The Habituation Process

Habituation is a process by which an animal becomes accustomed to human observers, to the point where the observers have little influence on their behaviour. However, this process is not always so easy: western lowland gorilla habituation requires an investment of over 5 years of time and effort. In addition, habituation is not without its associated risks: habituated animals are easier to kill and thus should not be outside of protected areas. Also, during ad after the process, there is a strong potential for negative behavioural impacts and disease transmission. Due to their close relation to humans, the latter is considered a priority for gorillas habituated for tourism or research and from the beginning their health must be monitored daily and a series of guidelines developed to minimise cross-transmission. Data collection on their daily diet and movements is also vital to identify their ecological needs and home range.

The height of gorilla habituation, Silo, a sub-adult male in the Makumba group, sleeping (Copyright by David Rouge)Once a group is located, the key to habituation is daily follows of the same group and repeated contacts at slowly-decreasing intervals. However, in dense lowland forest visibility can be poor (frequently less than 15m) and animals’ inherent fear of humans makes gaining their confidence a difficult task. For theses reasons the PHP habituation teams use a ‘clacking’ noise when in proximity to the animals. This method allows the animals to perceive the teams even in the densest of forest patches, and to eventually associate ‘clacking’ with gorilla-friendly humans.

 

For gorillas, fear and avoidance of human observers are the dominant behaviours during the first years of group contacts. These traits are gradually replaced by aggression, in particular from the male, including loud vocalisations and dramatic charges and displays. This aggressive period is perhaps the most testing stage of habituation and depending on the individual characters can last for over a year. Fortunately, the silverback gradually recognises the human observers as a more-or-less neutral element in the environment, allowing increasingly closer contacts; in general, his offspring follow suit.

Bombe, the most dominant female in group Makumba and the longest to habituate! (Copyright by David Rouge)However, this is not the end of the process, although the silverback may mostly ignore human observers within 2-3 years, the females resist! The reasons behind this negative response to the habituation team are unclear, but it could well be that females view human observers either as a risk to their young, or perhaps as competition for food, or their mate. Thus the last stage of habituation consists of renewed male aggression, provoked by the screams of insistent females. Eventually the silverback supports them less and less and perhaps at 3-4 years after the start of habituation, they too gradually begin to ignore the teams.