Avifauna of adjoining coastal areas of Purba Medinipur district, southern West Bengal, India: additional records and updated list

The present study was carried out in Digha-Shankarpur estuary region of Purba Medinipur district, West Bengal, India, during December 2018 to August 2020. During survey period, a total of 178 species of birds were recorded from the area including 29 previously unreported species from Purba Medinipur coast. With the compilation of previously published records and present records, the number of known avifauna of the coastal area of Purba Medinipur district goes to 225. Study also reveals the presence of nine near threatened and one vulnerable bird in the Purba Medinipur coastal area. Some of the new and noteworthy records are given in detail.


INTRODUCTION
Avifaunal diversity of a given area or region, act as significant indicator for the evaluation of habitat quality of that particular area or region. Moreover, avifaunal documentation helps us to understand the distribution of particular species in a particular area and time (Peterson et al., 2000;Colin et al., 2000). Through their immense role in ecosystem as pollinators, seed dispersal agents, pest control agents, predators and scavengers, birds provide us inestimable ecosystem functioning services.
The coastal area of state West Bengal with about 160 km long coastal tract includes two districts, namely Purba Medinipur and South 24 Parganas. Studies on Avifaunal diversity at West Bengal coast chiefly carried out in the Sundarban mangroves region (in South 24 Parganas), which is the largest known coastal wetland of the world, shared between India and Bangladesh. It lies at the delta region, formed by the confluence of Ganges, Brahmaputra and Meghna River in the Bay of Bengal (Gopal and Chauhan 2006). At present, Indian Sundarban represent about 360 species of Birds (Venkatraman et al., 2019), of which many globally threatened species like Spoon-billed Sandpiper Calidris pygmaea; Baer's Pochard Aythya baeri; White-rumped Vulture Gyps bengalensis etc. were recorded. However, knowledge on avifaunal diversity in the coastal area of Purba Medinipur district is very fewer and can be achieve from the previous studies of Patra and Chakrabarti (2014) who reported 86 bird species belonging to 10 orders and 35 families only from Digha region. Then Payra et al. (2017) listed a total of 171 species of birds representing 18 orders and 54 families from the six coastal sites of the district. To find out complete avifaunal assemblage and to upgrade the known Avifaunal diversity of coastal area of Purba Medinipur district, the present study was carried out in Digha-Shankarpur estuary region, Purba Medinipur district, West Bengal, India.

MATERIALS AND METHODS
Survey area ( Fig. 1-2) Purba Medinipur being the southernmost district of West Bengal is part of the lower Indo-Gangetic Plain and Eastern coastal Plains. The area of district is about 4151.64 km2 and with about 50-60 km long coastal tract from Talsari to khejuri-Hijli area, represent 27% coastal environment of West Bengal. The region experience mainly Tropical Climate. During March to June temperature ranges between 30⁰-38⁰C and during November to February temperature remains lower (15⁰-25⁰ C). Average annual rainfall varies between 1400 mm to 1700 mm.
Present surveys were carried out in about 1030 hectare area of Digha-Shankarpur estuary region (Lat 21°39'10"N, long 87°33'55"E, 5m a.s.l.). Habitats were characterized by coastal forest, coastal fishery lands, brackish water canals, Mangrove forest patch, village woodlands, wetlands, ponds and agri-culture lands. Coastal forests mainly dominated by Casuarina equisetifolia L. trees mixed with Eucalyptus globules Labill. and Acacia auriculiformis Benth. Dominated shrubs of the coastal forest are mainly Chromolaena odorata (L.) R.M.King & H.Rob., Clerodendrum infortunatum L., Lantana camara L., Carissa sp. etc. Mangrove forest patches chiefly consist of Avicennia officinalis L. plants, occupied mainly at the bank sides of brackish water Champa canal and its small streamlets. Only a few portions of fishery lands are used for fish culture and rest are remains as barren lands. The depths of the fishery ponds vary between 0.5 m to 1.5m and are connected with canals through water inlet-outlet system. During winter most of the ponds remains dry, but the deeper ponds and those are used for fish culture are occupied with water during most the season. Acacia nilotica (L.) and Prosopis juliflora (Sw.) DC are commonly seen plants at fishery lands.

SAMPLING AND IDENTIFICATION
Opportunistic field surveys were carried out during December 2018 to August 2020, by walking along the routes. More than 85 days field survey was carried out at different types of habitats in Digha-Shankarpur estuary. Birds were recorded in the field through direct observations by naked eye, during 6:00 a.m. to 11:00 am and 1:30 p.m. to 5:00 p.m. Photographs were taken in the field by using Nikon P900 Camera. Identification was done with the help of photographic guide books of Grimmett et al. (2011);Arlott (2015) and Grewal et al. (2016). Systematic arrangement, common names and scientific names follow Praveen et al., (2016Praveen et al., ( , 2018Praveen et al., ( , 2020. According to the seasonal dispersal, birds were categorized into Winter Visitor (WV), Summer Visitor (SV), Resident (RE) and Vagrant (VA) (Grimmett et al. 2011). Conservation statuses of birds were adopted from IUCN Red List. To updated the avifaunal list of Purba Medinipur coast, secondary data were obtained from previously published literatures (Patra and Chakrabarti, 2014;Payra et al. 2017) and avifaunal records of eBird along the Purba Medinipur coast (eBird 2020).

