生物多样性、生物勘探与发展杂志

Diversity and Abundance of Avian Species of Owena Multipurpose Dam, Ondo State, Southwest, Nigeria

Abstract

Odewumi OS*, Okosodo EF, Talabi O

The use of wetlands and their resources is widespread among many diverse bird taxa of the world. The diversity and abundance of avian species in Owena Multipurpose dam was assessed out between January and June, 2016 to provide baseline information of the birds in this area. The line transects method with lengths ranging from 350 m-1000 m was adopted for the survey. Birds recorded were categorized into order, family, species, migratory status and feeding guild. Relative abundance of bird species and diversity indices were determined. Significance in mean bird density in the two seasons was determined using T-test while One-Way ANOVA was used to test for significance in bird diversity indices. A total of 35 bird species belonging to 20 families and 10 orders were recorded in the study area. The common species includes Ardea alba, Vanellus spinosus, Ardea cinerea, Phalacrocorax carbo, Milvus migrans, Ardeola ralloides, Actophilornis africanus, Microcarbo africanus, and Bubulcus ibis. All the bird species recorded were in the Least Concern (LC) category. The bird species were categorized into seven feeding guilds. The granivores, insectivores and canivores were more in abundance than the nectarivores and frugivores. The order Passeriformes had the highest families (9) and species (17), followed by Pelecaniformes and Charadriiformes with 2 families each, 4 and 2 species respectively while others had one family each. The total mean number of bird was 428 ± 5.75/ observation. Lagonosticta sanguinodorsalis had the highest mean number (156.4/ observation) and relative abundance of 36.54% while Ardae cinerea and Phalacrocorax carbo had the lowest mean number (0.2/ observation) and relative abundance of 0.05% each. Transect 1 had the highest Shannon diversity index (Hl=1.664), while transect 3 had the least (1.168). All the transects had similar species evenness index except for transect 4. The findings can be attributed to the heterogeneity of the habitat resulting from alteration of the ecosystem through the construction of the dam. In conclusion, the Owena dam construction has both negative and positive impacts on avian species composition and abundance. The management programme of the Owena dam should incorporate avian conservation in the area.