Browsing by Author "Talukdar, G."

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Avian Responses to Varying Landscape Parameters in Mangrove Forests of Coastal Gujarat
(Wildlife Institute of India, Dehradun, 2015) Kulkadia, Devanshi; Talukdar, G.; Gopi, G.V.; Sivakumar, K.
Mangrove systems are the most productive ecosystems on the earth. The mangrove environment provides living space for dependent biota of more than two thousand species of flora and fauna of resident, semi-resident or migratory wildlife. The conversion of large contiguous tracts of the tropical mangrove forests to smaller patches embedded in a landscape matrix surrounded by human-altered habitats is one of the most serious concerns as it would affect their associated species such as birds, fishes, etc. In this context, this study was carried out aiming at discerning the responses shown by avifauna to varying landscape parameters like the mangrove patch characteristics, the level of disturbance and the structure of mangrove vegetation. Therefore, the abundance and diversity of the avifauna in mangrove forests at twenty selected sites on the coasts of Gujarat were investigated using point count surveys for a period of five months (December 2014-April2015). 2. A total of 98 points were laid across the twenty patches o(mangroves and surveyed twice during winter and summer seasons, respectively. Data were collected from the four replicates of each point during the entire study period. The total area surveyed during the study at these twenty mangrove patches was 47.97sq.km. These patches were ranging from various size classes with the smallest patch of the size of 0.125sq.km to the largest patch size was of 10.49 sq.km and were distributed throughout the coastline of 1650 km long. Habitat correlates such as structural and floristic characteristics of mangroves were quantified for each patch to establish their relationship with avifaunal abundances. 3. Despite recording only 7 species of mangroves in the twenty patches, a wide variety of birds totaling to 119 species were recorded from the mangroves during the two seasons, i.e. winter and summer during the study. 4. From the data collected by the variable-width point counts, the mean density of birds from the patches were calculated to be 6.485/ha in winter and 4.898/ha in summer. The diversity of birds varied across the seasons. A total of 104 species of birds were recorded during the summer season as compared to 117 species of birds in winter season. 5. Large contiguous patches of mangroves were found to be supporting fewer species of birds than the smaller patches. The avian species richness of the smaller fragments were largely governed by the adjoining environment settings (matrix) of the patch. Therefore, the study found that the diversity of the birds was not found to be getting influenced by the area of the patch as the species richness was found to be increasing with the number of the surrounding matrix. 6. It was found that the structural composition of mangroves especially the canopy cover was found influence the bird density and diversity greatly as with the increase in the canopy cover, the bird species diversity and density also increased in a patch. 7. The bird assemblages in the mangroves showed a significant response towards the disturbance. The disturbed patches contained an overlapping mixed composition of the forest birds and open country birds in an equal proportion, whereas the undisturbed patches showed less number of open country birds. 8. Based on the study, it is suggested that the larger sized mangroves patches are important for their ineffable ecological services, therefore, these patches should be protected and conserved. Similarly, the smaller and fragment of mangroves patches are also equally important as they hold a good number of avifauna! species and hence, we have to adopt some strategies to conserve all the remaining – large contiguous and small fragmented patches of the mangroves from further degradation.
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.
Riverine Habitats Under Changing Land-use : A Resource Selection Study of Smooth-Coated Otter (Lutrogale perspicillata Geoffroy Saint-Hilaire 1826) in Kabini River and Tributaries
(Wildlife Institute of India, Dehradun, 2015) Aneesh, C.R.; Hussain, S.A.; Johnson, J.A.; Talukdar, G.
Habitat selection is an important part of the ecology of semi-aquatic mammals since they are highly specialized animals. River otters are especially vulnerable animals in the present situation due to increasing human disturbance, altering riparian vegetation damming and channelization in river basins. This study looked at the effect of land-use pattern on the habitat selection by otters with special reference to smooth-coated otter (Lutrogale perspicillata) in Kabini river, South India. The study showed fewer presence sites of smooth-coated otter inside the protected areas, due to naturally unsuitable habitats for the species, with shallower stream habitats in hilly terrains. These sites were occupied by Asian small-clawed otters (Aonyx cinerea). However the sign intensity was more in presence locations inside protected area and least in urbanized area. The detailed study in presence only sites revealed that anthropogenic disturbance primarily increasing human presence, fishing and grazing is the most important factor affecting selection of habitat by smooth-coated otter. The intensity of usage of habitat is also governed by disturbance factors. Other environmental factors are only secondary to disturbance factors affecting habitat selection which includes a set of factors pertaining to land and water summarized as slow, deep waters with intact bank cover and/or grassy banks with close escape cover distance. Prey fish species of medium size class (21-40cm) affects the habitat selection. Although Asian small-clawed otter and smooth-coated otter occur in same river system , there is a clear niche partitioning between these two species. The study also Looked at the effect of dams on otters which is the primary factor negatively affecting otter habitats. Yet flow regimes are mostly compensated due to more streams joining the main river channel. Increasing degree of habitat disturbance in different land-uses seems to negatively influence the fluvial functionality which is positively associated with otter habitat. The combined effect of isolation due to reservoir and increasing disturbances in downstream area pushes smooth-coated otters to select habitats upstream that are marginal to them and more suitable for small-clawed otters.