PhD Theses (SACON)

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A STUDY OF THE ECOLOGY OF SELECT SPECIES OF WEEDS IN DIFFERENT VEGETATION TYPES OF NILGIRI BIOSPHERE RESERVE
(SACON, 2000) Mahajan, Maya V
Invasion by weedy species of plants has serious impact on natural and managed ecosystems. Weedy species invade agricultural lands, fallow lands, roadsides, disturbed forests and plantations. Invasion by such species modifies the ecosystem structure and function. Invading species may dominate and displace the native vegetation and cause extinction of certain native species, leading to alteration in the original biodiversity of an area. In recent years, biological invasion is being recognized as a serious threat to biodiversity conservation
A study of the ecology of select species of weeds in different vegetation types of Nilgiri Biosphere Reserve
(SACON, 2000) Mahajan, Maya V; Azeez, P A
Invasion by weedy species of plants has serious impact on natural and managed ecosystems. Weedy species invade agricultural lands, fallow lands, roadsides, disturbed forests and plantations. Invasion by such species modifies the ecosystem structure and function. Invading species may dominate and displace the native vegetation and cause extinction of certain native species, leading to alteration in the original biodiversity of an area. In recent years, biological invasion is being recognised as a serious threat to biodiversity conservation (Pimm and Gulpin 1989, Vitousek et al. 1996). In contrast to studies in agricultural fields, not much attention is given to plant invasion in natural ecosystems. Nevertheless, the colonisation of natural forest ecosystem by weedy species is growing as a threat. In recognition of the threats posed by plant invasions in natural vegetation and realising the scarcity of ecological information on various colonising plant species
A STUDY ON REPRODUCTIVE BEHAVIOUR OF NICOBAR LONG-TAILED MACAQUE (MACACA FASCICULARIS UMBROSUS) IN NICOBAR ISLANDS, INDIA
(SACON, 2018) Pal, Arijit; Kumara, H N
Nicobar long-tailed macaques (Macaca fascicularis umbrosus) live in three small isolated catastrophic prone Nicobar Islands. This study was conducted to understand the strategies adapted by these macaques to survive on such stressful condition, and compare it with other sub-species distributed in varying environmental conditions. The study suggested a high degree of similarities in demographic traits and social organization between the sub-species, which reflected the high adaptability of these macaques to manage the life-history traits by coping with the stressful condition. Contrasting to other sub-species, the distinct behavioral traits like the variation in age-sex ratio and non-seasonal breeding pattern in these macaques are the adaptive strategies to achieve the conservative life-history traits to maximize the reproductive output. Competition for mate resources was very evident in M. f. umbrosus, where individuals of both the sexes were involved in intra and inter-sexual competition to increase their reproductive success. Social hierarchy has a direct impact on the heterogeneous distribution of mate and food resources between individuals with different social status, which ultimately shapes the social organization in M. f. umbrosus. Consequently, to balance the disadvantages of living in such hierarchical group, individuals make a trade-off by adopting different behavioral strategies through policing specific inter-individual relationships. These macaques were involved in between-group contest to compete for food and mate resources rather than the territory defense. This study provided first-ever information about demography, social organization, reproductive behaviors, birth seasonality, and intra and inter-group competition in Nicobar long-tailed macaques. It also revealed that in due course of interactions with its environment, a species could become flexible with life history traits and adopt different strategies to increase survivability as well as inclusive fitness.
A study on the breeding biology of the Nicobar Megapode Megapodius nicobariensis
(SACON, 2000) Sivakumar, K; Sankaran, Ravi
The family Megapodiidae consists of 22 species in seven genera, most of which are island forms occurring in Australia, New Guinea and surrounding islands, eastern Indonesia, the Philippines, Niuafo’ou island, the Palau and Mariana islands and the Nicobar islands. Thirteen of these 22 species are currently threatened by habitat destruction, introduction of predators and over-exploitation of eggs. The megapodes are an unique group of birds as they utilise external sources of heat to incubate their eggs. Megapodes exploit external heat sources in two ways. Some species lay eggs in burrows in geothermally heated soil, or on exposed beach, and are called burrow nesters (e.g. Macrocephalon maleo). Other species construct mounds of sand, soil and decomposing vegetation within which they lay eggs and are called mound nesters (e.g. Megapodius freycinet). The chicks are supra-precocial; they are able to fly soon after emerging from the mound or burrow, and receive no parental care.
