Understanding the mangrove-associated avifauna and their conservation status in the Gorai Creek, Western Mumbai, Maharashtra, India: A Recent Study

— The research was conducted from June 2017 to June 2019 to better understand the diversity and current state of the avifauna in the Gorai Creek region. 96 species belonging to 39 families from 16 orders, including terrestrial and aquatic birds, were identified as surviving near the stream over the two-year research period, including residents, migratory, common, uncommon, and unusual species. 64 species were permanent birds, 28 were winter migrants, 4 were summer migrants, 23 were uncommon, 57 were common, and 16 were rare. Anatidae, Ardeidae, Cuculidae, Accipitridae, Sturnidae, Strigidae, Laridae, Charadridae, Scolopacidae, and Rallidae were the most regularly observed bird families. The extensive mangrove cover around the creek provided food for all the birds. The ferry system to Gorai village, as well as the Essel World Park, has been seen to mildly impair the birds' breeding and foraging. Seasonal changes have a significant impact on bird numbers. Except for the ferry system, anthropogenic disturbances are quite minimal in the area, therefore the creek has less pollution and dense mangrove foliage, which shelters the avifauna that thrives in the zone.


I. INTRODUCTION
Mangrove systems are a perennial, salt-tolerant plant community that thrives in tropical and subtropical intertidal coastal zones across the world. Mangroves have been found to contain a larger diversity of terrestrial and aquatic birds than tidal flats, floodplains, and coastlines (Mac Arthur and Mac Arthur, 1961). Mangrove habitats are regarded to be among the world's most prolific ecosystems (Mann, 1982). Despite their importance, mangrove ecosystems have been destroyed or degraded to the tune of 50% in the last two decades (Zakaria and Rajpar, 2015). They are important habitats for many faunal species, offering refuge, food, and breeding opportunities (Mestre, Krul, and Moraes 2007). More than 40% of bird species and roughly 12% of other faunal species are found in wetlands across the world (Rajpar and Zakaria, 2010). The health of a mangrove ecosystem is determined through detailed investigations of various physical and chemical factors, as well as studies of indicator organisms, particularly avifaunal species. Mangrove trees have long been known to play a critical role in estuarine ecosystems, sustaining most of the other creatures that rely on the lush mangroves for survival. Birds are regarded as the most effective biodiversity indicators among a range of creatures, owing to their resonance and connection with humans and their lifestyles (Gregory and Strien, 2010). In a mangrove community, the presence of birds is the best sign of the system's health (Holguin et al. 2006). Although birds are the finest bioindicators and mangroves act among the most favored nesting and feeding sites for the avifauna, there is little research on the avifauna of the mangrove The purpose of this study is to update existing data and to investigate and describe the avifaunal species that survive in the Gorai Creek mangrove habitat. A preliminary investigation of the impact of human activity in the area has also been made.

II. MATERIALS AND METHOD
The Gorai Creek area, which is roughly 10 feet above sea level and located between 19°14' 12.69" N and 72°49'12.51" E, is the research location for the current investigation. The creek is a 12-kilometer length of mangrove mudflats and low-lying marsh that runs inland. The creek's southern section is Gorai-Charkop, while the northern region is Gorai village. Semi-diurnal tides, which flood the creek's lower portions, have a big impact on the area. Avifaunal observations were made at ten sites along the stream channel. From June 2017 to June 2019, the avifauna was documented in the early mornings from 5.00 AM IST to 7 AM IST and in the evenings from 5 PM IST to 7 PM IST over a period of two years on alternate days. Using the point transect approach, the birds were watched and recorded at each position. The birds were photographed with a Nikon D300 digital single-lens reflex camera and binoculars for observation. Field guides were used to identify the birds (Grimmett, Inskipp C, Inskipp T-2011; Ali, Salim -1996; Salim Ali -2002). According to "The Book of Indian Birds," the birds were categorized and tallied based on their frequency and ecological condition (Salim Ali, 2002).

IV. RESULTS AND DISCUSSION
The current investigation, which lasted two years, discovered 96 species of avifauna from 39 families and 16 orders, both terrestrial and aquatic. Residents, summer and winter migrants were all seen to be reliant on the tidal creek for survival. Anatidae, Ardeidae, Cuculidae, Accipitridae, Sturnidae, Strigidae, Laridae, Charadridae, Scolopacidae, and Rallidae were the most regularly observed bird families. Residents (observed throughout the year and are residents of the locality); Winter Migrants (observed only during the winter season, i.e., December to January); and Summer Migrants (observed only during the summer season, i.e., June to August) (observed only during the summers i.e., April to June). There were 64 resident birds, 28 winter migrants, and four summer migrants among the observations. Depending on the observations made throughout the research period, the observed birds were additionally abundance categorized as Common, Uncommon, or Rare.
• C (Common) (Found in moderate to large numbers, and easily found in appropriate habitat at the right time of year).
• Uncommon (UC) (found in limited numbers, usuallybut not always-with some effort in proper habitat at the correct time of year) • Rare (r) (Occurs once a year in extremely small quantities.) It's not something you'd expect to find on any one day, but it may be located with enough effort throughout the course of the relevant season(s).
There were 57 common, 23 uncommon, and 16 rarely occurring species found and recorded. The percentage of birds spotted based on abundance codes is shown in graph 2.
Out of the total species of birds observed, there were 9 species whose conservation status is globally threatened according to the IUCN/ Birdlife International Red Data List 2011.
The presence of nine globally vulnerable bird species means that the species must be regularly monitored and conserved as needed. Even though the number of birds of each of these species seen was quite low, they were found in lonely groups spread throughout the extensive mangrove vegetation in the stream. They have been seen to rely on the ecosystem for reproducing and nesting as their primary means of survival.  1979). The number of birds in an ecosystem shows the area's environmental quality, pollution level, security, and food and habitat availability (Pachpande and Pejaver, 2016). This indicates that there is less pollution in the area and that anthropogenic activities in the area are minimal. The Maharashtra Maritime Board developed jetties on both banks of the Gorai stream. The only significant activity in the region is the ferries that connect Gorai Village to Borivali West and another that connects the amusement park Essel World to Borivali. A few fishermen rely on the region as their primary source of fish and income. However, given the abundance of avifauna in the area, it is reasonable to assume that these activities have little impact on the environment. Because of the Maharashtra Maritime Board's care, the waters of the tidal stream are also quite clean and pollution-free.
Due to the sensitive nature and significance of mangrove ecosystems and their thick lush green habitats for nesting and breeding birds, many comparable studies have been