Dissertations / Theses: 'Predation (Biology)'

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Bromilow, Amanda Marie. "Juvenile Blue Crab Survival in Nursery Habitats: Predator Identification and Predation Impacts in Chesapeake Bay." W&M ScholarWorks, 2017. https://scholarworks.wm.edu/etd/1516639467.

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Predator populations can have significant impacts on prey recruitment success and prey population dynamics through consumption. Young, inexperienced prey are often most vulnerable to predation due to their small size and limited evasion capabilities. to reduce the risk of predation, new recruits and young juveniles typically settle in structured nursery habitats, such as seagrass beds, which promote higher survival by acting as refuges from predators. Thus, successful recruitment to the adult portion of the population is often dependent on the availability of suitable nursery habitat. In this thesis, I used field tethering experiments and gut content analyses to assess the role of habitat, body size, finfish predation, and cannibalism on the survival of one of the most ecologically and economically important species in Chesapeake Bay: the blue crab Callinectes sapidus. In field tethering experiments, survival probability of juvenile blue crabs in York River nursery habitats (i.e. seagrass beds, sand flats) increased significantly and additively with crab size and SAV cover. Images of predation events during tethering experiments revealed cannibalism by adult blue crabs to be a major source of juvenile mortality. Gut content analyses from three field studies identified seven predators of juvenile blue crabs in lower Chesapeake Bay nursery habitats: adult blue crabs, striped bass Morone saxatilis, red drum Sciaenops ocellatus, silver perch Bairdiella chrysoura, weakfish Cynoscion regalis, Atlantic croaker Micropogonias undulatus, and oyster toadfish Opsanus tau. Using frequency of consumption and diet proportion metrics, I determined striped bass, red drum, and silver perch to be the most impactful finfish predators on juvenile mortality, in addition to cannibalism. Atlantic croaker and oyster toadfish play minor roles in juvenile mortality in Chesapeake Bay nursery habitats. The probability of juvenile crabs being present in a predator’s gut was also significantly higher in seagrass beds than in unvegetated sand flats. Food web dynamics are an important aspect of ecosystem-based fisheries management. Understanding the ecological interactions between populations, and their environment, can provide insight into natural population fluctuations of valuable fishery species such as the blue crab. This thesis demonstrated the positive effects of body size and SAV cover on juvenile crab survival, indicating the importance of seagrass nursery habitat for blue crab population dynamics in Chesapeake Bay. However, despite the predator refuge offered by SAV, high densities of predators and prey in seagrass beds resulted in greater consumption of juveniles in those habitats. Key predators of juvenile blue crabs were also identified and their relative impacts were estimated. The predator-prey relationships revealed in this thesis were integrated into a revised food web for blue crabs in Chesapeake Bay, in the hopes of informing future ecosystem-based management efforts.

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Becker, Matthew Smith. "Applying predator-prey theory to evaluate large mammal dynamics wolf predation in a newly-established multiple-prey system /." Thesis, Montana State University, 2008. http://etd.lib.montana.edu/etd/2008/becker/BeckerM1208.pdf.

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I studied wolf prey selection and kill rates during 1996-97 through 2006-07 winters in a newly established two-prey system in central Yellowstone National Park. Prey differed substantially in their vulnerability to wolf (Canis lupus) predation and wolves preyed primarily on elk (Cervus elaphus) but also used bison (Bison bison) to varying degrees within and among winters and packs. Winter severity, wolf abundance, distribution, and prey selection varied during the study, concurrent with variations in the demography, distribution, and behavior of elk and bison. A total of 759 wolf-killed ungulates were detected and prey selection by wolves was influenced by the absolute and relative abundance of prey types, the abundance of predators, and the duration of snow pack. Wolves strongly preferred elk calves relative to all other prey types, and elk calf abundance was inversely related to the occurrence of bison in wolf diets. Increasing wolf numbers also broadened prey selection from elk calves, and predation on bison and adult elk increased with increasing snow pack accumulation and duration, likely due to its long-term debilitating influence. Elk abundance and wolf pack size best explained variation in kill rates for elk while bison calf abundance and snow pack duration best explained kill rates of bison. The functional response of wolves for elk was best described by a Type II ratio-dependent model, indicating significant predator dependence. Prey-switching evaluations indicated increasing selection of bison with increasing bison:elk ratios, however no concurrent decrease in elk predation occurred. Increased bison predation is not solely dependent on relative abundance of the two prey species; therefore it is unlikely at this time that wolf prey-switching will stabilize the system.

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Delaire, Lari. "Predation, parasitism and colour in natural guppy populations." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=103592.

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Many studies of evolution adopt a unifactorial approach, where a single causal force appearing to account for a majority of the phenotypic variation becomes the focal point of investigation. However, it seems certain that no single force acts to the complete exclusion of other forces, and so multi-factorial studies can make a crucial contribution to our understanding of the evolution of phenotypic variation. In the Trinidadian guppy system, natural selection acting via predation has long been recognized as playing an important role in shaping trait variation. However, other environmental factors also likely contribute, and my thesis explores the potential role of one of them: parasitism. I specifically focus on Gyrodactylus, a monogenean ectoparasite that has important effects on many fish species and coexists with guppies in the wild. I evaluate the extent to which parasitism varies among guppy populations, particularly in relation to predation. I then ask whether parasitism influences phenotypic variation in guppy traits. This work was executed through a large-scale survey in northern Trinidad, where 26 guppy populations of known predation level (high or low) were surveyed across 10 different rivers. Individual guppies were scanned for Gyrodactylus and then photographed for image analyses aimed at quantifying body size and aspects of male colour. I found that among-population variation in parasitism levels was consistent between two dry seasons, and that high-predation localities tend to have higher levels of parasitism than do low-predation localities. However, I found few effects of parasitism on guppy traits and no major modifying influence of parasitism on inferences about the role of predation. Although more work certainly needs to be done with respect to parasitism, our results suggest it might be more profitable to concentrate on other potential causal factors that shape guppy trait variation.
De nombreuses études sur l'évolution adoptent une approche uni-factorielle qui se concentrent sur une seule force pouvant expliquer la plupart de la variation phénotypique observée. Cependant, il est évident qu'aucune force n'exerce son effet de façon isolée. C'est pourquoi les études multi-factorielles apportent une contribution cruciale à notre compréhension de l'évolution de la variation phénotypique. Dans le système d'étude des guppies de Trinité, la sélection naturelle imposée par les prédateurs a depuis longtemps été considérée comme un facteur important dans l'élaboration de la variation au niveau des traits. Cependant, d'autres facteurs environnementaux contribuent également à cette élaboration, notamment le parasitisme. Je me penche sur le rôle potentiel que peuvent avoir les parasites du genre Gyrodactylus sur les traits des guppies. Ces ectoparasites monogènes exercent de nombreux effets sur plusieurs espèces de poissons et coexistent avec les guppies dans leur environnement naturel. J'évalue le niveau de variation du parasitisme entre les populations de guppies, et plus spécifiquement en relation avec la prédation. J'explore par la suite l'influence potentielle du parasitisme sur la variation phénotypique des traits des guppies. Pour ce faire, une étude de grande échelle a été effectuée sur 10 rivières dans le nord de Trinité, dans laquelle 26 populations sujettes à des niveaux de prédation connus (élevé ou bas) ont été inventoriées. L'état d'infection par les Gyrodactylus a été répertorié pour chaque guppy, puis les poissons ont été photographiés pour analyser les images dans le but de quantifier la taille corporelle ainsi que de nombreux aspects de la coloration chez les mâles. J'ai trouvé que les niveaux de parasitisme entre les populations étaient consistants entre les deux saisons sèches recensées, et qu'il y a une tendance pour les sites de haute prédation à avoir des niveaux de parasitisme plus élevés que les sites de basse prédation. Cependant, j'ai trouvé que la parasitisme avait peu d'effets sur les traits des guppies et aucune influence majeure n'a été trouvée sur les inférences concernant la prédation. Bien qu'il reste encore beaucoup de travail à faire en ce qui a trait au parasitisme, nos résultats suggèrent qu'il pourrait être plus profitable de se concentrer sur d'autres facteurs potentiels pouvant expliquer la variation de traits chez les guppies.

