Muñiz, R. S.

Revistes Catalanes amb Accés Obert

METHODOLOGY USED FOR THE STUDY OF EARLY MOTHER-INFANT 
BEHAVIOUR IN BORNEAN ORANGUTAN (PONGO P. PYGMAEUS LIN- 
NAEUS, 1760) 
Muñiz, R.S., 1981 (1983). Methodology used for the study of early mother-infant beha- 
viour in Bornean orangutan Pongo p. pygmaeus linnaeus, 1760). Misc. Zool., 7: 21 3-219. 
Barcelona. 
Orangutans are endangered and some captive females have failed in rearing their offspring. 
Because of this a multiparous Bornean female, Pongo p. pygmaeus, and her 3-months-old 
daughter were studied for two weeks (30 hours of observation in all), using exact time, s e  
quential and point sampling methods. Most of the time the infant was in ventro-ventral 
contact with her mother end. when there was no contact, the infant was within the 
mother's arm reach; the carrying position was side-ventral; proximity between the pair 
was maintained mainly by the mother; there was little grooming of the infant by the 
mother, and the infant sucked one nipple as often as the other. After comparinginfant- 
rearing practices in captivity and in the wild, it is concluded that multiparous mothers are 
better mothers than primiparous ones and that the mother wav rearing her infant in the 
normal way. 
R.S. Muñiz, C/ Felipe Bertran y Güell 1, Barcelona 27. 
The importance of the mother-infant beha- 
viour, mainly in primates, has been reported 
by many scientists. 
This kind of interaction is related to the 
formation of nearly all social behaviour and, 
therefore, is important to the survival of the 
individual and of the species (KINGSLEY, 
1977). 
Apes, in general, require special attention 
not only because they are endangered but 
because some captive females have failed in 
rearing their offspring (NADLER, 1974). 
Therefore studies about maternal care are 
important for the attainment of a correct 
breeding prograrn. 
The present paper deals with mother- 
infant behaviour in Bornean orang-utans 
(Pongo p. pygmaeus). In the wild this ape 
has few social interactions and the infant 
meets few other orang-utans. Because of 
this the bond between mother and infant is 
all the more complete (MACKINNON, 
1974). 
In order to know which parameters 
should be studied, it is useful to  know what 
animals do in the wild. Infant orang-utans 
that are iess than 1 year old generally remain 
close to the mother and travel by her side. 
They feed by suckling but show interest in 
food being eaten by their mothers. Young 
infants sometimes play by dangling on bran. 
ches close to the mother when she is resting. 
Sometimes the mother plays with them tick- 
ling and biting them gently. Infants playing 
near the mother frequently come back t o  
her and touch her, or are embraced by her, 
then return to  their play (MACKINNON, 
1974). 
Therefore it has been considered con- . 
venient to study behaviour concerning the 
kind of contact between the mother and the 
infant, proximity, suckling and activities of 
booth individuals comparing, when possible, 
our data with that available from the wild 
Table 1.. Bali's breeding history. 
Date No. Borns Lasses No. Reared 
25 Mar 68 1 d 3 Months premature 
15 Apr 71 1 Q O 
17 Mar 75 1 d Killed by the father 
14 Jun 76 1 Q found dead 
21 Jun 77 1 d O 
29 May 82 1 9  O 
(MACICINNON, 1974) and in captivity 
(KINGSLEY, 1977). 
MATERIAL AND METHODS 
Animals 
The subjects of the study were a multiparous 
Bornean orang-utan (Pongo p. pygmaeus 
Linnaeus, 1760), Bali, and her female 
infant, Sandokan, resulting from the pair- 
ing with another Bornean male, Giles. 
Bali was born in 1960, and has been kept 
at the "Jersey Wildlife Preservation Trust" 
since 18.3.63. Since then she has been 
pregnant six times, the last time giving birth 
to  Sandokan. Table 1 shows Bali's Breeding 
history. 
For the rest of behaviours the point 
sampling method was employed (ALT- 
MANN, 1974), scoring each 15 seconds, 
and each check-sheet lasting 8 minutes. 
Signs were written on the check-sheet 
instead of words, in order to score very 
quickly and collect as much data on the 
pair as possible. 
In all 30 hours of observations were re- 
corded. 
Housing 
The pair was housed in a cage which inclu- 
ded inside and outside enclosures. 
