M Sc Dissertation(WII)
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Item Species Assemblage and Differential Basking Habitat Use of Freshwater Turtles in a Gradient of Mahanadi Riverine Ecosystem, Orissa(Wildlife Institute of India, Dehradun, 2009) Jani, Chandan; Choudhury, B.C.; Sivakumar, K.Of the seven species of turtles recorded in the Mahanadi River, this study recorded five species of freshwater turtles between Satkosia Gorge Wildlife Sanctuary and Khakadi (Near Cuttack city) during November 2008 to April 2009. Of these five species, four were softshell turtles (Nilssonia gangeticus, Nilssonia hurum, Chura indica, Lissemys punctata) and one was hardshell (Pangshura tentoria). Relative abundance in terms of mean number of individuals sighted per kilometre was estimated. The results showed that Pangshura tentoria was most abundant and was recorded over all the sampling zones, followed by Nilssonia gangetic vs Nilssonia hurum and Chitra indica. The latter three were not distributed as commonly as the former. Lissemys punctata was not included in the report as the species never sighted during the sampling secession. However, the species was found to get captured in incidental fish catch during the study period. The low abundance of Chitra indica and Nilssonia hurum might be due to degradation of their habitats. These two species are known to refer undisturbed and wider river stretches which are diminishing in the Mahanadi River. The habitats of the river stretch between Satkosia Gorge Wildlife Sanctuary and Kakhadi varied significantly and thus, explaining the variation in the species richness as well as abundance. The major habitat variables, which have highly influenced the turtle abundance were river flow, river width and river bank characteristics. Highest abundance of species was found in the non-riparian flow zones and river stretches with rocky and sandy banks, where the habitat heterogeneity was greater. These two sampling zones also experienced the least anthropogenic pressures. Choice in habitat use for basking in turtles was also observed. The choice of the habitat varied between species. Nilssonia gangetic and Nilssonia hurum preferred areas which had greater river bank width with shallow water near the bank. Chitra indica preferred areas where both river depth and river width were higher whereas bank slope, river slope, ground cover, alternative basking substrate and immediate water depth was lower. Pangshura tentoria preferred areas with greater river and bank slope along with greater availability of alternative basking substrate and greater immediate water depth. On the other hand they also preferred the habitat more close to the river with lower bank width and moderate river depth and moderate river width. Major threats to turtles in the Mahanadi river (sampling zones) are due to anthropogenic pressure and habitat degradation. Some of the threats were found to be consistent over the sampling zones. The study shows that Pangshura tentoria was highly tolerant to all prevailing threats in the Mahanadi river but, Nilssonia hurum and Chitra indica were adversely affected by these threats all along the river. This study found that there was a negative correlation between the turtle abundance and presence of threats such as sand mining, pump house, fishing and pollution. Sand mining adversely affected the basking habitat of most of the turtle species. Pump houses were largely avoided by the turtles which may be due to the vibrations or noise created at these stations. Unintentional by-catch of turtles during fishing was also observed especially in the braided flow zones and inundated static flow zones of the Mahanadi river. Sand mining and fishing are identified as the major threats to the turtles in the Mahanadi river, which should be monitored and regulated. Sand mining should not be allowed during the breeding season of the turtles especially in the area of Non riperian flow zone and braided flow zone. These two sampling zones were identified as the Important Turtles Areas (ITAs) in the Mahanadi River. Alternate livelihood options should be identified and implemented in order to reduce people's dependency on fishing in this region. Nature education and awareness programme clearly addressing the reason for declining of turtles and their habitat in the Mahanadi river needs to be launched.Item Nest Site Selection and Effects of Anthropogenic Changes to the Rushikulya Nesting Beah, Orissa on Olive Ridley Sea Turtes(Wildlife Institute of India, Dehradun, 2009) Muralidharan, M.; Sivakumar, K.; Choudhury, B.C.The Olive Ridley sea turtle Lepidochelys olivacea is known to nest both sporadically and in arribada's in the Indian coastline. Of the three mass nesting sites on the Orissa coast, the Rushikulya rookery has been considered as a key factor in maintaining the future populations of the Ridley's in the Indian coast. Though several studies have been carried out on various ecological aspects of the species along the Orissa coast this study looked into a finer scale of behavioural patterns exhibited by the females while selecting the nesting sites. Other aspects that are looked into in detail in this study included the various impacts of anthropogenic activities near the nesting habitat of the turtles including the impact of nest predators. The observed sporadic nesting turtles crawled an average of 47.39 m from the waterline before nesting (Range = 10.7(102m, SD = 21.0481, n = 70). Tests were conducted to check for the possibility of whether turtles were actively choosing their site of oviposition while compared to random placement over varying distances. Beach slope and soil temperature were not found to be significantly different from the nesting sites (Slope - F = 1.289, . Temperature - F = 2.241, df = 8 P>0.05) while compared to sites