Diversity of waterbirds in Wainganga river basin at Waghala near Armori, Maharashtra India

Introduction

The gradual shrinking of global wetlands area due to habitat degradation had already resulted in decline in number of waterbirds species around the world [1]. Many waterbirds species are under heavy pressure and at risk of extinction due to habitat loss that caused the degradation of breeding and feeding sites. [2]. Wetland birds are highly affected by anthropogenic activities as compared to terrestrial birds, that resulted into decline of around 41% of waterbirds population. [1]. Therefore, there is an urgent need to determine the ideal landscape for migratory birds in each geographical region of the world, where landscape-scale conservation is key component of every policy towards the protection of migratory birds. Here lies the significance of the present study, which has explored the riverine habitat of the waterbirds within the central pennunsular India terrain of eastern vidharbha in Maharashtra state, that is well known for both pristine semi-deciduous tropical forest which is also heavily affected by human activities. This study has aimed at finding out the importance of habitat profitability of the waterbirds in terms of easier landing accessibility, foraging status and nutrients resources and sense of security. Dutta in 2011 studied two wetlands of sub-Himalayan region and pointed out the anthropogenic threats of waterbird colonization like fishing, and agricultural practices[2].

The proximity of flooded rice fields in the periphery of monsoon nesting site at Waghala village provides ample amount of food, especially to water birds like Asian Openbill Stork, and Black Headed Ibis during fingerling stages, resulting in high relative abundance and density.  Most of the studies on the diversity of waterbirds in Vidarbha region of Maharashtra were focused on the Tadoba Andhari Tiger Reserve (TATR), while there is paucity of data regarding waterbirds diversity of riverine habitat. Riverine habitat site at Waghala on Wainganga river located at approximately 68 Km downstream to Gosikhurd Dam on Wainganga river near Pauni town in Bhandara district of Maharashtra. To address this data gap, we had conducted survey at Waghala riverine habitat of Wainganga River basin in order to study the fluctuations in the abundance of waterbirds during different seasons in order to plan conservation strategy of this wonderful wetland habitat. 

Material and Method

Study area

              The present study was We had undertaken monthly survey of waterbirds at Waghala riverine site (20º46’31.37”N and 79 º94’73.43”E) located at around 68 Km downstream to Ghosikhurd dam situated near Armori in the eastern part of Vidarbha of Maharashtra State in India between Nov. 2022 to Oct. 2023 in order to explore seasonal fluctuations in diversity and relative abundance (RA). (Fig.1). It spreads over an area of 1566133.43 mts² and located at an elevation of 241 mts from the mean sea level as per Google Earth data.  This riverine habitat have situated in the vicinity of communal nesting site at Waghala village, which is provided by conspicuous canopy of Tamarindus indica.  The region experiences strong seasonality with distinct winter (Nov. to Feb.), Summer (March to June), and Monsoon season (July to October). The total rainfall in the region averaged 550 mm. The highest temperature was 44 ℃ recorded in summer and lowest (13 ℃) in winter season. The landscape is dominated by the large trees of Tamarandus indicus all along the length and breadth of Waghala village. River basin is heavily explored for sand mining, apart from this fishing activity is carried out extensively. (Fig.2). Agriculture was the major land use, in which mainly paddy crop cultivated during both monsoon and summer season. Agriculture is supported by irrigation through natural as well as artificial wetlands including reservoirs, marshes, canals and village ponds within periphery of about 5Km. Region in the vicinity of study site had non-protected forest with mixed moist and dry deciduous tropical vegetation.

Bird Sampling and population estimation

            Monthly surveys of water birds were carried out between the months of Nov. 2022 to Oct. 2023. Observation of birds was done by Olympus 118760 10×50 DPSI Wide-Angle Binocular and wherever possible, photographed by digital camera Canon EOS 200D. The species identity, counting of birds, foraging habit, and feeding technique of water birds were recorded using the initial observation method (i.e. only the 1^st foraging observation of each individual was considered). [3,4] The line transect method was adapted to record the waterbirds of different species and to calculate the density (D) and relative abundance (RA). [4,5]The density of waterbirds per square acre (individuals/acre²) were calculated. Birds were also categorized according to their feeding guilds and migratory status based on bird observation guides [6,7].

Result and Discussion

During present investigation on water birds of riverine lotic freshwater habitat of Wainganga river wetland, seasonal fluctuations in the diversity of waterbirds were observed along the different orders, families, and foraging guild structure of water birds. These fluctuations along different hydrological gradients, due to the change in season correlated with the change in food resources, configuration of habitat, available surface area for waterbirds. [8,9]. Sediment transport, bank erosion and associated channel mobility represent key physical processes of rivers along with the flow regime are the key drivers of river and floodplain ecosystems[10]. These elements collectively shape the dynamic environments essential for the health and ecosystem of complex riverine ecosystes [11]. The movement of organic humus, decomposing material such as algae, leaves and inorganic particles carried by flood water impacts greatly the availability of essential resources to waterbirds [10].