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Morling, Frances. "Cape Town's cats: reassessing predation through kitty-cams." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/9099.

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Includes bibliographical references.
Domestic cats (Felis catus) are abundant generalist predators that exploit a wide range of prey within and adjacent to the urban matrix. Cats are known to have contributed to the extinction and endangerment (mostly on islands) of a number of indigenous species, including birds, small mammals, reptiles and amphibians. Most research on this important topic has been carried out in the developed world, predominantly in Australia, New Zealand, the U.K., the U.S. and Canada with only four studies carried out in Africa. Of these, two studies in Cape Town suggest that domestic cats have a big impact on wildlife but these studies may have underestimated predation because they failed to account for the proportion of prey not returned to participants’ homes. In this study I used kitty-cams in an attempt to provide a prey correction factor for urban cats in Cape Town, South Africa. I investigated hunting of wildlife by free-ranging domestic cats in Newlands, a suburb of Cape Town, South Africa over 5 weeks in 2013. I monitored 13 cats (6 deep-urban and 7 urban-edge) by questionnaire survey, asking cat owners to record all prey items returned by their cats. A total of 43 prey items were returned, 42% of which were small mammals, 30% invertebrates, 12% reptiles, 9% amphibians and 7% birds. Combining these data with two similar survey studies carried out in Cape Town I estimated that a total of 118 cats caught an average of 0.04 prey items per cat per day. Ten of the 13 cats were also monitored for 3 weeks using kitty-cam video cameras. Participating cats wore a video camera and all activity was analysed for prey captures and behavioural activity patterns.

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Brouillette, Amber Noelle. "Sex-Biased Predation on Taricha by a Novel Predator in Annadel State Park." DigitalCommons@USU, 2008. https://digitalcommons.usu.edu/etd/111.

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Newts of the genus Taricha have long been studied due to the powerful neurotoxin found in their skin. Tetrodotoxin (TTX) acts by blocking receptors in sodium channels, ultimately resulting in death via asphyxiation. The only documented predators of species in this genus have been snakes of the genus Thamnophis. Recently, predation on Taricha in Ledson Marsh in Annadel State Park, Santa Rosa, CA was discovered. Predation was in the form of laceration or evisceration, and tracking of predation from 1998-2008 showed that it was male-biased. Two species of Taricha were found living sympatrically at this location, the California newt (T. torosa) and the rough-skinned newt (T. granulosa). Fluorometric High Phase Liquid Chromatography (HPLC) analysis was used in order to quantify TTX levels in the skin of ten male and ten female newts of each species. Quantification of TTX was done to determine the influence, if any, that TTX levels may have on sex-biased predation in this population. I predicted that levels of TTX would be greater in females than males, and greater in T. granulosa than T. torosa since very few T. granulosa were preyed upon during the study period. My results indicated that there were significant differences between the sexes, and T. torosa were significantly more toxic than T. granulosa. An in-depth ecological study of relative abundances of both species and identification of the predator are needed at this site to obtain a clear picture of the predator-prey dynamics at Ledson Marsh

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Latif, Quresh S. "How predation risk shapes avian nest site selection and processes underlying nest predation patterns." Diss., [Riverside, Calif.] : University of California, Riverside, 2009. http://proquest.umi.com/pqdweb?index=0&did=1957706911&SrchMode=2&sid=4&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1268765320&clientId=48051.

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Thesis (Ph. D.)--University of California, Riverside, 2009.
Includes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed March 16, 2010). Includes bibliographical references. Also issued in print.

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Cleveland, Shawn M. "HUMAN PREDATION RISK AND ELK BEHAVIOR IN HETEROGENEOUS LANDSCAPES." The University of Montana, 2010. http://etd.lib.umt.edu/theses/available/etd-04282010-103245/.

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Elk (Cervus elaphus) are increasing in fragmented landscapes that result from exurban human development throughout western North America. This problem is increasing human-wildlife conflicts and represents a significant new challenge to wildlife managers. Elk hunting must be intensively managed, if allowed at all, to reduce public relations problems. For example, the Montana Department of Fish, Wildlife & Parks has focused three hunts on a rapidly growing (~11% annually) elk herd in the wildland-urban interface (WUI) of Missoula, Montana, USA. Their goals were to reduce population growth rate, crop depredation, and habituation to humans. However, little was known about the indirect effect hunting has on anti-predator behavior, movement, resource selection, and human-elk conflicts. We first investigated the indirect effects of hunting on elk using an extensive comparison of elk anti-predator behavior across four human predation risk levels in western Montana. We collected 361behavioral observations across this predation risk gradient from October 2008 to March 2009. Vigilance was highest in highest predation risk areas and lowest in lowest risk areas. Vigilance and movement attenuated with the removal of human predation risk within 3-5 weeks under intermediate human predation risk in Missoula, Montana. I then used an intensive investigation of elk outfitted with global positioning system (GPS) collars in the WUI of Missoula to test the indirect effects of hunting on elk. We used data from nine GPS collared adult female elk during three hunting seasons with increasing hunting pressure (2007-2009) to test relationships between movement rates measured by first passage time (FPT) and resource selection. FPT decreased annually, by season type, and by hunting mode (archery vs rifle), and was negatively correlated with hunter predation risk. Elk slowed down ~750 meters from and selected for areas ~1200 meters from houses and trails, suggesting habituation to humans contributed to WUI human-wildlife conflict. These results support the risk allocation hypothesis that elk modify behavior in relation to temporal and spatial variation in human predation risk, and provide some of the first insights as to the indirect effects of hunting on elk in the WUI.

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Svensson, Jonas. "Är den starkt växande vildsvinspopulationen ett hot mot tjäderns reden?" Thesis, Södertörn University College, School of Life Sciences, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:sh:diva-3161.

