An annotated checklist of the avifauna of Karangadu mangrove forest, Ramanathapuram, Tamil Nadu, with notes on the site’s importance for waterbird conservation

: Avifaunal inventories are crucial to the formulation of conservation and management strategies for habitats and species. An annotated checklist of the birds of the Karangadu eco-tourism area located in the Palk Bay in Ramanathapuram district of Tamil Nadu, was prepared. We listed a total of 107 species belonging to 18 orders and 40 families. Orders Charadriiformes, Suliformes, and Pelecaniformes dominated the habitat. Among the families, Scolopacidae (10 species) was dominant, followed by Ardeidae (9), and Laridae (8). In addition, the study also documented three globally ‘Near Threatened’ species: Painted Stork Mycteria leucocephala , Black-tailed Godwit Limosa limosa , and Black-headed Ibis Threskiornis melanocephalus. The observed frequency of the species was: 57% (61 spp.) common, 32.7% (35 spp.) uncommon, and 10.3% (11 spp.) rare. Categorization based on the residential status of birds revealed that 31% (33 spp.) were winter visitors, and one was a passage migrant (Rosy Starling Pastor roseus ). These baseline data highlight the importance of Karangadu as an important site on the southeastern coast of India for migratory shorebird conservation priorities.


INTRODUCTION
India is biodiversity rich, with several distinct biogeographical zones and habitats housing 12.5% of world avian diversity (Praveen et al. 2016;Praveen & Jayapal 2022). Birds are indicators of ecosystem health (Bilgrami 1995;Piersma & Lindstrom 2004), and data on their occurrence is important for ecological assessments and management initiatives (Kati & Sekercioglu 2006). The significance of a specific landscape for avifaunal conservation can be recognized by assessing the structure of local bird communities (Kattan & Franco 2004). Information on avifauna is vital for an ecosystem conservation effort, as well as to understand the implications of habitat degradation/loss and climate change (Daniels et al. 1991;Peterson et al. 2000;Llanos et al. 2011).
In Tamil Nadu, several studies have been carried out on the bird diversity of wetlands including Kaliveli (Pieter 1987), Karaivetti (Gokula 2010), Pallikaranai (Raj et al. 2010), Point Calimere (Sugathan 1982), Singanallur Lake (Reginald et al. 2007), and Vaduvoor (Gokula & Raj 2011). In the Ramanathapuram District of Tamil Nadu and adjoining areas of the Gulf of Mannar & Palk Bay regions, previous studies have been carried out from Rameswaram Island (Biddulph 1938) and Mandapam & its neighbouring islands (Balachandran 1990). Byju et al. (2023) described the avifaunal distribution on the 21 islands located in the Gulf of Mannar Biosphere Reserve.
In 2022, the Government of India announced the increase of Ramsar sites to 75, which included two wetlands (GOI 2022) from the Ramanathapuram District, prioritizing this area for bird and habitat conservation. Bird survey data provide useful insights for basic and applied ecology, as well as for identifying priority conservation areas (Daniels et al. 1991;Peterson et al. 2000). Some of the recently published records from this district include sighting of Artic Skua Stercorarius parasiticus (Byju & Raveendran 2022a), and the first Asian record of Light-mantled Albatross Phoebetria palpebrata (Byju & Raveendran 2022b). Previous findings highlight the importance of this area, and prompted us to undertake a baseline survey based on a need for monitoring in new areas in the rapidly changing landscape. This study of Karangadu on the Palk Bay adjoining the Gulf of Mannar region could act as a base for further research into avian systematics, taxonomy, distribution, assessment, and management. This study also remarks on the regularity of observations, the relevance of birds, especially longdistance migratory shorebirds, and the conservation significance of this mangrove habitat.

