Academic literature on the topic 'Feeding guild structure'
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Journal articles on the topic "Feeding guild structure"
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Mattos, Gustavo, Ricardo S. Cardoso, and André Souza Dos Santos. "Environmental effects on the structure of polychaete feeding guilds on the beaches of Sepetiba Bay, south-eastern Brazil." Journal of the Marine Biological Association of the United Kingdom 93, no. 4 (2012): 973–80. http://dx.doi.org/10.1017/s0025315412000707.
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Several studies have been conducted to explain patterns of the abundance, richness and diversity of sandy-beach macrofauna; however, such analyses have ignored the overall functional structure of macrofauna communities. Few studies have examined polychaete feeding guilds on sandy beach environments. To examine the effects of environmental factors on polychaete feeding guilds on sandy beaches, 12 sandy beaches from five islands in Sepetiba Bay were sampled. A total of 24 polychaete morphospecies, grouped among 21 families, were identified in these sandy beaches. The polychaete species were classified into 10 feeding guilds, and the SDT guild (suspended-deposit feeders, discretely motile, with tentacles) was the most abundant feeding guild, with 34.2% of total number of organisms. The highest trophic importance index and index of trophic diversity values were recorded on the sheltered beaches. A canonical correspondence analysis showed that the exposure rate, beach length, and grain size of the beach sediment significantly affected the polychaete feeding guild distribution and abundance. We can conclude that sheltered beaches have a higher diversity of feeding guilds than exposed beaches and that the biological descriptors of the feeding guilds are directly associated with the grain size of the sediment.
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Sudesh, Kumar, Bisht M.S., and Kumar Rakesh. "Avian Diversity and Their Feeding Guild Structure in Temperate Forests of Garhwal Himalaya, Uttarakhand, India." International Journal of Zoological Investigations 08, no. 02 (2022): 983–92. http://dx.doi.org/10.33745/ijzi.2022.v08i02.116.
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The study on avian diversity and their feeding guild structure with relation to their habitat use in temperate forest of district Pauri Garhwal was carried out between April 2015 to March 2017. Lines transect and direct visual methods were used to record the bird species diversity, their feeding habit and habitats. Frequent surveys were made in the study area and birds were counted. During the study period, a total of 152 species of birds belonging to 9 order and 43 families were recorded. The highest diversity index was recorded at Kandoliya (H¯= 3.98±0.06) and Adwani was recorded with minimum diversity (H¯= 3.34±0.08). The average bird diversity index at all sites was recorded as (H¯= 3.57±0.11). Further, on the basis of their feeding guilds the recorded birds were categorized into the six major categories such as insectivore (55.92%), omnivore (13.81%), grainivores (5.92%), carnivore (9.21%), nectarivorous (1.31), frugivore (5.92%) and 7.91% species remained unidentified. The insectivore guild was dominant in all the guild structures.
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Caleb, John T. D. "Spiders (Arachnida: Araneae) from the vicinity of Araabath Lake, Chennai, India." Journal of Threatened Taxa 12, no. 1 (2020): 15186–93. http://dx.doi.org/10.11609/jott.5393.12.1.15186-15193.
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This study documents the spider fauna in the vicinity of a suburban lake (Araabath Lake) in Chennai. A total of 70 species of spiders belonging to 58 genera and 21 families were recorded. Seven species are endemic to India and six are endemic to India and Sri Lanka. Salticidae was the most dominant with 24 species belonging to 19 genera. Guild structure analysis revealed seven feeding guilds of which, stalkers and orb-web weavers were the dominant feeding guilds followed by ground runners and ambushers, respectively.
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Adarsh, C. K., and P. O. Nameer. "Spiders of Kerala Agricultural University Campus, Thrissur, Kerala, India." Journal of Threatened Taxa 7, no. 15 (2015): 8288. http://dx.doi.org/10.11609/jott.2468.7.15.8288-8295.