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This case study is based on a previous documented method of manufacturing artificial nest containing pre-colored hen eggs. This method is going to be used to find, if the wild boar population, which is growing in number, is a threat to the capercaillie population. In comparison to the wild boar population, the capercaillie population is diminishing in different parts of Sweden. In order to find out if they are affect by each other, the case study was carried out during the months of April to May 2009. 100 artificial nests were placed out on various locations on the Södertuna estate just in the outskirts of Gnesta. The unique aspect of this study is that a fenced environment to keep out wild animals is used to conduct this study, which has been previously known to be free from wild boar, but the area outside has sittings of wild boar. So to fully understand how this affects the capercaillie population, 50 of the nests were placed outside the fence area, while the other 50 nests were placed inside the fenced area. The sites were visited on two separate occasions, and were noted of the changes inside and outside the fenced compounds. The result of these visits show that many of the nests inside the fenced environment has been consume by birds. It was not possible to prove that nests have been predated by wild boar, even the wild boar populations could be found outside of the fenced area. The statistical analysis has been carried out to determine the perdition rate on the nests and which of the two main groups the culprits belonged to. The significant difference came to a P <0.05. The predations on the artificial nests inside the fence were greater than the nest placed outside the fence. The total came to a 20 %, i.e. 20 of the 100 nests which were predated on, in total. 32%, i.e. 16 of the nests were attacked that were placed inside the fence and 8 %, i.e. 4 were attacked inside the fence. To observe closer at the species that targeted the nests inside the fence were crows/eurasian jay 18 % (9), badgers/fox 14 % (7) and wild boar 0 %. Outside the fence, the results were divided into division on crows/eurasian jay 2 % (1), badgers/fox 6 % (3) and wild boar 0 %. This study shows the wild boar population does not the pose a threat to the swindling population of the capercaillies population. But this case study demonstrates that there are other species that create a threat to the simulated nests, which is of an utter most importance to research into this particular subject into the future on reproduced artificial nests to investigate the perdition rates of capercaillies.

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Hechtel, Laura Johnson Juliano Steven A. "The effect of predation on size at and time to metamorphosis in tree hole mosquitoes." Normal, Ill. Illinois State University, 1993. http://wwwlib.umi.com/cr/ilstu/fullcit?p9411038.

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Thesis (Ph. D.)--Illinois State University, 1993.
Title from title page screen, viewed February 22, 2006. Dissertation Committee: Steven A. Juliano (chair), Scott K. Sakaluk, Douglas W. Whitman, James V. Robinson, Angelo P. Capparella. Includes bibliographical references (leaves 136-144) and abstract. Also available in print.

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Leighton, Patrick. "Mongoose predation on sea turtle nests: linking behavioural ecology and conservation." Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86646.

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The introduced small Asian mongoose (Herpestes javanicus) is a widespread predator of sea turtle eggs and hatchlings in the Caribbean. I studied the behavioural ecology of mongoose predation on the nests of critically endangered hawksbill sea turtles (Eretmochelys imbricata) in Barbados. Combining short-term field experiments with seven years of hawksbill nesting data, I investigated how mongoose foraging behaviour, antipredator behaviour and landscape use explain the spatial and temporal patterns of sea turtle nest predation. An experiment combining artificial nests and predator tracking revealed a direct relationship between fine-scale variation in mongoose activity and nest predation risk. The combination of mongoose avoidance of open areas and the spatial distribution of hawksbill nests relative to patches of beach vegetation accurately predicted the observed peak in nest predation near the vegetation edge. Egg-burial depth by nesting hawksbills also affected predation risk, but this was primarily due to the increased digging effort required rather than any increase in nest concealment with depth. A second experiment with artificial nests confirmed the causal relationship between burial depth and predation risk and showed that substrate disturbance is a primary cue for nest detection by mongooses. At the landscape scale, mongooses tracked local nest abundance but showed a fine-scale negative response to human beach use, suggesting that human activity on nesting beaches may improve nest survival by deterring predators. Finally, an analysis of nest survival times showed that nests were most vulnerable to predation in first days following oviposition and that predation risk increased over the nesting season, providing a general framework for planning where and when predation reduction methods should be applied. I conclude that predation risk for sea turtle nests is likely to depend on: i) how predator nest-finding behaviour is modulated by nest characteristics s
La petite mangouste indienne (Herpestes javanicus) est une espèce introduite dans de nombreuses îles des Caraïbes et est un prédateur important des oeufs de tortues marines. J'ai étudié l'écologie comportementale de la prédation par les mangoustes sur les nids de tortue imbriquée (Eretmochelys imbricata), une espèce en danger critique d'extinction, à la Barbade. En combinant des études expérimentales de courte durée avec des données de prédation des nids de tortues imbriquées s'échelonnant sur sept années, j'ai investigué comment le comportement d'approvisionnement, le comportement anti-prédateur, et l'utilisation du paysage par les mangoustes expliquent les patrons spatiaux et temporels de la prédation des nids. Une étude expérimentale combinant des nids artificiels et une mesure passive de l'activité des prédateurs a démontré une relation directe entre la variation spatiale de l'activité des mangoustes et le risque de prédation des nids. Conjointement, l'évitement des espaces dépourvus de végétation sur la plage par les mangoustes et la distribution spatiale des nids de tortues imbriquées en fonction de la végétation ont prédit de manière précise le patron de prédation élevé observé dans la zone bordée de végétation. La profondeur des nids affectait également le risque de prédation mais avait peu d'influence sur la détection des nids par les mangoustes. L'effet relié à la profondeur était surtout dû à l'effort d'excavation supplémentaire. Une deuxième étude expérimentale utilisant des nids artificiels a confirmé la relation directe entre la profondeur des nids et la prédation, démontrant que la mangouste utilise la perturbation du sable créée lors de la ponte comme principal indice de détection des nids. A l'échelle du paysage, l'activité des mangoustes suivait la disponibilité des nids de tortues sur la plage. Cependant, il y avait une relation négative entre l'activité des mangoustes et l'u

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Duffy, Sean. "Persistence in intraguild predation food webs: possible solutions to a paradox." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=114273.

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Predator-prey interactions occurring between competitors that share a resource is a food web configuration known as intraguild predation (IGP). Theory dictates that IGP in its most basic configuration is often unstable, with strict criteria for coexistence of intraguild predator and intraguild prey. However, IGP is quite frequent in nature. The main objective of my thesis was to show how modifications to IGP interactions can promote the persistence of this food web configuration. First, I theoretically analysed how prey switching by the intraguild predator affected coexistence. I then focused on IGP in a mussel aquaculture system and empirically tested for factors modifying IGP pressures exerted by mussels on zooplankton intraguild prey. My IGP model with prey switching yielded coexistence over a greater range of parameters compared to the basic IGP model. In the mussel aquaculture system, age/stage structures and ontogenetic niche shifts were identified as factors that alter IGP interactions and potentially prevent the zooplankton intraguild prey from being excluded. This research adds to the literature on IGP interactions and provides insight on mechanisms that allow these food webs to persist.
Les interactions prédateurs-proies se produisant entre les concurrents qui partagent une ressource représentent une configuration réseau alimentaire connu sous le nom de prédation « intraguilde » (IGP). La théorie dicte que l'IGP dans sa configuration la plus basique est instable, avec des critères stricts en matière de coexistence. Cependant les prédations intraguildes sont assez fréquentes dans la nature. Le principal objectif de ma thèse était de montrer comment les modifications des interactions IGP peuvent favoriser la persistance de ce réseau trophique. D'abord, j'ai analysé, de façon théorique, les effets de la commutation des proies par les prédateurs intraguildes sur la coexistence. Je me suis ensuite concentré sur les prédations intraguildes dans un système de mytiliculture. J'ai évalué, de façon empirique, les facteurs pouvant modifier les pressions provenant de la prédation intraguilde et étant exercées par les moules sur le zooplancton (proie intraguilde). Mon modèle IGP qui inclut la commutation des proies a abouti à la coexistence sur une plus grande gamme de paramètres par rapport au modèle de base IGP. Dans mon système de mytiliculture, la structure « âge / stade » ainsi que les déplacements de niches ontogénétiques ont été identifiés comme des facteurs modifiant les interactions IGP et qui empêchent potentiellement le zooplancton (la proie intraguilde) d'être exclu. Cette recherche s'ajoute à la littérature sur les interactions IGP et donne un aperçu sur les mécanismes qui permettent à ces réseaux trophiques de persister.

