Browsing by Author "Choudhury, B.C."

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An Investigation of the Relationship Between Green Turtle (Chelonia mydas herbibory and Seagrass in the Agtti Lagoon, Lakshadweep
(Wildlife Institute of India, Dehradun, 2007) Lal, Aparna; Choudhury, B.C.; Sivakumar, K.
Globally, nearshore ecosystems are being increasingly impacted upon by expanding coastal development. The almost complete dependence of marine mega herbivores like Green Turtles (Chelonia mydas) on these habitats for food together with their current low population levels in many regions highlights the need to understand this vital relationship. This study was an attempt within this framework. It aimed to quantify the intensity and potential impacts of Green Turtle grazing on the seagrass Cymodocea rotundata in the Agatti Lagoon, Lakshadweep. To map the habitat types in the lagoon, points generated from a grid were used, while 23 transects, perpendicular to the shore, formed the basic sampling unit to assess turtle density and map their distribution patterns across the lagoon. The study recorded exceptionally high turtle abundances within the lagoon with their distribution patterns being restricted to certain areas within the seagrass meadow. The magnitude and potential impacts of herbivory were quantified across the established gradient of turtle density in the lagoon. It was found that C. rotundata plant parameters like morphology, life history strategies, population dynamics and meadow level characteristics were significantly different in areas with less turtles, indicative of a response to turtle grazing, results supported by experimental evidence. It was found that increased shoot recruitment rather than increased shoot production could be a mechanism whereby seagrass deals with intense herbivory. This study shows that grazing intensity is an important factor potentially regulating the response of seagrasses to grazing.
Assessment of hydrologic functional and water budget of Keoladeo National Park watershed.
(2007) Singh, Ritu; Choudhury, B.C.
Keoladeo National Park (KNP) is situated in the plains of Bharatpur (27°7'6"N - 27°12'2"N and 77°29'5"E - 77°33'9" E), Rajasthan, India. It is considered to be the last remaining grassland- wetland complex in the Yamuna floodplains in this region. The wetland Protected Area CPA), located in the semi-arid tract of India is largely dependent on the erratic and short duration of the precipitation time. To enhance the wet characteristics of the protected area, additional water supply provisioning has historically been made from other large water harvesting structures within its watershed. However, due to the development of intense agriculture in the watershed and increased or incessant harvesting of surface water flow in the river systems and catchment combined together, the protected area is facing an acute water problem gradually decreasing the wet regime of its wetlands, this is also further diminishing its functional values. In case of KNP, as it is located in semi-arid region and fed by ephemeral rivers, the affects of water crisis are acute as well as immediate in the Park. Further, the wetlands of KNP perform several important hydrological functions like groundwater recharge that have value not only for sustaining the ecology of the region but also for the surrounding villagers in the area in providing water for irrigation. These functions and values of the national park need to be highlighted. The present study is an assessment of the current situation of hydrological regime of KNP and the watershed. Objectives The main goals of the study are: • to ascertain water budget of the Keoladeo National Park, • to identify hydrological functions of the Keoladeo National Park wetland based on Hydrogeomorphic approach, • to assess the functional value of the wetland and its role in maintaining water table and contributing to quality and quality of groundwater in areas adjacent to the Keoladeo National Park • to know the impact of the hydrological regime on the biodiversity of the Keoladeo National Park
Density Related Behaviour of Select Ungulate Species in Four Zoos of Southern India
(Wildlife Institute of India, Dehradun, 2003) Panda, Prajna Paramita; Choudhury, B.C.
Density Related Behaviour of Select Ungulate Species in Four Zoos of Southern India
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.
Effect of Habitat Alteration On Herpetofaunal Assemblages on Evergreen Forest in Mizoram, North-East India
(Wildlife Institute of India, Dehradun, 1999) Choudhury, B.C.; Panwar, Samraat; Rawat, G.S.
