Mother-infant relations in Wild Orangutans (Pongo pygmaeus morio) in Sabah, Borneo Renata Mendonça1, Susana Carvalho2,3, Cláudia Sousa4,5, Tetsuro Matsuzawa6 1Department of Life Sciences, FCT, Universidade de Coimbra, Coimbra, Portugal, renatadasilva.mendonca@gmail.com, 2 University of Cambridge, United Kingdom, 3 CIAS – University of Coimbra, Portugal, 4 Departament of Anthropology, FCSH, Universidade Nova de Lisboa, Lisbon, Portugal, 5 Centre for the Research in Anthropology (CRIA), Lisbon, Portugal, 6 Primate Research Institute, Kyoto University, Inuyama, Aichi, Japan.

Key words: infant development; social learning; mother-infant dyad.

[1] Munn C, Fernandez M. 1997. Infant development. In: Sodara C(ed). Orangutan species survival plan husbandry manual. Chicago (IL): Orangutan Species Survival Plan ,59-66 . [2] Which et al. 2009. Orangutan life history variation in Wich et al (eds.). Orangutans: Geographic Variation in Behavioral Ecology and Conservation. Oxford University Press, Oxford, 65-75. [3] van Noordwijk, et al. 2009. Developmenre of independence. In: Witch et al (eds.). Orangutans: Geographic Variation in Behavioral Ecology and Conservation. Oxford University Press, Oxford, 189- 203. [4] Adrichem, et al. 2006. The development of wild immature Sumatran orangutans (Pongo abelli) at Ketambe. Primates, 47:300-309. [5] Miller L C, Nadler R D. 1981. Mother-infant development in captive chimpanzees and orangutans. Int J Primatol, 2:247–261. [6] van Noordwijk, et al. 2005. Development of ecological competence by Sumatran orangutans. Am J Primatol, 127:79-94. [7] Jaeggi A V, et al. 2010. Social learning of diet and foraging skills by wild immature Bornean orangutans: implications for culture. Am J Primatol, 72:62–71. [8]Kanamori, et al. 2010. Feeding ecology of Bornean Orangutans (Pongo pygmaeus morio) in Danum Valley, Sabah, Malaysia: A 3-Year record including two mast fruitings. Am J Primatol, 72: 820-840. [9] Martin P, Bateson P. 1986. Measuring Behaviour: An Introductory Guide. Cambridge, Cambridge University Press. [10] Delgado R, van Schaik C P. 2000. The behavioral ecology and conservation of the orangutan (Pongo pygmaeus): A tale of two islands. Evol Anthropol, 9: 201-218.

Introduction

Goals

Methods

Acknowledgments

Predictions

During five years at Danum Valley Field Center, in Sabah, Borneo, ad libitum, focal and instantaneous sampling will be used [9]. Frequency of

contact between mother and infant, distance between mother-infant,

rejections by the mother, suckling, playing, feeding behaviour and other

variables including any social contact will be measured.

Samples of feces and urine will be collected for DNA analyses to reveal

the kinship between the individuals who may interact with the infant, as

well as food samples, in order to analyze potential differences in the

composition of the food eaten by the female and her infant.

Mother-infant relationships represent the strongest social bond in orangutans [1]. Since orangutans have a long inter-birth

interval (six-nine years) [2], females invest plenty of time raising their offspring [3]. Mothers are essential behavioural models

during the long-term attachment with their offspring, that lasts approximately eight years [4], influencing the development of

their social behavior repertoire [5]. Around the age of three (Sumatra) and four-five (Borneo), infants reach locomotory and

foraging independence but still need some maternal support in difficult situations [4,6]. Only around six-eight years of age

are they seen sleeping alone in their own nest [4,7]. This seems to coincide with the infant’s weaning age, around seven years

old [6]. Recently, It has been shown that infants follow their mother’s diet choices and mimic their gestures during feeding

activities, suggesting the existence of a vertical transmission of diet [7].

• To know in detail the mother-offspring behaviour of the little

known subspecies of orangutans that occurs in Sabah.

• To understand which motherhood variables are more

relevant for the development and independence of the

infant.

• To supplement and to compare the results with existing

data from other field research sites, to understand how the

ecological factors may link to potential differences between

species, subspecies and populations.

• To provide important guidelines when implementing

conservation and rehabilitation measures.

As the ecological factors seem to influence orangutans’ behaviour [8], it is expected that

the rate of contact between Sabah dyads show differences from other Borneo and Sumatra

sites. Borneo is known for their high fluctuation in fruit productivity and for less resources

compared to Sumatra [10]. In order to save energy, it is expected that mother-infant dyads

from Borneo spend more time resting or less time in activities that require a higher

consumption of calories.

Orangutans have a similar development to chimpanzees, neverthless, they show a later

weaning age and longer interbirth interval [6], probably because Southeast Asian forests

are less productive than African [6] and orangutan mothers must forage alone, postponing

weaning until their offspring forage by themselves.

Following this reasoning, and considering all the ecological variables mentioned above we

would expect that Sabah orangutans would have a larger interbirth interval and a later

weaning age. However, this is not what seems to happen. In Borneo, the orangutans’

interbirth interval is shorter and weaning occurs at an earlier age compared to Sumatran

ones [3, 6]. This study is aimed to provide new data to help clarify these questions.

Fig. 1 – In the “Orangutan Island Bukit Merah”, infants are separated from the mothers due to health issues or lack of maternal care and treated like human babies. When they grow up they may be disabled in providing an efficient care to their offsprings. And the same may occur with their future offspring. It’s a vicious cycle!

Fig. 3 – Suckling behaviour. This behaviour seems to be a poor indicator milk intake [4] and it is hard to quantify in wild conditions

[6].

References

We are very grateful to Susana Carvalho (PhD student); to Profs Cláudia Sousa, Tetsuro Matsuzawa, Eugénia Cunha for suporting the develompment of this project. We also thank to Dr. Noko Kuze for her availability in Danum Valley Field Center, and Dr. Sabapathy, for allowing the training program in Orangutan island, BukitMerah. This project is financially suported by MEXT- Kyoto University to T. Matsuzawa.

Fig. 2 – Food sharing in semi-wild condition. BJ Island, Bukit Merah.

Photo by Renata Mendonça

Photo by Renata Mendonça

Photo by Renata Mendonça