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204 Rare Animals of India, 2013 , 204-241Natarajan Singaravelan (Ed)All rights reserved-© 2013 Bentham Science Publishers CHAPTER 10 Ecology and Conservation of Endemic Bengal Marsh Mongoose inEast Kolkata Wetlands, a Ramsar Site in West Bengal Jayanta K. Mallick * Wildlife Wing (Headquarters), Forest Directorate, Government of West Bengal, Bikash Bhawan, North Block, 3 rd floor, Salt Lake City, Kolkata 700091, India Abstract: Population of the endangered Bengal Marsh mongoose Herpestes palustris Ghose, 1965 (Mammalia: Carnivora: Herpestidae), previously considered a subspecies of H. javanicus, is endemic to the swampy southern West Bengal. It is the latest mongoosespecies in India, distributed in the peri-urban, non-forest, natural or manmade wetlands inHowrah, South and North 24-Parganas districts, situated on both banks of the river Hooghly. Now, only the undisturbed core area ( bheries or fisheries) of East KolkataWetlands, a RAMSAR site spread over 125 km 2 , is the last stronghold of this marshmongoose in the world. Although this typical wetland mongoose was recognized by theZoological Survey of India forty five years ago, no field studies were conducted to updateinformation on this rare animal until recently. Consequently, the Bengal marsh mongooseremained a poorly known and data deficient species. Recent researches have developed aknowledge-base on this marsh mongoose. This chapter highlights the past and presentdistributions, morphological features, ecology, behaviour, food habits, reproduction,conservation threats and status of H. palustris . During the field surveys, being conductedsince mid-2005, a sizeable population of this mongoose was found only in the largest bheries of Nalban, but probably dwindled in other habitats due to rapid reclamation of itshabitats for two new satellite townships, the Salt Lake City (Bidhannagar) and RajarhatMegacity in North 24-Parganas district, as well as other anthropogenic threats. Immediateconservation measures are required to be taken by the nodal authorities to prevent habitatencroachment and extinction of H. palustris in near future. Keywords: New native species, piscivorous bengal mongoose, controversialtaxonomy, dorsal guard hair identification, peri-urban freshwater wetland,reclamation, habitat loss, population decline, endangered. 1. INTRODUCTION1.1. Herpestids vs. Viverrids The mongooses are small to medium-sized, elongated and short-limbed predatory *Address correspondence to Jayanta K. Mallick: Wildlife Wing (Headquarters), Forest Directorate,Government of West Bengal, Bikash Bhawan, North Block, 3 rd floor, Salt Lake City, Kolkata 700091, India;Tel: +91 9432220015; Fax: +91-33-23345946; E-mail:
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[email protected] Ecology and Conservation of Endemic Bengal Marsh Mongoose Rare Animals of India 205 animals with highly tapered snouts unlike the cats. The mongoose’s fur is oftengrizzled and brown or gray in colour. The scientists have now put the mongoosesunder their own family, the Herpestidae (Bonaparte, 1845). But the older classifications sometimes placed them in the Viverridae (Gray, 1821) family, because the mongooses were srcinally descended from the viverravines, whichwere civet- or genet-like mammals. But both the morphological and molecular evidences go against the monophyly of this group.The family Herpestidae is a widespread mongoose group, but confined only to theOld World. In Africa and Asia, the evolution of Herpestidae may have beenconstrained by competition with other carnivore families that dominated severalspecialized niches. As a result, the mongoose radiations in these two continentsinvolved numerous, but rather subtle, adaptations and specializations in habitatand diet. Species distinction is most evident in the morphology of their ears,cranium, muzzle, whiskers, jaw, etc. The mongooses do have the same basic dental formula 3.1.3-4.1-2/3.1.3-4.1-2 asthe Viverrids, but they have some morphological and behavioural features thatdistinguish them from the Viverrids and other feliformian families. TheHerpestids are differentiated by their rounded ears and presence of a welldeveloped anal pouch containing glandular opening (not perineal civetoneglands). Scent deposits from their anal pouch function as olfactorycommunication. Whereas the Viverrids are often arboreal in habit, the Herpestidsare mostly terrestrial predators. However, most of the mongooses conform to thetypical Viverrid feeding regime of the small vertebrates, arthropods and plantfood, whereas a few exceptional species prefer a completely different regime for their sustenance, i.e., the aquatic diet like small pisces or mollusca, which areavailable at large in the wetlands. 1.2. Herpestid Diversity The Herpestidae is comprised of twenty one genera and about forty speciesworldwide. On the basis of molecular evidences, this family is divided into threesub-families:(1) the Herpestinae, composed of primarily the solitary or pair-livingmongooses, including the Asian genus Herpestes, 206 Rare Animals of India Jayanta K. Mallick (2) the African Mungotinae, small and highly social mongooses, and(3) the Galidiinae, consisting of all endemic Malagasy mongooses . There are thirteen species of the genus Herpestes (Illiger, 1811), in Greek meaning “creeping thief”, in the world. Of them, India is the home of sevenspecies - (1) Small Indian Mongoose: H. auropunctatus Hodgson, 1836 (synonym javanicus E. Geoffroy Saint-Hilaire, 1818) , (2) Grey Mongoose: H. edwardsi E.Geoffroy Saint-Hilaire, 1818 , (3) Indian Brown mongoose: H. fuscus Waterhouse,1838, (4) Ruddy Mongoose: H. smithii Gray, 1837 , (5) Crab-eating Mongoose: H.urva Hodgson, 1836 , (6) Stripe-necked mongoose: H. viticollis Bennett, 1835, and(7) Marsh mongoose: Herpestes palustris Ghose, 1965. Four mongoose species(serial numbers 1, 2, 5 and 7) are found in different habitats of the state of WestBengal. H. palustris is one of the few mammal species of freshwater eco-region andcommonly known as Bengal or Salt Lake marsh mongoose (also called Indianmarsh mongoose). It is locally called Jalabhumir Neul (in Bengali). Inasmuch asother mongoose species of India were discovered within mid-19 th century, H. palustris could only be traced after mid-20 th century and, therefore, is the latestmongoose species discovered in the country. 