Longitudinal study of delayed reproductive success in a pair of white‐cheeked gibbons (Hylobates leucogenys)

Abstract

Concern over a lack of breeding success in a pair of white-cheeked gibbons (Hylobates leucogenys) prompted a four-part study of gibbon behavior and physiology at the Lincoln Park Zoo. Data were collected to determine the female intermenstrual interval (IMI) and identify periods of peak receptivity. Subsequent behavioral data were gathered during both female menses and estrous periods to formulate a behavioral profile for each gibbon. The female experienced a speciestypical IMI of 21.6 days and exhibited heightened levels of behavioral receptivity toward the male during estrus. The male exhibited high levels of human-directed behavior throughout the day. Closing the exhibit to visitors did not result in higher levels of social proximity or prosocial behavior between the pair, although it did eliminate the male's human-directed behavior during the experimental condition only. The female exhibited higher levels of social grooming, solicitation of the male, and proximity to the male when the pair was locked indoors. Based on those findings, the pair was moved to an exclusively indoor exhibit. The female's visibility to the public decreased substantially in the alternate exhibit, but there were no other significant behavioral changes. Nearly one year after the exhibit change, the female gibbon was confirmed to be pregnant. Although the results of this study cannot be used to infer causal conditions that resulted in the pregnancy, they do support the notion that systematic documentation of animal behavior and physiology may be used as a tool for monitoring reproductive behavior and informing management decisions.

Siamangs (Hylobates syndactylus) and White-Cheeked Gibbons (Hylobates leucogenys) Show Few Behavioral Differences Related to Zoo Attendance

“…In addition, whereas other research has suggested differences in solitary behaviors, such as increased activity (Lukas et al, 2002) or autogrooming (Wells, 2005), this research disclosed no differences in solitary behavior patterns.…”

“…Kuhar (2008) reported an increase in aggression in a group of young adult male gorillas, but not in a family group, when exposed to large crowds and proposed that certain age-sex classes may be more likely to react to zoo visitors. Lukas et al (2002) reported differences in activity levels and autogrooming in a pair of white-cheeked gibbons. Vrancken, Van Elsacker, and Verheyen (1990) found a single female gorilla sat close to a glass viewing window when visitors were present but found no changes in behavior from the other four group members.…”

Observation of intra‐group and extra‐group copulation and reproductive characters in free ranging groups of western black crested gibbon (Nomascus concolor jingdongensis)

“…Another conceivable explanation is females' importance in shaping the mating system in this species. Among gibbons, copulations initiated by females have been reported in captive western black crested gibbons (Zheng 1988), hoolock gibbons [Hoolock leuconedys (Groves, 1967)] (Yang 1998), white-cheeked gibbons [Nomascus leucogenys (Ogilby, 1840)] (Lukas et al 2002), free-ranging Hainan gibbons (Zhou et al 2008) and Hoolock gibbons (Huang et al 2010). Most observed EPCs have been initiated by males (Palombit 1994;Reichard 1995), although in some cases females have been involved in the initiation (Palombit 1994).…”

The visitor effect in petting zoo-housed animals: Aversive or enriching?

“…Zoo visitor effects on behaviour which have been interpreted as possibly enriching have usually involved feeding by the public, even in circumstances where this was not permitted by the zoo (Cook andHosey, 1995, Fa, 1989). However, although there are reports of individual animals, such as parrots (Nimon and Dalziell, 1992), gorillas (Vrancken et al, 1990) and gibbons (Lukas et al, 2002), who actively solicited contact with the public, there appear to be no empirical studies, other than that of Anderson et al (2002), of whether contact with zoo visitors in itself could be enriching for captive terrestrial mammals.…”