Both cages had climbing frames and acce- 
sories for the orangs' amusement. They had 
a "canopy" of frames on the top of the cage. 
The outside enclosure was separated 1.15 
I meters from the public. Place and Date 
The study was carried out at the "Jersey 
Wildlife Presewation Trust" between the 
20th and the 31st of August 1982, during 
the third Summer School. The infant was, 
therefore, 13 and 14 weeks old. 
Sampling Method 
The observations were made between 09.15 
and 12.45. 
Exact time was recorded for data con- 
cerning grooming and suckling by using a 
stopwatch. 
Patterns of grooming behaviour were re- 
cordetl by using a sequential method (ALT- 
MANN, 1974). 
Hinde's proximity index (HINDE, 1968, 
1971). 
Difference between the percentage of ap- 
proaches and the percentage of leavings due 
to  the infant (% AI  - % LI). 
A negative index indicates that the 
mother is mainly responsible for maintaining 
proximity whereas a positive index indicates 
that the responsability lies with the infant. 
Grooming of infant by mother 
The body of the infant was subdivided into 
4 parts: head, body, arms and legs. 
Table 2. Different type of contact expressed as a percentage of the scores in contact. 
V-V V Neck Another 
RESULTS D. Percentage of scores without contact in 
which the infant was not within the 
Contact between the mother and the infant mother's arm reach: 17.16%. 
Percentage of scores in which the infant was 
in contact with the mother: 91 .9O0/0. Hinde's proximity index 
Type of contact 
V-V: ventro-ventral contact. (Infant's chest 
against mother's chest or mother's side). 
V: ventral contact. (Infant's chest against 
another part of the mother's body). 
On neck: One hand clings to  the hair of the 
mother's shoulder, the foot holds the hair of 
her back, the opposite hand and foot hold to  
the ventral hair so that the infant is on the 
mother's side behing her arm. 
Another: The infant is in another type of 
contact with the mother. 
Table 2 shows the percentage of contact 
scores in which the infant was in each of 
the four types of contact. 
Infant's behaviours: (Expressed as a percen- 
tage of the total number of scores). 
1. Mouth activities: Such as biting, licking 
and chewing (suckling is not included): 
18.41 '/o. 
2. Handling: All manual activity which in- 
volves grasping or hoisting of objects: 
15.87%. 
3. Body activities: Jumping, climbing and 
other actions which inply movements of 
all the body: 22.37OI0. 
4. Resting: The infant remains without 
making any movement and maintains its 
eyes open: 3.47%. 
5. Sleeping: 33.48%. 
Transports The mother bites gently the infant 
Almost all the transports were on the "neck" Percentage of the total number of scores: 
position. Only one transport was on the 0.28%. 
mother's left arm, and another on the 
mothef s abdomen. 
Grooming of infant by mother 
Without contact 
A. Percentage of contact scores in which the 
mother restrained the infant: 7.07%. 
B. Percentage of total scores in which the 
infant was not in contact : 8.10%. 
C. Percentage of scores without contact in 
which the infant was within the mother's 
arm reach: 82.84%. 
The mother could groom with her mouth 
(by using lips, teeth and tongue), or with her 
fingers. 
Of the 31 intervals (parts of bouts) ob- 
served, the mother groomed: 
- 22 with her mouth. 
- 9 with her fingers. 
Of these 3 1 intervals: 
- The head was groomed O tirnes. 
Table 3. Suckling (total duration expressed in seconds). 
Nurnber of Times on nipple Total duration of suckling 
Bouts 
Suckling Left Right Left Righ t Total 
- The body was groomed 12 times. 
- The arms were groomed 18 times. 
- The legs were groomed once. 
- Total number of grooming bouts: 13. 
- Total number of intervals: 31. 
- Total time spent in grooming: 620 se- 
conds, that is the 0.57% of the total time 
of observation. 
- Mean duration of each sequence: 47.69 
seconds. 
- Mean duration of each interval: 20 se- 
conds. 
- Mean number of intervals of each bout 
(sequence): 2.08. 
Suckling 
Table 3 shows the suckling behaviour. 
Percentage of the total time of observa- 
tion in which the infant was sucking: 5.39%. 
Mkan duration of each bout: 67.02 seconds. 
DISCUSSION 
Before comparing these results with those of 
K ~ N G S L E Y  (1977) it is useful to note that 
she collected data during 5 different periods 
(08.00 - 10.00 hrs; 10.00 - 12.00 hrs; 
12.00 - 14.00 hrs; 14.00 - 16.00 hrs). The 
present data was collected between 09.15 
and 12.45 and, therefore, it may have some 
bias, due to the daily variation of behavjour. 
