Association of grassland birds with Saccharum-Imperata patch in a northeastern tea estate of Bangladesh

Abstract

Saccharum-Imperata grasslands in Bangladesh were once directly associated with 10 native extirpated birds and still harbor many diminutives. These habitats are now pocketed only in northeastern regions of the country due to intensive conversion, overstocked grazing and fire suppression. After a hiatus of about four decades, composition and interaction of grassland specialist birds within a managed habitat of a tea estate was studied between November 2015 and May 2016 at micro-habitat scale using line transects, diversity indices, Bray-Curtis cluster analysis and linear mixed models. Including 819 individuals of 39 grassland specialists, a total of 2,586 individuals of 110 species were recorded. The analyses indicated the landscape to have a significant effect on species richness. Of six micro-habitats, the area along the creek and dense tall grasses are important habitats for grassland specialists. The latter ranked top in Shannon’s index (H′) for specialists (33 species, H′ = 2.988) followed by micro-habitats along the creek (18, 2.592) and sparse short grass (16, 2.401), comparing marked difference with micro-habitats of sparse grass along the road (21, H′=2.279), bush associated (11, 2.206) and crop associated areas (11, 2.124). The effect of slash-and-burn was stark on specialists, no significant association was found with grazing. This has been surmised as relationship among specialists’ ecology, long-term treatment effect and unpalatable nature of Saccharum ravennae as fodder. Based on the hypothesis, the study emphasizes exigencies of a potential management strategy for avian habitats within tea estates of Bangladesh.

Keywords

• aves
• community ecology
• composition
• grazing
• interaction
• poaceae
• unpalatable grasses.