Abstract
Seasonal breeding in primates is related to the degree of environmental seasonality, particularly the availability and predictability of food. Southeast Asian species in general show moderate birth seasonality due to either low environmental seasonality or unpredictable fluctuations of mast-fruiting food resources. One Southeast Asian primate, the simakobu (Simias concolor), however, has been reported to be a strict seasonal breeder with births occurring in June and July only. It is unclear whether these observations are characteristic of the species or result from a sampling bias. To address this question, we documented the annual distribution of 11 births in eight groups of simakobu over two consecutive years at Pungut, an undisturbed site on Siberut Island, Indonesia. We assessed annual variation in ecology and reproduction via rainfall, temperature, food availability, feeding time, physical condition, conceptions, and births. Mean monthly temperature was nearly constant (26.3–27.1 °C), and monthly precipitation always high (219–432 mm). Although simakobu foods were abundant year-round, there were two fruit-feeding peaks in June and September. In contrast to previous reports, we documented births in 7 mo. Most births occurred in October (45 %), the wettest month of the year, and most conceptions in March and April, following a peak in unripe fruit availability. Although sample sizes are very small, females seemed to conceive when their physical condition was best, suggesting that simakobu time conceptions flexibly to the recovery of energy reserves. Across study sites, births occurred in 10 calendar months, indicating that simakobu reproduction is not strictly seasonal.
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Acknowledgments
W. M. Erb gratefully acknowledges contributions from members of her dissertation committee —Julia Fischer, Charles Janson, Ryne Palombit, and Patricia Wright— as well as field assistants Edith Sabara, Ira Sari, Rima Agustina, Hermanto Salamanang, Lucien Salamanang, and Karta Salamanang. We thank Jan Gogarten for help with statistics and the editor-in-chief Joanna Setchell and two anonymous reviewers for their very helpful comments on the manuscript. This work was supported by the American Society of Primatologists; the Margot Marsh Biodiversity Fund; the National Science Foundation (BCS-0752504); the Primate Action Fund; Primate Conservation, Inc.; and Stony Brook University. We are grateful to the Indonesian Institute of Sciences and the Indonesian State Ministry for Research and Technology for granting permission to undertake this research.
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Erb, W.M., Borries, C., Lestari, N.S. et al. Annual Variation in Ecology and Reproduction of Wild Simakobu (Simias concolor). Int J Primatol 33, 1406–1419 (2012). https://doi.org/10.1007/s10764-012-9630-3
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DOI: https://doi.org/10.1007/s10764-012-9630-3