Study Area
Karangadu mangrove forest (9.6479 0 N & 78.9569 0 E) is located on the southeastern coast of India, adjoining the Palk Bay in the Ramanathapuram District of Tamil Nadu, India (Figure 1). It is an eco-tourism area run by the forest department with the support of the Eco Development Committee (EDC), involving the local fishermen community providing boating and birdwatching facilities for the public. The predominant vegetation of Karangadu is mangroves, which consists of Avicennia marina and Rhizophora mucronata. Many of unused areas were planted with mangroves in the last decade, converting the area to a mangrove forest from the estuary to the east coast road. This aids in supporting wading birds. Crabs, prawns, and other invertebrates inhabit the mangroves, regularly attracting a number of birds. Fishing activity and fish landing centres attract fish-eating birds. Small water bodies left over by unused salt pans as well as artificial pools with water released from prawn culture areas aid bird populations. The main habitat types observed in the study area include: Open water habitat and Mangroves (WL = Wetland); Trees (Tr) Palm and Tamarind trees; Shrub habitat (OS = Open Scrub type). The district receives rain from both the south-west and north-east monsoons. The district experiences a tropical climate. The months of May and June are generally hot and dry (Balachandran 1990).
This study on the avifauna of the Karangadu ecotourism area was carried out between January 2017 and March 2018. A total of 12 field visits (one per month) were conducted to observe the diversity of birds. Field surveys were conducted in the morning (0700-1000 h) and evening (1600-1900 h), depending on the season when birds were most active. Opportunistic sightings were also made to compile the checklist of the birds of the region during the years 2019 to 2021, from September to March. Direct count for individual species and block count methods were employed for flocks for data collection (Howes & Bakewell 1989;Bibby et al. 2000). In the study area, waterbirds were counted at three scanning points (Figure 1), selected on the basis of preliminary surveys done in January 2016. Additional observations recorded while moving from one scanning point to another were treated as incidental records. Birds were observed using Nikon binoculars (10x50) and photographed with Canon 100-400 mm tele-lens, and were identified with the help of a field guide (Grimmett et al. 2011).
The residential status of birds was assessed as Resident (R), Passage Migrant (PM), and Winter Visitor (WV) depending on their timing and duration of occurrence (Grimmett et al. 2011). The International Union for the Conservation of Nature (IUCN 2022) status was additionally used to compare the local status with the global status. During the surveys, other informationlike the role of EDC or threats to birds were noted. The data recorded in each survey was analyzed for relative abundance based on frequency of bird sightings, categorized as: Common (C), encountered on >60% of visits; Uncommon (UC), encountered 21-60% of visits; Rare (R), encountered on less than 20% of visits (McKinnon & Philips 1993).

RESULTS AND DISCUSSION
Avian community structure A checklist of the Karangadu eco-tourism area in Ramanathapuram, Tamil Nadu, produced in the study includes a total of 107 avian species representing 40 families belonging to 18 orders. Passeriformes, with 17 families and 31 species, was dominant. But waterbirds (n = 45) belonging to 11 families were abundant in numbers.
Among the total birds documented from the area, water birds were in the majority during all the surveys. We observed that several species of gulls and terns

