The avian diversity of Chemmattamvayal Wetlands and adjacent areas of Kasaragod District, Kerala, India

We are


INTRODUCTION
Wetlands are beautiful landscapes. They are important habitats for fishes, amphibians, insects, reptiles, birds, and other wildlife (Hosetti 2002). Wetland ecosystems occur in places where precipitation exceeds the rate of evapotranspiration leaving behind an accumulated water surplus (Mitsch & Gosselink 1993). About one-third of India's land area falls under this category, and wetland systems are, thus, common throughout the country (Hosetti 2002).
Ecologically, wetland systems are important ecotones, transitions between open waters and land, having a definite structure and function to perform specific ecological roles (Mahajan et al. 1981a,b;Mahajan 1988). They are productive areas and need to be treated as ecological treasure houses. The hydrology of the landscapes influences and changes the physiochemical environment, which in turn, shapes the biotic communities that are found in here (Mitsch et al. 2009). Lal (2008) opined that to maintain the atmospheric carbon cycle, restoration of wetlands around the world is crucial.
The major objective of the Ramsar Convention is to conserve the global degradation of wetlands through sensible use and sustainable management (Roy et al. 2022). During the Ramsar Convention, it was demonstrated that wetlands were the most fertile waterbodies required for migratory birds and other aquatic biota (Uttangi 2001). Roy et al. (2022) emphasized the importance of Ramsar sites as socialecological systems that focuses on socio-political, cultural and economic elements that induces biotic and abiotic features to recover. The convention also prescribed the conservation of wetlands as waterfowl habitats (Uttangi 2001). As of now, Kerala has three Ramsar sites namely Vembanad-Kol Wetland, Sasthamkotta Lake, and Ashtamudi Wetland (Ramsar Sites information Service 2023).
Since 1953, studies have documented avian fauna in the wetlands of Kerala and adjacent areas. Nair (1994) studied birds of Aakkulam-Veli back waters. Sivaperuman & Jayson (2000) and Jayson (2002) documented the avian diversity in Kole wetlands, Thrissur. Kumar (2006) made a checklist of avifauna of the Bharathapuzha River Basin, Kerala. Narayanan et al. (2011) documented ornitho-fauna and the importance of its conservation in the Kuttanad Wetland. Recently, Chandran et al. (2023) updated the checklist of birds of Kerala. Apart from the studies on avian diversity, more comprehensive species studies were also conducted in many parts of Kerala. Ravindran (1993) documented the breeding of Purple Swamphen Porphyrio porphyrio in the Kole lands of Kerala, followed by Menon (2004) evaluating the ecology of this species. Narayanan et al. (2006) studied the nesting behaviour of Great Cormorant Phalacrocorax carbo. In this present study, an attempt has been made to document the diversity of birds in the wetlands of Chemmattamvayal and adjacent areas.

Study area
Chemmattamvayal and adjacent wetland areas are located 4 km from Kanhangad, Kasaragod District, Kerala ( Figure 1, Image 1). It lies in between 12.28°-12.32° N & 75.10°-75.12° E and is located very close to the Kariangodu River. The wetland has a total area of 330.24 ha (825.6 acres) and the adjacent habitat includes paddy fields, freshwater marshes, ponds, backyards, plantations of coconut, arecanut, plantain and vegetable fields. Major habitats in this region include non-tidal, freshwater systems dominated by grasses, sedges, and other freshwater emergent hydrophytes (Image 2a,b,c). The average temperature in summer is 35°C while the average winter temperature is around 20°C. The area receives both south-west and north-east monsoons, however, the south-west monsoon tends to dominate. The area falls under the tropical monsoon climate (Köppen 1936).

Methods
The study was conducted between December 2014 to March 2018. Regular surveys were conducted by establishing fixed transects through different habitats across the study area. Birds were observed in the morning at 0630-0930 h and in the evening at 1600-1800 h using 8 x 42 Bushnell and 10 x 50 Olympus binoculars. Opportunistic records were also collected during other times of the day. Records were collected as multiple 15-minutes checklists and all the birds observed in a span of 15 minutes were counted as one checklist. Records included species of birds, number of individuals, habitat types, and other habitat & behavioural notes including the breeding observations, if any.
Wherever possible, observations were supplemented with photographs. In most cases, observations were recorded and uploaded to the online platform 'eBird'.
The birds were identified with the help of field guides (Neelakandan et al. 1993;Sashikumar et al. 2011;Rasmussen & Anderton 2012;Grimmett et al. 2014). The  (2015), Praveen et al. (2018Praveen et al. ( , 2019, and Praveen & Jayapal (2023). Following the protocol established by Kumar & Gupta (2009), the status of the species was categorized on the basis of number of sightings as: Common (Co), i.e., recorded 8-10 times out of 10 visits, Uncommon (U) recorded 4-7 times out of 10 visits, and Rare (R) recorded 1-3 times out of 10 visits. Birds were also categorized as Year-round (YR), Winter Migrant (WM), and Uncertain (UC). UC are those species that pop up anytime without a predictable pattern or are those that do not have clear data on sightings.
A measure of relative abundance of all birds was calculated. It is the percentage of occurrence of a species in a checklist which is calculated by the number of checklists in which a bird is recorded, divided by the total number of checklists. This includes checklists that did not report species and provides a measure of how frequently a species was reported relative to other species in the region. Relative abundance was analyzed for different ecological groups of birds such as parasitic cuckoos, primary hole-nesters, raptors and woodland understory birds. We assigned all species to different feeding guilds based on their dietary categories and foraging strata (Ding et al. 2015(Ding et al. , 2019Harisha et al. 2021;Panda et al. 2021;Jangral & Vashishat 2022;Rodrigues et al. 2023).

