Browsing by Author "Kumar, R.S."

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Age Estimation of a Breeding Population of Olive Ridley Sea Turtle (Lepidochelys olivacea) Along the Odisha Coast, Eastern India: Using skeletochronology
(Wildlife Institute of India, Dehradun, 2013) Baburam, Anupya D.; Pandav, Bivash; Kumar, R.S.
A migratory population of olive ridley sea turtle (Lepidochelys olivacea) forms huge reproductive congregations in the coastal waters of Odisha every winter. This breeding population of olive ridley has been subjected to heavy fisheries related mortality for the past two and half decades. Although a number of studies have been carried out on olive ridleys congregating and nesting along the Odisha coast, the impact of such large scale mortality on the demography of this breeding population has been least understood. The effect of this continued mortality on the age class of olive ridleys nesting along Odisha coast is not known. In order to understand the age class of this breeding population I carried out this study from December 2012 till May 2013. I used skeletochronological analysis to estimate the age class of this breeding olive ridley sea turtle population. Although this technique has been applied for marine turtles mostly in North Pacific, Atlantic and Gulf of Mexico coast of United States of America, no studies of this kind have been carried out on sea turtles of Eastern Pacific as well as Indian Ocean region. This study provides the information needed to bridge this gap and establish baseline for future skeletochronological studies on the breeding population of olive ridley. Humeral samples from 85 dead turtles (29 males and 56 females) washed ashore the Odisha coast was collected for skeletochronological studies. Cross sections were taken from the mid-diaphysis, just distal to the deltopectoral crest and beneath the insertion scar on the humerus were taken using first a Dremel 4000 round saw, then a freezing stage microtome. These sections were processed according to standardized histological techniques; growth rings on the stained humeral cross sections were counted to estimate age of dead turtles. Two age estimation protocols were used; the correction factor protocol and the ranking protocol; which yielded age estimates of 19.9 - 51.8 and 24 – 49 years respectively; for a size class of 56 - 74 cm (SCL). No correlation between size class and age was obtained from this analysis. This relationship was not established because the samples collected were from an adult breeding population, whereas, in the previous studies, sample collection represented individuals that greatly varied in size (hatchlings to adult). This study suggests that adult breeding population size class has no correlation with age; however, age can be correlated with size class of a younger population. This breeding population is sustaining a wide age group even though mortality rates are high in this area
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
Nest site selection in Pallas’s Fish-eagle and nesting behaviour in the Rajaji-Corbett landscape
(Wildlife Institute of India, Dehradun, 2024) Tangaria, Abhishek; Jha, Ashish; Pandav, Bivash; Kumar, R.S.
This study investigates the nest site selection and nesting behavior of Pallas's Fish-eagle (PFE) across the sub-Himalayan tract in India, addressing a significant knowledge gap in the species' natural history. PFE, classified as Endangered globally and of high conservation concern nationally, exhibits unique nesting preferences and ecological requirements. Prior research, including studies from Bhutan and Bangladesh, has highlighted the species' preference for unobstructed nest trees and proximity to water sources and human settlements. However, comprehensive data from India remains limited. The study aims to explore factors influencing PFE's nest site selection, such as habitat quality, microclimate, food availability, and protection from predators and human disturbance. Additionally, it seeks to document the species' reproductive behavior, including hatchling development, parental duties, and nest predation pressures. Surveys covered segments of the Ganga, Kohlu, Kho, Palain, Mandal, Asan Barrage, Dakpatthar Barrage, and Ramganga, recording data on sightings and nest characteristics. A total of twelve nests were found, with only one destroyed by a storm. The majority of nests were built on Bombax ceiba and Shorea robusta trees, with an average height of 29.9m and GBH of 473cm. Behavioral observations were conducted at three accessible nests, monitoring parental presence, predator interactions, and nest guarding behavior. Spatial analysis in ArcGIS Pro considered various land cover types and environmental factors, finding that barren land and rangeland significantly influenced nest site selection. Euclidean distances to different land cover types and elevation were also key factors. Statistical analyses using R revealed correlations between tree height and nest height, and generalized linear models highlighted the impact of land cover and environmental variables on nest presence. Nest trees were typically tall and robust, with Bombax ceiba and Shorea robusta being the most commonly used species. These trees provided unobstructed branches and greater accessibility. The study also highlighted the importance of open land around the nest tree, aiding in vigilance and territory defense. At a macro scale, the presence of barren land and flooded regions positively influenced nest site selection, while slope and distance from rangeland showed negative correlations. Behavioral observations at three nests revealed high predation pressure, particularly from crows, and kites. The presence of human settlements increased predation incidents, affecting parental investment in nest defense.