Acoustic communication of passerine birds of Anaikatty hills with special emphasis on Common Iora Aegithina tiphia
(SACON, 2019) Divyapriya, C; Pramod, P
Bird acoustic communication is intended for species identification between groups (interspecific communication) and for individual identity within a group (intraspecific communication (Simmons, 2002). Bird vocal signals comprise a mixture of tones (harmonic sounds) such as chirps, clicks, less harmonic mumbles, wheezy chats, rattles and buzzy noises. Male birds use complex songs for territorial establishment and maintenance (Catchpole & Slater, 2008; Bhatt et al., 2000; Marler, 2004); and mate attraction (Marler, 2004). Songs have various other functions, for; (i) distracting potential predators (Ritchison, 1991); (ii) informing the mates about the threat (Kermott, & Johnson, 1991); and (iii) coordinating nest exchanges between mates
Aggression and Conflict Resolution in Nicobar Long-Tailed Macaque Macaca fascicularis umbrosus.
(SACON, 2019) Partha Sarathi, M.; Kumara, H.N.; Thayumanavan
A strong dominance hierarchy with high linearity and steepness in females indicates high competition among the females for food. This pattern was absent in the study with a moderately wrong hierarchy, possibly due to the avoidance of competition for food. This, in term, suggests that food distribution is uniform and abundant for each individual of a small group, which is the foundation of the socio-ecological theory. Furthermore, low competition in the group allows females to form close bonds and exchange affiliative behaviors as recorded in the study. Low monopolization is depicted by low steepness values and under such a regime. subordinate females do not use grooming as currency to gain access 10 food from dominant females.
Air Quality of Coimbatore with Emphasis on Respirable Suspended Particulate Matter
(SACON, 2002) Mohanraj, R; Azeez, P A
Particulate matter (PM), a complex mixture of organic and inorganic substances is an ubiquitous air pollutant, contributed by both natural and anthropogenic sources. Ever since the advent of industrial era, anthropogenic sources of PM have been increasing rapidly. Increasing amounts of such potentially harmful particles being emitted into the atmosphere on a global scale has resulted in damage to the health and environment. Recently it is also reported that soot particles have a heating effect to the atmosphere. Such heating effect can have wide implications on various systems of earth including climate. PM in the atmosphere is categorized according to size because of different health impacts from particles of different diameters. PM with diameters of less than 50 pm are generally classified as Total suspended Particulate Matter (TSPM). Particles that are greater than 50 pm in diameter do not remain in the atmosphere for appreciable lengths of time and present no health risk. Particulates with a diameter less than 10 pm defined as PM 10 or Respirable Suspended Particulate Matter (RSPM), enter the respiratory system and may become lodged in the alveoli resulting in wide range health effects including cancer and heart failures. PM 10 has the potential to travel long distances and cause cumulative effects. Other hazardous air pollutants may adhere to these particles, increasing their toxicity. These particles on wet and dry deposition are known to pollute local, regional and global land and water resources.
AN ANALYSIS OF THE ENVIRONMENTAL CHANGES IN THE BHARATHAPUZHA RIVER BASIN, SOUTHERN INDIA
(SACON, 2010) Raj, Nikhil PP; Azeez, P A
Rivers are considered as an open ecological system, which play a major function in integrating and organizing the landscape and moulding the ecological setting of an area. The dynamism of the free-flowing rivers for long have challenged and fascinated humans and are a cradle of human civilization. The economic value of river basins could be in billions of dollars (Schuyt, 2005) if it could be reasonably estimated. However, rivers and streams are among the most human affected ecosystems in the globe and exceedingly exploited (Neilson et al., 2005) for water, energy and transportation by its stake holders. The genesis and development of the modern human civilization is believed to have happened in the banks of various global river systems. The Egyptian, Mesopotamian, Chinese and Indus valley civilizations were developed respectively in the basins of the rivers Nile, Tigris–Euphrates, Yangtze-Yellow, and Indus during different geological time scales. Most of the important and highly populated cities of the present day are also located along river banks.
