TY - JOUR
T1 - Multi-year lactation and its consequences in Bornean orangutans (Pongo pygmaeus wurmbii)
AU - van Noordwijk, Maria A.
AU - Willems, Erik P.
AU - Utami Atmoko, Sri Suci
AU - Kuzawa, Christopher W.
AU - van Schaik, Carel P.
N1 - Funding Information:
Acknowledgments We are indebted to the Tuanan team of assistants and students over many years for their efforts in data collection. We thank Tatang Mitra Setia MSc and the students of the Fakultas Biologi Universitas Nasional (UNAS) in Jakarta, and in particular Rahmalia N. Amda and Neneng Mardianah as well as Erin Vogel, for their collaboration and support for the Tuanan project. We gratefully acknowledge the Indonesian Institute of Science (LIPI), and the Indonesian State Ministry for Research and Technology (RisTek), the Director General Departemen Kehutanan (PHKA), Departamen Dalam Negri, the local government in Central Kalimantan, the BKSDA Palangkaraya, the Bornean Orangutan Survival Foundation (BOSF) and MAWAS in Palangkaraya for their permission and support to the project. For major financial support we thank the University of Zurich, and the A.H. Schultz Stiftung. We appreciate the constructive comments by the anonymous reviewers.
PY - 2013/5
Y1 - 2013/5
N2 - In most mammals, females pay for reproduction by dramatically increasing net energy intake from conception to mid- or late lactation. To do this, they time their reproductive events in relation to environmental cycles so that periods of peak food availability coincide with peak demand or are used to build energy stores. This timing is not possible in species with slow development in which lactation is prolonged over a multi-year period with fluctuating food availability. Here, mothers are expected to sustain a stable but generally lower level of nutrient transfer. In a sample of over 1,050 complete follow days of eight mother-infant pairs collected over 7 years, we document maternal effort for wild Bornean orangutans (Pongo pygmaeus wurmbii) over their average 6. 5-year lactation period. As predicted, maternal feeding time was independent of the age of her growing offspring, indicating a stable sustained "plateau" effort of ≤ 25 % above baseline level, instead of a short peak lactation as seen in seasonal breeders. Infant orangutans started to regularly supplement milk with self-harvested food when they were 1-1. 5 years old, indicating milk intake was insufficient from this age onwards, even though maternal effort did not decrease. We expect the same regulation of sustained maternal effort in other large and large-brained mammals with slow infant development. We also predict that mother-infant conflict over suckling may show another peak at the onset of the milk + solid food phase, in addition to the well-known conflict around the endpoint of lactation (weaning), which is reached after a long and gradual increase in solid food intake by the infant.
AB - In most mammals, females pay for reproduction by dramatically increasing net energy intake from conception to mid- or late lactation. To do this, they time their reproductive events in relation to environmental cycles so that periods of peak food availability coincide with peak demand or are used to build energy stores. This timing is not possible in species with slow development in which lactation is prolonged over a multi-year period with fluctuating food availability. Here, mothers are expected to sustain a stable but generally lower level of nutrient transfer. In a sample of over 1,050 complete follow days of eight mother-infant pairs collected over 7 years, we document maternal effort for wild Bornean orangutans (Pongo pygmaeus wurmbii) over their average 6. 5-year lactation period. As predicted, maternal feeding time was independent of the age of her growing offspring, indicating a stable sustained "plateau" effort of ≤ 25 % above baseline level, instead of a short peak lactation as seen in seasonal breeders. Infant orangutans started to regularly supplement milk with self-harvested food when they were 1-1. 5 years old, indicating milk intake was insufficient from this age onwards, even though maternal effort did not decrease. We expect the same regulation of sustained maternal effort in other large and large-brained mammals with slow infant development. We also predict that mother-infant conflict over suckling may show another peak at the onset of the milk + solid food phase, in addition to the well-known conflict around the endpoint of lactation (weaning), which is reached after a long and gradual increase in solid food intake by the infant.
KW - Great apes
KW - Maternal investment
KW - Parent-offspring conflict
KW - Sustained lactation
KW - Weaning
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U2 - 10.1007/s00265-013-1504-y
DO - 10.1007/s00265-013-1504-y
M3 - Article
AN - SCOPUS:84876115701
SN - 0340-5443
VL - 67
SP - 805
EP - 814
JO - Behavioral Ecology and Sociobiology
JF - Behavioral Ecology and Sociobiology
IS - 5
ER -