Early introduction of hand‐reared Gorillas Gorilla gorilla to conspecifics at Barcelona Zoo: general procedures and three case studies

Abstract

The purpose of this paper is to describe the early introduction protocols developed for four (1.3) hand‐reared Gorillas Gorilla gorilla that were introduced to conspecifics at Barcelona Zoo. The introduction process for each was initiated when the infants were <1 year old. The introductions began in 1999 and ended in 2001, and the difficulties faced while carrying out such procedures were novel at that time. The protocols had to be improved following the assay error results. In the first instance, the infant Gorillas were introduced into their family group of two hand‐reared adult ♀♀ and a silverback. However, the development conditions and rearing inexperience of the adult ♀♀ resulted in failure to nurture the young. The ♀♀ did not protect or take care of the infants well enough to keep them safe. Appropriate maternal behaviours did not develop in the adults, although some social contacts between the adults and young were observed during the process. However, a silverback managed to kill a 6 month‐old ♂ infant after a slide‐gate malfunction. The three ♀ infants were successfully integrated into a group of conspecifics but not into their family group.

Progress in the Western lowland gorilla Gorilla gorilla gorilla European Endangered Species Programme: a review of the decade 2002–2011

“…The years between 2002 and 2011 have not only shown a decrease in hand rearing but also the social management of hand‐reared infants has improved. Four of the 19 hand‐reared offspring have successfully been reintroduced to their natal groups at an early age (<1 year) (Vermeer, ; Abelló & Colell, ), and two individuals were bottle fed by keepers while being cared for by their mothers.…”

Behavioral changes following alterations in the composition of a captive bachelor group of western lowland gorillas (Gorilla gorilla gorilla)

“…These challenges can be exacerbated by instability resulting from introductions of new members and deaths of existing members in bachelor groups. Numerous studies on the introduction of single individuals or the formation of a new group from two previously separate groups have been conducted on zoo‐housed western lowland gorillas (Abelló & Colell, ; Bowen, ; Sunde & Sievert, ). At the Barcelona Zoo, researchers found that infants under 1 year of age were more flexible and adaptable to new situations, while individuals over a year old were more reluctant to engage with keepers or unfamiliar adult gorillas (Abelló & Colell, ).…”

“…Numerous studies on the introduction of single individuals or the formation of a new group from two previously separate groups have been conducted on zoo‐housed western lowland gorillas (Abelló & Colell, ; Bowen, ; Sunde & Sievert, ). At the Barcelona Zoo, researchers found that infants under 1 year of age were more flexible and adaptable to new situations, while individuals over a year old were more reluctant to engage with keepers or unfamiliar adult gorillas (Abelló & Colell, ). Additionally, the adults were found to be more permissive of younger individuals (Abelló & Colell, ).…”

“…At the Barcelona Zoo, researchers found that infants under 1 year of age were more flexible and adaptable to new situations, while individuals over a year old were more reluctant to engage with keepers or unfamiliar adult gorillas (Abelló & Colell, ). Additionally, the adults were found to be more permissive of younger individuals (Abelló & Colell, ). Researchers observed a temporary increase in aggression when adult females were moved between four breeding groups at Zoo Atlanta (Hoff, Hoff, Horton, & Maple, ).…”

An analysis of breeding results for hand‐reared Gorillas Gorilla gorilla born over a 25 year period in the European Endangered Species Programme (EEP) population

“…The methods and conditions of hand rearing, and the age at reintroduction into a group of conspecifics could affect the social and specifically the breeding performance of the individuals when they reach adulthood (Abelló & Colell, 2006a, 2009). Our study analyses the breeding results of hand-reared gorillas in the EEP population born between 1980 and 2004.…”