Fisheries in the Southern Border Zone of Takamanda - Impact ...

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132 Sunderland-Groves et al. proved unnecessary. All evidence of human activity (traps, snares, hunter paths, bush houses, spent cartridges, gunshots heard, etc.) was recorded to evaluate hunting pressures. We also recorded changes in topography and vegetation along each transect. The sampling effort between transects was standardized by keeping the number of observers, speed of travel, and time of day consistent. Transects were not walked during heavy or medium rainfall as this affects mammal movements and observer reliability (see Sunderland-Groves and Maisels this volume). For ape nests, care was taken to distinguish “definite gorilla nest” (nest on the ground or tree nest with gorilla dung underneath) from “definite chimp nest” (tree nests with chimp dung underneath). If a nest site had both tree and ground nests, it was a definite gorilla nest site because chimps never build ground nests. Ape dung is easily distinguished by smell and form, but old tree nests without dung cannot be assigned to gorillas or chimps with confidence. Therefore, nest sites where all nests were in trees were recorded as “tree-only nest sites.” Upon locating a nest site each area was thoroughly searched to ensure that all nests within the group were identified and recorded. These data were then used to calculate mean nest group size. Random nest searches were conducted in highland areas either after data collection on transects had been completed or to confirm presence or absence of apes at sites where time was not sufficient to conduct transect surveys. The additional data recorded during nest searches were used to calculate overall mean group size. Nest data collection during random nest searches followed the same protocols as those undertaken during transect surveys. 4.4 Data analysis 4.4.1 Distribution of apes and of human pressure Distribution of gorillas and chimps within the Takamanda Reserve and adjoining forests was inferred from the geographic location of sign that could be definitely assigned to one of the two species. Takamanda: the Biodiversity of an African Rainforest 4.4.2 Group size Each nest site is the sleeping site for one group of apes for one night. All weaned individuals make one nest per night, so the size of each nest group is an indicator of group size. There are variations as occasionally apes may make a second nest during the night or sleep on the ground without making a nest. However, mean group size can be roughly calculated for gorillas using all nest groups that can definitely be assigned to gorillas. Mean nest group size and standard deviation for nest groups that could only be assigned to “apes” were calculated from the tree-only nest sites. 4.4.3 Abundance of apes and of human sign The encounter rate (number of observations per km of transect) was used to estimate relative abundance of humans and apes throughout the survey and also to compare between sites and seasons. Because DISTANCE could not be used, gorilla and chimpanzee densities were roughly calculated under the formula proposed by Tutin and Fernandez (1984): [(N/A)/V][M]=D, where N=number of sleeping sites, A=area sampled in km 2, V=mean number of days the nest remains visible, M=median nest group size, and D=number of weaned individuals/km². Encounter rates were calculated (number of nests or nest sites per km walked, per stratum, and/or per season) and compared between strata and seasons between this study and previous work by March (1957) in the same region, and gorilla surveys carried out elsewhere in Africa (Williamson and Usongo 1995, Maisels and Cruickshank 1996, Hall et al. 1998). In the lowland forest at Lopé, Gabon, gorilla nests remained visible for an average of 78 days (Tutin et al. 1995). Mean chimp nest duration in Gabon was 113.6 days (Tutin and Fernandez 1984). Since no data are available on the deterioration rate of nest sites in
Gorilla and Chimp Surveys Cameroon, this survey used the same figures recorded in Lopé. It is possible that by using average nest duration for Gabon in this study, errors may have occurred. Due to the faster decay rate and disappearance of ground nests, it is possible that some of the tree-only nests sites were actually made by gorillas. Subsequent work in Gabon by Tutin et al. (1995) showed that about 26% of gorilla nest groups “convert” to chimpanzee nests as they age. If a gorilla group made nests in trees and on the ground, which is common (Tutin et al. 1995), only the tree nests will be visible after a given time, and the nest group may be erroneously assigned to chimps. Therefore, when the densities of chimps and gorillas at a site have been calculated from formula 1, the missing 26% of the gorilla nest groups must be calculated from the chimp density and reassigned to gorillas. It is not known whether the ratio of gorilla ground nests to tree nests is the same at all sites. Until evidence proves otherwise, we use the same conversion factor as the Lopé team. Site Approximate altitude (m) Gorilla 5 Results 5.1 Sampling Effort We walked 122 km of transects in the lowlands in 1998- 1999 (some transects were walked twice in different seasons) and 8 km of transects and 6 km of baseline in the highlands. An additional 28 km of transects and baseline were walked (some transects were walked during two different seasons) in the highlands in 2000- 2001, and additional nest searches were conducted at each site. 5.2 Ape Distribution 133 During the course of surveys between 