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<p>A total of 86 species of spiders belonging to 56 genera of 20 families have been recorded from the Kerala Agricultural University (KAU) campus, Thrissur, Kerala, southern India. This represents 5.1% of the total spiders’ species and 33.33% of the total families of spiders recorded in India. The dominant spider family at KAU campus is Araneidae with 18 species of nine genera. Salticidae is represented by 14 species of 13 genera. Out of 252 endemic spiders of India, 16 have been reported from KAU campus. Guild structure analysis shows spiders belonging to seven types of feeding guilds present in KAU campus. Orb-web builders are the dominant feeding guild accounting for 34%, followed by stalkers (22%), ground runners (20%), ambushers (8%), scattered line weavers (8%), foliage runners (7%) and sheet-web builders (1%).</p><div> </div>
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Lehnert, Matthew S., Charles E. Beard, Patrick D. Gerard, Konstantin G. Kornev, and Peter H. Adler. "Structure of the lepidopteran proboscis in relation to feeding guild." Journal of Morphology 277, no. 2 (2015): 167–82. http://dx.doi.org/10.1002/jmor.20487.
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Barnes, Gregory G., and Vernon G. Thomas. "Digestive organ morphology, diet, and guild structure of North American Anatidae." Canadian Journal of Zoology 65, no. 7 (1987): 1812–17. http://dx.doi.org/10.1139/z87-274.
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Discriminant function, cluster, and covariate analyses of gizzard, small intestine, and ceca weights were used to quantify the structure of feeding guilds and the effects of diet on gut morphology for 18 species of North American anatids. Guild structure based on gut measurements closely approximated that identified by generalized feeding habits. Herbivorous species such as Brant (Branta bernicla), Gadwall (Anas strepera), Redheads (Aythya americana), Canada Geese (Branta canadensis), and Mallards (Anas platyrhynchos) consistently had heavier gizzards and ceca than carnivorous species such as Common Goldeneye (Bucephala clangula), Bufflehead (Bucephala albeola), Oldsquaw (Clangula hyemalis), and Common Mergansers (Mergus merganser). Omnivorous species such as Lesser Scaup (Aythya afftnis), Greater Scaup (Aythya marila), and American Black Ducks (Anas rubripes) were characterized by heavy gizzards, intermediate ceca, and heavy intestines. The results provide further evidence that intestine size is primarily influenced by overall diet diversity and suggest that gut size may be used to indicate general food habits. The ability of waterfowl to adjust gut sizes and accommodate dietary changes is restricted to ranges dictated by the most frequently eaten foods. Thus, predictions of general food habits can be made without knowledge of the foods being consumed at a particular time and location.
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Prajapati, Dhruv A., Krunal R. Patel, Sandeep B. Munjpara, Shiva S. Chettiar, and Devendrasinh D. Jhala. "Spiders (Arachnida: Araneae) of Gujarat University Campus, Ahmedabad, India with additional description of Eilica tikaderi (Platnick, 1976)." Journal of Threatened Taxa 8, no. 11 (2016): 9327. http://dx.doi.org/10.11609/jott.1835.8.11.9327-9333.
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We report a checklist of spiders based on a survey made from August 2013 to July 2014 in Gujarat University Campus, an urban area located in the middle of Ahmadabad City, Gujarat State. A total of 77 species of spiders belonging to 53 genera and 20 families of spiders were recorded from the study area represented by 31.74% of the total 63 families reported from India. Salticidae was found to be the most dominant family with 18 species from 14 genera. Guild structure analysis revealed six feeding guilds, namely stalkers, orb-web builders, space-web builders, ambushers, foliage hunters and ground runners. Stalkers and orb-web builders were the most dominant feeding guilds representing 28.58% and 20.78% respectively among all studied guilds. Species Eilica tikaderi (Platnick, 1976) is reported for the first time from Gujarat with additional description and detailed genitalic illustrations.
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Sheetal, Z. L., P. Madhuri, and K. Hemant. "Spider (Arachnida: Araneae) diversity at Godrej mangroves, Vikhroli, Mumbai, Maharashtra, India." ENTOMON 47, no. 3 (2022): 305–12. http://dx.doi.org/10.33307/entomon.v47i3.765.
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Among the varied aquatic and terrestrial invertebrates diversity of mangrove ecosystem, spiders are considered to be an important bioindicators of ecological health. Studies on the spider diversity in the mangroves at Vikhroli, Mumbai, Maharashtra conducted resulted in the documentation of a total of 38 spider species belonging to the 33 genera under 12 families. Salticidae was found to be the dominant with 10 species from 10 genera, followed by Araneidae (9 species and 7 genera). The survey done in three mangrove zones revealed that zone II with moderate mangrove density resulted in the highest diversity (H=0.89) of spiders. Guild structure analysis revealed six different guilds. Stalkers (Salticidae and Oxyopidae) were the predominant feeding guild (34.00%). Seasonal (pre monsoon, monsoon and post monsoon) analysis showed more species diversity in the month of June to September.