Kingsley recorded mother-infant beha- 
viour in an orang-utan (Samarinda), whose 
mother was also Bali, and in a gorilla, 
N'Pongo. 
Contact between mother and infant 
During early infancy, close contact with the 
mother is of great importance to  the protec- 
tion of the infant, for regulation of body 
temperature, and it is necessary for nursing 
(ROGERS & DAVENPORT, 1970). 
91.90% of the observation time the in- 
fant was in contact with the mother. This 
percentage is closer to Kingslye's data for 
Samarinda than for N'Pongo (table 4). 
Type of contact 
During the first six weeks the apes spend 
most of the time in ventro-ventral contact 
with their mothers. This was found in 
captive conditions (KINGSLEY, 1977) and 
in nature (SHALLEK, 1963;MACKINNON, 
1974). 
A rapid decline in ventro-ventral contact 
during tke first few weeks seems to be one 
of the main indications of breakdown in 
maternal behaviour in captive apes (CLIFT 
& MARTIN, 1978). 
Table 4 shows that in the three indivi- 
duals only half of the time was spent in 
ventro-ventral contact, as it can be expec- 
ted the infants being more than 3 months 
old. 
Nevertheless the Sandokan's data con- 
cerning the ventral position is closer to that 
of the gorilla than to that of the orang-utan 
(table 4). 
Transports 
In chimpanzees most of the early transports 
are on the mother's ventral area: ventro- 
ventral contact (LAWICK-GOOD ALL, 1968 ; 
SABATER, 1969). 
In orang-utans there is no shift in the fe- 
male carrying-position as is common in 
Table 4. Percentage of total time in observation. 
Within the Out of the 
Con tact V V-V Mother. s Mother's 
Arm rearch Arm reach 
Samarinda 90.80 27.25 
Sandokan 91.90 8.47 
N'Pongo 67.5 1 4.10 
terrestrial monkeys and apes. Orang-utan 
infants are rarely carried in a fully dorsal 
position. The normal rinding position for 
young or adult infants is sideventral (that is 
the "neck" position described above). The 
effect of this carrying position is that the 
infant does not get in the way during the 
tree travel (MACKINNON, 1974). 
COFFEY (1971) reported that Bali 
carried, at first, the infant on the ventral 
side close to the breast and face. Then, 
from the age of two months, the infant 
was carried across the shoulder. 
During the observations alrnost all of the 
transports were on the "side-ventral" posi- 
tion, as it is usual. Therefore the mother 
was carrying her infant in the normal man- 
ner. 
Without contact 
Refering to the percentage of time spent 
by the infant within and out of the mother's 
arm reach, table 4 shows that Sandokan's 
data agrees with that of Kingsley for Sama- 
rinda, and that the three individuals spent 
more time within the mother's arm reach. 
Hinde's proximity index 
HINDE (1968, 1971) found that in the 
rhesus monkey, for severa1 months the 
infant left the mother more frequently than 
he approached her, i. e. there was a negative 
proximity index. Later the index increased 
to  zero at about week 15 and from week 20 
to  2 years the infant approached his mother 
more than he left her. 
KINGSLEY (1977) gave an index of 4.o0/o 
for the orang-utan, and 1.7% for the gorilla, 
when both infants were between 17 and 19 
weeks old. 
Unfortunately Sandokan and Bali7s data 
belongs to a previous period and it would 
expect to find a lower index, as indeed it 
was found. The index found is - 38.09% 
which shows that the mother was mainly 
reponsible for maintaining proximity. 
Infant's activities 
During 56.65 % of the observation time the 
infant was "handling", doing "oral" ac- 
tivities or "body" movements (see defini- 
tions in Results), and during 26.95 % of 
the total time the infant was resting or 
sleeping. 
COFFEY (1971) reported that the 3.5- 
months-old orang-utan which he observed 
started to chew some banana skin, and this 
agrees with the present observations. 
Coffey also saw that the infant climbed 
the bars of the cage and made independent 
locomotion at this age. This behaviour was 
also noticed in the present study. 
Sandokan was able to focus on distant 
objects, to be aware of their movement and 
t o  follow them (as COFFEY (1971) re- 
ported in the 2.5-months-old orang-utan). 