The response of frogs and Lizards to habitat alteration was studied in South Mizoram. Chronoseres were selected such that two successional gradient were represented- jhum fallows regenerating to mature forest. and jhum allows converted to teak plantations. Herpetofauna were sampled by three techniques- strip transects, pitfall trapping. and systematic searching. Species richness of herpetofauna increased along the jhum-mature forest gradient. However. teak plantation had a depauperate herpetofauna. similar in composition to the 1- year jhul1l fallows. All frogs and lizards were c1assilied into 6 guilds on the basis of their activity period (diurnal or nocturnal) along with whether they were terrestrial , arboreoterrestrial or arboreal. Analysis of the strip-transect data showed that there were distinct differences in the distribution and abundance patterns of diurnal and nocturnal species. To examine patterns, multidimensional scaling (MDS) was used for indirect gradient analysis in two ways- firstly to summarize differences between sites and secondly, to explore possible associations between herpetofaunal guilds and habitat parameters across categories. The MDS differentiated two different groups of habitat variables. One group makes up the gross structural components of the habitats. while the other represents microhabitat parameters. All guilds were more strongly associated with trends in microhabitat distribution. than macrohabitat-parameters. while species richness showed diffuse associations with habitat parameters. The assemblages in the I to 10 yr. jhum fallows and teak plantations were dominated by a set of terrestrial and arboreo-terrestrial lizard species. Most of those species are distributed widely. either in the Indian subcontinent. or further east and south. into South-east Asia. On the other hand. a number of frogs and some lizards were restricted to mature forest. Most of these species are restricted either to North-east India. or to the study area itself. and some are apparently hitherto undescribed species. The fact that so many narrowly distributed species were found in mature forest has obvious conservation implications. Overall. the results suggest that in a mosaic of habitats resulting from jhum-cultivation. even remnants of primary forest may be of immense importance for persistence and recolonization by mature forest herpetofauna. Teak plantations offer a very marginal habitat for a large set of herpetofauna. even after a long period of growth.
Factors Influencing Movement Pattern Habitat Use and Distribution of King Cobra (Ophiophagus hannah)- A Multiscale Approach
(Wildlife Institute of India, Dehradun, 2011) Rao, Chetan S.; Talukdar, G.; Choudhury, B.C.
The king cobra (Ophiophagus hannah) is the largest species of venomous snake in the world. It is a widely distributed species occurring in India and Southeast Asia. Most of the habitat use studies of ophidians are responses of ambient temperature. These results are often correlated with temperate areas where there is a significant shift in temperature annually. In tropical ecosystems, to understand ecology of a large bodied species like the king cobra would be interesting, knowing the fact that very little work has been done so far. The objective of my study was to procure relationship of ecographic variables on movement pattern, habitat use and distribution of king cobras at an individual and at a population level. This study was carried out in Agumbe, Karnataka in the Western Ghats region of India for 4 months during December 20 I 0 to April 2011 . Habitat utilization points were sampled throughout the study area, which basically was placed within the boundaries of a 2x2 sq.km grid enclosing all the presence locations collected during five years from the ongoing King Cobra Telemetry Project conducted by the Agumbe Rainforest Research Station and the University of Arizona in collaboration with the Karnataka state forest department. Retreat sites (n=262) were selected where the tagged (n=5) had been recorded and sampled for microhabitat variables. Nest sites (n=13) were also looked into, to explore site selection by females. A total of 30 ad libitum sightings of king cobras were recorded during the study. Prey density walk was carried out to derive a relative abundance based on encounter rate in the study area that came to be 1.24 animals/km. A total of 9 species of prey were encountered during prey density walks. The kernel estimates and minimum convex polygon for four radio tagged individuals was calculated for home ranges and area vs. availability was computed for habitat preference and use using Jacob's (1974) Index. The results of this study show a strong correlation of ambient temperature of range 20- 35°C (Beta coefficients 7.7eI0-l ± 0.0545) and relative humidity (70-90%) (Beta 15 coefficients 1.25 ± 1.14) with movement pattern and habitat site selection and also affect distribution patterns of this particular king cobra sub population. It is also found that king cobras do not particularly obligate themselves to a particular habitat type except for some degree of preference towards evergreen forest. The microhabitat however, influencing king cobra movement and habitat use are fallen logs on the forest floor (Beta coefficients 2.327e+00 ± 5.113e-Ol) and dead vegetation on the forest floor (Beta coefficients 2.042e-02 ± 6.796e-03) which have a stronger correlation with presence while ground burrows show a negative correlation. Leaf Litter Depth in the forest floor in sites with range of 4-7 inches deep (Beta coefficients 0.64269 ± 0.30998) influences nest site selection. Using secondary rescue data of five years and all the other presence records for king cobras in the wild, I ran a MaxEnt presence only model (auto model) using only environmental variables taken from BIOCLIM to test environmental parameters influencing distribution. The places of higher precipitation within the study area indicate a higher influence on occurrence and places of higher temperature and aridity regimes does not indicate occurrence of king cobras. The management recommendations for conserving such large bodied snakes would be a multidimensional approach. The local people within the study area do not kill king cobras, due to religious reasons. However, these attitudes are changing and so also some of the tolerant ideologies of the local people. King cobras have been found to occur more in a landscape matrix dominated by evergreen forests and decline in evergreen forest due to land use conversion could be the emerging possible threats to king cobra in the Western Ghats.