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Qin, Jianguang. "Effects of fertilization and fish predation on trophic dynamics in aquatic ecosystems /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu148784937729584.

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Nieset, Julie E. "The Effect of Protozoan Predation on Four Bacterial Communities." University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1145300999.

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Eggers, Sönke. "Behaviour and life-history responses to chick provisioning under risk of nest predation." Doctoral thesis, Uppsala University, Population Biology, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3077.

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This thesis examines risk management in breeding Siberian jays (Perisoreus infaustus), which is indigenous to the northern taiga. Parent behaviour and the nest are cryptic. A new nest is built each year. It is placed on spruce or pine branches close to the trunk and well insulated with lichens, feathers and reindeer hair.

Nest failure rate was the main factor driving annual variations in jay numbers. The probability for nesting attempts to be successful ranged annually between 0.08 and 0.70. Nest predation was rampant and a main cause of nest failure. Nest predators were mainly other corvids (primarily the Eurasian jay Garrulus glandarius). Habitat quality was the main factor determining the risk of predation. The risk for nest failure due to predation was higher in thinned forests with an open structure and with a high abundance of man-associated corvid species (jays, crows, raven).

Siberian jay parents show several strategic adjustments in life-history and behaviour to the risk of nest predation. Parents traded reduced feeding rates for a lower predation risk and allocated feeding to low risk situations. Chick provisioning imposes a cost by drawing the attention of visually hunting predators to the location of nests, and parents adjusted their daily routines and avoided exposure by allocating provisioning to times of low activity among nest predators. These strategic adjustments of feeding efforts were estimated to reduce the exposure to nest predators by 26 percent. Also, parents adjusted their reproductive efforts to the perceived presence of predators in a playback experiment. Siberian jays reduced their reproductive investment by laying a smaller clutch size when high risk of nest predation reduced the value of current reproduction, as predicted from life-history theory.

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Cushing, Paula Elizabeth. "A study of disturbance behaviors in Uloborus glomosus (Araneae; Uloboridae) as possible predator avoidance strategies." Thesis, This resource online, 1988. http://scholar.lib.vt.edu/theses/available/etd-10022008-063248/.

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DeBlois, Elisabeth M. "Invertebrate predation on the benthic eggs of marine fish." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=39387.

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The character and magnitude of predation by Calliopius laeviusculus on the intertidal eggs of capelin (Mallotus villosus) were examined. Average endobenthic densities at Bryant's Cove (NFLD) in 1988 for both amphipods and capelin eggs during capelin egg development (June 17-August 8) were 0.78 amphipods cm$ sp{-2}$ and 62 eggs cm$ sp{-3}$ (750 cm$ sp{-2}$) respectively. At this average capelin egg density, laboratory results suggest that, on a daily basis, only gut capacity and clearance time limit amphipod predation on eggs. In situ, C. laeviusculus biomass closely tracked capelin egg biomass indicating that reproductive cues operating for both capelin and amphipods may be linked. In 1988, ca. 50% of the annual production of C. laeviusculus resulted from predation on capelin eggs. Given the bioenergetic demands of C. laeviusculus and the annual variation in capelin spawning effort, the temporal overlap between capelin eggs and high amphipod biomass could result in predation mortalities ranging from ca. 15-30% of the total capelin egg deposition.

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Jobin, Benoît. "The impact of human disturbance on nest predation patterns in freshwater marshes." Thesis, University of Ottawa (Canada), 1991. http://hdl.handle.net/10393/7466.

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Although predation is the major factor responsible for nest losses in birds, predation patterns in marshes and adjacent uplands are poorly known. This study examined the factors affecting nest predation on marsh-nesting birds found in areas affected by different intensities of human disturbance (urban, agricultural, natural). Artificial nests simulating waterfowl and passerine nests were used for that purpose. The nests, located along transects running from the center of the marshes to the adjacent upland habitats, were set up in the months of May, June and July 1989 and 1990. Eggshell remains were used to identify the predators. Predation was higher on passerine than on waterfowl nests and on nests located in upland habitats. Deep water prevented mammalian predators from foraging deep in the marsh. Predation rates in urban and natural areas were high while nests located in agricultural areas suffered lower predation. Nest camouflage was generally unimportant in reducing chances of predation. Mammals were responsible for most of the predation events. Differences in density and/or diversity of predators in urban, agricultural and natural areas were the main causes of different predation patterns observed in the three areas.

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Hirsh, Morgan L. "Influence of predation on feeding and giving-up density of forest rodents." Kent State University Honors College / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ksuhonors1588332202908538.

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Fishman, James. "The Role of Predation on Zostera marina L (Eelgrass) Seed Abundance." W&M ScholarWorks, 1994. https://scholarworks.wm.edu/etd/1539617673.

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Barr, Brian R. "Analysis of the impact of flathead catfish predation on the abundance of four centrarchid species." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-12042009-020154/.

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Roger, Caroline. "Mechanisms of prey selection in the ladybeetle Coleomegilla maculata Lengi Timb. (Coleoptera:Coccinellidae)." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ50249.pdf.

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22

Winnie, John Arthur Jr. "Behavioral responses of elk (Cervus elaphus) to the threat of wolf (Canus lupus) predation." Diss., Montana State University, 2006. http://etd.lib.montana.edu/etd/2006/winnie/WinnieJ0506.pdf.

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23

Savino, Jacqueline Frost. "Behavioral interactions between piscivorous fish and their prey as mediated by body form and plant abundance /." The Ohio State University, 1985. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487260859496303.

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24

Taylor, David Lenox. "Predation on the early life history stages of winter flounder (Pseudopleuronectes americanus) by the sand shrimp (Crangon septemspinosa) /." View online ; access limited to URI, 2003. http://0-wwwlib.umi.com.helin.uri.edu/dissertations/dlnow/3115638.

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25

Rock, Brevin Shae. "Two-patch predator-prey system coupled with migration of both species." View electronic thesis (PDF), 2009. http://dl.uncw.edu/etd/2009-3/Rockb/brevinrock.pdf.

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Pereira, Luís Felipe de Toledo Ramos [UNESP]. "Predação e defesa de anuros: revisão, descrição e evolução." Universidade Estadual Paulista (UNESP), 2007. http://hdl.handle.net/11449/106549.

