Diversity and richness of avian community in Ekonde and Owala dams, Osun State, Nigeria

Abstract

Birds have been shown to be an effective means of identifying priority areas for conservation action and mitigation measures. A field survey of birds at Ekonde and Owala dams in Osun State, Nigeria was conducted between March and June 2018 to determine the species diversity, abundance and feeding guilds. Data were collected using line transect method. The birds sighted during the survey were categorized based on their species, migratory/ non-migratory status, and feeding guild. Mean bird density within the two dams was determined and compared using t-test, and species diversity indices were analyzed using PAST software. A total of 2,152 birds from 67 species (33 families and 12 orders) were recorded where Ekonde dam had 1,286 birds (59.76%) and Owala dam had 866 (40.24%). In Ekonde dam, Vanellus spinosus was the most abundant species (n = 72, 8.31%), while at Owala dam, Oriolus nigripennis was the most abundant (n = 204, 15.86%). Bird density was apparently higher at Ekonde dam (51.44 birds/km2) than Owala dam (30.95 birds/km2), yet there was no significant difference (t value=1.679; p= 0.097). At Ekonde dam, Black-winged oriole had the highest density (8.16 birds/km2) while at Owala dam Spur-winged lapwing had the highest density (72 birds/km2). Shannon diversity index and evenness were higher at Ekonde dam (3.702 and 0.862) than at Owala dam (3.102 and 0.654). The birds were categorized into 10 and 8 feeding guilds in Owala and Ekonde dam respectively. Most reported species were insectivores (27, 33%) and carnivores (15, 19%). It can be suggested that as two dams have high avian richness, these can be sites for avian conservation and avitourism if properly managed. It is therefore recommended that strategy for avian conservation be incorporated into the dam management program for sustainability of the ecosystem.

Keywords: Avian conservation, avitourism, bird density, feeding guilds.