title: Birth seasonality and pattern in black-and-white snub-nosed monkeys (Rhinopithecus bieti) at Mt. Lasha, Yunnan.
abstract: Seasonal variation in environmental factors is vital to the regulation of seasonal reproduction in primates. Consequently, long-term systematic data is necessary to clarify the birth seasonality and pattern of primates in highly seasonal environments. This study indicated that black-and-white snub-nosed monkeys (Rhinopithecus bieti) at Mt. Lasha exhibited strict birth seasonality with a pulse model. Infants were born with a certain degree of synchronization. Birth distribution showed three birth peaks, and the birth pattern showed a "V" style in even-numbered years and a gradual increase in odd-numbered years. The beginning date, end date and median birth date were earlier in even-numbered years than those in odd-numbered years. The higher latitude of their habitats, earlier birth date, shorter birth period, fewer birth peaks and stronger birth synchrony might be adaptations for strongly seasonal variation in climate and food resources. After the summer solstice when daylight length began to gradually shorten, R. bieti at Mt. Lasha started to breed during the period with the highest environmental temperature and food availability, which implied that photoperiod may be the proximate factor triggering the onset of estrus and mating. It appears that R. bieti coincided conception and mid-lactation with the peak in staple foods, and weaning with the peak in high quality of foods. Thus, food availability was the ultimate factor regulating reproductive seasonality, and photoperiod was the proximate factor fine-turning the coordination between seasonal breeding and food availability.
authors.affiliation: Key Laboratory of Forest Disaster Warning and Control in Yunnan Province, Southwest Forestry University, Kunming, Yunnan 650224, China.
authors.forename: Jin-Fa
authors.initials: JF
authors.lastname: Li
authors.affiliation: Bureau of Yunling Provincial Nature Reserve, Lanping, Yunnan 671400, China.
authors.forename: Yu-Chao
authors.initials: YC
authors.lastname: He
authors.affiliation: Key Laboratory of Forest Disaster Warning and Control in Yunnan Province, Southwest Forestry University, Kunming, Yunnan 650224, China.
authors.forename: Zhi-Pang
authors.initials: ZP
authors.lastname: Huang
authors.affiliation: Key Laboratory of Forest Disaster Warning and Control in Yunnan Province, Southwest Forestry University, Kunming, Yunnan 650224, China.
authors.forename: Shuang-Jin
authors.initials: SJ
authors.lastname: Wang
authors.affiliation: College of Life Science and Technology, Central South University of Forestry and Technology, Changsha, Hunan 410004, China.
authors.forename: Zuo-Fu
authors.initials: ZF
authors.lastname: Xiang
authors.affiliation: Institute of Eastern-Himalaya Biodiversity Research, Dali University, Dali, Yunnan 671003, China . gcuilw@gmail.com;xiaowen.dali@gmail.com.
authors.forename: Juan-Jun
authors.initials: JJ
authors.lastname: Zhao
authors.affiliation: Institute of Eastern-Himalaya Biodiversity Research, Dali University, Dali, Yunnan 671003, China . xiaowen.dali@gmail.com.
authors.forename: Wen
authors.initials: W
authors.lastname: Xiao
authors.affiliation: Key Laboratory of Forest Disaster Warning and Control in Yunnan Province, Southwest Forestry University, Kunming, Yunnan 650224, China.gcuilw@gmail.com.
authors.forename: Liang-Wei
authors.initials: LW
authors.lastname: Cui
mesh_terms: D000818:Animals; D002681:China; D016673:Colobinae / Q000502:physiology*; D004777:Environment; D005260:Female; D036801:Parturition / Q000502:physiology*; D011247:Pregnancy; D012621:Seasons; D013997:Time Factors
keywords: Birth pattern; Birth seasonality; Birth synchrony; Rhinopithecus bieti