Abundance, Distribution and Population Trends of Waterbirds in the Usangu Wetland: A Biodiversity Hotspot Threatened by Human Activities

Abstract

ABSTRACT Waterbirds play essential ecological function contributing to maintenance of species diversity, pest control, seed dispersal, and vectors for invertebrates. Approximately one‐third of the waterbird assemblage inhabits wetland environments. However, waterbirds and their habitats are threatened by human activities capable of disrupting ecosystem. This study was conducted in Usangu Wetland Important Bird Areas to investigate the abundance, distribution, and population trends of wild avian species. Bird counting survey and questionnaire were conducted from to elicit information about abundance and distribution, and bird population trend respectively between March and May, 2022. Bird counts were conducted using 2.5 km line transects at three sites. Each site had six transect replicates to estimate relative abundance and distribution. Structured and key informant interviews were used to elicit trends of bird populations over the past 20 years and their influencing factors. Data were analyzed using R‐studio version 4.0.3. Furthermore, content analysis was employed to scrutinize perceived population trends. The study cataloged a total of 34 distinct species of waterbirds. The most prevalent species included lesser moorhen ( Gallinula angulata ) 47.56%, Fulvous Whistling Duck ( Dendrocygna bicolor ) 12.01%, and Glossy ibis ( Plegadis falcinellus ) 10.15%. The distribution patterns of waterbirds were determined by habitat type, geographical location, farm characteristics, and the specific rice scheme type, with a greater concentration in rice plantations and outgrowers rice schemes. Local accounts underscored a declining trend in waterbird populations over past 20 years due to illegal hunting and habitat conversion. Usangu wetland has a higher abundance of water birds with disproportionate distribution bias in rice farms. In spite of rice farms suitably holding a high assemblage of water birds, its sustainability is subject to owners' decision, vegetation cover changes after rice harvest characterized by illegal hunting.