Summary
- Knowledge of the relationship between biodiversity and environmental
factors provides insight into patterns of species richness and
distribution in limnetic ecosystems. To this end, this study was
conducted to test the effect of limnological characteristics of
reservoirs on bird species richness and distribution along an age
gradient of limnetic ecosystems in Tigray National Regional State.
- To evaluate the relationship between limnological characteristics of
reservoirs and patterns of bird species richness and distribution, six
physicochemical variables, three morph-edaphic and biological
variables were recorded for 35 reservoirs and analyzed by multivariate
statistical techniques. Species richness data was subjected to a
multiple regression analysis at limnological variables, biological
variables and age of the reservoirs in order to investigate the most
important explanatory factors influencing avian species richness and
their distribution using Redundancy analysis (RDA).
- 85 bird species from 54 genera, 25 families and 15 bird orders were
recorded, with mean species richness 14.23±6.72 (mean ± standard
deviation) per reservoir. Five of these species are near threatened
(NT) while other two species fall under critically endangered (CR) and
vulnerable (VU) conservation status designations, respectively. Bird
species richness was positively correlated with surface area of
reservoirs. The RDA analysis identified two significant RDA axis and
34.4% of the variation in species richness is explained by
environmental variation (R2adj =
0.34375; P < 0.001). Generally, water chemistry appears to
play only a minor part in affecting bird species richness in reservoir
in Tigray, Northern Ethiopia. However, chemical variables may be
helpful to distinguish between used and unused sites for some species.
- The result provides an important insight on the ecological
relationship between waterbirds species richness and limnological
characteristics of reservoirs. And plays a role towards strengthening
our knowledge on aquatic bird ecology and natural history of African
Eurasian Migratory waterbirds.
Key words : Abdim’s Stork; Bostrychia carunculata ;Numida meleagris ; Reservoirs; Tigray; Waterbirds