The Dian Fossey Gorilla Fund, Karisoke Research Center, Musanze, Rwanda.
Department of Biology, College of Science and Technology, University of Rwanda, Kigali, Rwanda.
Am J Biol Anthropol. 2023 Mar;180(3):506-518. doi: 10.1002/ajpa.24681. Epub 2022 Dec 26.
Studying reproductive seasonality helps us understand changes in the energetically demanding periods of pregnancy and lactation. We investigated how diet variability and key food plant phenology relate to mating and birth seasonality in both remaining populations of endangered golden monkeys in the Virunga massif and the Gishwati forest in Rwanda.
Using scan and ad libitum sampling, we recorded feeding, mating, and births in two social groups (K and M) living in Volcanoes National Park (VNP), in the Virunga massif, from 2004 to 2018, and in one group (G) in the Gishwati forest in 2017-2018. We also monitored bamboo shoot and fruit availability in the groups' home ranges in 2017-2018.
Mating was observed year-round but peaked four to 6 months prior to each group's respective birth season. Despite the two VNP groups ranging only 16 km apart, they had different birth seasons. Females from group K gave birth during the late bamboo growing season, from September to December, while females from group M gave birth during the early bamboo shooting season, from February to April. This pattern was linked to differences in the availability and consumption of bamboo shoots between low-elevation (group K) and high-elevation (group M) habitat. In group G, births occurred from March to April, coinciding with the period of high fruit availability and consumption in the Gishwati forest.
Our findings suggest that food availability shapes golden monkey birth seasons, even at a small spatial scale. Current changes in key food plant regeneration, potentially driven by climate change, need to be closely monitored to inform golden monkey conservation management.
研究繁殖季节性有助于我们了解怀孕和哺乳期对能量需求较高的时期的变化。我们研究了饮食变异性和关键食物植物物候与维龙加山脉和卢旺达吉斯瓦蒂森林中濒危的金猴剩余种群的交配和生育季节性之间的关系。
使用扫描和随意采样，我们记录了 2004 年至 2018 年生活在火山国家公园（VNP）中的两个社会群体（K 和 M）的进食、交配和出生情况，以及 2017 年至 2018 年在吉斯瓦蒂森林中的一个群体（G）的情况。我们还监测了 2017 年至 2018 年群体栖息地中竹笋和果实的可用性。
交配全年都有观察到，但在每个群体各自的生育季节前 4 到 6 个月达到高峰。尽管维龙加山脉的两个群体仅相隔 16 公里，但它们的生育季节却不同。来自 K 组的雌性在晚竹生长季节（9 月至 12 月）分娩，而来自 M 组的雌性在早竹笋季节（2 月至 4 月）分娩。这种模式与低海拔（K 组）和高海拔（M 组）生境之间竹笋的可用性和消耗差异有关。在 G 组中，分娩发生在 3 月至 4 月，与吉斯瓦蒂森林中高果实可用性和消耗期相吻合。
我们的研究结果表明，即使在较小的空间尺度上，食物的可用性也会影响金丝猴的生育季节。当前，关键食物植物再生的变化，可能是由气候变化驱动的，需要密切监测，以便为金丝猴的保护管理提供信息。