Habitat use by the Great Indian Rhinoceros (Rhinoceros unicornis) and the other sympatric large herbivores in Kaziranga National Park
(Wildlife Institute of India, Dehradun, 2001) Banerjee, Gitanjali; Rawat, G.S.; Choudhury, B.C.
A study on the habitat use by the Great One horned rhinoceros (Rhinoceros unicornis) and three other sympatric ungulates was carried out in Kaziranga National Park (KNP), Assam during December 2000 to April 2001. KNP supports more than half the world's population of the Indian Rhinoceros, a highly endangered species. Since this park also supports a high diversity and density of herbivores coexisting in a typical floodplain habitat, it was an ideal place to conduct the following study. The study aimed to determine how 4 large herbivore species rhino, wild buffalo, swamp deer and hog deer achieve spatial and temporal separation across two seasons. The study also investigated how nutritive content of the forage determines habitat selection by these species. KNP was an ideal place to study habitat use patterns by these four sympatric species due to the seasonal variation of forage quality caused by the practice of annual burning. Sampling for animal abundance within each habitat type over two seasons was done by monitoring transects. Feeding observations were obtained by scan sampling. Laboratory analysis was done to determine the nutritive content of the available forage during winter and summer. Seasonal and spatial differences observed in habitat occupancy patterns by the ungulate species within KNP seem to be a way of partitioning resources in order to minimize competition. During the winter season all ungulates selected the short grasslands for feeding. The wild buffalo and the swamp deer showed no variation in the habitat occupancy patterns showing a positive selection for the short grasslands. However, rhinos and hog deer were observed to prefer the tall, burnt and sprouting grasslands in summer for feeding during summer. When habitat occupancy patterns were correlated with the nutritive value of the forage it was found that all ungulates tracked high crude protein levels in available forage. Rhinos and hog deer formed an association that exploited areas that have high crude protein and low silica content. Wild buffaloes and swamp deer show less flexibility in habitat occupancy patterns and were observed to feed in short grasslands where there was a relatively high amount of crude protein available during both the seasons. The study revealed that crude protein played an important role in determining habitat use by hog deer, which shows a linear relationship with crude protein. Forage volume, an indicator of available food played a significant role in determining habitat use patterns for the large bodied ungulates, namely the rhino and the wild buffalo which is in keeping with their physiology and body requirements. There seems to be partitioning of space by the ungulates on the basis of body size and dietary separation. Rhino and hog deer were observed to formed one guild whereas wild buffalo and swamp deer formed another one. These two groups differed in the pattern of habitat occupancy suggesting that ecological separation in Kaziranga National Park, perhaps occurs on the basis of differential use of the habitat by ungulates that have a similar body size. There was an observed complementation of body sizes within each association. A large bodied ungulate associated with another ungulate that was much smaller in size. and therefore, had different ecological needs.
Impact of land use changes on the habitat, bahaviour and breeding biology of Indian Sarus Crane (Grus antigone antigone) in the semi-arid tract of Rajasthan, India.
