Abstract:
A preliminary avifaunal survey was conducted at Hapugastenne Tea Estate, Ratnapura, Sri
Lanka from October to December 2015 with objectives of assessing the bird diversity
within different habitats and documenting threats to biodiversity. Bird populations were
sampled in 39 line transects and 17 point counts (respectively for terrestrial and aquatic
habitats) representing eight habitat strata (tea fields, home gardens, scrublands, secondary
forests, natural forests, stream-side vegetation, riverine forests, and water-logged areas)
within the estate, replicated in its nine divisions. Transects were conducted during the
morning between 07:00 and 09:00 hrs. A total of 91 species, including nine Sri Lankan
endemics and nine winter visitors were recorded, which included three nationally
threatened (two endangered and one vulnerable) and six near threatened species.
Estimates of relative abundance indicated a high degree of rarity, with only few abundant
species, the red-vented bulbul being the most abundant. Among the habitats, highest
species richness (39) was recorded in stream-side vegetation where Simpson’s diversity
index (0.947) was also the highest, while the Shannon-Wiener diversity index (H’=3.247) is
marginally second to tea fields (H’=3.382), where the evenness was highest (J=0.994).
Interestingly, the Shannon-Wiener diversity and the evenness of the secondary forest
fragments were comparable to those of home gardens (H’=2.591; J=0.795 and H’=2.515;
J=0.791 respectively). The results of the feeding guild analysis indicated a greater
abundance of the insectivore guild in tea fields than in other habitats. In contrast, the
relative abundance of frugivore guild was higher in the natural and secondary forests.
Cluster analysis indicated a highly dissimilar species composition in scrublands compared
to other habitats, while tea fields and home gardens were very similar in their avifauna.
The study revealed that this managed landscape provides a diversity of niches maintaining
the natural biodiversity to a certain extent. Nevertheless, 14 alien invasive species (nine
plants and five animals) were identified from the area among several other threats to the
biodiversity. Increasing plant diversity, introduction of native shade trees and connecting
remnant natural habitat patches via stream reservations are recommended to conserve
and enhance the avifaunal diversity in the study area.
