WII Technical Reports/Books/Manuals
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Item Tracking the nearshore and migratory movements of Olive ridley sea turtles occurring in the Coastal waters of Maharashtra(Wildlife Institute of India, Dehradun, 2023) Mudliar, M.M.; Kumar, R.S.In a first, a satellite tracking study of solitary nesting olive ridley sea turtles was taken up on the west coast of India during 2022-2023 along the Maharashtra coast. Seven olive ridley sea turtles were captured (five in 2022 and two in 2023) and were tagged with Argos satellite transmitters (model-K2G 576E) manufactured by Lotek Wireless Inc. (New Zealand). The tags were attached to the turtle's carapace using a 2-part epoxy-resin adhesive and further secured using fiberglass tape. The tags were programmed to remain on for 24 hours and a transmission limit of 577 messages per day was fixed for each tag. Five turtles tagged in 2022 were tracked for an average duration of 138 days (3 to 173 days), while the two turtles tagged in February 2023 were tracked for 212 and 213 days. rhe turtfe locations received from the tags were checked for erroneous data and filtered accordingly. Following this, a continuous-time State-Space Model (SSM) was used for track correction and modelling. For every 6-hour interval, a location from the modelled track was extracted for the separate analysis of breeding period. Further, for the analysis of the post-nesting period, the locations were extracted for every 24-hour interval. A movement persistence model was then used to determine the behavioural state of the turtles based on changes in speed and direction of travel between subsequent time steps. This resulted in a Movement Persistence Index (MPI) for every time step that ranged between 0 and 1, where higher values indicated directed movements associated with migration and lower values indicated a slow-moving phase associated with stop-over. The high-use areas of tagged turtles during the nesting period were determined using Kernel Density Estimates (KDE). Further, the diving data obtained for each tagged turtle was summarised for dive depth and duration, and daily time spent on the surface. The diving behaviour was also compared for the turtles in the continental shelf waters and in the open ocean. During the nesting period, the tagged turtles resided in the nearshore waters for a period ranging from 22 to 41 days and, on average, remained 10 km from the coast. During this period, the high use area (50% KDE) determined for the tagged turtles ranged from 142 sq. km to 735 sq. km and fell within the 30 m depth contour. The high-use areas were primarily associated with turtle-nesting beaches adjoining river mouths in the region. Two of the tagged turtles from the 2022 season, Prathama and Saavni, were observed to nest again after 34 and 31 days, respectively, suggesting that the solitary nesting turtles lay multiple clutches in a season. The average time spent at the surface per day (time the tags remained dry) during this period was 50 minutes. This suggests that turtles possibly spent most of their time resting underwater which was also evident from the long U-shaped dives recorded during this phase. The tagged turtles started on their post-nesting movements from late February to mid-March. In the case of three turtles, their initial movements were oriented to the North while the others iii headed South. The northernmost location of the tagged turtles came 95 km off the coast of Gujarat, where the turtle named Prathama resided for 31 days, and then began moving South. The post-nesting movements of the tagged turtles in the following months had clear directionality and were not nomadic. The tagged turtles were observed to have a median speed of 1.1 km/h, and the speed increased from 0.6 km/h (range: 0.3-0.9 km/hr) to 1.32 km/h (range: 0.6 -1.79 km/h) when they moved from the continental shelf to open waters. The turtles were observed to have stop-overs in areas off the Gujarat coast, the Karnataka coast, the waters。仟 northeastern Sri Lanka, and the open waters of the Bay of Bengal. At the time of the last tracking location, the displacement distance of the tagged turtles was 190 - 2338 km from their nesting beach and they had travelled 1015-5267 km in 80-213 days. the turtles were observed to dive to an average depth of 15.7 ± 8.2m during the breeding phase and 61.43 ± 36 m during the post-breeding phase. During these dives, the turtles stayed underwater for an average duration of 27.2115 and 31.9 ±18 minutes in the breeding and post-breeding phase, respectively. An increase in V-shaped dives (exploration dives) was observed when turtles moved into deeper waters. The turtles performed shallower dives at night in open waters, while no such difference was observed when the turtles were on the continental shelf. A gradual increase in daily surface duration was observed during the post-breeding phase for turtles. At the same time, it was observed that the deepest dive performed in a given day gradually increased, and turtles that moved into the shelf break and open ocean habitat performed exceptionally deeper dives sometimes more than 400 meters. A general southward movement and reduction in MPI in the continental shelf break of the Karnataka coast was observed for most turtles starting from the month of May. This area falls in the well-known Malabar upwelling zone and appears to be an important foraging area for the west coast olive ridley population. Being first of its kind for west coast of India, this tracking study has been successful in creating awareness about olive ridley sea turtles through extensive media coverage on tagging and movement updates. Even with a small number of tagged turtles, it also provided crucial information on the movement and diving ecology of this lesser-studied population. Most