Assemblage of Shorebirds in the Sindhudurg District Maharashtra
(SACON, 2022) Babu Rao, Golusu; Babu, S
Migratory shorebirds are the most threatened waterbird species around the world. Shorebirds in India have received little attention, particularly on the west coast. Thus, this study was conducted in the coastal areas of the Sindhudurg district, Maharashtra. The coastal habitats in the district are dominated by beaches, mudflats, and mangroves, which have been identified as potential habitats for shorebirds. Thus, the distribution, abundance, and factors influencing habitat use of shorebirds were studied from these three habitats across seven sites and five seasons. Among the three habitat types, mudflat was an important area for shorebirds thus fine-scale habitat selection for select shorebird species was carried out in the mudflats. Total count and photographic methods were used to count the birds. A total of 36 species of shorebirds were recorded, of which 21 and 10 species used Sindhudurg coast as stopover and wintering sites respectively. Mudflats had a higher species richness (21) than the beach (20) and mangroves (14) habitats. Plovers were the most common and abundant species in the study area. nMDs showed various pattern of shorebird species composition across the habitats and seasons. The cluster analysis revealed five distinct migratory seasons in shorebirds along the Sindhudurg coast: 1) arrival phase, 2) wintering phase, 3) early departure and late arrival phase, 4) departure phase, and e) breeding phase. The physiochemical parameters of water and prey varied significantly between habitats and seasons. Salinity showed decreasing trend from beach (34.67±5.94) towards the mangroves (28.07±7.66). Prey abundance was higher in mudflats and during the wintering season. BIO-ENV analysis showed that among the measured environmental parameters salinity was the key factor influenced prey distribution (ρ=0.51). The shorebird richness (X2=56.5, P=0.00) and abundance (X2=32.6, P=0.00) positively influenced by crustacean density, salinity and bivalve density. Prey availability and accessibility had a major impact on the finescale habitat selection of the studied species. The Lesser Sand Plover and Kentish Plover avoided areas with oyster beds and preferred fine sand substrates with higher crab densities. Eurasian Curlew selected high profitable foraging sites close to the waterline with increased surface penetrability
ASSESSMENT OF MANAGEMENT STRATEGIES OF THE BIRD HAZARDS TO AIRCRAFT IN SELECT INDIAN AIR FORCE AIRFIELDS
(SACON, 2021) Srinidhi, S; Pramod, P
Bird Strike to aircraft is a serious aviation safety concern. Many aircraft and lives of pilots have been lost the past due to this hazard. In addition, airlines incur huge amounts of money to repair the damages caused by the birds. They also lose financially due to delayed departures in addition to the inconvenience to the passengers. Considering these aspects, efforts are mad to mitigate the problem through various means. These mitigation measures include simple measures like scaring away of birds using crackers to high end measures such as deploying bird detection radars. Each of these means has its strengths and limitations and its exact efficacy is not well documented. The birds are the natural occupants of air. They have been in the air for nearly 150 million years. The human created aircraft are just about 120 years old. Hence, the birds have a right to live in the air. However, there is a need to look for ways and means to co-exist without conflict. To create such a situation, there is a need to understand the bird community and its activity over each of the airfield and its surroundings. Hence, while designing methods to mitigate bird strike hazard is an inescapable requirement. Considering these requirements, five different studies were carried out by selecting twenty one Indian Air Force airfields/ its surroundings.
Avian Species selection in Urban Habitats: A study in Coimbatore, India.
(SACON, 2013) Rajini, J.; Azeez, P.A.
Survival of a species is closely associated with changing habitats. We studied this in the context of urbanization that brings massive changes in the landscape. The study is contextual in view of high rates of conversion of natural landscapes into urban areas. With the ascent of urbanization, many species disappear while some species become abundant. The present study investigated avian species and their distribution along a rural-urban gradient of the Coimbatore city - a fast growing city in Tamil Nadu, India. The study was taken up to explore the factors that affect the distribution of avian species across an urbanisation gradient and to identify survival strategies adopted by avian species in urban areas.