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Delariva, Rosilene Luciana, Norma Segatti Hahn, and Elaine Antoniassi Luiz Kashiwaqui. "Diet and trophic structure of the fish fauna in a subtropical ecosystem: impoundment effects." Neotropical Ichthyology 11, no. 4 (2013): 891–904. http://dx.doi.org/10.1590/s1679-62252013000400017.
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This study examined the diet and trophic structure of the fish fauna, over temporal and spatial scales, as affected by the impoundment of the Iguaçu River in the region of Salto Caxias, Paraná State, Brazil. Sampling was conducted before (March 1997 - February 1998) and after the impoundment (March 1999 - February 2000), at four sampling sites. The stomach contents were analyzed by the volumetric method. The species could be organized in 10 trophic guilds: algivores, carcinophages, detritivores, herbivores, aquatic insectivores, terrestrial insectivores, invertivores, omnivores, piscivores, and planktivores; the first and last guilds were represented only in the post-impoundment period. Similarity patterns and feeding changes were summarized by a non-metric Multi-dimensional Scaling (nMDS) analysis and statistically tested by a Permutational multivariate analysis of variance (PERMANOVA). Most species showed feeding changes, except for the piscivores and detritivores. These changes were related to the temporal factor (impoundment phases), such as reduced intake of benthic organisms and allochthonous food, which were usually replaced by resources from the reservoir itself (algae, microcrustaceans, and fish), simplifying the food spectrum of the fish fauna. A different indicator of food resources (IndVal) corroborated these changes in the feeding of the species. The proportions of the trophic guilds evaluated based on the catch per unit of effort (CPUE) and tested by ANOSIM were significantly different before and after the impoundment. Herbivores and piscivores were the guilds that contributed (SIMPER) to these differences, especially the high increase in biomass of the piscivore guild after the impoundment. Variations in the abundance of trophic guilds were more directly related to changes in the feeding habits of the fish fauna than to increases in the number and biomass of the species that constitute these guilds.
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LIM, BURTON K., and MARK D. ENGSTROM. "Bat community structure at Iwokrama Forest, Guyana." Journal of Tropical Ecology 17, no. 5 (2001): 647–65. http://dx.doi.org/10.1017/s0266467401001481.
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With 86 species, Iwokrama Forest in central Guyana has the highest reported bat biodiversity for a protected area in the world. Using standardized capture data for 73 of these 86 species, we document community structure of bats in terms of species diversity, relative abundance, gross biomass, feeding guilds, vertical stratification and a trophic-size niche matrix. Based on faunal surveys in 1997, with similar amounts of effort in the forest canopy and at ground level, the greater fruit-eating bat (Artibeus lituratus) was by far the most ecologically dominant species in terms of frequency of capture and biomass. In total, frugivores comprised 70% of the species diversity and 78% of the biomass. The most common species of bat were fully partitioned in a resource niche matrix of size and trophic guild when vertical stratification was included as a variable. We conclude that resource partitioning and species packing differentially affect relative size in tropical bats, and are better summarized and analysed in three dimensions.
Dissertations / Theses on the topic "Feeding guild structure"
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Field, J. P. "Provisioning strategies, intraspecific parasitism and guild structure in solitary wasps (Hymenoptera: Sphecidae, Pompilidae)." Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233015.