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Made available in DSpace on 2014-06-11T19:35:43Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-08-20Bitstream added on 2014-06-13T18:47:10Z : No. of bitstreams: 1 pereira_lftr_dr_rcla.pdf: 1890208 bytes, checksum: 494aae6f71d5d96e2d79e4d2660b0777 (MD5)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Até a presente tese, a informação sobre predação e estratégias defensivas em anuros estava fragmentada e desconexa na literatura científica. Na ausência de uma revisão sobre o tema, algumas especulações foram geradas baseadas nas impressões pessoais de diversos pesquisadores. Por exemplo, existem muitos ou poucos relatos de anuros sendo apresados? Um determinado comportamento defensivo já foi descrito em algum lugar, ou é inédito? Qual a relação entre os predadores e os mecanismos de defesa dos anuros? Essas e outras perguntas estavam em aberto. Mesmo em livros texto, os quais geralmente revisam os assuntos abordados de forma abrangente, nota-se o parco conhecimento sobre o tema, sendo estes sempre os menores capítulos dos livros e de conteúdo razoavelmente superficial. Todavia, muita informação já foi gerada e muita ainda está por vir. É nesse sentido que idealizamos e realizamos o presente estudo, visando reunir grande parte do conhecimento atual e gerar novas previsões e hipóteses testáveis. Assim, relacionamos os predadores atuais e naturais dos anfíbios anuros (incluindo as desovas e pós-metamórficos) e revisamos as principais estratégias defensivas dos adultos (pós-metamórficos). Muitos dados apresentados são inéditos e outros compilados da literatura, mas ambos analisados de maneira integrada e sempre dando enfoque evolutivo nas discussões apresentadas. Consideramos este estudo um ponto inicial para compreendermos mais profundamente as estratégias defensivas dos anuros e sua relação com os predadores naturais.
Until the present moment, the information about defensive strategies and predation upon anurans was fragmented and disconnected in the scientific literature. In the absence of an overview of the subject, some speculations have been raised based on personal points of view of several scientists. For example, are there many or few reports of predation upon anurans? A specific defensive behavior has already been described or not? How is the relationship between the defensive strategies and predator mechanisms? These and odder questions were hard to answer. Even in text books, where the subjects are treated in a broad way we can notice the poor knowledge of the subject and these are always the shorter and superficial chapters. However, many information is already available and many is about to come. Therefore, we idealized and did the present thesis, aiming to joint a large part of the current knowledge and promoting some previsions and testable hypotheses. So, we related the actual and natural predators of anurans (including eggs and post-metamorphics) and reviewed the main defensive strategies of the adults (post-metamorphics). A great amount of the data presented is novel and other set of data were found in the available literature, but both were analyzed simultaneously with an evolutive approach. We consider this thesis a starting point of a deeper comprehension of the anurans defensive strategies and their relationship with natural predators.

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Sommers, Pacifica. "Interacting effects of predation and competition in the field and in theory." Thesis, The University of Arizona, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10007216.

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The principle of competitive exclusion holds that the strongest competitor for a single resource can exclude other species. Yet in many systems, more similar species appear to stably coexist than the small number of limiting resources. Understanding how and when similar species can stably coexist has taken on new urgency in managing biological invasions and their ecological impacts. Recent theoretical advances emphasize the importance of predators in determining coexistence. The effects of predators, however, can be mediated by behavioral changes induced in their prey as well as by their lethality. In this dissertation, I ask how considering multiple trophic levels changes our understanding of how a grass invasion (Pennisetum ciliare) affects species diversity and dynamics in southeastern Arizona. In considering interactions with plant consumers, and with the predators of those consumers, this research reveals more general ecological processes that determine species diversity across biological communities. I first present evidence from a grass removal experiment in the field that shows increased emergence and short-term survival of native perennial plants without grass. This is consistent with Pennisetum ciliare causing the observed concurrent decline in native plant abundance following invasion. I then present results from greenhouse and field studies consistent with that suppression of native plants being driven primarily through resource competition rather than increased rodent granivory. Granivorous rodents do not solely function as consumers, however, because they cache their harvested seeds in shallow scatter-hoards, from which seeds can germinate. Rodents thus act also as seed dispersers in a context-dependent mutualism. They primary granivores in areas invaded by Pennisetum ciliare are pocket mice (genus Chaetodipus), which have a well-studied tendency to concentrate their activity under plant cover to avoid predation by owls. Because the dense canopy of the grass may provide safer refuge, I hypothesized the pocket mice may be directly dispersing native seeds closer to the base of the invasive grass. Such a behavior could increase the competitive effect of the grass on native plant species, further driving the impacts of the invasion. By offering experimental seeds dusted in fluorescent powder and tracking where the seeds were cached, I show that rodents do preferentially cache experimental seeds under the grass. This dispersal interaction may be more general to plant interactions with seed-caching rodents across semi-arid regions that are experiencing plant invasions. Finally, I ask how the predator avoidance behavior exhibited by these rodents affects their ability to coexist with one another. Not only could their diversity affect that of the plant community, but the effects of plant invasions can cascade through other trophic levels. Theoretical understanding of how similar predator avoidance strategy alters coexistence had not yet been developed, however. Instead of a field study, therefore, I modified a general consumer-resource model with three trophic levels to ask whether avoidance behavior by the middle trophic level alters the ability of those species to coexist. I found that more effective avoidance behavior, or greater safety for less cost, increased the importance of resource partitioning in determining overall niche overlap. Lowering niche overlap between two species promotes their coexistence in the sense that their average fitness can be more different and still permit coexistence. These results provide novel understanding of behavioral modifications to population dynamics in multi-trophic coexistence theory applicable to this invasion and more broadly.

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Cheng, Yi-Ru. "Differential growth of body components among coexisting passerines in response to nest predation risk." The University of Montana, 2009. http://etd.lib.umt.edu/theses/available/etd-01132009-180702/.

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Environmental sources of mortality can exert strong selection pressures on growth strategies across taxa. Studies of growth responses need to consider multiple body components because components can compete for resources during growth in an integrated growth strategy. However, such studies are lacking and little is known about the extent to which body components may differ in their growth responses to environmental selection pressures. Theory predicts that growth of body components with relatively higher advantages for survival should be prioritized. For example, increases in time dependent mortality, like nest predation risk in birds, should favor growth of body features that enhance the ability to leave nests earlier. We studied 12 coexisting species of passerines to specifically test predictions that species with higher nest predation rates would prioritize growth of locomotor components (e.g. tarsi and wings) at the expense of growth of body mass. We also tested the prediction that these altricial birds should develop endothermy earlier to facilitate their ability to leave the warm nest environment. We found species that experience higher nest predation rates exhibited relatively faster growth rates of wing chord, but not tarsus, compared with body mass. Furthermore, species with higher nest predation rates achieved adult-sized tarsi and 60% of adult wing-chord lengths at relatively smaller body mass, further demonstrating the prioritization of wing and tarsus development. Species with higher nest predation risk also developed endothermy earlier at relatively smaller body mass. Thus, our results suggest that growth responses among species to differences in nest predation risk include an integrated strategy across body components to facilitate an ability to escape a risky environment.

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Durà, i. Franch Carles. "Understanding predation of tortoises by nesting Pied Crows (Corvus albus) in western South Africa." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/24982.