AVIFAUNAL COMPOSITION AND DISTRIBUTION PATTERNS ALONG ELEVATIONAL GRADIENTS IN THE SUTLEJ AND YAMUNA RIVER BASINS OF HIMACHAL PRADESH AND UTTARAKHAND, WESTERN HIMALAYA, INDIA
(SACON, 2019) Shantakumar, B; Arun, P R
Understanding the spatial difference in species diversity is a key challenge in ecology (Gaston, 2000). The well-known spatial pattern is the latitudinal diversity gradient, where species richness peaks at tropics and declines towards the poles (Rosenzweig, 1992). The richness of species along the elevational gradients is just a microcosm of the global latitudinal gradient (Rahbek, 1995). Species richness along the latitudinal gradient is the most striking and perhaps best-documented pattern (Yu et al., 2013). The complex elevational diversity of birds has been investigated on every continent (Cavarzere & Silveira, 2012). These patterns of species distribution along elevational gradients vary across taxonomic groups. Species richness patterns along the elevational gradients generally follow three patterns; 1) the monotonic decline of species richness, 2) the hump-shaped pattern with a peak at mid-elevation and 3) increase in species richness with increasing elevation (Figure 1.1). Among these, the first two patterns are the most common ones. i.e. either decreasing richness with increasing elevation or a hump-shaped pattern, in which diversity peaks at mid-elevations (
Avifaunal Diversity of the Andaman Islands and their Conservation
(SACON, 2010) Rajamannan, M.A.; Vijayan, Lalitha
Biodiversity hotspots in the world are chiefly tropical region is featuring high concentration of endemic species and has claimed ha lf of the world's terrestrial species, if all hotspot's are combined. These natural habitats are under threat now due to habitat loss and destruct ion. Consistently the islands, a small body of landmass are having a major role of its high endemism in the world. Nevertheless, the increasing demands on resources in the islands have resulted in their ecosystems being severely threatened and facing in its extreme habitat destruction. For example over 12.1 % of all bird species in the world are threatened with extinction today in which the majority of these are found in tropical forest and islands. There is disputing that global biodiversity is declining, but accurate measures are very hard to come by. Bird’s, the best known major group of organisms and just one component of biodiversity and far from the most significant in species numbers or biomass can help us to understand the problems and piece together the solutions, where the maintenance or restoration of the biological integrity of urban and Sundarbans areas must begin with a comprehensive study of the links between biota and land use. In this context bird communities are often used in investigations of habitat changes as the best indicators of the environment. Though the Indian mainland harbours rich avifauna diversity the Andaman and Nicobar Islands. The information on community structure and general bird ecology of these islands are little known and very few attempts have been made to study the bird community along their island distribution. Hence, the present study was initiated with the major objectives to: i) document the avifaunal diversity and status in different islands/vegetations, ii) observe the bird species distribution pattern in the Andaman Islands with their biogeographical importance, iii ) study the nested·subsets of the birds in different outer islands in terms of their presence/absence which will be providing a risk assessment of the extinction probability of the various species' populations isolated on the islands of fragmented habitat, and iv) understand the insular biology of the endemic and threatened species in Andaman Islands as of baseline information for their conservation.
Bird communities and their distribution pattern along the elevation gradient of Teesta Valley, Sikkim
(SACON, 2008) Acharya, Bhoj Kumar; Vijayan, Lalitha
Studies on ecology of local communities are important for understanding environmental problems and planning area-based conservation management (Simberloff, 2004). Community composition, species richness and diversity of birds in five different elevation zones of Teesta valley, Sikkim were studied from June 2003 to March 2006 using point count sampling method. A total of 329 species of birds (299 during regular quantitative sampling and 30 during. opportunistic observations) belonging to 44 families was recorded in the Teesta valley during the study period. The study shows that Teesta valley harbors high diversity and abundance of birds. Broadleaved vegetation, situated at mid-elevation region, is the most diverse zone as compared to tropical, coniferous or alpine vegetation. Species accumulation curves based on number of point counts indicated that most of the species were detected in all the zones. Species richness (observed and estimated) was the maximum in zone II, whereas density, abundance and diversity were the maximum in zone iii. The species-abundance pattern of birds followed truncated log-normal distribution for total bird population as well as for all the zones except zone II which did not fit to any models. Bird data showed the presence of both types of species, exclusive (restricted to one elevation zone) and generalists (present in two or more zones), in the Teesta valley. Out of the total species observed (329), 156 (47.4%) were exclusively recorded in one specific elevation zone. Only three species, namely Blue Whistling Thrush, Greenish Warbler and White-capped Water Redstart occurred in all the five zones.