1.3. Taxonomy of H. palustris Validity of the species as well as endemicity of H. palustris (Mammalia:Carnivora: Herpestidae) has been recognized by the Zoological Survey of India(ZSI), Kolkata [1]. Out of forty four endemic mammals of India, H. palustris isthe only mongoose species [2]. The Wildlife Institute of India, Dehradun, hasdocumented occurrence of this endemic species [3, 4]. The ConservationAssessment and Management Plan for Mammals of India also categorised thisspecies as endemic to West Bengal [5].The Bengal Marsh Mongoose H. palustris was first reported as a new natural aswell as native species from the swamp of the present Salt Lake City anddistinguished from the superficially similar small Indian mongoose, H.auropunctatus, by examining the skin and skull of the adults in the stock of ZSI Ecology and Conservation of Endemic Bengal Marsh Mongoose Rare Animals of India 207 [6]. Previously, palustris was considered a subspecies of H. javanicus [7]. It isalso synonymized with H. auropunctatus [8]. Whereas palustris, auropunctatus and javanicus are considered conspecific [9, 10], such a relationship between palustris and urva was also speculated on the basis of some morphological and behavioural similarities [11].Though the nearest relative of H. palustris appears to be H. auropunctatus, thetwo species appear to inhabit quite different ecological niches. Their dissimilar morphological characters, occurrence in different ecological conditions, shortduration of foraging, dissimilar food habits, typical hunting techniques andabsence of hybridisation tend to indicate that the two species are siblings [12]. 1.4. Literature H. palustris was a least known and data deficient species until recently. Thoughthis mongoose species was first discovered by the scientists of ZSI more thanforty five years ago, information regarding its ecology and population status wasscanty during 1970–2005. Even though ZSI have conducted status surveys of many endangered species of mammals during this period, H. palustris remainsunfocused.Since ZSI recommended that the taxonomic status of this controversial species of mongoose requires further study with fresh specimens [2], such attempts weremade in 2005–2006 in the East Kolkata Wetlands (EKW). Accordingly, thesrcinally identified characteristics of the type species have been reestablished.Further, on the basis of recent comparative laboratory analysis of the guard hairsof five Indian mongoose species by ZSI, entity of the Bengal marsh mongoose asa distinct species has been proved.Occurrence of the Bengal marsh mongoose in the south Bengal eco-tone was,however, recorded earlier in a few literatures [13-21]. Some site-specificinformation was, however, available subsequently [22, 23]. The habits, food preference and family life of the marsh mongoose are known recently [24]. Thecurrent status of this species is also documented [25]. H. palustris is recentlyincluded in ‘Handbook of the Mammals of South Asia’ [26]. 208 Rare Animals of India Jayanta K. Mallick 1.5. EKW EKW was the northern limit of the estuarine Sundarban mangroves till the 18 th century, but is now remnant of the vast stretches of the erstwhile Salt Lakes. Theearliest known history of these Salt Lakes goes back to the year 1748, when thiswidespread habitat, teemed with a rich variety of the fish, birds and mammals,was extended right up to a mound known as Dumduma (= Dum Dum), near whichthe Burmese and Mug traders were arriving on boats. But due to siltation anddeterioration of the tidal river Bidyadhari on the eastern side of EKW, the areawas cut off from the Sundarbans. Being unaffected by the tidal variation and dueto diversion of the city sewage and rain water into the salt lakes, there had been agradual change in the aquatic environment of EKW from saline to non-saline, i.e., freshwater.Geologically, EKW forms the southern part of the Indo-Gangetic Basin. It islocated 8 km to the east of Kolkata metropolis. Its elevation is 2 m above msl. Thegeneral slope of this marshy tract is towards the south-east. The climate istropical. Total rainfall during the monsoon months varies between 1200 mm and1300 mm. The relative humidity fluctuates between 80 percent and 85 percent,while the average wind speed remains at 5 kmph.Depth of the water bodies (268 in number) is rarely more than one metre(maximum 2 m), but they normally have water throughout the year (a few driedup in the summer), except when these are drained out for drying of the bed andremoving the siltation, which takes about 3 to 4 weeks’ time before water refilling. The depth of water increases by about 10 to 15 cm during the monsoon.The downstream area is mostly paddy growing with occasional patches of settlements. At present, a tannery complex has come up beyond the eastern boundary of the designated wetland conservation area.The resource recovery systems developed by the local people through ages, usingthe wastewater from the city is largest in the world. In the process, it treats thewastewater for pisciculture and agriculture and has saved the city fromconstructing and maintaining a wastewater treatment plant. This wetland area is particularly efficient in sediment trapping and more importantly trapping of
