Data collection

Basically there exist several approaches to collect biological data and each approach is subject to advantages and disadvantages. Beside the use of scientists, trained local people with experience in animal tracking and hunting were selected within the villages of the study sites.

This approach which is termed as community-based prepares local people for wildlife conservation and management of their village forest territory but also promotes the sense of ownership over forest resources, resulting to enhance local people’s commitment towards natural resource management.

2.4.5.2 Vegetation

The vegetation was studied in plots of 0.25 ha each or 50 m x 50 m (O’Brien and Kinnaird, 1997; Rosenbaum et al., 1998) established systematically left and right along transect lines commencing from point 0. The distance between one plot to another was 250 m. The starting point (point 0) in each transect was selected at random and a total of 7 plots were sampled per transect.

In each plot, all trees higher or equal to 10 inches or 8,02 cm diameter at breast height (dbh) were identified and measured (Struhsaker, 1997). Trees were measured with the use of a diameter tape and all measured trees were thereafter marked to avoid double counting. For stems with irregular circumferences, the average of the largest and smallest diameter was used and trees with buttresses were measured above the buttresses in case they reached over breast height. An average of two hours was spent in each of the plots for counting, marking and identifying all trees within the required dbh in a plot. About 98% of trees were rightly identified to species level. Barks, leaves seeds/fruits and other parts of unidentified trees were taken to the herbarium of the Korup project headquarter for further identification.

2.4.5.3 Primate species

Prior to the study, a rapid survey was carried in the area with the objective to establish a list of primates present in the Korup region. This list was cross-checked with available literatures (Infield, 1988; Edwards, 1992; Usongo, 1995; Oates, 1996; Struhsaker, 1997; and Kingdon, 1997), but also through participatory rural appraisal methods: semi-structure interviews with hunters, village meetings and household interviews. After the production of the species list

(primates and hornbills) in the local dialect, the selected team members were trained in ecological fieldwork and identification skills. Identification of primates was also facilitated by the use of colour plates redrawn from Kingdon (1997). Calls and other primates behaviours were also recorded and used during the training sessions. Perpendicular distance estimation (Figure 2.7 and Figure 2.8) was conducted at regular intervals and with the use of the laser rangefinder. Though trained at the same level, each of the three team members was assigned with a specific function. The team leader filled the form using information from his colleagues who were to identify the species and estimate perpendicular distance from the observer to the object. The monitoring team was under the supervision of a trained field supervisor who was supported by the project leader. Primates data were collected along the two kilometres transect line using Distance Sampling in which measurements of the distances of the objects observed from the transect line are used to estimate the probability of observing an object and hence to estimate its density (Buckland et al., 2001 and Thomas et al., 2002).

Estimates were made of the perpendicular distance from the transect to the estimated centre of primate groups, both for visual and acoustic encounters. Group sizes were estimated from visual encounters. Each transect was surveyed once a week at different time intervals from 06:30 to 09.00 am and from 15.00 to 18.00 pm with an average speed of < 1 km/h, direct (animals seen) and indirect (calls, noise) animal cues were recorded.

The team was advised to avoid making noise, lightening fire or smoking while walking along the transect.

Figure 2.7: Line transect sampling approach with a single, randomly placed line of length L.

Six objects were detected at distance x1, x2,….x6,. Source: Buckland et al., 2001.

Figure 2.8: Measurement of perpendicular distance. A is the size of the area, L is the transect length, θ is the sighting angle to allow perpendicular distance x while r is the sighting distance. Thus the distance from the observer parallel to the transect at the moment of detection is: z = r cos (θ). Source: Buckland et al., 2001.

2.4.5.4 Hornbill species

Hornbills data were collected using the approach and methods described for primates data collection. Estimates were made of the perpendicular distance from the transect to the estimated centre of hornbill clusters, both for visual and acoustic encounters. Estimation of perpendicular distance of animals in movement (flying) was avoided as well as surveys which were disturbed by rain and other unforeseen events.

2.4.5.5 Food resources for primates and hornbills

Data on food bearing trees (fruits, seed, leaves barks) used by the monitored primates and hornbills were collected using the same method described for the vegetation survey. In addition, a list of food resources for primates of the Korup region was compiled by an experienced field botanist. This list was compared with existing literatures (Usongo, 1995;

Lien & Mambo, 1997 and Astaras et. al., 2007), but also with the traditional knowledge of local people.

In each plot, all food trees from our species list, higher or equal to 10 inches or 8,02 cm diameter at breast height (dbh), were identified and measured (Struhsaker, 1997). Trees were measured with the use of a diameter tape and all measured trees were thereafter marked to avoid double counting. Parts of the trees (bark, leaves, flowers, seed, fruits) that were

considered as potential food resources for primates, but unknown by the field botanist were taken to the herbarium for further identification.