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Group-living, within the Hymenoptera, is restricted to taxa in which females return to their nests repeatedly with food for their offspring (multiple provisioning), increasing the opportunities for helping (e.g. by guarding the nest). Some solitary wasps provide only one large prey item per cell (single provisioning). <i>Ammophila sabulosa</i> (Sphecidae) females provision half of their cells singly and half multiply. The costs and benefits of these two alternatives are compared in terms of : a. Total weight of prey (caterpillars) provided. b. Time taken to capture and transport prey. c. The probability of intraspecific theft of prey from cells. d. The incidence of parasitism by miltogrammine flies. There is no evidence that either strategy is more successful than the other. An advantage of flexible provisioning is suggested by a study of <i>Anoplius viaticus</i> (Pompilidae), females of which provision all cells singly with spiders. Despite provisioning prey of a smaller size range than does <i>Ammophila</i>, total prey weight in <i>Anoplius</i> cells is more variable and dependent upon seasonal changes in prey availability. <i>Ammophila</i> females steal caterpillars from each others' nests, and both they and <i>Anoplius</i> females brood-parasitize cells of conspecifics. Intraspecific parasitism as an alternative nesting strategy is discussed and compared with work on other solitary wasps. Patterns of resource utilization are documented for the guild of spider-hunting pompilid wasps at one site. Data were collected on : a. Microhabitat utilization. b. Seasonal occurrence. c. Female size distributions. d. Prey species and sizes. Observed patterns of utilization and overlap are compared with 'neutral' models of guild structure in which various aspects of the species x resources utilized matrix are randomized. Some of the results are consistent with the idea that interspecific competition has partly determined pompilid guild structure, but problems of methodology and interpretation are discussed.
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Wyma, Rindert. "Birds of the riparian corridors of Potchefstroom, South Africa / Rindert Wyma." Thesis, North-West University, 2012. http://hdl.handle.net/10394/9545.
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A riparian ecosystem is the area between the aquatic and terrestrial setting of a stream, and serves as a corridor and habitat for birds. Several riparian ecosystems are located in urban environments, and three main riparian corridors are located in Potchefstroom. They are the Mooi River, Wasgoed Spruit, and Spitskop Spruit, which encompass a wide range of different vegetation types and anthropogenic factors. Therefore, different habitat types for birds occur along the riparian corridors of Potchefstroom. Factors such as food and water availability, nesting sites, competition, predation, learning, presence of other species, and those species that are able to adapt to environmental changes influence the avian diversity and communities along riparian corridors.
The hypothesis is that bird variables along the riparian corridors in Potchefstroom are affected by vegetation, anthropogenic, and seasonal influences. To investigate these affects, two secondary objectives were formulated. The first was to characterise riparian avian habitats (CAHs) according to vegetation and anthropogenic factors, and the second was to identify temporal and spatial changes in avian variables.
The three streams were divided into 79 consecutive transects, each 300 m long. The study area consisted of: 17 transects along Spitskop Spruit, 12 along Wasgoed Spruit and 50 along the Mooi River. Bird observations were conducted monthly from June 2006 to June 2007. Birds that were observed with a perpendicular distance ≤ 30 meters towards the streams were included in the results. The bird species that were observed were also classified into different nesting and feeding guilds.
Environmental data recorded included: vegetation structure (estimated cover percentages and height classes of trees, shrubs, grasses, herbs, sedges, and reeds), anthropogenic structures (estimated cover percentages of roads, footpaths, bridges, electrical pylons, houses, and drainage pipes), and the presence of informal settlers along each transect (the mean number of people and the space they occupy). Vegetation was monitored in summer– (February 2007 until April 2007) and winter months (June 2007 until August 2007). The anthropogenic structures and the presence of informal settlers (anthropogenic factors) were monitored simultaneously with the bird counts.
Transect-time profiles were drawn for the four parameters, which differed on spatial and time scales. Multivariate analyses included non-metric multidimensional scaling (NMS), cluster analysis, and indicator species analysis. Cluster analyses and NMS bi-plots were used to define characterised avian habitats (CAHs). Two types of CAHs were characterised: Summer CAHs (summer vegetation and anthropogenic factors) and Anthropogenically CAHs (Anthropogenic factors alone). Bird species were then ordinated with the summer and anthropogenically CAHs on NMS successional vector graphs. The successional vectors illustrate the avian community trajectories of the different CAHs. Indicator species analyses were performed to describe associations between the bird species and the summer and anthropogenically CAHs.
The summer and anthropogenic CAHs that were characterised had different avian community trajectories and different species were associated with these CAHs. Different levels in avian diversity appeared among these CAHs, and convergence and divergence in communities appeared among these CAHs. Birds also selected their habitats according to feeding and nesting behaviours.
Consequently, it can be deduced that environmental factors such as vegetation structures and anthropogenic factors, as well as seasonality, had an effect on the distribution of birds along the riparian corridors of Potchefstroom.<br>Thesis (Master of Environmental Sciences)--North-West University, Potchefstroom Campus, 2013
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Wang, Ming-Chih, and 王明智. "Feeding habits, food resource partitioning and guild structure of odontocetes in Taiwanese waters." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/74559737841955360904.
