Birds of Mahi River estuary, Gujarat, India

Pranav J. Pandya ¹& Kauresh D. Vachhrajani ²

^1,2 Department of Zoology, Faculty of Science, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat 390002, India

Email: ¹ pranavpandya1@yahoo.com,² kauresh@gmail.com

Date of publication (online): 26 June 2010

Date of publication (print): 26 June 2010

ISSN 0974-7907 (online) | 0974-7893 (print)

Editor: Nishith Dharaiya

Manuscript details:

Ms # o2316

Received 17 September 2009

Final received 12 January 2010

Finally accepted 06 April 2010

Citation: Pandya, P.J. & K.D. Vachhrajani (2010). Birds of Mahi River estuary, Gujarat, India. Journal of Threatened Taxa 2(6): 994-1000.

Copyright: © Pranav J. Pandya & Kauresh D. Vachhrajani 2010. Creative Commons Attribution 3.0 Unported License. JoTT allows unrestricted use of this article in any medium for non-profit purposes, reproduction and distribution by providing adequate credit to the authors and the source of publication.

Acknowledgements: The authors are thankful to the Department of Science and Technology, New Delhi, India, for financial assistance. PJP is thankful for the award of fellowship under the scheme.

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The Mahi River is one of the major rivers of Gujarat. The estuarine stretch extending up to 50km was considered for the present study. The vast and complex ravines of the Mahi River make the habitat more suitable for terrestrial birds just in the vicinity of the river channel. The salinity flux, a typical estuarine character, also provides a freshwater habitat upstream while the estuarine mouth downstream can be considered as a high marine influenced zone. These eventually may result in changes in the inhabitant water fowlcommunity. Sparse studies have been carried out and documented so far for the Mahi Estuary. The estuary has been studied previously by Jadhav & Parasharya (2004) who detailed the distribution of flamingoes at Khambhat and Dhuvaran (downstream of the Mahi). Work has been done on the avian diversity of Vadodara District which covers some part of the present study area (Padate et al. 2001). Moreover, literature surveys of a few years show notes of some important sightings like Black-necked Stork and Blue-tailed Bee-eater (Patel 2008). Unusual sightings of Crab Plovers (Dromas ardeola) have been reported by Parasharya (2008) on Dhadhar Estuary, Gulf of Khambhat; whereas it is well reported in Gulf of Kutch (Palmes & Briggs 1986). In the present study the same was sighted at the mouth of the Mahi Estuary which could be the supportive observation and new for the upper part of Gulf of Khambhat. The present study provides a comprehensive checklist of birds of the Mahi Estuary by covering more than 15 sites along the estuarine stretch.

Study Area

The Mahi estuarine stretch extends up to 50km, from Kamboi (22⁰12’52.38”N & 72⁰37’17.89”E) to Fajalpur (22⁰26’08.95’’N & 73⁰04’26.98”E) (Fig. 1). The estuarine belt covers around 50km passing through Anand, Vadodara and Bharuch districts. The uppermost reaches (Fajalpur and Vasad) typically serve as freshwater habitat with floating and emergent vegetation, very rarely having saline flux; while the lowest reaches (Kamboi and Khambhat) reflect marine habitat with daily tidal cycles. The estuarine part also provides the isolated islands in the channel and the ravines and cliffs on the adjacent banks at many sites which serve as good habitat for the terrestrial birds. Aquatic pollution due to industrial effluents is the major cause of the degradation of the habitat.

