Walia Special Edition on the Bale Mountains (2011) - Zoologische ...

Discussion
This preliminary assessment suggests that the Harenna Forest, in particular, the belt containing the
bamboo and mixed-bamboo forest, supports a population of Bale monkeys that is large enough to
consistently be encountered. In the discussion that follows, we will consider sampling issues and
observations that maybe relevant for future efforts in monitoring and management of the species
and its habitat.
Sampling strategies
As discussed earlier, there are major challenges associated with conducting field observations of
the Bale monkey. High rainfall, thick fog, steep and undulating terrain, and thickness understory
vegetation characterize the area. On top of these site conditions, the shy nature of the species and
its tendency to hide when disturbed make it a challenge to sample the species. One implication of
these challenges is that our estimates are probably conservative and that total transect length needs
to be relatively long to get density estimates with narrow confidence intervals.
Our observations and those of the local people we spoke with suggest that the Bale monkey
prefers the dense, inaccessible part of the forest. The monkeys have been seen to visit forest glades
or clearings to forage on the ground materials (Authors, personal observations) but these events are
uncommon. The results of this study document the association of the Bale monkey with the bamboo
and mixed-bamboo forest. Sampling in the non-bamboo forest was limited to one roadside transect
More sampling in this and other similar habitats in adjoining areas are needed to determine if the
distribution of the Bale monkey is, indeed, restricted to the bamboo and mixed-bamboo forest.
Although the climatic conditions were different during our two survey periods, the mean
encounter rate and group size were similar but our survey methods differed and sample sizes were
small, precluding a statistical comparison. The survey methods used during the first field season
were relatively rigid and laborious given the terrain occupied by the Bale monkey; the methods
used in the second season were more flexible, in that the distance between transects and length of
transects was defined by the terrain and accessibility.
Threats
The expansion of settlements toward the core habitats of the species raises concerns about the
protection of the species and its habitat. A remarkable concentration of settlements was recorded
around Herelle and Wgie-Gora. Settlements recorded near Bijamo, Haduqa and Asreda are seasonal,
used by pastoralists during the dry season. It is unknown whether or not the monkeys are influenced
by the presence of humans or livestock.
In other regions, conflicts have arisen between vervet monkeys and farmers because of their
proclivity for crop raiding. Currently, no cultivation is associated with the seasonal settlements on
the Herelle side that lie close to the bamboo forest. On the Wegie side, however, there are large
expanses of wheat and barley cultivation. Local informants indicated that it is rare for the Bale
monkeys to enter the fields, therefore crop damage due to the monkeys is insignificant.
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