Niche partitioning between assamese and rhesus macaque in the Askot landscape of Uttarakhand, Northern India
(Wildlife Institute of India, Dehradun, 2017) Justa, Priyanka; Kumar, R.S.; Talukdar, Gautam
Closely related species often have similar requirements and these species need to have certain ecological adaptations to live in sympatry. Two congeneric species the Assamese (Macaca assamensis) and the rhesus macaque (Macaca mulatta) co-occurring in the Askot landscape of Uttarakhand were studied to understand the mechanisms allowing their coexistence. 2. Ecological niche differentiation for the two species was investigated by examining three possible modes of separation: activity pattern, diet and spatial use following observational protocols over a period of five months (December 2016-April 2017). Crop-raiding by macaques often results in human-macaque conflict. With the help of semi-structured interviews, attempts were made to access the level of conflict and people’s perception of these two macaque species. 3. Limited niche overlap was found between two primate species across the study duration. The Assamese macaque differed from the rhesus macaque in time spent on various activities. The former spent more time feeding and the latter in resting. Although 44% of all food items were consumed by both the species, only three of the ten major food items were shared. Assamese macaques preferred leaves and had broader niche breadth compared to rhesus macaques who fed more selectively on fruits. There was a significant difference in feeding heights, habitat and roosting site preferences of the two species. Differences in diet choice and roosting sites, in turn, resulted in differences in daily movement and home range of these species. Despite a partial home range overlap, both these species were found to be spatially segregated at a local scale. 4. The extent of niche overlap across winter and spring seasons in the area showed the greatest divergence in the diets of the two species in winter, while diet overlap was more pronounced in spring. As resources were abundant in the spring, an increase in niche overlap may not have lead to competitive interactions. Synthesis and application: Knowledge about differential resource use of macaques might help in assigning conservation priorities to the different species and their specific ecological niches along with designing species-specific management strategies. The study was able to distinguish the macaque's tendency to co-exist with humans.
Social Behaviour and Duetting in Hoolock Gibbons in Gibbon Wildlife Sanctuary, Assam
(Wildlife Institute of India, Dehradun, 2009) Sankaran, Sumithra; Rawat, G.S.; Kumar, R.S.
The hoolock gibbon (Hoolock hoolock), only anthropoid primate found in India, is a pair-living, territorial species, which duets extensively. Various hypotheses regarding the function of this behaviour in monogamous primates include territory advertisement, pair-bonding, mate defense, resource defence and group cohesion. This study aimed to understand the nature of social behaviour of this species, and how duetting fits into the repertoire of social behaviour seen in this animal. Three groups of Hoolock gibbons were habituated and studied intensively over a three month period. Relationships between the different group members were explored, alongside time budgets of various activities of the adult pair, the synchrony in their behaviour and frequency and nature of all affiliative and agonistic behaviours. Relationships between territory sizes, group sizes, frequency of duetting and nature of other social interactions have been examined in detail. A considerable amount of individual difference were found between the different study animals in their interactions with other group members. These animals display complex affiliative interactions with rare displays of aggression. It was found that although the proportion of time spent in social interactions was comparable between the three groups, the proportioning of this total time among different social interactions may vary considerably. The primary difference was found to be in allogrooming interactions with the proportion of time time spent increasing with increase in group size. The study also found considerable evidence for the possible existance of male-care in this species.
