Laboratory of Wildlife Medicine, Nippon Veterinary and Life Science University, 1-7-1 Kyonan-cho, Musashino, Tokyo 180-8602, Japan.
Shimokita Peninsula Municipal Liaison Conference for Damage Control by Wild Monkeys, Wakinosawa, Mutsu, Aomori 039-5323, Japan.
J Vet Med Sci. 2021 Sep 3;83(9):1389-1394. doi: 10.1292/jvms.21-0141. Epub 2021 Jul 6.
The Shimokita Peninsula in Aomori Prefecture, Japan, which is inhabited by Japanese monkeys (Macaca fuscata), is the northernmost habitat for wild primates in the world. This study was the first to determine the conception dates of specific individuals and estimate the pregnancy rate of wild populations in this region. The pregnancy rate of animals aged 5 years or more at delivery was estimated to be 40.9% (27/66). Conception dates of each fetus were also estimated using a regression line of Pig-tail monkeys (Macaca nemestrina), which are taxonomically related to Japanese monkeys and have a similar physique. The conception dates were distributed across 90 days between September 24th and December 23rd, with a mean conception date of November 4th (SD=22.3 days, n=53). Using these findings, the mean birth date was estimated as April 25th, more than two weeks earlier than the mean birth date in previous research determined using direct observations carried out over the past 20 years ago. Global warming due to climate change is thought to be one of the main causes of this difference.
日本青森县的下北半岛栖息着日本猕猴（Macaca fuscata），是世界上野生灵长类动物的最北栖息地。本研究首次确定了特定个体的受孕日期，并估算了该地区野生种群的妊娠率。分娩时年龄在 5 岁及以上的动物的妊娠率估计为 40.9%（27/66）。还使用与日本猕猴在分类上相关且体型相似的猪尾猴（Macaca nemestrina）的回归线来估算每个胎儿的受孕日期。受孕日期分布在 9 月 24 日至 12 月 23 日之间的 90 天内，平均受孕日期为 11 月 4 日（SD=22.3 天，n=53）。根据这些发现，平均出生日期估计为 4 月 25 日，比过去 20 年来通过直接观察确定的平均出生日期早两周以上。气候变化导致的全球变暖被认为是造成这种差异的主要原因之一。