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Many species in a wide variety of taxonomic groups have shown shifts in their distribution ranges in recent decades. Rapidly changing distributions may lead to novel biotic interactions between species that have not historically interacted. As generalist predators, corvids are a potential threat to other species in areas where they have recently colonized or where their numbers have increased. Tortoise species appear to be one taxonomic group that may potentially suffer serious negative effects from increased corvid abundance. One species of corvid which has shown a significant range increase in the last two decades in western South Africa is the Pied Crow (Corvus albus). In conjunction with this expansion have come observed accounts of large numbers of tortoises being found depredated under Pied Crow nests, raising concerns over their impact on tortoises in these areas. Southern Africa has the richest biodiversity of tortoises in the world and a high rate of endemism. The endemic species are mainly restricted to the Cape region, where the genera Chersina, Homopus and Psammobates have their evolutionary centre. In this thesis, I explore how widespread tortoise predation by Pied Crows was during the crow's breeding season. I aimed to quantify the proportion of Pied Crow pairs that provision tortoise to their chicks and the numbers being depredated, as well as the species of tortoises involved. During the 2016 breeding season, I monitored 125 active Pied Crow nests in western South Africa. For the majority of these nests (n=93) there was no evidence for any tortoise predation. For the 32 pairs, where predation was recorded, I found that 15 pairs depredated ≤1 tortoise – week, five pairs depredated depredated between 1 and 2 tortoise–week , and 12 pairs depredated >2 tortoises–week. The tortoises prey remains found depredated depredated under Pied Crow nests had an average straight carapace length of 5.57 cm (range 3.5 cm - 9.8 cm) and 91% of them were Angulate Tortoises. Crows favour smaller tortoises with impacts for smaller species, or younger age classes. I also explored whether any environmental variables explained probability of tortoise predation or predation rates. Environmental variables examined included weather variables, land cover types, distances to roads and primary productivity values, and for a subset of nests the abundance of tortoises counted from transects. Although predation rate showed spatial variation among the study areas with most predation occurring in arid areas with high mean temperatures and low rainfall, no single environmental variable successfully predicted the variation in spatial predation.

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Watson, Sue-Ann. "Latitudinal gradients in marine invertebrate shell morphology : production costs and predation pressure." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/69049/.

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31

Neal, Orin J. "Responses to the audio broadcasts of predator vocalizations by eight sympatric primates in Suriname, South America." [Kent, Ohio] : Kent State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=kent1245291915.

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Thesis (M.A.)--Kent State University, 2009.
Title from PDF t.p. (viewed Jan. 26, 2010). Advisor: Marilyn Norconk. Keywords: predation; anti-predator strategies; alarm calls. Includes bibliographical references (p. 111-120).

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Biancucci, Atilio Luis. "Does nest size constrain clutch size? A tropical-temperate test." The University of Montana, 2009. http://etd.lib.umt.edu/theses/available/etd-04292009-160802/.

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The smaller clutch size of tropical as opposed to north temperate birds has intrigued researchers for a long time. An untested hypothesis posits that higher nest predation in the tropics favors smaller nests thereby constraining clutch-size. We tested this hypothesis by conducting an experiment to test whether nest predation increases with nest size in a tropical forest. Furthermore, we studied north temperate and tropical birds to examine if: (1) predation rates increased with nest size, (2) nest sizes were smaller in the tropics, and (3) clutch size was explained by nest size controlled for body size. We used data on predation rates, nest sizes, and clutch sizes for > 2000 north temperate and tropical bird nests of 36 altricial bird species that nest in open cups. Nest predation risk increased with nest size in both the experiment and in the comparison across latitudes, justifying a major premise underlying the nest size hypothesis. However, nest sizes were not smaller in the tropics. As a result, clutch sizes were not related to nest sizes either between latitudes or within sites. Nest sizes were strongly correlated with adult body sizes. Hence, (1) body size might influence reproductive success by affecting nest predation through nest size; and (2) we rejected the hypothesis that nest size explains clutch size in the tropics.

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Meadows, Laurie E. "Efficacy of Guard Llamas (Lama glama) in Reducing Canid Predation on Domestic Sheep." DigitalCommons@USU, 1999. https://digitalcommons.usu.edu/etd/6584.

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Predation, especially by canid predators, is a significant cause of sheep loss for many producers. In recent years, the use of llamas to protect sheep from predators has gained recognition as a depredation control method. I conducted a field experiment to test the effectiveness of llamas in reducing canid predation on domestic sheep. Twenty-one llamas were placed with Utah sheep producers. Data collected from these flocks over 20 months were compared to similar data collected from flocks without llamas. Comparisons between treatment and control flocks included (l) proportion of flocks with losses to predators, (2) mean predation rates on ewes and lambs, and (3) lamb predation rate distributions. Two surveys were conducted during the study to assess producer opinions on the inclusion of llamas in their sheep management programs. In all 3 comparisons of lamb losses between treatments and controls, losses sustained by control flocks in Lambing Season l (LS l) were significantly higher than those of flocks with llamas. Among treatment flocks, losses were similar for LS l and Lambing Season 2 (LS2). Among controls, LS2 losses dropped to the level of treatment flocks. My results suggest predation may have to reach some threshold before guard llamas have an effect on losses. Results of surveys of producers with llamas indicated they support the use of llamas as guard animals for sheep.

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Winters, Amanda. "Effects of Warming and Predation on Invertebrate Activity." Bowling Green State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1499357799174464.

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35

Johansson, Tomas. "Habitat selection, nest predation and conservation biology in a Black-tailed Godwit (Limosa limosa) population." Doctoral thesis, Uppsala : Acta Universitatis Upsaliensis : Univ.-bibl. [distributör], 2001. http://publications.uu.se/theses/91-554-4958-1/.

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36

Engström, Henri. "Effects of Great Cormorant Predation on Fish Populations and Fishery." Doctoral thesis, Uppsala University, Department of Evolutionary Biology, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-1506.

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The strong increase in number of Great cormorants Phalacrocorax carbo in Sweden in recent years has led to conflicts - particularly with fishery. This thesis focuses on the possible effects of cormorant predation on fish populations. In total, data from 15 lakes in South Sweden were included in this study while most studies were carried out in Lake Ymsen. The results suggest that the impact of cormorant predation on natural fish populations was small, and I observed no decline in fish mass after cormorants established. Cormorant predation on eel was difficult to evaluate because of several confounding factors.

Ruffe, roach and perch were the most important prey species to the cormorants and most fish taken were small. Cormorants do not seem to catch species and sizes in proportion to their occurrence in the fish community.

Total fish removal by cormorants varied considerably among lakes (0.2-15.0 kg/ha) and cormorant population sizes at the different lakes were significantly positively correlated with fishery catches, which in turn was significantly positively correlated with total phosphorous levels. Thus, cormorant densities in lakes, and perhaps elsewhere, seem to be governed chiefly by fish densities. The fact that cormorant predation appears not to reduce fish densities suggest cormorants to be regulated by other means than prey depletion. The mechanism behind population regulation could be a behavioural response of fish, making fish more difficult to catch for the cormorants.