The change in habitat surface, the amount and kind of food resources available to water birds during the different seasons, affects their foraging guild and community structure [12]. In the same way proximity of human habitation to the water body and their interference also contributes to the maintenance of foraging waders on the mudflats and on hydrophytes [13].  The data on the relative abundance (RA) of water birds (at Waghala riverine habitat of Wainganga river reveals that, Asian Openbill Stork (Anastomus oscitans) recorded maximum abundance throughout study period spanning winter (29.325), summer (37.696) and monsoon (27.173) season. It is followed by Little Egret (11.689) and Black Headed Ibis (9.812) in winter season, Little Cormorant (11.324) and Cattle Egret (8.235) in summer season, while in monsoon season, Black Headed Ibis (22.648) and Little Egret (14.340) respectively. Likewise, waterbirds belongs to Order – Pelicaniformes(n=10) dominates avian community at Waghala riverine habitat followed by Order- Ciconiformes (n=9) were illustrated in Fig.3. Seasonal fluctuation in avian community structure were observed; Family- Ciconidae (n=2) shows year-round domination in terms of relative abundance of waterbirds followed by Family – Ardeidae (n=7).

Water birds are strong colonial in nature and choose areas for breeding after careful evaluation of prevailing nest safety from predators, climatic conditions that offers nesting resources, and seasonal availability of food for coming generations after successful breeding. [14] Season-wise fluctuations in the waterbird densities at riverine habitat site were recorded throughout year reveals particular pattern that is illustrated in Fig.3. Monsoon season recorded peak congregation of waterbirds (44.0622 ind.ha^-1) followed by winter (27.2481ind.ha^-1) and summer season (10.4289 ind.ha^-1) at this riverine habitat situated near nesting site of Waghala village, that shows approximately 76.33% influx of birds during winter season as compared to summer season. Observations on avian community structure of waterbirds during different seasons reveals that, Asian Openbill Stork (Anastomusoscitans) dominates the density (D) of waterbirds population, that is 7.9904ind.ha^-1, 3.9313ind.ha^-1 and 11.9728ind.ha^-1 during winter, summer and monsoon season respectively as illustrated in Fig.3. It was followed by Little Egret (3.1849ind.ha^-1) and Black Headed Ibis (2.6737ind.ha^-1) in winter season, Little Cormorant (1.1809ind.ha^-1) and Cattle Egret (0.8589 ind.ha^-1) in summer season, while in monsoon season, Black Headed Ibis shows increasing trend in the density of population (9.9790 ind.ha^-1) and Little Egret (6.3187 ind.ha^-1), belonging to ord- Ciconiformes (22.4017ind.ha^-1). All these observations highlighted the change in the habitat structure which might have impacted the essential resources available to waterbirds during different seasons. These findings of ours finds its parallels in the research work in similar conditions. [13] Data on seasonal variations in observed waterbird community indicates, dominance of order-Pelecaniformes during both winter and monsoon season. It was followed by order – Ciconiformes (8.2869ind.ha^-1) and order –  Anseriformes (2.6123ind.ha^-1) in winter season, and in monsoon season, order–Ciconiformes (14.4931ind.ha^-1) and Order –Suliiformes (6.0120ind.ha^-1). The sudden rise of overall density of waterbirds during monsoon season, especially that belongs to Orders, Ciconiformes and Peliconiformes attributed to approximation of habitat in the vicinity of Waghala nesting colony.  The seasonal variations in relative abundance (RA) and density (D) among different orders and families at this study site related to their position along fresh water gradients, habitat types and human land use in the vicinity. [15]. The dominance of Asian Openbill Stork, Anastomus oscitans throughout study period spanning all the three seasons was in stark contrast with similar studies on lentic freshwater habitat like ponds and lakes and riverine habitat where, different waterbird species dominates during different seasons.[15,16]. Proximity of nesting site having profusely branched large trees of Tamarindus indica with flooded agricultural landscape and riverine habitat would have provide ideal optimum required conditions for high breeding success of nesting colonial water birds. [14,17,1819,20]

The dominant waterbird species in other water reservoirs are the representative of particular foraging guild, the changes in the factors due to the change in season makes conditions favourable for their survival and breeding. [13,16]. With the onset of winter there was influx of waders from order – Charadiformes, may be, mostly due to exposure of mudflat by receding water of monsoon flood, leaves behind plenty of food trapped available to mud probing waders. [21]. Water birds from family – Anatidae like Northern Pintail, Common Teal, Bramhany Rudy Shelduck and Bar Headed Geese migrates to this habitat in large numbers during winters may be due to the fact that paddy fields after kharip harvest in the vicinity of Waghala riverine site, acts as perfect night roosting ground. [19,22]. Such group of waders may be considered as wetland bio-indicators for an accurate assessment of the health of a particular wetland. [23].

Conclusion

The dominant waterbird species in other water reservoirs are the representative of particular foraging guild, the changes in the factors due to the change in season makes conditions favourable for their survival and breeding. Data on waterbirds community observed seasonal fluctuations as it is revealed by the fact that, order- Pelicaniformes shows domination during both winter and monsoon season. Data on Waterbird community observed seasonal fluctuations as it is revealed by the fact that, order- Pelicaniformes shows domination during both winter and monsoon season. It was followed by order – Ciconiformes and order –  Anseriformes in winter season, and in monsoon season, order – Ciconiformes and Order –Suliiformes. The sudden rise of overall density of waterbirds during monsoon season, especially that belongs to Orders, Ciconiformes and Pelecaniformes attributed to approximation of habitat in the vicinity of Waghala nesting colony.

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