Role of Vegetation Characteristics on the Distribution of Three Hornbill Species in and around Pakke Tiger Reserve, Arunachal Pradesh, India

The change in physiognomic and floristic characteristics of vegetation composition affects the bird community assemblage and the relative abundance of different species within the community. Hornbills are mutualistic to the forest with their dependency on roosting, nesting and feeding, and helping in the regeneration of different plant species by dispersing the seeds. The relationship between various vegetation characteristics and the relative abundance of three hornbill species (Great Pied Hornbill (GPH, Buceros bicornis), Wreathed Hornbill (Rhyticeros undulatus) and Oriental Pied Hornbill (OPH, Anthracoceros albirostris)) was studied in and around Pakke Tiger Reserve, Arunachal Pradesh, India. We walked transects (n = 11; 22 walks) in three study sites to detect hornbills. Vegetation sampling was done using circular plots (n = 33; 10 m radius) at every 400 m interval along each transect. Encounter rate (1.5 ± 0.188/km) of GPH was highest in the protected and undisturbed forest area, where food and roosting tree density were also high (114/ha). OPH was common in both the sites in the Reserve, near riverine forests (0.75 ± 0.25/km) and the dense undisturbed forest (0.875 ± 0.226/km). Multivariate analysis revealed that tree density, presence of fruiting trees (utilized by hornbills), canopy cover and tree diversity in a particular area are the major factors responsible for the assemblage of more than one hornbill species. The study shows that protection of forest patches to keep the diversity and density of the tree species intact is crucial for the survival and distribution of hornbills in the landscape.