Abstract:
Biodiversity and population changes of waterfowl and waterside birds are considered as one of the indicators of evaluating the desirability of coastal habitats. In this research, the biodiversity of Waterfowl and waterside birds in the coastal habitats of Chabahar has been investigated and evaluated in a four-year period. In the four-year census in five coastal habitats of Chabahar, which was carried out by the total counting method, 43,946 birds belonging to 6 orders, 13 families and 46 species of Waterfowl and waterside wintering birds were observed and identified Waterfowl species with 82.62% and waterside species with 17.38% of all birds were included. The Laridae family was counted with 53.18% of the most birds. And the Charadriidae family (Plovers) with 20 species had the highest species diversity among Waterfowl and waterside wintering birds. The study of bidiversity indices showed that the highest species diversity index of Shannon Weiner belonging to Govater  habitat in 2018 (  ) and the lowest related to the Pasabandar habitat in 2016 ( 1/68). The highest species richness index of Margalef related to Govater habitat in 2017 the (R=5/25) and the lowest value related to the Pasabandar habitat in 2016 (R=2.43). The highest value of Pielou's evenness index related to the Govater habitats was J=0.77 in 2016 and the lowest value was J=0.56 for the Pasabandar habitat in 2018. The highest value of Simpson's dominance index related to Govater habitat (D = 0.93) in 2017 and the lowest value related to Govater habitat (D = 0.08) in 2016. The highest value of Berger-Parker index number related to Pasabandar habitat (d=0.45) in 2017 and the lowest value related to Govater habitat (d=0.17) in 2018. The highest value of Buzas-Gibson's evenness index related to the Ramin habitat ( =0.24) in 1998 And the lowest value related to the Pasabandar habitat (  in 1997. The results of biodiversity indicators show that Govater and Tis habitats have more favorable conditions for aquatic and aquatic migratory birds than other habitats. (p>0.05)
 

INTRODUCTION

Studying and comparing the density and diversity of birds in several consecutive years in a habitat can well represent the desirability or undesirability of habitat quality and living conditions for any species (Ashoori, 2014). Identification of important coastal wintering areas is very important for the conservation of bird species (McGowan et al., 2017). Coastal habitats located in Chabahar, especially estuaries and coastal wetlands, during the migration season of waterfowl and waterside, are receptive to these wintering migratory birds due to suitable weather conditions and the presence of shelter and plenty of food.
     2- MATERIALS AND METHODS
In this research, based on the field visits, five coastal habitats in Chabahar were selected to investigate the biodiversity of wintering migratory birds (aquatic and coastal migratory bird census sites), including the following habitats: Tis (N=25, 24, 21, E=60) 33 36 36), Ramin (N=25 16 08, E=60 44 42), Beris (N=25 09 32, E=61 10 36), Pasabandar (N=25 04 53, E=61 23 28) and Govater (N=25 09 59, E=61 29 51). Birds were counted in the five mentioned habitats for four years (2018-2021) and in the winter season from January 5th to February 4th every year by daily walking around the habitats and by direct observation and total counting. Excel and SPSS 26 programs were used for statistical analysis and graphing. In order to review ecological studies and compare biodiversity, Shannon Weiner species diversity indices, Margalef species richness, Simpson and Berger-Parker index, Pielou and Buzas-Gibson evenness index were used.
    3- RESULTS
A total of 43,969 birds belonging to 6 orders, 12 families and 46 species of wintering waterfowl and waterside birds were counted and identified in five coastal habitats of eastuary and beach of Tiss, Ramin, Beris, Pasabandar and Govater. Most of the families of aquatic migratory birds include egrets, cormorants, pelicans, ducks, cockatoos, and sea swallows, and the families of aquatic birds include flamingos, crab-eaters, oyster-eaters, herons, egrets. The highest number of observed species is related to the family of Scolopacidae with 15 species, followed by the Ardeiade with 7 species. The most number of birds counted during four years was related to the Laridae family (53.24 percent), followed by the Phalacrocoracidae (19.56 percent).
The most observed and identified species of waterfowl and waterside birds were related to Govater habitat in 2018 with the number of 42 species, and the least were related to the habitats of Pasabandar and Beris in 2016 with the number of 17 species. waterfowl with 83% and waterside birds with 17% of all counted birds were included. Based on statistical investigations related to biodiversity indices in different stations and years, Shannon Weiner species diversity indices, Margalef species richness, Simpson and Berger-Parker index, Pielou and Buzas-Gibson evenness index have not significant difference (p>0.05).
   4-DISCUSSION AND CONCLUSION
The survey of the birds census in the studied habitats shows that in terms of the number of counted birds, there has been a downward trend in the four years of 2018-2021, and in terms of diversity and number of species, except in 2018, there are ongoing fluctuations in other years. Birds are seen in a wide geographical range based on their ability to fly, so the increase or decrease in diversity and density of their population in one place can indicate environmental changes (Azami, 2018). In the coastal habitats studied in Chabahar, 46 aquatic and aquatic migratory birds species were identified. This number of identified bird species is more than waterfowl and waterside birds species identified in the Helleh protected area in Hormozgan (Tabiee and Sharifi., 2011). Mond Protected Area in Bushehr (Tabiee and Sharifi., 2014) and Mangrove Protected Area in Hormozgan (Karami et al., 2013) and less than the species counted in Dez Protected Area in Khuzestan (Behdarvand et al., 2015) and Almagol and Ajigol wetlands in Golestan (Golshahi et al., 2009). The destruction of habitats, the introduction of pollutants into the environment, and illegal hunting, global factors such as climate change and greenhouse effects affect the diversity and density of bird populations (Azami, 2018).
The size and diversity of coastal aquatic habitats play the most important role in attracting waterfowl and waterside birds due to their feeding habits, and habitats with suitable feeding opportunities can greatly affect the population and diversity of birds (Asgari et al., 2022). From these studies, it can be concluded that the coastal habitats of Chabahar (the studied habitats) have more favorable conditions for aquatic migratory birds than other areas. There are three types of coastlines in the studied coastal habitats. Rocky beaches, sandy beaches, and muddy beaches (Hamzeh et al., 2014). Muddy, sandy and rocky beaches with diverse morphology and tidal and sedimentary hydrographic conditions have provided a suitable shelter for waterfowl and waterside migratory birds (Ahrari roudi et al., 2012). Coastal habitats with mud beaches provide vegetation that can be a suitable source of food and habitats for waterfowl and waterside birds (Kargar et al., 2017). Vegetation can play an important role in habitat security (Hattori and Mae, 2001). Field investigations show that the habitat of Govater, with its abundance of mangrove forests, the existence of muddy beaches and the distance from fishing piers, has been able to provide more favorable conditions than other habitats for waterfowl and waterside migratory birds, and as a result, the amount of species diversity in Govater habitat is more than other habitats. High biodiversity indices in a habitat indicate the quality and desirability of the habitat (Behrouzi Rad, 2019 and Karami et al., 2013 and Tabiee and Sharif., 2013). The highest calculated value of the Shannon Wiener species diversity index belongs to the Govater habitat and the lowest value of the Simpson dominance index is also obtained in the Govater habitat. The Margalef species richness index shows the environmental condition in terms of suitable conditions for living species because favorable environmental conditions increase the presence of species (Bagheri Tavani and Jamalzadeh, 2014).
The calculation of biodiversity indices showed that among the studied habitats, Tis and Govater habitats have more favorable and quality habitats and have been able to have more species abundance and species diversity of waterfowl and waterside migratory birds.
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