Checklist and nesting patterns of avifauna in and around Mayiladuthurai region , Tamil Nadu , India

1 New No.12, Old No. 3/10, New Street, Kollapuram, Tiruvarur District, Tamil Nadu 609608, India 2 Associate Professor, 3Lecturer, & 4Ph.D. Research Scholar, Department of Zoology & Wildlife Biology, A.V.C. College (Autonomous), Mannampandal, Mayiladuthurai, Tamil Nadu 609305, India Email: 1 amsamsoor@yahoo.co.in (corresponding author), 2 beeasokan@gmail.com, 3 manikannanr@yahoo.co.in, 4 samyradhakrishna@yahoo.co.in

The information on checklists and nesting patterns of birds in Mayiladuthurai region is scattered.A few reports that exist (Asokan 1998 a,b;Chandru & Asokan, 1999;Asokan et al. 2003Asokan et al. , 2009b;;Sivakumaran & Thiyagesan 2003;Neelanarayanan 2007) are chiefly related to the population and feeding ecology of birds.Barring a few observations on the nesting behaviour of birds (Thiyagesan 1991;Sivakumar & Jayabalan 2004;Asokan et al. 2008Asokan et al. , 2009a) ) there are no detailed studies of their nesting patterns.We present in this paper a detailed account of our observations on checklists and nesting patterns of avian species in Mayiladuthurai region.

Materials and Methods
Study area: The Mayiladuthurai Taluk is located on the Cauvery River bank between 18 0 18'N and 79 0 50'E in Nagapattinam District, Tamil Nadu, India.Agriculture is the major economics of this area, which contributes a high share of rice production to the state.Sugarcane, groundnut, green gram, black gram, cotton, etc are the other major crops cultivated in this area.The Cauvery River and its tributaries are major perennial water sources used for irrigation.Woody vegetation is sparse in the form of groves and roadside trees.The predominant tree species found in the study area are Bird survey: The checklist is primarily based on field work conducted in two habitats, viz., river banks (Cauvery River) and agricultural lands of Mayiladuthurai region from January 2006 to December 2006.Birds were observed between 0500 and 0900 hr with the help of 7x50 field binoculars.Birds sighted during the study period were categorized according to their status as residents and local migrants.The identification of birds was done using field guides (Grimmett et al. 1999;Ali 2002).The checklist was prepared using standardized common and scientific names by Manakadan & Pittie (2001).
Nesting patterns: The nesting behaviour study was carried out during January 2006 to July 2006, when most birds breed.Nests were located and data on nest characteristics, eggs and nest sites were recorded with standard methodologies as described by Pettingill (1985) and Soni et al. (2004).The photographs were taken with a NIKON Digital Camera.

