Chimpanzees, Pan troglodytes,
like all the Great Apes, face increasing conflict with Humans throughout their
range, driven by logging, poaching, mining, the illicit trade in wild animals
and agricultural incursion into their territories, all of which are ultimately
driven by sharply rising human populations (the Human population in the tropics
is growing twice as fast as elsewhere, but rising populations in other parts of
the world also drive Human consumption of tropical products). Chimpanzees can
be particularly badly hit by logging, which removes essential fruit-bearing
trees from their territories, causing them to seek out alternative food
sources, which in turn brings them into conflict with human agriculturalists.
In a paper published in the journal PLoS One on 22 October 2014, a
team of scientists led by Sabrina Krief of Eco-anthropologie et
d’ethnobiologie, Hommes, Natures, Sociétés at the Museum national d’histoirenaturelle in Paris and the Projet pour la conservation des grands singes at
Kibale National Park in Uganda report the results of a camera trap study by the
Sebitoli Chimpanzee Project, into crop-raiding by Chimpanzees on the western
fringe of Kibale National Park.
The project focused on a maize field on the western edge of the
park. This is separated from the park itself by a trench 2 m wide and 2 m deep,
dug by the Uganda Wildlife Authority to prevent Elephants crossing from the
park into agricultural land, but crossed at one point by a fallen tree, known
to be used as a highway by Chimpanzees entering the field. The Sebitoli
Chimpanzee Group comprises about 80 individuals, 26 of which show deformities
caused by snares associated with poaching activity, with eight individuals
missing parts of limbs.
The local population of Batooro and Bakiga farmers do not eat Chimpanzees,
but actively defend their crops (the lead male of a neighbouring Chimpanzee
group was severely injured by a spear), and are themselves facing pressures due
to rising a population and limited land availability (due to logging, tea
plantations and designated parkland), causing them to farm right up to the
borders of the park, and the field is actively defended by Human farmers, who
have guard huts within the field manned day and night and also keep Dogs in the
field. However Chimpanzees are highly adaptable, and the Sebitoli Group have
long experience of dealing with Humans, with a territory that shares 32 km of
border with human communities (out of a total of 39 km of border) and which is
crossed by a tarmac road.
Krief et al. predicted a
number behavioural traits and adaptations that would be observed in the
Sebitoli Chimpanzees, based upon prior observations of Chimpanzees foraging on
agricultural land. Typically when staging raids into
agricultural land or the territory of rival Chimpanzee groups the raiding
parties are smaller than typical foraging parties, and led by dominant males
from within the group (who are more prone to high risk activities). Chimpanzees
taking part in raiding activities are usually more cautious and vigilant than
at other times, spending more time scanning for threats and producing less
noise; they have also been known to make use of moonlight when moving about
near potentially hostile humans, taking advantage of the full moon. Finally
Chimpanzees taking part in high-risk activities typically show signs of stress,
such as increased scratching or even attacks of diarrhoea.
Uganda-Kibale National Park-Sebitoli area, home-range
and maize field monitored (location of the guarding huts, thefallen tree and
the video-trap). Krief et al. (2014).
Surprisingly the Chimpanzees of Sebitoli showed few of these
behaviours. The raiding parties were slightly larger than typical foraging
parties for the group, and were often led by females. Members of the group that
would typically be considered vulnerable, such as young infants, disabled
adults, and even a juvenile with an unhealed broken limb took part in the
raiding parties, and only the loudest vocalizations were avoided; on one occasion
two Chimpanzees were observed copulating at the edge of the field. The
Chimpanzees did not appear overly concerned about Human or Canine guards in the
field, and while they would retreat if threatened or chased, often simply
waited out of view before retuning to foraging in the field.
On defensive behaviour they did exhibit, and which was completely
unexpected, was switching the time of day at which they were active, often
foraging after dark and favouring nights around the new moon, when light levels
are lowest, rather than around the full moon, when light levels are high. This
is surprising, as while Chimpanzees are highly adaptable, they are not usually
considered to be nocturnal animals, and have not previously been shown to alter
their foraging times to avoid humans.
Only one previous study has shown Chimpanzees targeting a human crop
at a particular time of day, when a group of Chimpanzees were found to be more
likely to consume Cassava later in the day. However Cassava is considered to be
a low preference food for Chimpanzees, and it is thought that these animals
were only seeking it out after attempts to locate other food sources had
failed. The Sertoli Chimpanzees were, in contrast, clearly switching to a
highly atypical foraging schedule in order to access a high preference food
(Maize), which shows a considerable degree of pre-planning.
See also…
Apes (Hominoidea) are large, tailless Primates found in Africa, eastern Asia, and in one case (Homo sapiens)
globally. Apes are commonly divided into Lesser and Great Apes, with
the 17 species of Gibbon...
Palaeontologists Martin Pickford of the College de France and Brigitte Senut of the Musee National d'Histoire Naturelle in Paris announced the discovery of an almost complete skull of the extinct ape...
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