importantly, the patterns of movement from this study suggests that turtles nesting on the Maharashtra coast comprise two foraging populations. Firstly, those that are resident to the Arabian Sea and the others from the Sri Lankan waters or from the Bay of Bengal. Further tracking efforts are recommended where the turtles are tagged early in the nesting season to understand their inter-rookery movements and find nesting frequencies per season. More tracking efforts from Maharashtra and elsewhere along the West coast of India are suggested to be taken up. This will help understand how the turtles from different nesting areas move and forage. Moreover, this will help identify the overlap between fishing zones and critical breeding and foraging areas along the West Coast to better manage and conserve the species through appropriate interventions.Item Impact of artificial illumination on sea finding behaviour of olive ridley sea turtle at Gahirmatha Rookery, Odisha. Report submitted to the Directorate of lighthouses and lightships(Wildlife Institute of India, Dehradun, 2025) Pandav, Bivash; Kumar, R.S.This study has the following objectives: I. To study the impact of artificial illumination on nesting sea turtles using the Gahirmatha rookery. II. To assess the level of disorientation by turtle hatchlings and suggest measures to minimize this.Item Assessing the impacts of Power-lines on avian species in the Arid plains of Western Gujarat : Final Technical Report(Wildlife Institute of India, Dehradun, 2021) Kumar, R.S.; Baroth, A.The Kachchh landscape in western Gujarat has witnessed rapid industrial growth in the last few decades. Also, the landscape has a high potential for wind energy generation and as a result, a number of wind farms have been established and continue to expand. Rapid industrialization and wind energy production has resulted in extensive power-line network crisscrossing the landscape. These energy infrastructures are known to pose potential risks to birds primarily those that are large-bodied in the form of collision and electrocution mortality. In lieu of this, a -four study was carried out in the Kachchh landscape to assess the impact of power-lines on large avian species in the arid plains of western Gujarat. In order to assess the power-line collision risk, data were collected at multiple levels, which includes (1) mapping the network of transmission lines in the Kachchh district, (2) GPS telemetry of six flamingos (two Greater and four Lesser Flamingo) (3) flight behavior of cranes around power-line, and (4) mortality surveys. The distribution and abundance of migratory Raptors were studied on three selected sites across Kachchh to know the electrocution risk to raptors. Also, surveys were carried out to collect data on space use by Common Crane with respect to wind farms to study the impacts of windmills on large birds. Finally, the data were analyzed using GIS modelling and various R packages to understand the space-use by large birds and identify risky power-line stretches that could pose threats to large birds. The analysis of Flamingo distribution surveys revealed that greater flamingos are widely distributed and occur in a much larger area than Lesser Flamingo. The analysis of tracking data showed that Flamingos make a greater number of flights during the breeding season. Further, it was documented that Lesser Flamingo use saltpans and mudflats primarily while Greater Flamingo used inland wetlands and coastal areas more often. The comparison of flight time showed that flamingos make most of the flights during night time. In the case of Cranes, Common cranes occurred in both agricultural and grassland habitats, while Demoiselle cranes were more localized and used only agricultural fields and feeding stations where local people practice food provisioning. Flamingos tracking data helped identify two main flight corridors, one at Nanda Bet and one at Surajbari, through which they made flights. These two corridors are also the only entry points from mainland Gujarat to Kachchh and hence are the corridor for transmission lines. As a result, these transmission lines are suggested to be a potential threat to Flamingos. The overlaying of transmission lines on the suitable habitat of Flamingos and Cranes revealed that 6% and 39% of the total power-line length is falling in Flamingo and Crane suitable habitats, respectively. It was found that 84.4% and 70% of total occasions, Lesser Flamingo and Greater Flamingo crossed power-lines during night times while making long-distance flights. The flight behavior observations of Common Crane around power-lines showed that 81% of total flocks observed altered either their flight path or their flight height.The data on raptor distribution with respect to distribution lines revealed that the Banni area has a high encounter rate (0.6 sightings/km) of raptor species and is home to several large raptors. The distribution lines in the Kachchh district do not have bird-safe spacing between conducting parts and hence can pose a potential risk to large raptors. The study investigating the impact of windmills on the space-use by Common Crane revealed that the encounter rate of Common Crane flocks in the areas dominated by windmills is six times less than in the areas with no windmills, suggesting possible functional habitat loss for the large birds due to windmills. This study is the first detailed landscape-scale effort to assess risks by energy infrastructure on avian species that forms a baseline for any future site-specific impact assessment studies in the region. This project identified the areas where powerlines likely pose a threat to large birds such as Flamingo and Crane. This study also suggests different strategies to minimize the impacts of existing and future energy infrastructure in different habitats in the Kachchh region