Behavioural flexibility in wild mountain gorillas and implications for its conservation: Anthropogenic impacts on species-specific behaviours

概要

Behavioural plasticity is the ability to adapt conventional behavioural strategies to respond to novel conditions or challenges. Data on individual behaviour and social plasticity provides the framework to understand behavioural variations in population dynamics (i.e. survival and reproduction) as a reaction to environmental changes. Fully adaptive behaviours may also show faulty adaptation or disfunction if environment changes, so it is expected that individuals to swift their behavioural strategies to adapt to the new conditions, through learning and explorative processes.

In this thesis, the author investigated key elements of habituated mountain gorillas’ flexible behavioural responses including individual innovative traits, individual stress responses and social plasticity. She collected data over a 9-month period (between December 2017-February 2019), following a 2-month pilot study (September-October 2017), on one group of mountain gorillas (N=15) living in Bwindi Impenetrable National Park, Uganda. In chapter 2 and 3, she found that gorillas are relying on tension reduction strategies in response to the new environmental factor of Ecotourism. With tourists closing within 3 meters to the gorillas, she observed increased physical gorilla-human interactions, and an increase of time spent in close association with the same associate individuals, in addition to the increased stress signs in the animals that may imply higher susceptibility to disease. She also investigated flexible behavioural responses of mountain gorillas unrelated to human presence. She reported the first observation of water play behaviour in the population, providing cumulative support for the discussion of geographic variation of behaviour and cultural traits in this species, as well as potential negative effects consequent to the propensity for higher risk situations. In chapter 5, she provides evidence of infanticide in the Bwindi population, where this reproductive strategy is rare in comparison with other mountain gorilla populations. She was able to add to the literature, one of the few reports on infant corpse epimeletic behaviour in the species. In chapter 6, she found that mountain gorillas maintain social cohesion and consistent relationships when their social environment changes following a change in the group`s demography while being able to integrate the new migrant individuals into the social network.

Finally, she discusses the growing human pressure on the environment and its resources, and how it has challenged and confronted management measures for wildlife conservation, demanding better scientific consultation to increase efficiency of such plans. How animals behave dictates the success (or failure) of wildlife conservation actions. We need the conservation of species typical behaviours as well as the genetic pool. Put together, the results in this thesis support the utmost importance of considering behavioural flexibility into conservation plans and contributes to the overall understanding of mountain gorillas` complex behaviour and social structure.