BIRD COMMUNITIES OF THE THORN AND DRY DECIDUOUS FORESTS IN MUDUMALAI WILDLIFE SANCTUARY, SOUTH INDIA
(SACON, 1998) Gokula, V; Vijayan, Lalitha
Birds are important components of forest ecosystem, playing a major role as pollinators, consumers and dispersers of plant seeds, and predators of insects. In nature different species form intricate assemblages as a result of the local ecological make up. Whittaker (1975) states that communities are assemblages of populations of species which occur together in space and time. Studies on bird community ecology starting from MacArthur and MacArthur(1961) have attracted wide attention. The main focus of community ecology is the manner in which groupings of species are formed and distributed in nature and the ways in which these can be influenced or caused by interactions between or among the species and the physical and biological factors of their environment. The cause-effect relation of such assemblages led to an increased interest in studies on bird communities (Cody, 1974; Cody and Diamond, 1975). An understanding of the determinants of bird community structure is extremely important for the practical development of guidelines for the habitat management
Bird Community of Andaman Islands with Emphasis on Human Associated and Introduced Birds
(SACON, 2013) Rajan, P.; Pramod, P.
Andaman and Nicobar Islands are very rich in bird diversity and hence have high importance in conservation planning. Both in species endemism and species diversity these islands are notable. Andaman and Nicobar Islands is also a significant place in India which is exposed to very high human mediated species introduction. These introduced species can have serious effects on the native biodiversity and it can be the agent for the breakdown of native species equilibrium. On the background of this context, this study was undertaken to examine the bird species composition of Andaman Islands especially on human influenced areas and the role of introduced birds among the avifauna of these Islands. The study was carried out in nine inhabited islands in the Andaman group and later these nine study sites were clubbed into five groups for easy analysis. The study emphasis on introduced birds and their impacts on native ecosystem especially on Islands. Both secondary and primary data collection methods are employed in the study. All the published information on distribution of birds in Andaman Islands were collated synthesized and analyzed to elucidate the characteristics of Andaman Bird fauna. Systematically 221 transect counts of birds from nine human inhabited islands which can be classified into 6 habitats were collected. These collected field observation data on birds were analyzed with special emphasis on the introduced birds.
Bird community structure along the altitudinal gradient in Silent Valley National Park, Western Ghats, India
(SACON, 2008) Anoop Das, K.S.; Vijayan, Lalitha
My research on bird community along the altitudinal-habitat gradients and their nest-site partitioning across habitats in Silent Valley National Park (SYNP) has portrayed several patterns. The work has explored some aspects of the processes which accounted for the patterns of variations in the community structure of birds in a pristine forest representative of the post Miocene and Pleistocene uplifted Western Ghats of India. In particular, the study addressed how altitude affected the distribution of birds and how the breeding birds shared their resources. The present study resulted in 5253 birds of 108 species, including 14 endemic species, from the 2314 point counts conducted in six habitats. The total number of species observed was 145 including opportunistic observations. Bird community structure of various habitats in corresponding altitudes varied significantly in terms of composition, abundance and diversity. The maximum species (59.2%) and individuals (27.2%) were in evergreen forest habitat and minimum in BLHF (22.8 % and 5.73% respectively). Shola habitats located at higher altitudes in the study area possessed higher species richness than mid-elevation broad leaved hill forest, which occurs within the altitudinal range of 1500- 1700 m. BLHF could be considered as a transitional zone between evergreen and shola forest. The significant difference in tree species richness of BLHF with adjacent EG and SHOLA habitats partly explain the reduction in number of bird species in this transitional zone.