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博士<br>國立臺灣大學<br>動物學研究所<br>91<br>In order to reveal the feeding habits, food resource partitioning and guild structure of odontocetes in Taiwanese waters, the stomach contents were used to identify and enumerate the prey they consumed. Using data collected during 1994 to 2001, which included a total 150 stomach samples collected from 14 odontocetes species. The Risso’s dolphin predominantly fed on enoploteuthid squid, with 90.5% of total number of prey. The diet of Fraser’s dolphin was dominated by hatchetfish, with total prey count of 50.6%. The pantropical spotted dolphin primarily consumed lanternfishes which comprised 49.8% of total number of prey. The diet composition of these three dolphins all showed seasonal variation. The food niche width (B=1.6) of Risso’s dolphin was much narrow than that of Fraser’s dolphin (B=4.4) and pantropical spotted dolphin (B=5.1). The low global overlaps found among the food niches of those three sympatric dolphins, indicating that they have succeeded in partitioning the food supply. Difference in feeding depth and food preferences could reduce the direct food competition. Enoploteuthis chunii, Sthenoteuthis oualaniensis and Taonius pavo was the primary prey in the diet of pygmy sperm whale, while E. chunii, Histioteuthis miranda and T. pavo were the most important preys ingested by dwarf sperm whale. Although the primary preys they ingested were very similar, the ratio of each primary prey comprised differently. Pygmy sperm whale fed on much larger T. pavo than those were ingested by dwarf sperm whale, while dwarf sperm whale ingested more H. miranda than pygmy sperm whale did. This result supports the view that the pygmy sperm whale lives seaward of the continental shelf and the dwarf sperm whale lives in the more coastal waters.
Five major feeding guilds were identified by cluster analysis, which included a total 150 stomach samples collected from 14 odontocetes species. The first to forth group were predominantly fish eaters, while the fifth group comprised all teuthivorous odontocetes. The odontocetes off west coastal Taiwan fed primarily on croakers (Sciaenidae), needlefishes (Belonidae), jacks (Carangidae), octopus (Octopidae) and loliginid squid (Loliginidae). Off eastern Taiwan waters, the lanternfishes (Myctophidae), enoploteuthid squid (Enoploteuthidae) and flying squid (Ommastrephidae) were primarily consumed by odontocetes. The dendrogram of guild structure was very close to dendrogram of phylogenetic relationships among delphinid cetaceans. The third group belonged to the subfamilies Delphininae, the forth group belonged to Stenoninae and the second guild in fifth major group belonged to Globicephalinae in this study. The odontocetes in the same guilds could reduce the competition by partitioned the habitat spatially and temporally.
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Peters, Sandra Leslie. "Effects of selective logging on bat communities and feeding guild structure in southeastern Amazonia, Brazil." 2004. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=95066&T=F.
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Ye, Nian-Tsyr, and 葉念慈. "Studies on the Fish Community Structure, Feeding Guilds and Trophic Model in Yenliao Bay." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/93689256333200445346.
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碩士<br>國立臺灣海洋大學<br>海洋生物研究所<br>95<br>Abstract
The forth Nuclear Power Plant built at Gungliao,Taipei county. may pose potential environmental threats to the nearby Yenliao Bay coastal ecosystem due to the thermal discharge, impingement and entrainment in the water of outlet and intake areas after the plant starting to operate in the 2009. Therefore, collecting ecological data in Yenliao Bay before the operation of the 4th Nuclear Power Plant and use it as the baseline information is important for the assessment and monitoring programs for the environmental impact of the 4th Nuclear Power Plant.
The purposes of this research are: 1) to demonstrate spatial and a temporal variation of fish community in Yenliao bay; 2) to assemble feeding guilds of dominate fish species using their gut contents; and 3) to construct trophic model of Yenliao bay coastal ecosystem using ECOPATH with ECOSIM.
Results showed that species richness, total biomass, and abundance are all larger in the outlet station than the station near intake area. It may be due to the ecotone effect which resulted from the mixed sand and reef seabed near the outlet area and has an isolated reef located nearby.
According to stomach contents examined, there were five feeding guilds: 1) benthic feeding fish; 2) piscivorous fish; 3) herbivorous fish; 4) zooplanktivorous fish; 5) polyp-feeding fish in the Yenliao Bay. Among them, benthic feeding fish account for the largest proportion (81.3%). The reef dominant species are almost belonging to the zooplanktivores.
