Dynamics of Farmland Birds in Traditional Agroecosystems: The Value of Countryside Elements in Avian Conservation

Abstract

In India, urbanization and growth of cities have fragmented farmlands and the area under cultivation is dwindling. This study examined the ecological characteristics of rice fields, the inherent value of countryside elements and the relative occurrence of four species of farmland birds Dicrurus macrocercus, Turdoides affinis, Pavo cristatus, and Psittacula krameri along the Cauvery delta region, widely known as the granary of Tamil Nadu. The abundance and distribution of birds were analyzed at 30 sampling points for a year using the unlimited-radius point-counts. Among the four species recorded, D. macrocercus utilized more heterogeneous farmlands, while P. krameri was recorded in more intensively cultivated regions of the farmland. Pre-harvested rice fields predominantly supported species abundance and richness and exhibited a greater value for farmland birds than plowed, flooded or post-harvested fields. The abundance and richness of birds in agroecosystems increased with native vegetation cover and woody shelterbelts. D. macrocercus displayed greater tolerance towards monoculture plantations and elements within the mosaics like cable poles and power lines. Bird abundance in farmlands also correlated positively with decreasing distance from the mainland for D. macrocercus and T. affinis and showed a negative correlation for P. cristatus and P. krameri. D. macrocercus also displayed specialized resource utilization foraging techniques coinciding with cultivation activities resulting in bird-farmer mutualism. Cross-validation of the AIC models also showed that rice fields margined by greater amounts of vegetation cover and retention of species-specific modified elements supported the greatest abundance of farmland birds.