Social Interactions Between an Adult Female Buff-Cheeked Gibbon (Nomascus gabriellae) and a Juvenile Male White-Cheeked Gibbon (Nomascus leucogenys)

Abstract:

Restrictions on space and number of individuals in managed care can make it difficult to effectively raise and care for animals with complex social requirements, such as gibbons. Zoos and other captive settings must strive to create the necessary social structures for gibbon development with the individuals and space provided to them, so understanding the way relationships form between individuals is key. This study focuses on a juvenile white-cheeked gibbon (Nomascus leucogenys) introduced at 8 months of age to an adult buff-cheeked gibbon (Nomascus gabriellae) and the social dynamics that have emerged between them at the Cinncinati Zoo and Botanical Gardens. I hypothesized that the relationship between the two would most closely resemble one between two differently aged siblings in a typical gibbon social group. Social behavior between the two subjects was recorded over the course of four full sessions with the behavior type, proximity of the subjects, and the initiator being noted. The juvenile male gibbon was found to have initiated nearly every instance of social play, while the adult female initiated all embraces and most food sharing. Ultimately, the relationship between the two gibbons most closely resembled that of a mother-child pair, despite the fact that the adult never nursed the juvenile, was introduced to it later in its infancy, and was of a different species. These results indicate that the requirements for social development in Nomascus gibbons can be met with individuals of other species within the genus, allowing for greater opportunities for animal excellence in managed care.

Introduction

Gibbons mature at 7-8 years of age, and until then rely on their social group for behavioral development1
These social groups usually consist of two parents and their offspring of various ages2
Encounters between gibbons from different familial groups show more neutral or agonistic interactions compared to those from the same group3
Unusual situation at the Cincinnati Zoo and Botanical Gardens, with a weaned juvenile male Nomascus leucogenys (Kip) sharing a habitat with an adult female (Skittles) Nomascus gabriellae

Research Questions

What typical gibbon social relationship does the relationship of the two subjects most resemble from the categories of maternal, sibling, or external group member?
What animal welfare implications do the social dynamics between the two subjects have for raising gibbons in captivity?

Hypothesis:

Skittles and Kip's social relationship most resembles that of two differently aged siblings in a typical gibbon social group.

Researcher: Jakab Lippman

Zoology Major
Creative Writing Minor

Faculty Mentors

Dr. Kelsey Ellis, Department of Anthropology
Dr. Katie Feilen, Department of Biology

References:

1 Burns, B.L., Dooley, H.M. & Judge, D.S. Social dynamics modify behavioural development in captive white-cheeked (Nomascus leucogenys) and silvery (Hylobates moloch) gibbons. Primates 52, 271–277 (2011). https://doi.org/10.1007/s10329-011-0247-5 2Brockelman, W., Reichard, U., Treesucon, U. et al. Dispersal, pair formation and social structure in gibbons (Hylobates lar). Behav Ecol Sociobiol 42, 329–339 (1998). https://doi.org/10.1007/s002650050445 3Inoue, Y., Sinun, W. & Okanoya, K. Non-aggressive inter-group interactions in wild Northern Gray gibbons (Hylobates funereus). acta ethol 26, 59–74 (2023). https://doi.org/10.1007/s10211-023-00415-7

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