Use of habitats by aquatic and terrestrial avifauna in tropical coastal lagoons

Tropical coastal lagoons comprise several habitats, which have great importance for avifauna by providing nesting, roosting or foraging sites. However, various anthropogenic activities have caused coastal habitat degradation globally. To sustain conservation, it is crucial to understand the seasonal habitat utilization patterns of avifauna. Additionally, how coastal habitats are influencing terrestrial avifaunal distribution is not well documented. Therefore, this study was carried out to examine the habitat utilization patterns by aquatic and terrestrial avifauna in Batticaloa Lagoon in eastern Sri Lanka from September 2017–August 2018. Compared with past studies, our study indicated a lower diversity of aquatic birds. Findings revealed that 47% and 27% of aquatic and terrestrial avifaunal species, respectively occurred in all habitats indicating their utilization of different habitats as alternative habitats. However, terrestrial bird composition was more similar between the different habitats (compared with aquatic birds) as per non-metric multi-dimensional scaling (NMDS) plots. Overall bird density variation was significant with season and habitat. Considering the avifaunal density, both aquatic and terrestrial birds mostly preferred swamp habitat. Abandoned shrimp farms were least preferred by aquatic birds and terrestrial birds indicating that anthropogenic habitats do not provide many of the required resources that are provided by natural habitats. Mangroves (comprising true mangrove species and mangrove associates) support a relatively high diversity of terrestrial birds, but recorded the lowest diversity of aquatic birds. Suggestions were made to improve habitats to attract more species especially aquatic birds.