Breeding Biology of Olive Ridley Sea Turtle, Lepidochelys olivacea (eschcholtz, 1829) along the Poompuhar Coast, Tamilnadu, South India
(SACON, 2011) Gokulakrishnan, J.; Bhupathy, S.
The Olive Ridleys is the most common marine turtle found in Indian waters, and is distributed on both east and west coasts including the offshore island s. Most of the ecological works on the Olive Ridleys in India have been carried out in mass nesting beaches of Orissa. This species nests sporadically all over India, but barring a anecdotal notes, information on the ecology of this species is scanty in sporadic nesting areas. Hence, the present study was carried out to, (1) Understand the nesting habitats of Olive Ridleys along the (Poompuhar) Tranquebar- Pazhaiyar coast (2) Study the breeding biology of Olive Ridleys including offshore activities along the southeast coast. Bay of Bengal (3) Study the mortality and other anthropogenic pressure on marine turtles along the Tranquebar- Pazhaiyar coast, and (4) Conservation of Olive Ridleys along the southeast coast, Bay of Bengal. The present study was conducted along the Poompuhar coast (51 km), Bay of Bengal, Tamil Nadu from November 2004 to May 2010. Fishing and agriculture are major occupations of the local inhabitants.
Breeding Ecology of the Edible-nest Swiftlet Aerodramus fuciphagus and the Glossy Swiftlet Collocalia esculenta in the Andaman Islands, India
(SACON, 2009) Manchi Shirish, S.; Pramod, P.
The intriguing biological feat of making nest with its saliva is threatening the survival of the edible-nest swiftlet. Ever since the16th century when bird’s nest became a delicacy in Chinese cuisine and an important item in their pharmacy, edible nest swiftlets are found overexploited all over. In the past two to three decades the production of the edible bird’s nests has reduced drastically because of overexploitation and uncontrolled harvesting that is directly affecting the population of this cave-dwelling species. The high demand in the international markets has put so much pressure that despite strict regulations on nest collection, the wild populations of the edible-nest swiftlets is plummeting by as much as 80% to 90% and has reached local extinction across some of their ranges. To understand the nest-site requirements of the species, their nest-site characters, preference and the relationship with nesting success were studied. Results showed that the edible-nest swiftlet and the glossy swiftlet are cave dwelling trogloxenes and do not nest randomly inside the caves
BURROW USE PATTERNS BY TERRESTRIAL VERTEBRATES IN KEOLADEO NATIONAL PARK, BHARATPUR, INDIA
(SACON, 2018) Mukherjee, Aditi; Kumara, H N
Most animals use some refuge either daily or seasonally. Burrow in terrestrial habitats is one of the oldest forms of engineered shelters (Voorhies, 1974) reported as early as carboniferous period (Olsen and Bolles, 1975). Burrows appear to be crucial refuge especially in arid and semi-arid regions providing protection against temperature extremes, fire and predation (Campbell and Clark, 1981; Reichman and Smith, 1990). Three major categories of burrowing vertebrates have been identified by Kinlaw (1999). These include ‘primary excavators’ for whom digging burrows is an inevitable part of their survival; ‘secondary modifiers’ that occupy and further transform the burrows of primary excavators and the third category of ‘simple dwellers’ that take advantage of the mere existence of the burrows and occupy them. Burrow inhabitants are even reported to be either in obligate and/or non-obligate commensal associations (Kiviat, 1978; Kinlaw, 1999). Burrowing vertebrates are the potential ecosystem engineers. These organisms have the capability of modifying habitats and directly or indirectly regulate resource availability for other species (Hansell, 1993; Jones et al., 1994; Lynn and Detling, 2008). They are known to have positive and negative effects on the ecosystem, species richness and abundance at small scales, but an overall positive effect at larger scales in ecological and evolutionary time and space (Jones et al., 1997). In Negev desert, Israel, the digging behavior of porcupine Hystrix indica has been studied as a model of disturbance and recovery of plant species (Gutterman et al., 1990). The burrows are important for newborn porcupines for their survival (decrease in vulnerability), energy conservation and thermoregulation