RESULTS AND DISCUSSION
During the present survey a total of 178 species of birds under 16 orders and 57 families were recorded from about 1030 ha area of Digha-Shankarpur estuary region (See Table- 1,. With the compilation of previously published papers (Patra and Chakrabarti, 2014;Payra et al. 2017) and records of eBird (eBird, 2020), the number of total recorded birds of the Coastal areas of Purba Medinipur goes to 225 species under 17 orders and 61 families (Table 1). Passeriformes represent highest number of species (n=85) in the coast of Purba Medinipur, followed by Charadriiformes (48 species), Pelecaniformes (22 species), Coraciiformes (11 species), Piciformes (10 species), Accipitriformes (9 species), Anseriformes and Cuculiformes (7 species each), and others. Among these 225 species of birds 130 species are resident, 2 species are summer visitors, 96 winter visitors and one species is vagrant. From the previously published list of Payra et al. (2017), eight species of birds were not incorporated in the present compile list due to doubtful and misidentified records. These are Dunlin Calidris alpine; Isabelline Shrike Lanius isabellinus; Tickell's Leaf Warbler Phylloscopus affinis; Rusty-tailed Flycatcher Muscicapa ruficauda; Jungle Prinia Prinia sylvatica, Chestnut-shouldered Petronia Petronia xanthocollis and Eastern Yellow Wagtail Motacilla tschutschensis; Rufous-tailed Lark Ammomanes phoenicura. In this present survey 29 species of birds under 8 orders and 22 families were newly recorded from the coastal area of district.
Some notable and newly included birds in the updated avifaunal list of the adjoining coastal area of Purba Medinipur district are discussed here.    Great Thick-knee Esacus recurvirostris (Fig. 3O): A single individual was sighted on 27.06.2020, near salt pan area of Kuliyata village. Conservation status of this bird is Near Threatened. In coastal area of West Bengal, it has been reported only from some places of Sundarbans (Zöckler et al., 2005). Here reported for the first time from Purba Medinipur coast.
Ruff   Tickell's Thrush Turdus unicolor (Fig. 5O): First one individual was observed on 26.11.2019 at coastal forest of Shankarpur, while foraging on the ground. Then on 6.12.2019, two individuals were recorded from the same place.

CONCLUSIONS
The present study bring forth, presence of 225 species of birds in adjoining coastal areas of Purba Medinipur district, including 29 previously unreported species. The study also reveals occurrence of more than 200 bird species only from Digha-Shankarpur region and 48 species of waders from Purba Medinipur coast. Among the waders Himantopus himantopus; Vanellus indicus; Rostratula benghalensis; Hydrophasianus chirurgus; Metopidius indicus; Glareola maldivarum were found to breeding in the Digha-Shankarpur estuary area. The coastal area of this district represents 24.01 % avifauna of West Bengal (n=937) and 62.5 % of the Indian Sundarbans (n=360). According to IUCN Red List, among these 225 species, 9 species of birds (Mycteria leucocephala; Anhinga melanogaster; Calidris ferruginea, Threskiornis melanocephalus; Esacus recurvirostris; Numenius arquata; Limosa limosa; Sterna aurantia and Psittacula eupatria) are come under Near Threatened category, one species is Vulnerable (Leptoptilos javanicus) and rests are under Least Concern. The varied habitat types of this region, such as coastal forest, fishery lands, fresh water wetlands, agricultural fields encompasses many resident birds, and as well as attractants for many migratory birds. In the coastal regions of Purba Medinipur district, requirement of public awareness is also very much essential to protect the varied habitat types of this region; those are used by the birds for feeding and nesting. As, due to increasing anthropogenic activities such as land conversion, tourism activities, road constructions, wood logging, potential habitats of avifauna are decreasing day by day. Erosion is also one of the major issues in Digha-Shankarpur region, as Pitchaikani and Mukherjee (2015)  The result of the present survey will serve as a significant baseline data and will be very useful to understand the status and distribution birds in West Bengal coast. The study also emphasizes the need of further long term qualitative and quantitative survey along the coastal area of this district. As, in the present communication only a small portion the Purba Medinipur coast was studied for the documentation of avifauna, therefore further studies needs to be done in future to get a complete insight into the Avifaunal assemblages of coastal area of the district.