Highlight Activities 2022: Microhabitat variables influencing the presence and abundance of birds in floodplain grassland of the lower Ganges and Brahmaputra rivers, Bangladesh

Abstract: Grassland bird communities are declining globally due to habitat loss and modification. We used point counts and vegetation surveys to investigate the bird community structure and habitat associations in seasonal floodplain grassland along the lower Ganges and Brahmaputra Rivers, Bangladesh (part of the Indo-Gangetic Plain) during 2018–2019. Bird responses were assessed by diversity indexes, non-metric multidimensional scaling ordination and linear models. The resident bird community (31 grassland specialists, 34 generalists and 10 waterbirds) overlapped among the four major vegetation types in the study area (forbs and bushes, Saccharum sp., Cynodon sp. and cropland). Community diversity increased with cover of forbs and bushes, while the overall diversity of grassland specialists (those adapted to and reliant on some variety of grassland habitat for part or all of their life cycle) increased with Saccharum sp. cover but decreased with increased crop cover. The diversity of the total bird community showed no variation with vegetation height. However, the abundance of grassland specialists was correlated with increasing vegetation height. Nine grassland specialists that were entirely dependent on tall grasses for breeding were considered as obligate tall grass breeders. Their abundance decreased with greater cover of both Cynodon sp. and crops but increased with greater cover of Saccharum sp. The retention of vegetation with heights > 150 cm was therefore important to conservation and management of this community. The diversity of neither the total bird community nor that of grassland specialists showed any association with grazing intensity. However, grazing impacted negatively on the abundance of obligate tall grass breeders

Israt Jahan, Tommaso Savini, Paul M. Thompson, Philip D. Round & George A. Gale. 2022. Microhabitat variables influencing the presence and abundance of birds in floodplain grassland of the lower Ganges and Brahmaputra rivers, Bangladesh Global Ecology and Conservation https://doi.org/10.1016/j.gecco.2022.e02201