Could sexually experienced Gorillas Gorilla gorilla gorilla help hand-reared Gorillas to breed successfully?

Abstract

To maintain a self‐sustaining European Endangered Species Programme (EEP) population of Gorillas Gorilla gorilla gorilla, it is necessary that as many individuals as possible contribute their genes to the population. It is believed that hand‐rearing may prevent the development of a good repertoire of natural social behaviours that would facilitate successful breeding when individuals reach sexual maturity. Between 1980 and 2004, 464 Gorilla births resulted in 117 individuals [63.54 (♂.♀)] being hand‐reared. In this review, we analyse information gathered from a questionnaire survey, augmented with data from the international studbook and other publications, to identify the conditions that contribute to breeding success. Hand‐reared ♀♀ should initially be introduced into socially competent groups that breed (so they can observe breeding by conspecifics) and, in addition, be introduced to an experienced breeding ♂. Similarly, hand‐reared ♂♂ should initially be placed in socially competent groups and, in addition, should be introduced to mother‐reared adult ♀♀ that, where possible, have also had previous breeding experience. Although the receptor group and the personality of hand‐reared individuals need to be considered before making decisions about introduction to conspecifics, in order to increase the genetic contribution that hand‐reared Gorillas make to the EEP population, factors recorded in this article may provide guidance on how to improve captive breeding for the conservation of this species.

Effects of Hand-Rearing on Reproductive Success in Captive Large Cats Panthera tigris altaica, Uncia uncia, Acinonyx jubatus and Neofelis nebulosa

“…The majority of studies on the effects of hand-rearing in relation to reproductive success have focused on non-human primates. For example, hand-reared western lowland gorillas ( Gorilla gorilla gorilla ) had lower breeding success than mother-reared gorillas and were less likely to breed with other hand-reared individuals [ 4 , 18 , 19 , 20 , 21 ]. Some studies on carnivores have begun to show that hand-rearing affects their behaviour and reproductive success as well.…”

“…As parental rearing positively impacts future reproductive success of gorilla offspring, the gorilla SSP is placing a strong emphasis on the management protocols that encourage maternal competence before and after the actual birth of an infant [ 4 ]. There is a reproductive skew present in gorillas due to rearing type [ 4 , 18 , 19 , 20 , 21 ] and evidence of a similar trend in domestic cats as well [ 23 ]. Research has shown that hand-reared gorillas have fewer opportunities to reproduce.…”

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

“…Males, and especially those who are genetically important for the population, have to remain in their natal groups as long as possible, at least until the age of 10–12 years (Abelló et al ., ). This will not only improve their social skills but also it is a way to decrease the number of surplus ♂♂.…”

“…Recent research has shown that there is a higher chance for breeding when genetically important ♂♂ that may have a reproductive behavioural deficit or are suspected to be infertile are placed with experienced breeding ♀♀ (Abelló et al ., ). Psychological factors and a mate showing natural behaviour seem to play an important role in the chance of achieving positive outcomes.…”

“…There are a few cases where ♀♀ reached sexual maturity at the age of 6 years but this is unusual. Leaving ♀♀ with their family for longer will improve their social (maternal and breeding) skills and also facilitate their introduction into a new breeding group (Abelló et al ., , ). To prevent inbreeding of young ♀♀ with their fathers, zoos are advised to use oral contraceptives until a transfer recommendation is received from the GEEPC.…”