Avian species diversity in three major forest types in part of northern Eastern Ghats, Odisha, India

We documented the forest avian species diversity (FASD) and tried to establish a relationship between FASD with different vegetation structure variables, e.g., tree density, herb density, shrub density, and canopy cover, along with disturbance levels in nine forest sampling sites (FSS) under three major types of forests, namely (1) tropical semi evergreen (TSE), (2) moist mixed deciduous, and (3) dry mixed deciduous (DMD) of Northern Eastern Ghats in Ganjam district, Odisha, India from January 2018 to December 2020. We identified 92 bird species under 13 orders, 38 families, and 71 genera. The highest bird diversity was found in TSE (84 species, 814 individuals out of 2158 recorded individuals in all three forest types, Shannon's diversity index or H & PRIME;= 4.207). This is attributed to rich vegetation and lower disturbance level. Least species were observed in DMD (70 species, 619 individuals, H & PRIME;= 4.028). Predominance of insectivorous birds among the different types of feeding guilds was found among all forest types. Tree density was shown to be the only variable to positively correlate with species abundance in the study region (r(2) = 0.99, P< 0.05), whereas the other vegetation structure variables did not. Continuous anthropogenic pressure, unchecked grazing, and deforestation are all major threats to the native avifauna in each FSS of the Ganjam district. The present study will help the community understand the value of forest avifauna in preserving forest ecosystems, which will ultimately lead to the protection of biodiversity.