(Wildlife Institute of India, Dehradun, 2007) Kaur, Jatinder; Choudhury, B.C.
The Sarus Crane has been recorded all over the northern India and central region of the Indian sub-continent historically. However, this once abundant tallest flying bird species has now become threatened. The present study was undertaken during the year 2000-2002 to i) to determine the habitat use, breeding biology and behavioural ecology of the Sarus Crane in the semi-arid tract of Kota, and Bharatpur in Rajasthan, and ii) to determine the changes in land-use and its impact on Sarus Crane in the semi-arid landscape and to suggest the conservation strategies for the long-term survival of Sarus Crane. The study was conducted in the semi arid tract of Kota, and Bharatpur districts of Rajasthan. District Kota, the first intensive site falls under arid Zone V (the humid south-eastern humid plain zone,) where the development of canal irrigation has made this area rich in agricultural production. The population of Sarus Crane in Kota are dependent mainly on the canal system induced and other natural wetlands. Data on distribution and habitat utilization of Sarus Crane in Kota and in Keoladeo Ghana National Park were carried out
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.
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.
Seasonal Change in Social Structure, Behaviour and Habitat Use by Sarus Crane in the Semi Arid Region of North-Western India
(Wildlife Institute of India, Dehradun, 2001) Latt, Tin Nwe; Choudhury, B.C.
The seasonal change in social structure and habitat use by sarus cranes was examined in the semi arid region of North- western India. The study was conducted in Keoladeo Ghana National Park and in the surrounding areas in Bharatpur district of Rajasthan. The methods involved censusing of cranes in the park and in surrounding areas by moving on motorcycle in preidentified routes. The detailed methodology included quantification of habitat availability and focal and scan sampling for studying the behaviour of sarus crane. Eight sarus groups were intensively monitored to examine parent and juvenile relationships and juvenile weaning process. The mean encounter rate of sarus crane outside the park was greater than that of inside. Though the data was not tested for the lack of uniform effort in these two areas, the difference is likely to be statistically significant. The overall group composition during the study period differed inside and outside of the park. The agricultural areas outside had greater number of social family group sighted during the study period than within the park. The mean encounter rates had greater standard errors associated with them outside the park than inside the park. During the present study most of the social family, pair, congregation, and solitary crane were seen outside of the park except that of pair with juvenile. The seasons (winter and summer) had an influence on the sarus crane group composition apart from the fact that the groups were either seen within the protected area or outside. With the data from the present study it is not possible to test the effects of these two variables on the sarus group composition. However, in winter sarus cranes were seen in social family and pair with juvenile more often inside the park than outside the park. The other forms of groups of sarus such as social group, pair and solitary members were not very different inside and outside the park. In winter season, juveniles were not able to fly more than 0.61 m height and 45m distances restricting their movements within the park. During summer the juveniles could fly outside of the park in the 1st week of February onwards and were seen frequently outside of the park. Sarus cranes spent more time outside the park than inside, except pairs with juveniles. Inside the park the safety, food and space supported small groups and pairs all through the year. The group composition showed a dramatic change in summer where greater number of social family and pair with juveniles were observed outside the park than inside, while other forms of groups did not vary much in the two areas. During the study period a maximum of 67 sarus cranes were recorded inside the park in roosting areas. During the study period, wetlands were the most used habitat by sarus cranes than any other habitat types. Grasslands and dry wetlands were used distinctly by sarus next to the wetlands, and the agricultural fields have the least utilization. The later could be because of bias in sampling more inside the park than in the agricultural fields outside the park. During summer, the sarus cranes occurred more often in wetland and grasslands than in dry wetland or agricultural fields. During winter and summer sarus cranes mostly used wetland habitat (winter 20.5 % & summer 35%). In late summer, as all agriculture field were harvested and there was no water patches outside the park. The Forest Department pumped in water throughout the late winter and summer in the areas where group no (Block L), group no.4 (Block D) and group no.5 (Block E) spent more of their time. During summer, sarus cranes used this shallow water. The area