The ratio of total primary production to total respiratory is 1.0 which indicates the Yenliao bay was an autotrophic system. It was comprised of 4 trophic levels(4.03). The geometric mean of the trophic transfer efficiencies was 11.1%. The most prominent biological group in terms of biomass and energy flow in the bay was herbivorous zooplankton, its consumption was 983gWW m-2yr-1. Manipulations of the biomass of detritus and benthic feeding fish would have a distinct impact on most compartments. Trophic transfer efficiencies among the 4 trophic levels were 10.7%, 19.3%, and 6.6% respectively. Comparing cycling and ecosystem properties with other coastal ecosystems, it appeared that overall biomass of Yenliao Bay was lower than ones in Chiku and Topony lagoon ecosystems and was equivalent to Kuosheng Bay in the north coast. It is an autotrophic system and has phytoplankton-based food sources, low proportion of the recycled flow, and short food chain. In conclusion, Yenliao Bay is a developing ecosystem which was suffered from disturbances continuously.
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Carvalho, Russell G. "Factors Shaping Macrofaunal Polychaete Communities in the Gulf of Mexico." Thesis, 2013. http://hdl.handle.net/1969.1/149313.
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This dissertation addresses large-scale trends in composition, density, taxonomic and functional diversity in deep-sea benthic polychaete communities in the Gulf of Mexico (GoM). The study includes samples from two major sampling programs: the Deep Gulf of Mexico Benthos (DGoMB) program (2000–2002) (51 stations, 200-3700 m) and the SIGSBEE program (Universidad Nacional Autónoma de México), 2008-2010 (27 stations on the Sigsbee Abyssal Plain). Polychaete density decreased exponentially with depth. Alpha diversity did not show a mid-depth maximum and reached its peak near the Mississippi trough. Feeding guild diversity was also highest in the Mississippi trough. The environmental parameters that determine diversity and density of polychaete assemblages and species distribution ranges were examined. Depth, export flux of particulate organic carbon (POC), percent sand and silt were the best predictors of heterogeneity of polychaetes in the GoM. We performed an ecological niche modeling analysis (ENM) based on ‘presence-only’ data of four cosmopolitan species belonging to the Cirratulidae and Spionidae in the GoM.
The GoM, being a semi-enclosed ocean basin, offers complex topographic features and hydrographic processes. Comparisons of the overall polychaete diversity and richness patterns from this study for this region indicate a strong geographic variation with increasing depth and distance from the shore. Additionally, the environmental gradients observed play a major role in shaping the spatial distribution of polychaete communities in this region.
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Potgieter, Henriette Cornelia. "Avian ecology of arid habitats in Namibia / Henriette Cornelia Potgieter." Thesis, 2015. http://hdl.handle.net/10394/15505.
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Examination of bird assemblages along an environmental gradient which encompasses both climate and habitat change is needed if we are to better understand the potential effects of these changes for avians and the ecological process that depend upon them. Climate change is predicted to have a significant impact on deserts and desert margins, resulting in distributional shifts of entire ecosystems and new community associations. This study explores the probable responses of avian communities to increasing desertification.
In general, species richness and numbers of birds in arid zones are low compared to more mesic areas. Different combinations of habitat types and the variety of patches in a landscape influence the diversity and community structures of avians in that landscape. The role of vegetation structure in avian habitat selection in semi-arid areas is dictated by horizontal habitat density as well as vertical structure. Although bird distribution is determined by habitat boundaries, most birds are flexible and can disperse across small habitat barriers.
The hypothesis tested, was that bird species assemblages along an aridity gradient are affected primarily by rainfall and secondarily by habitat type. Assessing the impacts of rainfall and habitat on bird variables, such as species richness, abundance, diversity, biomass, and life history traits, were the objectives of the study.
An east-west aridity gradient of 300 mm, stretching over 370 km, was chosen in central Namibia for the study area. The climate is harsh with localised rain and considerable daily fluctuations in temperature. Grasses, and trees and shrubs up to 7 m in height are the co-dominant life-forms. Surveys were conducted over three years; one winter and one summer survey in each year. Rainfall, seasons and vegetation height were recorded as environmental variables.