Spatial Dynamics and Drivers of Nearshore Aggregations in Olive ridley Sea Turtles along the Gahirmatha Coast by
(Wildlife Institute of India, Dehradun, 2024) Sarkar, Arnab Dey; Prabakaran, Nehru; Kumar, R.S.; Pandav, Bivash
Olive ridley sea turtles (Lepidochelys olivacea) exhibit a well-documented phenomenon known as nearshore aggregation during their breeding season. These aggregations, comprising large numbers of turtles in shallow coastal waters, are a common feature observed along most of the mass nesting beaches. The ecological benefits of such aggregations are multifaceted, potentially including enhanced predator avoidance and increased opportunities for mate encounter. The importance of studying these nearshore aggregations stems from their vulnerability during this period. Olive ridley turtles within these aggregations are susceptible to various threats, including bycatch mortality from fishing gear. Understanding the spatial and temporal dynamics of these aggregations is crucial for developing effective conservation strategies. The Gahirmatha nesting site presents a unique case due to the influence of the Brahmani-Baitarani River system. The substantial freshwater inflow and sediment discharge from this river system have resulted in a vast area of shallow seabed compared to other nesting grounds. This distinct ecological setting necessitates a dedicated investigation into the dynamics and influencing factors of nearshore aggregations specific to Gahirmatha. The study examined the distribution and density of olive ridley sea turtles near Gahirmatha, India, a critical nesting site, with a particular focus on how environmental factors influence the location of these nearshore aggregations. Surveys were conducted throughout the breeding season, recording turtle sightings and environmental data. The findings reveal that olive ridley turtles are not distributed randomly in the nearshore waters. Instead, they form concentrated aggregations in shallow depths (less than 5 km offshore and 5-15 meters deep) before nesting. The location and density of these aggregations were not static but shifted throughout the breeding season. During the pre-nesting season, turtles were more dispersed across a wider area. As the season progressed and nesting approached, the aggregation grew denser and shifted closer to the nesting beach. The study also identified distance from the coastline and the nesting beach as the key factors influencing the distribution of these nearshore aggregations. Additionally, the unique shallow seabed near Gahirmatha, created by the discharge from the Brahmani-Baitarani River, might influence the preferred depth range of turtles compared to other nesting sites. Understanding these dynamic aggregation patterns is crucial for effective conservation efforts. Protecting these areas is essential for the well-being of this globally significant olive ridley population. However, it's important to acknowledge that the exact locations of these aggregations can vary between years. This year's lower nesting numbers suggest fewer turtles arrived in the nearshore waters, potentially impacting the size and distribution of the observed aggregations. This study emphasizes the need for long-term studies to gain a more comprehensive understanding of these variations and the factors influencing them. The study suggests a targeted approach of focusing on areas with high turtle usage. By implementing stricter patrolling measures within these zones, the forest department can significantly reduce threats like bycatch mortality from fishing activities. This targeted approach would be more effective in safeguarding the turtles compared to focusing on reducing illegal fishing in the entire sanctuary, considering the limited resources available.
Species interactions with in mixed species bird flocks along an Elevational gradient in the Western Himalaya.
(Wildlife Institute of India, Dehradun, 2021) Gokhale, Pranav; Kumar, R.S.; Mohan, D.
Mixed-species bird flocks (hereafter, “flocks”) are an interactive community of largely insectivorous birds, which move and forage together to gain enhanced access to resources and protection from predation. In this study, I aimed to investigate a question: do interspecific interactions within mixed-species flocks change along an elevational gradient? To test this, I carried out this study in the Garhwal region of the Western Himalaya in Dehradun District, Uttarakhand from January to April 2021 (spanned across two seasons). The study areas comprised of three field sites along an elevation gradient from western part of the Rajaji Tiger Reserve (300 m ASL) to Mussoorie (2200 m ASL). I sampled flocks and relative abundances of birds on the two pre-existing trails in each of the three field sites. I walked each trail 10 to 13 times. I recorded species identity, group/cluster size of all birds seen inside as well as outside flocks on the trail and within 10 m on either side of the trail. I assessed arthropod prey availability in winter for the flocking species by using branch bagging technique on the same trails. In total, I clipped 150 branches for the three elevations. I calculated species-specific flocking propensity for each elevation from the information on birds seen within and outside flocks. I used network density (potentially realised associations) and weighted degree (associated strength) to quantify the interspecific interactions (associations) within flocks. To control for the influence of species availability on flock network properties, I generated null flocks using an abundance-based null model. I recorded 80 flocking species in 412 flocks, of which, 179 flocks were observed at the High elevation, 156 at the Mid elevation and 77 at the Low elevation. Majority of species in the Western Himalayan flocks were insectivorous gleaner. I found insect prey availability (resource) to decrease with increasing elevation in winter. As expected, flocking propensity, network density and weighted degree increased with elevation in both seasons indicating greater potentially realised associations and high strength of associations between species. Interestingly, the Low elevation flocks disintegrated completely at the onset of summer possibly due to the greater availability of resources, or an upward migration of species for breeding. I did not analyse the Low elevation flocks in summer due to small sample size (n=5). Flocking propensity and network density decreased from winter to summer at Mid and High elevation while, weighted degrees decreased only for the Mid elevation. This is likely that true summer may not have started at the High elevation during the course of my fieldwork. To conclude, with increasing elevation in both seasons, species not just flocked more, but associated with many species and these associations became stronger, potentially due to the scarcity of resources. It is possible that species may not be able to access resources efficiently when foraging on their own at the High elevation, compelling them to participate in flocks to avail complementary benefits from many other species.