interaction, in a sense, assuring
the most dominant sib that "what follows is
play, and not an attempt to overthrow you!"
Similarly, when the dominant female in
pair 1 a'ttempted to initiate chase play without previously communicating play intention, she failed 39 out of 39 times. The only
successful initiation of chase play occurred
after she had sent a play signal. Loizos
(1969), in her study of chimpanzee social
play, found that in order for chase to result in play, and not flight, the subordinate
had to do the chasing.
In the wolves, exaggerated head and body
movements (e.g., head-tossing and side-toside swaying of the shoulders) were most
successfully used to initiate play. In the
beagles, all actions were successful mo're
than 56% of the time. High-pitched barking by the beagles was also successful in
initiating an approach by the partner and
subsequent play 56% of the time, and it
was often combined with another play-soliciting action. Barking may be a way in which
an animal calls attention to itself and play
signals may also serve as attention-getting
devices (Steiner, 1971), in addition to intention movements. Beer (1973) has written
that "an effective signal is one that gets
attention and is unambiguous" (p. 69).
Sex differences
In the present study, no sex differences
in social play were observed with respect
to the "roughness" of the playing. It is possible that this was due to the fact that the
animals were not reared with their mothers,
however, observations of other canids reared
with their mothers (Bekoff and Jamieson,
unpublished, Bekoff, personal observation)
indicate no sex differences during 3 to 8
weeks of age. The only sex differences involved the frequency of occurrence of "precocious" sexual behavior by the male bea-
SOCIAL PLAY IN CANIDS
gles. Rheingold (1963) points out that only
male dogs were observed to mount other
animals during the course of her observations.
Self-directed play
Qualitative observations of the development of social behavior in various canids
led Fox (1971, p. 52) to suggest that self
directed play might serve as a substitute for
social play when the possibility for social
play was blocked. Rather than block social
play using experimental techniques (e.g.,
Muller-Schwarze, 1968; Chepko, 1971; Reynolds, Oakley, and Noble, personal communication) we found that this occurs naturally. It appeared that an animal could be
"play deprived" even in the presence of a
partner(s), if that partner was unresponsive
to play solicitations and/or generally inactive. Being unable to successfully solicit
play, an organism might then redirect its
play towards its own body.
When the possibility for social play was
blocked, due either to the intolerance of
one animal for the proximity of its partner
(coyotes) or to one animal's inactivity (beagles and wolves), there were substantial increases in self-directed play behavior by
the more active animal. Kruijt (1971) wrote
that the most important influence of social
experience appears to be that it guides the
responses of the organism toward social
companions, and in the absence of such
partners, the animal forms relationships
with its own body. Mason (1965) suggested
that in the absence of social companions, an
animal disposed toward social play would
engage in strenuous motor activities. As
mentioned above, absence does not necessarily imply physical absence, but can also
refer to unresponsiveness. While the animals we studied did not have the opportunity to play with inanimate objects during observation sessions, observations of
free-roaming dogs has indicated that it is
not uncommon to observe an unsuccessful
solicitor immediately begin playing with an
inanimate object. Finally, in-cage observations of these and other canids that have
been housed individually for methodological purposes have shown that these animals
337
perform very little self-directed play during
this limited social isolation at this age (Bekoff and Fox, personal observation). The
presence of another animal appears to serve
as a stimulus.
Self-directed play does not always follow
an unsuccessful play solicitation. After a
period of time, self-directed play occurred
•without a prior play soliciting. Since animals adjust their actions to the "expected"
actions of others (McFarland, 1966; Bindra,
1969), an animal may learn not to expect
another animal to play. After repeated
"play deprivation," it may forego soliciting
play and engage in self-directed play without prior play soliciting. Bindra (1969) has
discussed the above idea in terms of the central motive state (CMS). The CMS occurs
through an interaction between physiological states and incentive stimuli. Indeed,
more studies are needed concerning the
physiological state of playing animals (Muller-Schwarze, 1971).
Why play?
Space does not allow me to go into a
full discussion of why animals play. Various authors have considered the functional
aspects of social play (Beach, 1945; Millar,
1968: Dolhinow and Bishop, 1970; MullerSchwarze, 1971; Bekoff, 1972a), and no one
theory of play has been found to be applicable to all animals (Lowenfeld, 1936; Beach,
1945). Indeed, ecological factors are important to consider when discussing even a
single species (e.g., Barash, 1973). Animals
obviously get physical exercise while playing (Brownlee, 1954), and they may also
acquire skills which will increase the facility with which they can move through their
environment (Ripley, 1967).
There have also been repeated assertions
that social play experience is necessary for
animals to become "socialized" to conspecifics (Harlow, 1969; Jolly, 1972). In an earlier paper, I overenthusiastically (and perhaps naively) accepted this point of view.
There is some evidence that it is not mandatory for animals to have had social play
experience in order to acquire species-typical social communicatory skills (Baldwin
338
MARC BEKOFF
and Baldwin, 1974) and that methods which
have been used to experimentally deprive
animals of social play behavior have not
specifically affected only social play experience. However, social play experience does
appear to lead to an increase in flexibility
of an individual's behavior repertoire (Miller, 1973) and in the subtlety of social cues
to which it can appropriately respond
(Baldwin and Baldwin, 1974).
It has also been suggested that animals
play in order to pre-exercise "instincts"
which will be needed in later life (Groos,
1898). Suffice it to say, this theory has
not been supported in various mammalian
groups (Poole, 1966; Fox, 1969; Welker,
1971; Bekoff, 1972a). What appears to be
the case is that play experience increases
the "smoothness" of carrying out certain
sequences of behavior, but that it is not
necessary for achieving the consummatory
phase of the sequence (e.g., the killing of
prey) (see Beach, 1968).
In canids, play appears to be important
in learning to control the intensity of the
bite and in facilitating the formation and
continued maintenance of social relationships within a group. In coyotes (and red
foxes) play does not usually occur until
after dominance relations are formed, while
in wolves, play appears before dominance
fights. That the more social canids play
more earlier in life is interesting, and there
appears to be some relationship between
social ontogeny and later social organization in Canidae, namely, that "animals that
play together, tend to stay together" (Bekoff and Jamieson, unpublished). Tembrock
(1958) wrote that the frequency of play between two individuals was a measure of
"fondness."
Finally, animals may play because it is a
"pleasurable" experience (Bertrand, 1969;
Bekoff, 1974). Young animals devote a lot
of time and energy to social play, and perhaps this good "feeling" is indicated by
the looseness of their gait, the bouncy movements observed during play, and the "smilelike" facial expression. External cues are
frequently used by ethologists and other
behavioral scientists to infer mood (e.g.,
Darwin, 1872; Hebb, 1946; Vine, 1970; Ditt-
mann, 1972; Ekman, 1973), and the overt
behavior associated with social play indicates a "pleasurable" experience. Neurophysiological studies may provide some
further support for this contention (e.g.,
Lindsley, 1951; Clynes, 1973).
In conclusion, social play appears to be
an important category of social behavior
and should not be dispensed with as being
a "wastebasket" into which unmanageable
concepts are deposited. Data which have
been and are currently being collected on
a wide range of animals are providing evidence that social play may be studied in
its own right.
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