where group no.3 (Block K) sarus stayed much of the time had very large grasslands. Within this area the wetland was closer to road and sarus crane appeared to be stressed while foraging in this wetland. The large expanse of grasslands used by group no. 3 (Block K) area, it prevented people to approach closer to the cranes and hence they used this grassland extensively during summer. Among the pair, the female was more the wary and cautious while using these water patches. Solitary sarus cranes preferred foraging in grasslands. In summer, water spread became small and narrow and sarus cranes spent more time in grasslands (winter 5% & summer 12%). Sarus crane did not use dry wetlands in summer due to lack of moisture in this area which, hinders growth of grasses and other aquatic flora and also insects in such dry wetlands were less. Generally, sarus crane used agriculture land more for foraging at the time of sowing and harvesting of cereal and pulses. The encounter rates (sightings/ hour) of sarus crane correlated with water level. During large water spread times, more cranes were encountered. Water depth was correlated with mean encounter rates (r= 0.77, N= 1 Z) , similarly water spread also had a significant positive correlation (r=0.64, N= 12). As expected water depth and water spread had a strong positive correlation (r=0.95, N= 12). At the beginning of the study in November the juveniles were estimated to be three months old, and when the study was concluded in May, the juveniles were nine months old and they continued to remain in the vicinity of the parents. Although the distance increased with time it is speculated that the quantum of time spent by the adults parenting the juvenile would diminish with time and also the distance between parents and juveniles. The major interaction between parent and juvenile during the observation period was "nursing" behaviour, where the parent fed the juvenile directly into its mouth. Subsequently, the parent "induced the juvenile to forage" by leading the juvenile to some areas in the wetland where food was abundant and the disturbance from tourists was low. From the last week of February juvenile started to move farther away from the parents and maintained an average distance of about 65 m. During this time the parents started courtship behaviour and paid less attention to the juveniles, even though the juveniles showed interest on their parents. In reciprocation of the lack of attention from the parents the juveniles continued to forage away from the parents. Till the end of the study period in May the juvenile still continued to tag along with the parents. To summarize, seasonal shift in sarus crane social structure was observed in the study area. Following factors appear to affect the sarus crane group structure and behaviour: (a) Availability and limitation of food.(b) Changes and availability of water in wetland. (c) Age of juveniles appears to be a factor for their attachment to parents.(d) The diurnal weather appears to be relative to sarus crane behaviour and social structure,which change on cloudy, sunny and rainy days .
Seasonal Habitat use of and Resource Partitioning between Two Sympatric Crocodilian Populations (Gavialis gangeticus and Crocodylus palustris) in Katerniaghat Wildlife Sanctuary, I
(Wildlife Institute of India, Dehradun, 2011) Choudhary, Shikha; Choudhury, B.C.; Gopi, G.V.
Gharial (Gavialis gangeticus) and Mugger (Crocodylus palustris) are sympatric in their distribution range in some of the Northern River system of Indian sub-continent. Katerniaghat Wildlife sanctuary along Indo-Nepal border in Uttar Pradesh harbours the second largest breeding population of critically endangered Gharial, after National Chambal Sanctuary. Several studies have been carried out on the ecological aspects of Gharial and Mugger separately but very few studies exist on the sympatric populations and the mechanisms favouring the coexistence of the species. This study has tried to fill this gap by investigating how the resources are shared (Basking sites and Nesting sites) and what are the key requirements that lead to the selection of a particular basking and nesting site. Temporal separation across species and size classes and preference for nearest neighbor has been established. Relative abundance in terms of encounter rate across season, river segments and a gradient of disturbances were studied. Other aspects that have been looked into detail in this study are the impact of tourism and illegal fishing on the flight distance of Gharial and Mugger. Data were collected from December 2010 to May 2011, covering two seasons (late winter and early summer). Entire study was carried out using a non-mechanised boat. Habitat parameters for every sighted basking crocodile were recorded for habitat use and for determining the habitat availability variables at every 100 meters on both banks and on islands were recorded. Nests were located by following the spoor marks of crocodiles. Gharial and Mugger were divided into three size classes (SCI - 3m). Once in a month day survey was carried out to estimate the relative abundance and on every alternate Monday