In recent years, cormorant populations have been subjected to intensive legal and illegal actions with the aim to reduce cormorant numbers. However, the actions currently carried are well below the efforts needed to limit population sizes. To conclude, cormorants appear to compete little with fishery, with regards to free-living fish. The main problem is that cormorants sometimes damage and take away fish in fishing gears.

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37

Footen, Brian. "Impacts of piscivorous predation on juvenile chinook (Oncorhynchus tshawytscha) and other salmonids in Salmon and Shilshole Bays of Puget Sound, King CO. WA." Online pdf file accessible through the World Wide Web, 2001. http://archives.evergreen.edu/masterstheses/Accession86-10MES/Footen_B2001.pdf.

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38

Le, Roux Elizabeth. "The role of apex predators in ecosystem function: fear triggered cascades regulated by differential prey vulnerability." Thesis, Nelson Mandela Metropolitan University, 2016. http://hdl.handle.net/10948/14774.

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Trophic cascades involving large terrestrial mammals are very seldom empirically demonstrated. The high species diversity often associated with terrestrial systems is thought to modulate the strength of trophic cascades. In speciose systems, species often vary in vulnerability to consumption, hence some species are less responsive to top-down pressure. African large mammalian herbivores are highly diverse and vary greatly in body size, a characteristic linked to vulnerability to predation. Moreover, Africa is one of the last places to still support megaherbivores, species that have grown large enough to be practically impervious to non-human predation. Thus an African ecosystem is the ideal setting to explore trophic cascades in speciose terrestrial systems. In this study I explored patterns in trophic interaction amongst carnivores, vulnerable mesoherbivore and predator-invulnerable megaherbivores in an intact African savanna at a variety of spatial scales. I examined the mechanistic links between trophic levels at the patch scale through fine scale empirical manipulation of predation risk. In addition, I assessed the landscape scale biological relevance of these trophic interactions through correlative observations over large spatiotemporal scales. I present the first evidence of community level trophic cascades explicitly involving megaherbivores. I demonstrate how megaherbivores’ disregard of predation risk masks the effects of predator-triggered trophic cascades and weakens their impact on the ecosystem. The risk of predation triggered a spatial response in vulnerable species, driving them into safe areas, yet did not influence the space use of megaherbivores. This species-specific spatial response had contrasting effects on nutrient distribution. Vulnerable herbivores’ fear-induced foraging behaviour led to localised nutrient accumulation whereas the foraging behaviour of predator-invulnerable megaherbivores led to nutrient redistribution across the landscape. In addition, the fear-driven spatial differences in mesoherbivore grazing impact and nutrient deposition led to landscape scale changes in the distribution and persistence of herbivore maintained grass communities, so-called grazing lawns. However, the grazing activity of the in-vulnerable megagrazer, white rhino (Ceratotherium simum) weakened the effect of this trophic cascade by creating and maintaining grazing lawns within the risky habitat avoided by mesograzers. This study contributes to our understanding of what drives the variation among patterns of trophic control and provides the first evidence of the modulating influence that megaherbivores have on predator-triggered trophic cascades.

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Chakraborty, Aspriha, and achakraborty@swin edu au. "Numerical study of biological problems in a predator-prey system." Swinburne University of Technology, 2005. http://adt.lib.swin.edu.au./public/adt-VSWT20060608.151547.

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The logistic Lotka-Volterra predator-prey equations with diffusion based on Luckinbill's experiment with Didinium nasutum as predator and Paramecium aurelia as prey, have been solved numerically along with a third equation to include prey taxis in the system. The effect of taxis on the dynamics of the population has been examined under three different non-uniform initial conditions and four different response functions of predators. The four response functions are Holling Type 2 Response, Beddington Type Response or Holling Type 3 Response, a response function involving predator interference and a modified sigmoid response function. The operator splitting method and forward difference Euler scheme have been used to solve the differential equations. The stability of the solutions has been established for each model using Routh - Hurwitz conditions, variational matrix. This has been further verified through numerical simulations. The numerical solutions have been obtained both with and without prey-taxis coefficient. The effect of bifurcation value of prey-taxis coe�cient on the numerical solution has been examined. It has been observed that as the value of the taxis coefficient is increased significantly from the bifurcation value chaotic dynamics develops for each model. The introduction of diffusion in predator velocity in the system restores it back to normal periodic behaviour. A brief study of coexistence of low population densities both with and without prey-taxis has also been done.

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40

Christianson, David Alan. "Risk effects in Elk (Cervus elaphus) behavioral and nutritional responses to wolves and environmental conditions /." Thesis, Montana State University, 2008. http://etd.lib.montana.edu/etd/2008/christianson/ChristiansonD0508.pdf.

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Until recently, predators have been though to regulate prey primarily through direct predation, in ecosystems where top down effects have been shown to be important. However, experiments and recent empirical observations show that the costs of antipredator responses in individuals that successfully avoid predation can exert equal or larger driving forces on population dynamics than the numerical effect of direct predation. Such a mechanism has not been explored in a large terrestrial vertebrate. I explored the antipredator responses of elk (Cervus elaphus) to wolves (Canis lupus) in the Upper Gallatin Canyon of southwest Montana, USA, December through May in the winters of 2003-2006. First I reviewed elk winter diet studies to understand what drives elk foraging behavior. Next I modeled the consequences of diet shifts in grazing and browsing on mass dynamics in wintering female elk. I also developed a new nutritional index, fecal chlorophyll, that I used primarily between winter and spring periods of nutrition as foraging constraints (and costs of antipredator response) would be quite different between these two periods. Specifically, I measured foraging behavior, diet selection, and nutrient balance in wintering elk and monitored daily predation risk as wolves moved naturally, in and out of four creek drainages that formed the primary winter range. Elk showed great sensitivity to fine-scale descriptions of wolf predation risk in nearly every response variable. In particular, adult female elk increased browsing on woody stems, sagebrush, and confers while adult males showed the opposition response and increased grazing on days when wolves were present in the same drainage. This work implies that predator may in fact play a large role in ecosystems including ecosystems where predators were deemed non-influential and bottom up effects important.

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Liley, Stewart Grayson. "Elk (Cervus elaphus) vigilance levels in response to predation risk from wolves (Canis lupus)." Thesis, Montana State University, 2007. http://etd.lib.montana.edu/etd/2007/liley/LileyS0507.pdf.

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42

MacLeod, Ross. "Mass-dependent behaviour and the starvation-predation risk trade-off in passerine birds." Thesis, University of Oxford, 2003. http://ora.ox.ac.uk/objects/uuid:09e62b32-7059-4e61-b568-35689d15d58f.

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43

Wells, Patricia Marie. "Intraguild predation by Harmonia axyridis (Coleoptera: Coccinellidae) : effects on native enemies and aphid suppression." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610773.

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44

Pangle, Kevin L. "The role of non-consumptive effects in the net effect of an invasive predator in the Laurentian Great Lakes." Diss., Connect to online resource - MSU authorized users, 2008.

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Thesis (Ph. D.)--Michigan State University. Fisheries and Wildlife, Ecology, Evolutionary Biology, and Behavior, 2008.
Title from PDF t.p. (viewed on July 2, 2009) Includes bibliographical references (p. 143-159). Also issued in print.

