Avifauna Composition of an Abandoned Dam Site in Biu, Borno State, Nigeria

Abstract

Dam construction, a common anthropogenic activity, leads to significant habitat loss and fragmentation, mainly impacting aquatic ecosystems and also the surrounding terrestrial habitats. In addition, dams alter natural river flow impacting heavily on water-dependent bird species and other aquatic fauna. In this study, we examined a dam site abandoned 46 years ago for the presence of water bird species and other terrestrial avifauna within and around the dam/reservoir. Point count census method was employed to record avian species during morning and evening hours. A total of 1,263 individuals from 84 species of birds were recorded. Sixty-six (66) genera in 38 families and 16 bird orders were also recorded.  The most species rich family was Ardeidea (herons and egrets) with a total of 8 species, followed by Columbidea (doves and pigeons) and Estrildidea (finches) families with 7 species each. Passeriformes was the most species rich order with a total of 36 species drawn from 18 families of birds. Insectivores were the most abundant feeding guild accounting for 32.1% (N=27) of the total species recorded, followed by granivores (N=21). The most abundant bird species was the white-face whistling duck (Dendrocygna viduata) (N=177 individuals). We recorded 11 African Eurasian Wetland Agreement (AEWA) listed species, 10 of which are migratory. The presence of the Red-necked Falcon (Falco chicquera), a near threatened species (IUCN, 3.1) in the study area underscores the ecological and conservation significance of the Dam/reservoir. Overall, our findings highlight the ecological and functional roles of birds in agricultural landscapes as potential agents of insect and pest control, dispersers and pollinators. The high number of granivores recorded in the study area is a reflection of the type of crops cultivated around the dam/reservoir - constructed primarily as source of water for Biu municipality. The absence of a buffer zone and regulatory authorities to reduce human pressure around this crucial wetland ecosystem is a major threat to avian species well-being. Biu dam if properly managed could in addition to its current role as a perennial source of water for irrigation, also serve as a haven for migratory and resident bird species.