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

site lies in the Harenna Rira, as it accounts for a larger coverage of bamboo zone (Ali, personal
communication, 2006).
The first survey, December 06 to January 07, was held during the dry season, and the second
in August 2007, during the rainy season. Sampling was conducted during both the dry and wet
seasons in order to capture any variability in the population that may be related to environmental
conditions.
A pilot study was made in October 2006 to record the presence or absence of the target
species in the Harenna Forest and assess the feasibility of this work. The reconnaissance survey
confirmed the species presence and provided information on the geographical range of Bale Monkey
with recordings of the locations of previous Bale monkey sightings.
Sampling design
Within both blocks of the study area, the habitat was stratified into three survey stations: the bamboo
forest, bamboo-mixed forest and the non-bamboo forest (Table 1). These habitat types were selected
following discussions with local informants during the reconnaissance visit.
Table 1. Habitats sampled during the field seasons, with sampling intensity. Each sample array had
eight transects (700m long) separated by 100 m.
Habitat December 06-March 07 August 07
Bamboo Forest
8 sample arrays
44.8 km surveyed
12 sample arrays
49 km surveyed
Bamboo-Mixed Forest
4 sample arrays
22.4 km surveyed
6 sample arrays
30 km surveyed
Non-bamboo forest
2 sample arrays
17 km
Not sampled
The bamboo forest: this sampling area incorporated the escarpment area of Harenna Forest
that fringes the ericaceous zone (2800-3200 m a.s.l.). This region is predominantly characterized
by Arundinaria alpine. Ten sample arrays were randomly established in the field station (5.6 km2 ).
Each array was composed of eight line transects, 700 m long, separated by 100 m.
The bamboo-mixed forest: this sampling area incorporated bamboo and other plant species
(i.e., Schefflera, Hagenia, Dombeya ), and falls adjacent and at a similar altitude to the bamboo
escarpment. Six sample arrays were randomly placed in the field station (3.36 km2 ).
The non-bamboo forest it refers to the area where bamboo vegetation is entirely absent.
It characteristically encompasses the lower elevation of the study area (1773-2376 m a.s.l.).
Erythrina, Croton, Syzgium and Prunus are the commonest trees in the zone. This sample station
was systematically established in Yadot and Awo areas as they were considered representative of
the habitat in the south and west, respectively. Less sampling effort was expended in this station
because preliminary research and local knowledge indicated that the Bale monkey was unlikely to
occur in this habitat.
<strong>Walia</strong>-<strong>Special</strong> <strong>Edition</strong> on the Bale Mountains 82