along the track of the nesting turtles, whereas pH and moisture were found to be significantly different from the nest-site to all sites prior to them (pH - F=37.640, Moisture - F = 44.208, df = 8 P<0.05). This shows the possibility of both pH and slope to be amongst the possible proximate cues used by a turtle in deciding a final nest. The effects of beach lighting on the disorientation of turtle hatchlings at this site has already been studied at various levels and this study re-affirms the results of the previous studies by including the effects of lighting acting upon various distances away from the water-line as well as different photic conditions present along the beach and from the adjoining villages. With areas near the villages showing maximum disorientation while compared to areas shielded from light by Casuarina plantations. Associated human activities near the Rushikulya rookery could also act in supporting and maintaining populations of certain animals (feral dogs, jackals), which have had an increased threat to turtle nests. The plantation of Casuarina adjoining the nesting beaches could also act in providing refuge to such predators apart from the known effect of changing the geomorphologic profile of the beach. These predators are known to be able to thrive even in marginalized habitats sustaining their numbers near human occupied areas. These plantations may thus also be aiding an artificial boom in their numbers thus having an increased impact of their predation on turtle nest while compared to natural levels ·of predation loss. A Passive Tracking Index (PTI) for the predator presence and activity observed a minimum presence before the mass nesting which increased immediately after the commencement of the mass nesting. Protective chain link fencing laid across sections of the beach flanked by Casurina to reduce the predator pressure in these areas may not have proven to be completely successful as high activity was still observed in the weeks following the mass nesting.Item Diurnal and Seasonal Activity Pattern of Water Monitor (Varanus salvator) in Bhitakanika Wildlife Sanctuary, India(Wildlife Institute of India, Dehradun, 1993) Pandav, Bivash; Choudhury, B.C.This study investigated the diurnal and seasonal activity pattern of water monitor, Varanus salvator in Bhitarkanika Wildlife Sanctuary, India. The study was conducted in an intensive study area of 17 sq.km selected after a pre sampling survey in the Sanctuary. The methodology involved to record the activity pattern of water monitor was monitoring of two permanent standard paths every three hours on diurnal basis. Sightings of water monitors were recorded while walking on the standard path. Behaviour of water monitor was divided into four categories such as basking, foraging, resting and non-foraging. Microhabitat of water monitor was recorded on each sighting. Ambient and substrate temperatures and ambient relative humidity were recorded along with diurnal activity pattern of water monitors. Results show a shift in diurnal activity pattern with season. The activity pattern of water monitor was unimodal in winter and uniform in summer. Basking was the major activity of water monitor in winter, whereas all the activities were evenly spread out in summer.The lizards used different microhabitats for different activities. Maximum lizards were recorded active at cooler substrate temperatures (29°C). The relation of ambient and substrate temperatures with activity was curvilinear. At low ambient temperature basking was prevalent. With increase in temperature other activities, such as foraging and resting were recorded. At high ambient temperature lizards selected cooler substrates. Ambient temperature and ambient relative humidity varied inversely. The activity was low at high levels of humidity It is concluded that behavioural thermoregulation plays a major role in water monitor’s activity.Item Pollinator Visitation and Reproductive Success in Two Species of Mangrove Plants, in Bhitarkanika Wildlife Sanctuary, Orissa(Wildlife Institute of India, Dehradun, 1997) Pandit, Shalini; Choudhury, B.C.Visitation patterns to the flowers of Sonneratia caseolaris and Aegiceras corniculatum were investigated between December 1996 and April 1997, in the mangrove forests of Bhitarkanika Wildlife Sanctuary, Orissa. The objectives of the study were to determine the pollination effectiveness of the different categories of visitors by quantifying their rate of visitation. The effect of environmental variables on visitation was examined, and the importance of the visitors to the reproductive success of the plant was investigated by conducting exclusion experiments (Le. bagging flowers to prevent visitation). Nectar was analysed for volume and sucrose content in S. caseolaris, and the impact of predation on the reproductive success of the plant was examined. The results of the study indicated that the flowers of both plant species attracted a wide array of visitors and did not show a specialised relationship with anyone visitor species/category. Different categories of visitors were seen to vary in their pollination effectiveness for the two plant species. Environmental variables such as temperature, sun intensity and wind velocity were seen to influence the visitation of Lepidoptera to the greatest extent, and Hymenoptera to a lesser extent. Visitation by birds was found to be independent of the environmental variables. The territorial behaviour of purple-rumped sunbirds at the S. caseolaris site was seen to reduce visitation of other birds and of bees to the flowers of this species. Results of the bagging set-ups indicated that there was no difference in the pollinator effectiveness of the nocturnal and diurnal visitors. Reproductive success was not pollinator-limited in either of the two plant species.