1998 and 2001,we investigated 12 highland areas and two lowland sites (Makone east/west and Oyi east/west). Gorillas were found to exist at six of the highland sites, and chimpanzee or tree-only nests were located at nine of the highland sites. There was ape sign at two of the highland sites (Takamanda and Mende). Table 1. Summary of gorilla and chimpanzee distribution from transect surveys and nest searches, Takamanda Forest Reserve, Cameroon, 1998 - 2001 (+ indicates that the species was present; T=transect; NS=nest search) Treeonly sites Transect/nest search Makone east and west (lowland) 0-720 + + T, NS Oyi east and west (lowland) 0-700 T, NS Takpe Hill 560 + + T East Takpe Hills 400 + + NS Basho Hill 640 + + T, NS Obonyi 1 Hills 725 + + T, NS Obonyi 3 Hills 260 + NS Mblishe Hills 740+ + T, NS Atolo Hills 1250 + T, NS Takamanda Hill 570 NS Mende Hills 1530 NS Umbuli Hills (nr Matene) 240-1500 + NS Matene Hills 420-875 + T, NS SI/MAB Series #8, 2003
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Smithsonian Institution SI/MAB Biod
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ii 10. Fisheries in the Southern Bo
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Mercy Abwe Dione Dept. of Biology,
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The Smithsonian Institution has lon
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The editors of this publication ext
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2 Sunderland-Groves et al. Figure 1
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4 Sunderland-Groves et al. Rainfall
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6 Sunderland-Groves et al. 7 Conser
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8 Sunderland-Groves et al. Europe,
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10 Comiskey and Dallmeier 2 Challen
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12 Comiskey and Dallmeier 5 Adaptiv
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14 Comiskey and Dallmeier identifie
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16 Comiskey and Dallmeier 5.4 Evalu
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18 Takamanda: the Biodiversity of a
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20 Sunderland et al. preliminary la
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22 Sunderland et al. avoided protru
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24 Sunderland et al. Table 2. Summa
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26 Sunderland et al. lowland forest
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28 Sunderland et al. impressive cat
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30 Sunderland et al. Herbaceous flo
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32 Sunderland et al. Table 3. Compa
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34 Sunderland et al. 5.5 Economic P
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36 Sunderland et al. Table 5. Summa
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38 Sunderland et al. monitoring pro
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40 Sunderland et al. Letouzey, R. 1
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42 Sunderland et al. Appendix 1. Pl
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44 Sunderland et al. Agelaea pentag
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46 Sunderland et al. Afzelia pachyl
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48 Sunderland et al. Rhabdophyllum
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50 Sunderland et al. Aningeria robu
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52 Sunderland et al. Nervilia sp. P
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54 Sunderland et al. g—2˜— @y
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56 O’Kah f22 y2@w—˜A g—22@IE
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58 O’Kah Table 3. Species found i
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60 O’Kah Table 6. Indicators of s
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62 O’Kah Larsen, T. B. 1997. Butt
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64 O’Kah Appendix 1 (cont.). Chec
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66 O’Kah Appendix 1 (cont.). Chec
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68 O’Kah Species distribution Tak
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70 O’Kah Species distribution Tak
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72 Takamanda: the Biodiversity of a
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74 h—2@y——A 2 IE2— y2@w—
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76 The sites which have been survey
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78 species from a phylogenetic poin
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80 Appendix 1. Species list and sam
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Page 94 and 95: 84 LeBreton et al. 3 Methods A team
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Page 106 and 107: 96 Languy and Motombe f 5 q—2˜
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Page 170 and 171: 160 Sunderland et al. No. of indivi
Page 172 and 173: No. of individuals (n = 315) 200 15
Page 174 and 175: No. of individuals (n = 1065) 1000
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Page 184 and 185: 174 Slayback 7 H S IH type of autom
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182 Sunderland-Groves et al. Mone F
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