Three structurally different habitat types were selected for stratified sampling: open areas, rivers and thickets. Open areas were dominated by grass; river refers to ephemeral dry river lines with mature trees; and thickets comprise woody shrubs and trees. At each site, the same three habitats were used for bird sampling, resulting in 15 sample units. Sampling took place on 51 discontinuous line transects of 1km in length and without a width limit.
Univariate analyses included ANOVA and t-tests. Multivariate analyses consisted of cluster analysis, MRPP tests, indicator analysis, Shannon diversity index and NMS ordinations. NMS bi-plots were used to define avian community structures responding to aridity, habitat, migration and life history traits.
The results showed that bird species richness, abundance, and diversity remained relatively constant across the aridity gradient, until they declined significantly once a certain aridity threshold was crossed at the most arid site. There were significantly more bird species and individual birds at the wetter sites than at the drier sites. Rivers contained more birds than thickened or open habitat types, suggesting the importance of riparian habitat types for maintaining avian diversity. The three more mesic sites included higher numbers of species from the nesting and feeding guilds, regardless of habitat type, than the two more arid sites. The aridity threshold had a significant effect on bird community structures: more migrant and nomadic species, and omnivore and insectivore species persisted in very arid conditions.
From the results it was predicted that climate change will cause avian species to undergo range shifts from west to east, resulting in community composition changes and a reduction in diversity. Life history traits affect the adaptive capabilities of bird species and it is predicted that nomadism, flexibility in diet, and adaptability of nesting requirements will contribute to species persistence in the drier conditions predicted under current climate change scenarios. Dry river lines will act as refugia for avian diversity, but crucial habitat types that currently contain less diversity are also important for maintaining unique avian assemblages.<br>MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015
Books on the topic "Feeding guild structure"
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Peters, Sandra Leslie. Effects of selective logging on bat communities and feeding guild structure in southeastern Amazonia, Brazil. 2004.
Find full textBook chapters on the topic "Feeding guild structure"
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Goldstein, Robert M., and Thomas P. Simon. "Toward a United Definition of Guild Structure for Feeding Ecology of North American Freshwater Fishes." In Assessing the Sustainability and Biological Integrity of Water Resources Using Fish Communities. CRC Press, 2020. http://dx.doi.org/10.1201/9781003068013-9.
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Gray, John S., and Michael Elliott. "The soft-sediment benthos in the ecosystem." In Ecology of Marine Sediments. Oxford University Press, 2009. http://dx.doi.org/10.1093/oso/9780198569015.003.0014.
Full textAbstract:
The benthos does not, of course, live in isolation from other parts of the ecosystem. Here we consider the roles that the benthos plays in the system and how the complex interactions that are found can be modelled using ecosystem models. First, we examine methods that allow us to establish food webs based not only on examining each species in the field and in laboratory feeding studies, but also using stable isotopes of carbon and nitrogen to ascertain the likely feeding mode of a species. It is relatively easy to determine the mode of feeding of some benthic organisms (see for example the excellent review of Fauchald and Jumars 1979, although this is now slightly dated and requires revision). Polychaetes have characteristic feeding structures, so one can determine from their morphology whether they are filter feeders, deposit feeders, or predators. Bivalves show similar morphological characteristics and it is easy to determine whether they are deposit or filter feeders. Some polychaetes have large jaws, e.g. the nereids, and one might assume that they are predators. Yet when Nereis vexillosa was studied in detail (Woodin 1977), it was found that it attached pieces of algae to its tube, which grew and were used for food, so-called ´gardening´. Nereids also are able to filter feed by creating a mucous bag and pumping water through their burrows, which filters the water; the mucous bag is then consumed. More recently, studies have shown varied and possibly opportunistic feeding by different benthic species; for example Christensen et al. (2000) showed how the suspension- and deposit-feeding abilities of nereids influenced sediment nutrient fluxes. These studies show that it is perhaps not so straightforward as once thought to interpret feeding mode simply from morphological features. The definition of functional groups and feeding guilds is increasingly used to help explain and interpret ecological functioning (e.g. Elliott et al. 2007 discuss the rationale behind functional groups). The eminent and immensely experienced benthic biologist Tom Pearson (2001) shows in detail that while the concept of functional groups gives us a greater understanding of the benthos, the idea is criticized by some as we do not have sufficient information about feeding types and modes of life of many benthic species.