Materials and Methods

The study was conducted from August 2006 to July 2009. Salinity was measured from different sites using handheld refractometer (ERMA made) with salinity range of 1-100 ppt. Salinity less than 1ppt from upstream reaches wasmeasured using titrimetric method (AgNO₃) (Eaton et al. 1995). For the sake of convenience, easy understanding of estuarine dynamics and to check variations in avian distribution, the estuary was divided into upstream (Fresh water condition: 0.05-0.1 ppt), midstream (Oligohaline condition: 0.09-1.6 ppt) and downstream (Euhaline condition: 9.6-39.3 ppt) based on the monitored salinity status and range. The study area was covered by delineating 15 different stations along the estuary covering all different parts. Birds were observed libitum using binoculars and identified using standard field guides (Ali 1996; Grimmett et al. 1998). Aquatic birds of the Mahi Estuary as well as the birds of the adjacent ravines/banks within the vicinity of 50m were recorded. In case of complications in identification, especially of gulls and terns, photographs were taken when possible and later identified. Data were divided into upstream, midstream and downstream and was further compiled and subjected to similarity (Jaccards and Sorenson indices) and diversity indices (Shannon-Wiener, Simpson and Berger Parker) using PAST statistical software.

Results and Discussion

A total of 118 species were reported belonging to 42 families during the study period (Appendix 1). Although, some of the families were represented by one or two species, family Scolopidae dominated with 10 representatives (Table 1) and was mainly confined to the lower reaches of the estuary. Species richness was higher upstream with 68 species contributing 37% of the total number followed by midstream 63 species (33%) and downstream 57 species (30%) (Fig. 2). However, no significant difference in diversities among the three zones was noted (Table 2). Jaccard’s and Sorenson’s similarity indices depicted higher similarity between upstream and midstream followed by midstream and downstream. The higher diversity in upstream and midstream can probably be attributed to the appropriate feeding landscape available for aquatic birds and the adjacent bushy habitat in the gorges and ravines for terrestrial birds.

Conclusively, it can be stated that the Mahi Estuary and the adjacent ravines/gorges and bushy habitat within provides excellent environment for a variety of birds. As the present investigation did not include a detailed study of interior ravines, further surveys in the ravines and adjacent terrestrial region can certainly make a good addition to the present checklist.

The upstream estuarine region is closer to the Vadodara industrial zone dominated by petrochemical and other organic industries. However, the effluent discharges of these industries are released in the lower estuarine region through Asia’s longest effluent channel. Therefore, the animal diversity and density in certain polluted pockets of the lower estuarine region is very low leading to lesser diversity of dependent avifauna. The freshwater upstream site has religious importance resulting in high pilgrim pressure. However, since the long term quantitative data on pilgrim inflow is not available, it cannot be correlated with present avifaunal diversity. Further, the analysis of biomagnifications of pollutants and their influences on avifauna require a long termstudy; it is not possible to establish direct relationship between these factors and the present avifauna. It can be suggested that the increased human interventions in the upstream areas and the pollution stress on the downstream habitat may pressurize the estuarine complex and, if not mitigated, can eventually result in decrease in avifaunal diversity.

References

Ali, S. (1996). The Book of Indian Birds. Bombay Natural History Society, Bombay, 354pp.

Eaton, A.D., L.S. Clesceri & A.E. Greenberg (1995). Standard Methods for the Examination of Water and Waste Water (19th edition). United Books Press Inc. Batimore, Maryland, U.S.A., 1126pp

Grimmett, R., C. Inskipp & T. Inskipp (1998).Birds of the Indian Subcontinent. Oxford University Press, Delhi, 888pp.

Jadhav, A. & B.M. Parasharya (2004). Counts of flamingos at some sites in Gujarat State, India. Waterbirds 27(2): 141-146.

Padate, G.S., S. Sapna & R.V. Devkar (2001). Status of birds in Vadodara District (Central Gujarat). Pavo39: 83-94.

Palmes, P. & C. Briggs (1986).Crab Plovers Dromas ardeola in the Gulf of Kutch. Forktail 1: 21-22.

Parasharya, B.M., C.K. Borad & D.N. Rank (2004). A Checklist of the Birds of Gujarat. Bird Conservation Society, Gujarat,185pp.

Parasharya, D. (2008). Crab Plover at Dhadhar Estuary in Bharuch District. Flamingo 6(3&4): 10.

Patel, P. (2008). Breeding record of Blue-tailed Bee-eater near Vadodara. Flamingo 6(3&4): 10.