temperature and number of basking individual were recorded at every hour from 0600 to 1800 hrs from a watch tower. Flight distance of crocodiles was recorded from a non-mechanised boat and a mechanised boat by accompanying the tourists. Relative abundance as mean encounter rate (#/20km) was maximum for Gharial juveniles followed by Gharial adult. Mugger juvenile had lowest mean encounter rate (#/20km). Encounter rate was not uniform for the river and it varies across season also. Maximum sightings took place in river segments with sand bars irrespective of moderate to high disturbance. With increase in mean ambient temperature encounter rate declined. Basking sites were selected during summer by Gharial based on depth gradient, current land usage, island, distance to water, slope, platform height and soil moisture while selection of basking site by mugger was based on current land usage, distance to water and depth gradient. In winter, Gharial selected sites based on slope, platform height, soil moisture, current land usage, distance to water and place while Mugger looked for current land usage, distance to water, islands and banks. In winter, there was no temporal segregation between different size classes of Gharial and Mugger while in summer there was a temporal segregation between and within size classes 0f Gharial and Mugger. Choice of slope, height, soil moisture, places and substrata for basking sites were different for Gharial and Mugger. Gharial preferred very gentle slope while Mugger preferred a slight slope. Gharials do not prefer elevated basking platforms whereas Mugger was found basking on elevated platform. GhariaI preferred moist areas for basking and Mugger basked even on little dry substrate. Gharial was seen mostly on Islands and Muggers on banks. Among basking substrate Gharial preferred sand & sand+silt, whereas Mugger was found on a variety of substrata. Mugger moved to side streams (Nalla) in summer while Gharial kept on preferring island for basking. For nest sites there is a significant difference in the use of slope, height, distance to water, places and substrate by Gharial and Mugger. Flight distance for crocodiles was more when there was a disturbance from non-mechanised boat than from a mechanised boat. Mechanised boat is mainly used for tourism purpose while non-mechanised boat for illegal fishing by local people. Between species Mugger was more tolerant to human presence than Gharial. Among hatchlings and adults of Gharial, hatchling showed a late response to disturbance while adults used to be the first one to slide in to water. Girwa river of Katerniaghat Wildlife Sanctuary is one of the very few rivers of India where Gharials re breeding in wild. Though the river stretch is about 20 - 21 km only a small stretch of 5-8 km harbours the maximum number of Gharial and Mugger. This small section is used for both basking and nesting and it is very crucial to protect this small stretch in order to save a critically endangered species from the brink of extinction.
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.
The Diel Activity Pattern of Indian Python (Python molurus molurus linn) at Keoladeo National Park and Some Factors Influencing it
(Wildlife Institute of India, Dehradun, 1991) Bhatt, Karamvir; Choudhury, B.C.
This study investigated die] activity pattern of Indian python (Python moJurus molurus Linn) at Keoladeo National Park Bharatpur. The study was conducted in an intensive study area of 0.5 Sq Km selected after pre sampling survey in the park. The methodology involved to estimate activity pattern of pythons was monitoring of a permanent transect every four hours, on diel basis, to record python’s tracks and sightings. The diel variations in temperature, humidity, burrow microclimate, prey activity and prey abundance were also quantified along with diel activity pattern of python. Results show a shift in diel activity pattern with seasons. The activity pattern of pythons was diurnal in winter, uniform throughout spring and bimodal crepuscular in summer. There was no significant correlation between python activity and other factors quantified, though temperature and humidity affected the diel activity pattern considerably. The microclimate variation gradient existing between outside and inside burrow possibly play an important role in occupation of the burrow and this in time influence the surface diel activity pattern. The shift in the diel activity is attributed to seasonal change in the abiotic factors. No relationship between prey abundance and activity pattern could be established possibly because python’s ability to go with out food during the cool season. Other factors not quantified during this study like reproductive behavior, body size and biotic disturbances are suspected to be responsible for the observed diel activity pattern of pythons. It is concluded that the diel activity pattern of pythons in KNP is not influenced by just one factor but is a manifestation of a combination of various abiotic, biotic and endogenous factors. A temperature sensitive telemetry study would help further in investigating the ecological aspects of this cryptic species.