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used the open regions inside the mangroves (Image 1) near the watchtower mainly for roosting. Waterbird abundance and diversity were influenced by factors in wetlands such as wetland area, depth of water and its quality, trophic level, and ideal roosting and breeding locations for birds (Wiens 1989;Mukherjee et al. 2002;Ma et al. 2010). Among the waterbirds, the order Charadriiformes dominated the study area, followed by the Pelecaniformes. Since most of the areas under study were covered with mangroves in the wetland area (Image 2), waterbirds represented the majority in numbers. As a result, we have focused on waterbirds (shorebirds, large wading birds, gulls, and terns) with special focus on shorebirds, both long-distance migrants and resident birds.
We recorded 18 shorebird species, of which 15 were Winter Visitors (WV), including the 'Near Threatened' Black-tailed Godwit Limosa limosa. Two species, namely Black-winged Stilt Himantopus himantopus and the Red-wattled Lapwing Vanellus indicus were Resident. One species, the Kentish Plover, could either be a Resident/Winter Visitor (R/WV), as we have recorded it during the non-breeding season. The most dominant species among the observed shorebirds were Common Sandpiper Actitis hypoleucos (peak count at one time: 620 in January), followed by Little Stint Calidris minuta (peak count at one time: 245 in January). Another 19 species of waterbirds, including herons, egrets, and ibises, were also recorded from this site, including the 'Near Threatened' Painted Stork Mycteria leucocephala and Black-Headed Ibis Threskiornis melanocephalus. The most dominant group of birds were the egrets: Great Egret Ardea alba, Intermediate Egret Ardea intermedia, and Little Egret Egretta garzetta (peak counts between 100 and 150 at one time, throughout the year). Moreover, this area also serves as an important foraging place for Greater Flamingo Phoenicopterus roseus (peak count at one time was 150 in February).
Six species of terns and two species of gulls were also recorded from the eco-tourism area. This was used as a roosting site by two gull species, namely Brown-headed Gull Chroicocephalus brunnicephalus and Black-headed Gull Chroicocephalus ridibundus, as well as two tern species, Lesser Crested Tern Thalasseus bengalensis and Greater Crested Tern Thalasseus bergii. Brown-headed gulls were the most dominant gull species (peak count at one time: 225 in February), and the Lesser Crested Tern represents the most dominant tern species (peak count at one time: 325 in February) among the terns. This observation goes in parallel with the reporting from

Conservation Significance
Stop-over sites are critical for long-distance migrant shorebirds migrating between wintering and breeding areas (Boere et al. 2006). Karanagadu's proximity to the Important Bird Areas of Sri Lanka and the Gulf of Mannar may provide a link between the country's other major east coast shorebird sites, and other wintering sites along the Central Asian Flyway. Karangadu sandwiches the established shorebird wintering sites of Point Calimere and the Gulf of Mannar. This site serves as an ideal place of roosting for gulls, terns, long-migrant shorebirds, and Greater Flamingos, which makes this wintering site very important for further monitoring and conservation-related activities.
For effective conservation to be implemented, and for future strategies to be adopted, the role, contribution, and participation of the local community are essential (Sinthumule & Netshisaulu 2022). The forest department-initiated EDC-run eco-tourism project in Karangadu is in the right perspective because of the active involvement of the fishermen community in boating and bird watching for the public. This helps in the general upkeep of the mangrove habitat along with avian conservation, as the revenue earned from tourism is being used by the local community. The newly planted 30-acre areas of mangroves (represented by Rhizophora apiculata, R. mucronata, and Avicennia spp.; developed with the help of the local community in 2015), are serving as an ideal habitat for waterbirds. This might have improved the area's avian diversity and richness. Nevertheless, in the tree habitat (Tr) in the peripheries, the avian richness was quite low, as only six species were recorded (Table 1). The current observations emphasize the value of wetlands and associated areas as avian habitats, as sizable number of species was found in more than one habitat. The inclusion of local communities in conservation has helped in habitat restoration and natural resource conservation programs in recent times (Silori 2007;Nepal & Spiteri 2011;Badola et al. 2012;Scholte et al. 2016;Sinthumule 2021). Controlled seasonal tourism by boating without disturbing habitats through the water channels could boost revenue, and the money raised could be further used for conservation initiatives. Hence, we propose that to check and devise strategies and activities for conservation, Karangadu mangrove areas should be declared a bird sanctuary.

CONCLUSION
Aside from the established shorebird monitoring sites, regular long-term monitoring, and assessment of the Karangadu eco-tourism area, an important wintering site on the east coast, should be carried out in the future to establish the importance of this area on the flyway. Furthermore, because the community members are engaged in ecotourism activities other than fishing and crab harvesting, they may be effectively educated on the significance and necessity of preserving and sustaining a balanced environment. This study has provided preliminary information on selected shorebirds as well as other waterfowl from the Karangadu eco-tourism area, which will be beneficial for future research in this area as well as demonstrating the importance of designating this as a protected area of conservation importance.