The mother used to encourage Sandokan 
to  move away from her by placing its hands 
on the cage bars so that the infant could 
climb away. 
Grooming of the infant by the mother 
Wild gorillas and orangs do not spend a large 
proportion of their time grooming each 
other (SHALLER, 1963; MACKINNON, 
1974; KINGSLEY, 1977). 
This was also observed in Bali, which 
spent 0.57% of the obsewation time groo- 
ming. 
Bali used the mouth more than the hands 
as a to01 to groom her infant, and the most 
of the grooming actions were directed to- 
wards the arms and the perianal zone. 
As far as sucking behaviour is concerned, the 
infant was seen performing this behaviour 
during 5.39% fo the total time of observa- 
tion, sucking one nipple as foten as the 
other. 
CONCLUSION 
The first infant to be reared by Bali was 
badly reared. The staff had to  teach Bali 
how to suckle her infant (COFFEY, 1971). 
Since the behaviour exhibited by Bali and 
Sandokan were similar to that found in wild 
(MACKINNON, 1974) and captive orangs 
( K I N ~ S L E Y ,  1977), it may conclude that: 
First: As it is well-known multiparous 
mothers are better mothers than primi- 
parous ones. 
Second: Bali was rearing her infant in the 
normal manner. 
ACKNOWLEDGEMENTS 
Thanks are due to the Jersey Wildlife Preservation 
Trust for assistance received. Thanks also go to 
Professor Robert D. Martin, reader in physical 
anthropology at University College, London, for 
supervising the research. Particular gratitude is 
expressed to Bryan Carroll, Head keeper of the mar- 
moseti; and bats section at the Jersy Zoo, and to 
Dr Arla Omedes and Rosario Nos, of the Bar- 
celona Zoology Museum, for provinding detailed 
commlents on the draft manuscrit. 
La rélation mbre-fils est la plus importante dans la 
vie des Primates et elle est la base pour la forma- 
tion de presque tout lien social. 
Les Pongidae est une Famille dont les représen- 
tants sont en danger d'extiction et, étant donné 
que quelques femelles captives n'ont pas réussi ?i 
allaiter leurs nourrissons de fapon correcte, les étu- 
des sur le comportement matemelle sont d'une 
importance vitale pour aider a la survie de  la dite 
Famille. b. cet effet on a étudié les premieres éta- 
pes de la relation m8re-fils en orang-outans du 
Borné, Pongo pygmaeus pygmaeus Linnaeus, 1760. 
Pour cela on gest servi d'une femelle multipare, 
dont les premiers fils étaient mort par des causes 
differentes, et sa filie agée de 3 mois. Le travail fut 
réalisé dans le "Jersey Wildlife Preservation Trust", 
du 20 au 31 d'aofit 1982 et de 09.15 i 12.45 
heures. 
On a prit note du genre de rapport entre la 
mbre et le nourrisson, activité de ce dernier, genre 
de transport, "grooming", allaitement et responsa- 
bilité de toutes les deux dans le maintien du 
contact. Pour cela on a appliqué 3 méthods: (selon 
ie comportement observé) évaíuation exacte du 
temps, séquentiel et contrBle ponctuel. En tout 
on a not i  30 heures d'observation. 
On a detecté que: 
1. Le 91.90% du temps d'observation, mere et 
fille étaient en contact, étant celui-ci la plupart 
du t e m F  ventro-ventral. 
2. Quand la mBre n'était en contact avec le nour- 
risson, celui-ci demeurait a la portée du bras 
maternelle étant la mbre la premibre responsable 
dans la prise de contact. 
3. Le transport du nourrisson par sa mbre fut du 
genre "lateroventral". 
4. La mbre nettoyait trbs peu sa fille (0.57% du 
temps d'observation). 
5.  Le fiile teta pendant 5.39% du temps total 
d'observation, le mBme temps aux deux ma- 
melles. 
Aprbs avou compare les resultats avec d'autres 
travails réalisés autant en conditions naturelles 
qu'en celles de captivité, on est arrivé a la conclu- 
sión que, en ler  lieu, les meres multipares sont 
meiUeures mbres que les m8res primipares et, en 
2 ond lieu, la mere qu'on a étudié était soignant 
correctement sa fille. 
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Methodology used for the study of early mother-infant behaviour in Bornean orang-utan (Pongo p. pygmaeus, Linnaeus, 1760)

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