A Case Study of Primiparous Maternal and Infant Gorilla(Gorilla gorilla gorilla)Behavior

Abstract

A primiparous mother and her infant were subjects of a longitudinal behavioral study at Lincoln Park Zoo in Chicago, Illinois. From November 1998 to November 1999, we collected a total of 100 hr of focal nonhuman animal instantaneous point sampling and all occurrence data on the mother and her infant. After 8 months, we introduced the 4-member focal group to an 8-member gorilla group, thus providing an opportunity to study the effect of the introduction on mother-infant behavior. Overall, time the pair spent physically apart was notably high with contact and proximate scores steadily decreasing over time. The infant was largely responsible for maintaining social proximity, rarely leaving the mother and frequently approaching her. In contrast, the mother left the infant frequently and approached the infant minimally. Maternal affiliative and nonaffiliative behaviors fluctuated throughout the study. Over time, both decreased. Despite a precarious maternal relationship, infant developmental trends were typical for captive gorillas. The results of this study suggest that allowing flexibility in judging maternal conduct can be of benefit to successful gorilla husbandry.

Social development of a captive gorilla infant in the zoo: relationship with the mother and a nonkin female

“…Only Ai changed her behavior toward Oki during the course of this study. The social environment has been reported to affect the early development of gorilla infants in groups that consisted of more individuals than the group in this study (Crosby & Lukas, 2004;Maple & Warren-Leubecker, 1983;Meder, 1989;Meder, 1990;Nakamichi, Silldorff, Bringham, & Sexton, 2004). As in those studies, Ai's demand for contact with her mother might have decreased, while her demand for other environmental factors, including the nonkin female, might have increased from the age of 7 months to 19 months in the group studied here.…”

Modeling variation in early life mortality in the western lowland gorilla: Genetic, maternal and other effects

“…Since gorillas have long life spans and few offspring, datasets with large samples sizes and high enough mortality to analyze are rare. Much of what is known about motheroffspring interactions comes from case studies of individual pairs or a few gorillas in one location [Crosby & Lukas, 2004;Maestripieri et al, 2002;Stokes et al, 2003]. The international studbook for the western lowland gorilla [Wilms, 2011] provides a large dataset for analyzing variables that influence early life mortality, potentially producing valuable insights regarding survival and reproduction.…”

Effects of early care on joint attention and social behavior in Pan, Gorilla & Pongo

“…Specifically, the responsive care chim panzees w ere m ore persistent in attaining goals, had longer attention spans, and exhibited higher levels o f cooperation than the chim panzees in the two standard care groups (Bard & Gardner, 1996). In a case study exam ining a m other-infant gorilla dyad, Crosby and Lukas (2004) found that the m other's care w as adequate, but not as robust as care dem onstrated by other gorilla mothers. F or exam ple, direct physical contact occurred infrequently and the mother rarely approached the infant, despite repeated attem pts by the infant to initiate contact.…”

“…The authors concluded that despite this m inim al level o f care, the infant w as not detrim entally affected. Specifically, Crosby and Lukas (2004) found that the infant did not…”