International Journal of Scientific Research in Environmental Sciences (IJSRES), 1(11), pp. 306-316, 2013 Available online at http://www.ijsrpub.com/ijsres ISSN: 2322-4983; ©2013 IJSRPUB http://dx.doi.org/10.12983/ijsres-2013-p306-316 306 Full Length Research Paper Assessment of Bird Population in Different Habitats of Agricultural Ecosystem Natarajan Mariappan 1* , B.K. Ahamed Kalfan 2 , Srinivasagam Krishnakumar 1 1 Assistant Professors, Vanavarayar Institute of Agriculture, Manakkadavu, Pollachi, Tamil Nadu, India 2 Research Scholar, Vanavarayar Institute of Agriculture, Manakkadavu, Pollachi, Tamil Nadu, India *Corresponding Author, Email: mariappann21@gmail.com Received 20 July 2013; Accepted 30 September 2013 Abstract. The study was carried out in Vanavarayar Institute of agriculture, Manakkadavu, Pollachi, Tamil Nadu, India during January, 2012 to January, 2013. The institute’s agricultural area classified four different habitats namely, crop land, wetland, plantations, and fallow land. The data were analyzed using Shannon–Wiener function formula; species diversity (H), maximum diversity (Hmax), and evenness (J). Based on this study we found variations in bird population distribution based on the cropping pattern and seasons of the year. Shannon–Wiener Index for diversity richness for different habitats of agroecosystem shows that fallow land recorded highest diversity (3.4619) and maximum diversity index (4.1271) compared to other habitats. Thus, fallow lands are not subject to practices of crop production and therefore supported bird’s nesting and breeding. Thus, most of the birds hunt their food from agricultural field and from water bodies and made their rest place at fallow land; therefore it indicates highest number of species in all the seasons of the year. Rare birds like Indian grey hornbill, yellow - footed green pigeon, common tern, paradise flycatcher, black headed ibis, white browed bulbul, striated heron, and barn owl were observed in particular season shows the richness of the habitats in the study area. The considerable numbers of trees in fallow land and boundary of agricultural land accommodate the large number of bird’s population. Thus planting trees in agricultural lands can increase bird population. Key words: Birds, species, agriculture ecosystem, habitats, richness, fallow land, India 1. INTRODUCTION Birds are the key species in an agricultural ecosystem for maintaining the ecological balance (Haslem and Bennett, 2008). Their positive and negative roles in agriculture production were very well illustrated (Ali, 1949 and 1971). Agriculture provides a concentrated and highly predictable source of food for birds. This food in general is of three kinds: (i) grain, seeds and fruits, (ii) green vegetation of the crop plants and grasses, and (iii) insects, other arthropods, rodents, etc., found in the soil, crops and other plants (O’Connor and Shrubb, 1986). There are many good reasons for counting birds but this study aims to promote better knowledge to help conservation. Within sites, it is fairly evident that habitat is likely to be an important determinant of the distribution and number of birds. For sites which are not protected, habitats might be changing, for instance as a result of developmental works. Adequate management obviously depends on understanding the relationship between birds and their habitats. If a study is oriented to a particular species, it is also evident that questions about its distribution, ecology and threats to its status, will partly be answered with an understanding of its habitat requirements. While much about a bird's ecology might be studied directly in terms of its diet, foraging behaviour or population dynamics, important knowledge of habitats can be gleaned from good census studies (Bibby et al., 1998). Approaches with a combination of both site- specific biodiversity measures and assessments of habitat diversity and heterogeneity at Vanavarayar Institute of Agriculture which is spread over 248 acres are yet to be established. In a time when the global environment around us is getting destroyed at an alarming rate, maintaining high levels of overall biodiversity in agro-ecosystems may become an important measure for ecological sustainability and to maintain the high abundances of presently well- adapted beneficial organisms (Duelli, 1997). But ever increasing population and the related urbanization has resulted in the depletion of the agricultural and wet lands. On the other side wetlands like rivers, streams, lakes, tank bodies and reservoirs in this area are getting deteriorated in an alarming rate due to their contamination with various pollutants and the increase in developmental activities. This is making the wetland lose its viability to support the aquatic organisms and the other organisms that birds depend on. Wetlands associated with agricultural lands also attract more number of bird species, especially migratory species. In the case of Pollachi, the water bodies are heavily polluted, which is seriously affecting the seasonal migration, nesting and breeding