Biodiversity of Mahale Mountains National Park, Tanzania | Report ...

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4. BIRDS Biodiversity of Mahale Mountains National Park 4.1 METHODS AND SOURCES OF INFORMATION Several quantitative and qualitative methods were used for the bird surveys to build up as complete a species list as possible for each site and for Mahale Mountains National Park. This allowed comparisons of overall species composition between sites as well as giving a measure of relative abundance. Species records from all methods were combined on daily lists at each site to allow calculation of a species accumulation curve. Point Counts Birds were surveyed systematically along the same transects as used for mammal and plant sampling. Sampling points were marked with flagging tape at 250 m intervals along transects. During surveys, a five-minute count was made at each sampling point. Surveys were begun around 0700 hrs and continued to late morning or the transect end point. All bird species seen and heard during the 5-minute count were recorded on a data sheet and distance from the observer as well as number of individuals recorded was noted. Distance categories used (in meters) were: 0–10; 10–20; 20–50; 50–100; 100–200; >200. GPS position was recorded for each sampling point as well as the general habitat type. Mist-netting Mist-net lines were set to sample cryptic understory birds that were not likely to be detected on transects. Net lines were set so as to optimally sample species in the target habitat. For instance, net lines set to sample forest edge birds extended from within the forest to the surrounding grassland. Nets used were 12m long, 5 shelf units with a 33mm mesh size. Net lines were set for two mornings at each sample site. The nets were opened at 0600hrs and closed at 1000hrs. All birds captured were fitted with a numbered metal leg band to allow identification of re-trapped individuals and to facilitate future studies on site fidelity, local dispersal, seasonal altitudinal movements and longevity. General observations and audio recording In addition to systematic sampling, lists were kept of all bird species seen and heard while walking between sampling points along transects. All other observations were also recorded on daily and site lists. Audio recordings were made of as many species as possible to facilitate the production of reference and training materials for future ecological monitoring activities in the park. 4.2 RESULTS Point counts and mist-netting were supplemented with general surveys and audio recordings to maximize the number of species recorded at the three sample sites of Kasoge, Kabezi and Mfitwa (Figure 1). Two hundred and forty two species were recorded during this survey – 135 of these during the point counts and mist-netting (Appendix III). The bird species list for Mahale now stands at 355. Thirty two first records were added to this total during this survey. The base list was compiled from all published and grey literature sources available (Moreau 1943, Ulfstrand & Lamprey 1960, Anon. 1980, Britton 1980, Nishida 1990, Anderson and Baker 2004). Further unpublished records by many observers were added from the Tanzania Bird Atlas database (Baker and Baker 2001-2005). Records of 52 species collected by Thorkild Andersen in Mahale in the 1948 –1949 were also included (Williams 1950, J. Fjeldså in litt. April 2006). A majority of these are housed in the Zoological Museum, University of Copenhagen. Atlas records were vetted carefully in consultation with Neil and Liz Baker and a number that were obviously in error were removed from the database. Thus, the list presented in this report has been reviewed carefully and represents an accurate summary of all bird distributional data available for Mahale Mountains National Park to the present (Appendix IV). Wildlife Conservation Society 11
Biodiversity of Mahale Mountains National Park Figure 1 Bird species accumulation curve for three sites in Mahale Mountains National Park. Total species recorded during sampling at Kasoge = 72; Kabezi = 103; and Mfitwa = 77. 120 100 80 60 40 20 0 Kasoge Kabezi Mfitwa 0 1 2 3 4 5 6 7 8 9 10 11 Days Recording The bird species assemblages at Kasoge and Kabezi were more similar to each other than either was to Mfitwa (Figure 2). However, the picture of the relationship between these three sites is somewhat incomplete because the species accumulation rate for Kasoge had not levelled off by the end of the sampling period (Figure 1). An apparent increase in accumulation rate at Kabezi near the end of the survey period was due to several transects extending into montane habitat. New species were from that community but very few new Miombo and riverine forest species typical of the Kabezi site were added. 4.2.1 Point Counts Two hundred and eighteen point counts of birds were made at three field sites in Mahale. Total counting time was 18.2 hours, during which 2643 individuals of 135 species were recorded (Appendix V, Table 5). Species accumulation curves suggest that sampling was incomplete for both Kasoge and Kabezi but had begun to level off at Mfitwa (Figure 1). Kabezi had the highest abundance of birds at 164.5 per hour of sampling. Mfitwa and Kasoge had similar abundances with 120.7 and 118.5 birds per hour of sampling. The number of contacts (record of a species during sampling) was also higher at Kabezi with 90 per hour, followed by Mfitwa with 78.9 per hour and Kasoge with 54.8 per hour. The only species to make the top ten list for all three sites and both categories was Yellowwhiskered Greenbul, Andropadus latirostris (Table 5). Common Bulbul was the most frequently encountered species and was recorded at 61.3% of sample points at Kabezi. It was also the most abundant species at both Kabezi and Mfitwa. The overall most abundant species was the migratory Eurasian Bee-eater, Merops apiaster, at Kasoge with more than 40 birds counted per hour. Wildlife Conservation Society 12
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Rothmannia longiflora Rothmannia ma
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