Dispersal and female philopatry in a long‐term, stable, polygynous gibbon population: Evidence from 16 years field observation and genetics

Abstract

Gibbons are generally reported to live in small socially monogamous family groups in which both sexes disperse when they reach maturity. For the first time, we documented the dispersal pattern in a population of gibbons living in stable polygynous groups (Nomascus concolor) integrating 16 years’ field observation and genetic information from fecal DNA. All subadult males except for one dispersed at 9.8 ± 1.4 years of age (range: 8–12, N = 10). The last male remained in his natal group and obtained the breeding position at age 11 by evicting the original dominant male. Females reached sexual maturity (as evidenced by the change in body color from black to yellow) at 8 years (N = 4). Three of them dispersed and one obtained a position as a breeding female and bred in her natal group. We also observed one female returning to her natal group with her infant after her presumed father was taken over by a neighboring male. We identified only three mtDNA haplotypes from 22 individuals at Dazhaizi. Individuals in one group shared the same haplotype, with only one exception. Genetic results showed that the two breeding females were mother‐daughter pairs in all three study groups at the end of this study, implying some degree of female philopatry. We argue that in the case of black crested gibbons, dispersal decisions appear to represent highly opportunistic events in response to reproductive opportunities in their natal and neighboring groups.

Mechanisms underlying altitudinal and horizontal range contraction: The western black crested gibbon

“…Hunting could cause range contraction of western black crested gibbons. Female western black crested gibbons start to reproduce at 8 years old, and give birth to one offspring every 3–5 years (Hu et al., 2018). The species' reproductive rate is very low and, therefore, it is vulnerable to illegal hunting (Fan & Jiang, 2007).…”

Monitoring occurrence, extinction, and colonization probabilities for gibbon populations

“…In the 10 years from 2000 (Geissmann, Dang, Lormee, & Momberg, 2000) to 2011 (Rawson et al, 2011), the populations of Colonization probabilities were also much higher than zero during both intervals from 2012 to 2014 and from 2014 to 2016; the probability that an unoccupied site became occupied by gibbons after 2 years was about 0.51-0.53. Gibbons, once reaching maturity, usually leave their parents and disperse to new sites and finally form new groups, often in areas of close proximity (Brockelman, Reichard, Treesucon, & Raemaekers, 1998;Hu et al, 2018;Matsudaira, Ishida, Malaivijitnond, & Reichard, 2018). As occupancy probability is scaledependent (Wilson & Schmidt, 2015), colonization probability depends on the size of a "site."…”

Influence of food availability and climate on behavior patterns of western black crested gibbons (Nomascus concolor) at Mt. Wuliang, Yunnan, China

“…Three bi‐female groups of western black crested gibbons have been systematically monitored at the site since 2003 (Hu et al, ; Huang et al, ). We studied two neighboring groups (G2 and G3) for one full year each in this study.…”

“…During the study period (from May 2008 to July 2009), G3 consisted of seven individuals: one adult male, two adult females, one subadult male, two juveniles, and one infant. All individuals were recognized and named (Hu et al, ; Appendix I).…”

“…It is classified as the First Level Protected Animals in China (Fan & Ma, ). Some western black crested gibbons live in bi‐female family groups (Guan et al, ; Hu et al, ) and occupy larger home ranges than tropical gibbons (Fan and Jiang, ). Our study subjects live in Mt.…”