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Snyder, Gretchen Beth. "Mechanisms driving increased prey consumption with increasing predator diversity." Pullman, Wash. : Washington State University, 2009. http://www.dissertations.wsu.edu/Dissertations/Summer2009/G_Snyder_051509.pdf.

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46

Gardiner, Mary Margaret. "Landscape scale and within-field influences on predator abundance and biocontrol services in soybean fields." Diss., Connect to online resource - MSU authorized users, 2008.

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47

van, der Walt Johannes Adriaan. "Black bass (Micropterus spp.) in the Olifants- Doorn River system: distribution, distribution barries, predatory impact and management." Thesis, Cape Peninsula University of Technology, 2014. http://hdl.handle.net/20.500.11838/856.

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Thesis submitted in partial fulfilment of the requirements for the degree Master of Technology: Nature Conservation in the Faculty of Applied Sciences at the Cape Peninsula University of Technology
In the Cape Floristic Region the Olifants- Doorn River (ODR) system is a known biodiversity hotspot in terms of endemic freshwater fish. Eight of the 10 described native freshwater fish species are endemic to this river system. One of the main threats to these fish is predation by introduced predatory fishes. Three species of alien invasive black bass (Micropterus salmoides, Micropterus dolomieu and Micropterus punctulatus) were introduced into the ODR system during the 1930s but prior to this study, their distribution and impacts had never been quantified on a system-wide basis. This study aimed to clarify the current distribution, distribution barriers, predatory impact and best management options for black bass in the ODR system. This was achieved by conducting a system-wide survey of 578 km of stream covering 41 tributaries in the ODR system. Black bass presence was tracked upstream within each tributary to its uppermost distribution point where physical barriers preventing further spread were identified and described. Fish species composition, abundance and size were recorded directly above and below these barriers to quantify black bass impact on the native fish. This research demonstrated that since introduction, natural and human assisted dispersal has facilitated not only the establishment of black bass in the Olifants and Doring main streams but also facilitated the invasions into 22 tributaries. Based on survey results it was estimated that 81.5 % of the ODR system that was previously occupied by native cyprinids is now invaded by black bass. Assessments of native fish abundance and size distribution above and below black bass invasion barriers demonstrated that in invaded tributaries only adults of larger cyprinids (Labeo seeberi, Labeobarbus capensis and Barbus serra) were able to co-occur with black bass species. Smaller fish such as juvenile L. seeberi, L. capensis and B. serra and native minnows (Barbus calidus, Pseudobarbus phlegethon and Barbus anoplus) were absent from the black bass invaded reaches. The findings of this catchment scale study are consistent with findings from other studies in the region. As a result, most native fishes are now restricted to streams above the natural barriers that limit the upstream invasions of black bass. Black bass eradication from invaded reaches is therefore necessary for habitat restoration. Effective eradication will however depend on the presence of barriers to prevent re-invasion from downstream sources. To better understand what constitutes the nature of such barriers, this study characterised the natural barriers that inhibited black bass invasions in 17 tributaries. Natural barriers comprised of 15 waterfalls, two cascades and one chute ranging in height from 0.49 m to 3.5 m with an average vertical drop of 1.21 ± 0.67 m. These findings suggest that black bass have poor jumping abilities and the recommended height of artificial barriers as part of a black bass management program should be between 80 and 100 cm depending on the size of the tributary. As a result, the presence of natural barriers or the construction of artificial barriers to prevent black bass invasions is considered a vital component of native fish conservation projects. Finally, the study assessed the feasibility of black bass eradication from the 22 invaded tributaries in the ODR system based on eight criterion covering aspects of biological, physical, anthropogenic and logistical importance. This assessment showed that effective eradication was most likely only feasible in seven tributaries. Prioritisation of these seven tributaries for black bass eradication based on the threatened status of the resident native species, the land-use in the respective catchments and the tributary length available for rehabilitation indicate that the Breekkrans, Biedouw and Thee Rivers should receive the highest priority.

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48

Baker, Patrick. "Predation on an introduced marine snail by native crabs." Thesis, Thesis (M.S.)--University of Oregon, 1988, 1988. http://hdl.handle.net/1794/9843.

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Typescript. Includes vita and abstract. Bibliography: Includes bibliographical references (leaves 55-58).
Ceratostoma ioornatum is an introduced marine snail in Puget Sound, Washington. Two of five native species tested as possible predators ate Ceratostoma. These two species, the crabs Cancer gracilis and Lopbppaoopeys bellys, did not eat native snails similar to Ceratpstpma, but ate native and introduced bivalves more than Ceratpstpma. The reasons for the differences in predation seemed to be explained by shell strength of the prey species. The presence of Ceratpstpma adds a new type of prey to the menu of the two crab species at the sites studied.

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Schel, Anne Marijke. "Anti-predator behaviour of Guereza colobus monkeys (Colobus guerez) /." Thesis, University of St Andrews, 2009. http://hdl.handle.net/10023/832.

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Black-and-white colobus monkeys are renowned for their impressive vocal behaviour, but up to date there have been only very few systematic efforts to study this. These monkeys are able to produce loud and low-pitched roars that transmit over long distances, which has lead to the assumption that these calls function in inter-group spacing and male-male competition. The fact that the monkeys sometimes produce the same calls to predators as well, has not received much attention so far. This thesis presents a detailed description of the form and function of the anti-predator behaviour of one species of black-and-white colobus monkeys, the Guereza (Colobus guereza), with a specific focus on their alarm calling behaviour. A second aim was to determine the effects of predator experience on their anti-predator behaviour, with a specific focus on call comprehension and production. Data were collected from two populations of Guereza monkeys in the Budongo Forest Reserve, Uganda, that differ in predation pressures experienced by their main predators: leopards, eagles and chimpanzees. Results showed that Guerezas use a basic form of zoo-syntax in order to compose predator-specific call sequences that vary in the number of roaring phrases and snorts. These sequences are meaningful to recipients, at least at the level of the predator class, but there were also indications for additional levels of encoded information: Guerezas appear to have evolved a second system, based on acoustic variants of individual phrases, which allows them to narrow down the information content of call sequences, generating the potential to communicate highly specific information by using a mix of syntactic and semantic cues. The monkeys’ vocal behaviour was influenced by predator experience, but not strongly so. Monkeys without prior experience with leopards lacked some of the behavioural nuances seen in leopard-experienced monkeys, but they nevertheless responded appropriately to visual and acoustic leopard models, suggesting they had retained the basic capacities to recognise this predator type as relevant and dangerous. Results are discussed in light of the comparative approach to the study of human language evolution. Although human language is unique in a number of ways, for example through its use of complex syntax and intentional semantics, some animal communication systems have revealed similar features, and Guerezas, the first member of the colobine family to be studied in this respect, are no exception. The Guerezas’ alarm calling behaviour is complex and flexible, and these monkeys have provided another piece of empirical evidence that is directly relevant for the comparative approach to human language evolution.

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Berry, William Alexander. "A hydrodynamic characterization of tidal ecosystems with respect to predation." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31848.

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Thesis (M. S.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2010.
Committee Chair: Webster, Don; Committee Member: Sturm, Terry; Committee Member: Weissburg, Marc. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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Dissertations / Theses on the topic 'Predation (Biology)'

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