Population Trends and Spatiotemporal Changes to the Community Structure of Waterbirds in Birbhum District, West Bengal, India

Proceedings of the Zoological Society 12/2011; 64(2):98 - 106; DOI 10.1007/s12595-011-0018-8. DOI: 10.1007/s12595-011-0018-8


Waterbird assemblages on five important wetlands of Birbhum district, West Bengal, were studied for thirteen years to examine the changes in the community composition of the waterbirds and to quantify their population decline during the period between 1998 and 2010. The spatiotemporal analyses revealed that the waterbird communities of these wetlands maintained high spatial but low temporal variations in their structure. Such within-wetland homogeneity was attributed to a relatively static distribution of some key resources. The spatiotemporal variations in the abundance and community structure were associated with a shift in distribution of some important winter migrants from a disturbed and deteriorating wetland to a newly built well protected one. Twenty one species of waterbirds acted as significant indicators in structuring the waterbird communities of these wetlands, revealing their species rich nature. However, comparisons between data collected for these wetlands in 1998 and 2010 showed that notable changes in these waterbird communities have occurred over longer periods of time, with 16 of the 25 most common and important species having declined in this period indicating an overall decline by 38%. These wetlands still regularly supports globally important populations of four waterbird species.

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    • "It also supports rich diversity of arthropods,molluscs and fish (Sinha and Khan, 2011). A detailed study on the bird species revealed that it harbors breeding grounds for Great Cormorant (Phalacrocorax carbo), Great Crested Grebe (Podiceps cristatus), Ruddy Shellduck (Tadorna ferruginea), Gadwall (Anas strepera) and Common Coot (Fulica atra) which are considered to be indicators of Bakreswar as a wetland (Sinha and Khan, 2011). These birds are common winter migrants which visit Bakreswar every winter (scientific names of each bird are given in parenthesis). "
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    ABSTRACT: Reservoirs and dams are engineered systems designed to serve purposes like supply of drinking water as well as other commercial and industrial use. A thorough assessment of water quality for these systems is thus necessary. The present study is carried out at Bakreswar reservoir, in Birbhum district, which was created by the dam, built on Bakreswar River. The major purpose of the reservoir is the supply of drinking water to the surrounding villages and Bakreswar Thermal Power Station. Water samples were collected fortnightly from three different stations of the reservoir. Physical and chemical factors like dissolved oxygen, atmospheric temperature, pH, conductivity, salinity, solar radiation, water temperature, alkalinity, hardness, chloride, productivity etc. were analyzed using standard procedure. Abundance data is calculated for four major groups of zooplanktons (Cladocera, CopepodaOstracoda, and Rotifera) with the software PAST 2.1. Multivariate statistical analysis like PCA, hierarchical cluster and CCA are performed in order to predict the temporal variation in the water quality factors using SPSS 20. Distinct seasonal variation was found for environmental factors and zooplankton groups. Bakreswar reservoir has good assemblage of zooplankton and distinct temporal variation of environmental factors and its association with zooplankton predicts water quality condition. These results could help in formulating proper strategies for advanced water quality management and conservation of reservoir ecosystem. Key elements for growth and sustenance of the system can then be evaluated and this knowledge can be further applied for management purposes.
    Full-text · Article · Sep 2015
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    • "To obtain arrival and departure dates for each species, we monitored the wetlands on a daily basis during the period from October to December (for arrival dates) and from February to April (for departure dates). These periods were chosen to coincide with arrival and departure periods of the waterbirds in this region (Khan et al., 2005; Khan, 2010; Sinha et al., 2011). "
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    ABSTRACT: We analysed the relationships of the arrival and departure, abundance and assemblages of 13 migratory waterbirds in three tropical wintering abodes, with calendar-effect and air temperature. The birds arrive at the wetlands in October-November and most of the long-distance migrants spent 4-5 months, while the short-distance local migrants stayed there for almost 7 months. Much like the onset of autumn migration from the breeding ground, the period of arrival at these wintering abodes was influenced by photoperiod confounded with other calendar-date effects. There was a significant negative relationship between this variable and the abundance of all the 13 species and their maximum abundances corresponded closely with the shortest day length. The temperature tended to fine-tune the migration schedule. The migration phenology and abundances of all the species exhibited strong negative correlations with this environmental variable and maximum abundances were observed during the middle of January, which experienced the coldest temperatures of the region. The long-distance migrants left the wetlands earlier than the short-distance local migrants. Both the photoperiod confounded with other calendar-date effects and temperature affected dissolved oxygen concentration and phytoplanktonic productivity of the wetlands, which influenced the waterbirds. Dissolved oxygen concentration affected the abundances of most of these waterbirds probably through its impact on their food resources. Phytoplanktonic productivity might also influence overall food supply to the waterbirds.
    Full-text · Article · May 2012 · Acta Oecologica
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    ABSTRACT: We studied the waterbird diversity and abundance in a newly constructed wetland in South Bengal for 14 years right from its establishment. Soon after its construction, the wetland began to attract rich diversity of waterbirds and through the passage of time has proved its potentiality to achieve the status of a wetland of international importance. Since 2005, it continues to support Greylag Goose at populations exceeding 1% threshold and from 2007 onwards harbours Ruddy Shelduck at populations exceeding 1% threshold. Since the populations of majority of the important species have been increasing it is expected to achieve the status of a Ramsar Wetland very soon provided we keep it undisturbed and allow it to follow its own course by implementing monitoring programme on a long-term basis.
    Full-text · Article · Jan 2011 · Current science
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