Species diversity and richness of wild birds in Dagona-Waterfowl Sanctuary, Nigeria

摘要

The study of bird species diversity and richness in Dagona-Waterfowl Sanctuary was carried out during the midst of both early wet and late dry seasons, to provide comprehensive data on wild birds. Dagona Sanctuary is located within the Bade-Nguru Wetland sector. It is one of the important bird areas marked for the conservation of avifauna species in sub-Sahara region, Nigeria. Line Transect method was used to carry out birds’ survey at three different lake sites, namely: Gatsu (site:1), Mariam (site: 2) and Oxbow (site: 3). The instruments used were GarminTM 12 Global Positioning System (GPS), a pair of binoculars for bird’s identification, a field guide test- book and a 1,000 meters tape-rule. The data were tested with the Kolmogorov- Smirnov method o determine distribution level and birds’ diversity was assessed using Shannon-Weiner Diversity Index, while parametric tests were applied for all data. The results showed that bird species diversity was normally distributed in all the sites, site 2 had the highest diversity (2.74) compared to site 1: (1.84) and site3: (1.62). Likewise, bird species richness in the area was normally distributed and significantly different (P<0.05) among the three sites. Site 1 had the highest number of bird species richness (16.36) (Species diversity is different species of birds at the site, while species richness is referring to specific species population), compared to site 2: (14.32) and site 3: (11.51). It was observed that there is a significant relationship between vegetation density and bird species diversity, because as treedensity increases, diversity of bird species decreases. Therefore, there is a significant relationship between vegetation density and bird species diversity. A total of 135 bird species in 40 families was recorded during the survey. Seventy-four percent were found in site1, sixty-three percent in site 2 and seventy-one percent in site 3. The majority of wetland birds observed during this study were resident (Ardeidae family), migratory (Accipitridae family) and palearctic species (Yellow Wagtail, Warblers,Northern Shoveler and Sandpipers). It can be concluded that wild birds are good indicators of environmental condition, revealing the state of the wetland. Some sites were more disturbed, as observed in site 1 and site 3. It was, however, recommended that regular monitoring of the sites should be carried out so as to control changes in the state of the wetland ecosystem.