In mammalian species with prolonged maternal investment in which high-ranking males gain disproportionate numbers of mating opportunities, males that quickly ascend the hierarchy may benefit from eliminating the dependent offspring of their competitors. In savanna baboons, high-ranking females are the most profitable targets of infanticide or feticide, because their offspring have higher survival rates and their daughters reach sexual maturity at a younger age. However, such patterns may be obscured by environmental stressors that are known to exacerbate fetal losses, especially in lower-ranking females. Using 30 years of data on wild olive baboons (Papio anubis) in Gombe National Park, Tanzania, we found evidence that rapidly-rising immigrant males induced miscarriages in high-ranking females outside of drought conditions. However, miscarriage rates were largely reversed during prolonged periods of low rainfall, suggesting that low-ranking females are particularly vulnerable to low food availability and social instability. Infanticide did not emerge as a recurrent male strategy in this population, likely because of the protective behavior of resident males towards vulnerable juveniles.
Bibliographical noteFunding Information:
We thank the Commission for Science and Technology (COSTECH), Tanzania Wildlife Research Institute (TAWIRI), and Tanzanian National Parks (TANAPA) for permission to conduct this long-term research project. A special thanks to the Jane Goodall Institute for continued financial support of the Gombe Baboon Project and to the National Science Foundation Graduate Research Fellowship Program for funding aiding in the analysis of these data. Additionally, we appreciate the daily contributions of Anthony Collins and the field assistants, especially Apollinaire Sidimwo, who collected, organized, and maintained the long-term data set.
© 2021, The Author(s).
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