Number of checklists in which a bird is recorded
Total number of checklists

RESULTS
A total of 565 checklists of birds were created with a duration of 15 minutes each. A total of 145 species of birds belonging to 17 orders ( Figure 2) and 50 families were recorded. Among them, 42 species were winter migrants and 97 species were seen throughout the year ( Table 1). The highest number of birds was recorded during the month of January (~5,000 birds) and the lowest in June (~400 birds

J TT
in Schedule I and one species, i.e., the Peregrine Falcon Falco peregrinus is mentioned in Appendix 1 of CITES, according to the Wild Life (Protection) Amendment Act, 2022 (The Gazette of India 2023). Among the waterfowls, the Lesser Whistling Duck is a resident and is commonly seen in the region, and all other Anseriformes found here are migrants.
Relative abundance of the birds of Chemmattamvayal indicates that the White-throated Kingfisher is the most abundant species, followed by the Indian Pond Heron and Spotted Dove. The survey also documented indicator species such as primary hole nesters, which include, White-cheeked Barbet Psilopogon viridis, Coppersmith Barbet Psilopogon haemacephalus, and Black-rumped Flameback Dinopium benghalense. The presence of primary hole nesting birds is highly significant as they are considered to be keystone species and the existence of the secondary hole nesting birds such as parakeet, myna, and starling are dependent on the primary hole nesters. The present study reported four species of parasitic cuckoos such as Asian Koel Eudynamys scolopaceus, Common Hawk Cuckoo Hierococcyx varius, Pied Cuckoo Clamator jacobinus, and Grey-bellied Cuckoo Cacomantis passerinus. The study site recorded 12 species of raptors. The presence of a healthy population of raptorial birds is an indication of healthy habitat. Brahminy Kite Haliastur indus was the most common raptor, followed by Black Kite Milvus migrans. The presence of the understory dependent birds indicates that areas adjacent to the wetland has sufficient undergrowth. The study location recorded 15 species of birds dependent on the presence of understory. The feeding guild analysis of birds of the study area is given in Figure 3. The canopy-insectivores (18%) form the dominant guild followed by the aquaticinsectivores (13%).

DISCUSSION
Some factors, which threaten the wetland ecosystem and consequently the wetland bird population were identified during the study. Landscape alteration was identified as one of the major factors that leads to biodiversity loss in these wetlands. Areas adjacent to the wetland are being converted into concrete structures and some farmers are trying to convert their paddy fields into vegetable gardens. These altered land use practices have significantly reduced the presence of wetland dependent birds in these areas. Such anthropogenic influences adversely affecting wetlands were also frequently use fire crackers to scare the birds away. At the same time, majority of the people living here are much more concerned about the beauty of this wetland and the birds visiting here. The presence of the exotic vegetation such as Eichhornia crassipes and Salvinia molesta was also noticed during the study. However, the density of these exotics are relatively less as compared to similar wetland habitats. It would be prudent to establish mitigation measures to control the spread of these two wetland weeds. Information on other faunal groups dependent on the Chemmattamvayal Wetlands is currently lacking; thus, further steps are needed to document the other forms of biodiversity in this region. Regular biodiversity monitoring of the wetland is needed to study the temporal variation and associated changes in the response of various flora and fauna. Environmental education and awareness with the involvement of local stakeholders is required to stop the vulnerability of inland wetlands (Shah & Atisa 2021). Thus, conservation of these wetlands and adjacent areas can be effectively done with the involvement and support of the local people.

www.threatenedtaxa.org
The Journal of Threatened Taxa (JoTT) is dedicated to building evidence for conservation globally by publishing peer-reviewed articles online every month at a reasonably rapid rate at www.threatenedtaxa.org. All articles published in JoTT are registered under Creative Commons Attribution 4.0 International License unless otherwise mentioned. JoTT allows allows unrestricted use, reproduction, and distribution of articles in any medium by providing adequate credit to the author(s) and the source of publication.  Kumar Lal, Pp. 23083-23090