Results and Discussion
A list of birds recorded from Mayiladuthurai region and their common name, scientific name, vernacular name (Tamil) and feeding habits is reported in Table 1.The study reveals the occurrence of 75 species of birds belonging to 41 families and 13 orders.Among the 13 orders, Passeriformes dominated the list with 35 species followed by Ciconiiformes, Cuculiformes and Coraciiformes with six species each; Falconiformes with five species, Charadriiformes and Columbiformes with three species each; Galliformes, Strigiformes, Apodiformes and Piciformes with two species each; Podicipediformes, Gruiformes and Psittaciformes with one species each.Out of the 75 species, 62 species were common residential birds and 13 species were local migrants.A greater diversity of avian species was recorded at the Cauvery River banks because of greater vegetation densities and food availability.Along both sides of the river banks, many wooded tree species, scrub and bushy type stumpy vegetation were distributed and it provided roosting and nesting-sites for many bird species.A number of birds were recorded in the agricultural fields.Paddy is the main crop of the study area and is cultivated round the year.Birds such as the Black Drongo, Indian Roller, Small Bee-eater, White-breasted Kingfisher, Common Myna, Pond Heron, egrets, etc., are very common birds in the agricultural lands and feed mostly on insects.Such birds are useful in the control of injurious insects in various crops (Asokan et al. 2009b).
The number of species recorded in the present study was low when compared to some earlier studies in Tamil Nadu (Jayapal 1995;Oswin 1999;Balasundaram & Rathi 2004;Reginald et al. 2007).The present study was carried out on two selected habitats only, future studies will cover all the areas of Mayiladuthurai regions and list more numbers of avian species.
In total, 30 species belonging to 22 families were recorded nesting in the study area (Table 2; Image 1).A total of 125 nests were recorded during the study period and the highest number of nests observed were of the Common Myna (n=16) followed by the Small Bee-eater (n=15) and the White-breasted Kingfisher (n=9).Five The birds used a variety of nesting materials for nest construction and most preferred soft fibres, grasses, twigs, sticks and leaves (Table 2).The Common Myna used more than five different varieties of nesting materials (twigs, roots, leaves, polythene, bird feathers and snake skin) for nest construction.Birds such as the Red-wattled Lapwing, Rose-ringed Parakeet, Whitebreasted Kingfisher, Small Bee-eater and Indian Roller did not use nesting materials and the Barn Owl laid its eggs on regurgitated pellets (Table 2).
Nest construction and placement are correlated with the breeding season, suitable nest sites, nesting materials availability, food availability and predator's interaction (Dial 2003).In the present study 11 species constructed cup nests with various materials and in a variety of locations (trees, bushes and shrubs).Many passerines and a few non-passerines (White-breasted Waterhen and Palm Swift) built this type of nest.Cavity / hole nests were used by numerous bird species and most bred either in natural tree holes / cavities and holes in walls or buildings.Some birds, such as the Rose-ringed Parakeet constructed their own nests and are referred to as primary cavity nesters.Species that use natural cavities / holes constructed by primary cavity nesters are called secondary cavity nesters (mynas, roller, robins, spotted owlet).The White-breasted Kingfisher and the Small Bee-eater are burrow nesting species and they dig a horizontal tunnel into sandy river banks, with a chamber at the tunnel's end to house the eggs.Platform nests were constructed by one raptor (Black Kite), two Columbiformes (Blue Rock Pigeon and Spotted Dove) and two crow species (House and Jungle crows).The Columbiformes constructed simple platform nests with small sticks and fibres.The Blue Rock Pigeon nests were man-made structures like temple towers and the Spotted Dove placed nests in small, thick vegetation and trees.The Black Kite and crows used strong sticks, fibres, roots, cloth, etc. and the nests were usually placed on tree canopy.The nests look like a jumble of materials, but the sticks are usually placed in layers, beginning with a triangle, followed by more rotated, triangular layers.The pendant nests were constructed by the Baya Weaver, Streaked Weaver and Purple-rumped Sunbirds.Pendant nests are elongated sacs woven of pliable materials such as grasses and soft plant fibres.The Baya Weaver mostly preferred Palm trees for nest construction and the Streaked Weaver preferred swampy and rain flooded areas, particularly where there were reeds and tall grasses.The Red-wattled Lapwing laid eggs in open bare ground.
Most species laid pure white eggs or white with various colour combinations.A few species laid blue or blue green, red and brown coloured eggs.Generally white eggs are formed by calcium carbonate; the pigments biliverdin and its zinc chelate give a blue or green and protoporphyrin produces reds and browns as the ground colour (Kilner 2006).Lack (1968) stated that egg colour had no taxonomic significance, but that did show a relationship with the type of nesting-site.For example the hole nesting species tended to have immaculate white eggs, ground nesters surrounded by vegetation laid eggs of obscured brown, gray or olive, those nesting in forks of tree branches had eggs with blotches or shadow-marks on a white or blue background.
Coconut Cocos nucifera, Palm Borassus flabellifer, Iluppai Madhuca indica, Mango Mangifera indica, Rain Tree Enterolobium saman, Tamarind Tamarindus indicus, Banyan Ficus benghalensis, Peepal Ficus religiosa, Poovarasu Thespesia populnea, Karuvai Acacia arabica, Odhian Odina wodier and Neem Azadirachta indica.Important shrub species are Kattukaruvai Prosopis juliflora, Kattamani Jatropha glandulifera and Adathoda Adathoda visica.Plantations of Casuarina Casuarina equisetifolia, Teak Tectona grandis and Bamboo Bamboosa arundinacea are also found in the study area.Based on the northeast monsoon the study area is divided into four seasons viz., post-monsoon, summer, pre-monsoon and monsoon.Summer ranges from April to June (with a mean maximum temperature of 38 0 C) and the northeast monsoon between October and December.The cold season starts in November and may last till January.