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Aims: To assess the influence of human-induced disturbances on bird communities.
Study Design: Longitudinal study.
Place and Duration of Study: Four forests; - Kion/Zaraninge, Kwamsisi/Kwahatibu,
Msumbugwe and Gendagenda in Pangani–Saadani ecosystem, from October 2010 to
January 2011.
Methodology: Eight permanent transects, each 500 m long stratified into forest core and
forest edge habitats were used in each forest to identify types and quantify levels of
human-induced disturbances, determine bird species composition, diversity and richness,
and abundance. Therefore three circular plots, each 20 m radius were allocated at
beginning, middle and end of each transect. The level of disturbance was assessed using
four disturbance indicators; tree lopping, human trails, Pit-sawing and animal snaring while bird species were identified by sight and call. One-way Analysis of Variance was used to
test for differences in bird abundance between forests. Moreover, Shannon-Wiener
Diversity Index (H’) was calculated for each forest to assess species diversity and
evenness, and Bray-Curtis Cluster analysis was used to determine similarity in bird species
composition between the forests.
Results: A total of 564 individuals composed of 88 bird species distributed in ten Orders
were recorded. The level of Pit-sawing and lopping differed significantly between forests
(P<.05) with Msumbugwe being more disturbed than the rest. Bird abundance differed
significantly between the forests (P<.05) with the highest abundance occurring in
Msumbugwe. As expected, species richness and diversity were greater in least disturbed
forests-Kiono/Zaraninge and Kwamsisi/Kwahatibu than in the highly disturbed forest, but
forest dependent species were not significantly different between the study forests.
Apparently, only Pit-sawing was found to correlate with bird abundance (P<.01) whereas
similarities in species composition were evident with Kion/Zaraninge and Gendagenda
exhibiting much overlap.
Conclusion: Increasing forest disturbances seems to negatively impact on distribution of
birds thus challenging conservationists to devising sustainable forest management
strategies in order to sustain bird diversity and abundances in these unique forests. |
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