provisioned (Wilson and Wrangham 2003). In consequence of our decision not to attract
our chimpanzees with food, we had to habituate them by the slow process of finding and
following them on a daily basis, remaining with them constantly until they became
accustomed to our presence and were convinced that we were harmless.
Before leaving the subject of habituation we should ask whether there is a downside
to the process, and indeed there is. Wallis and Lee (1999) and Woodford et al.(2002)
have studied the risks of habituation, focusing on disease transmission. The great apes
are susceptible to many human diseases which can cause severe morbidity or death.
The commonest routes for transmission are respiratory and faecal–oral. The danger
increases the more habituation has been achieved. The respiratory route can be very
dangerous. Five chimpanzees died of suspected pneumonia in the Kasakela community
at Gombe National Park, Tanzania in 1968 (Goodall 1986) and a further nine died from
a similar disease in 1987 (Wallis and Lee 1999). In the neighbouring Mitumba com-
munity a respiratory disease killed at least 11 chimpanzees in 1996. Similar events
have occurred at Mahale Mountains National Park in Tanzania (Hosaka 1995). It used
to be the case that visitors to gorilla tourism sites were encouraged to hold a baby gorilla
in their arms. Although it would be a peak experience for any tourist, it was a highly
dangerous moment in the life of the infant gorilla. In 1988 no less than 81% of the
gorillas in seven tourist and research groups in the Virunga Volcanoes region showed
signs of influenza-like symptoms, six females died and 27 cases were treated with
penicillin. As a result, a vaccination programme was implemented and 65 gorillas were
vaccinated using a dart-gun (Woodford et al.2002). A study by Kalema (1995) com-
pared two groups of gorillas at Bwindi Impenetrable Forest, one habituated tourist
group and one unhabituated group. She examined faecal samples and found higher lev-
els of parasites in the habituated group, probably due to contact with human excrement
in the forest.
As awareness of this problem has grown, measures have now been taken to reduce
the risks, and most sites where habituated apes can be seen have rules limiting the
proximity of visitors to the apes. At Budongo, sick visitors, especially those with
respiratory diseases such as the common cold or intestinal diseases such as diarrhoea,
are not allowed into the forest. Inside the forest, we adhere to a 7-metre rule: you
must not go closer than 7 metres to any chimpanzee. This may actually be too close.
A study of the Sonso community (Phillips 2003) found that some of our chimpanzees
responded by glancing or moving away when observers arrived on the scene. Lone indi-
viduals were particularly wary of oncoming humans. Females were more affected than
males. Phillips recommends that observers should normally remain at a distance of
16 m or more from the chimpanzees, unless closer proximity is demanded for particular
reasons.
In most cases we do not get very close to our chimpanzees, but in the case of the adult
males, most notably the senior males Duane and Maani, closer proximity could
be achieved and we have to make conscious efforts not to get too close. We also have
a rule that all human faeces must be safely disposed of. The health and diseases of the
Sonso chimpanzees are discussed in Chapter 3.
26 The Sonso community