Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 227-263). Available also in a digital version from Dissertation Abstracts.

Thesis (M.S.)--Ohio University, June, 1991. / Title from PDF t.p.

Thesis (M.Sc.)--University of the Witwatersrand, Faculty of Science, 1969.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2005. / Includes bibliographical references.

Thesis (Ph. D.)--Joint Program in Biological Oceanography (Massachusetts Institute of Technology, Dept. of Biology, and the Woods Hole Oceanographic Institution), 2000. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Florida, 1983. / Description based on print version record. Typescript. Vita. Includes bibliographical references (leaves 126-135).

Thesis (Ph. D.)--Massachusetts Institute of Technology and Woods Hole Oceanographic Institution Joint Program in Oceanography/Applied Ocean Science and Engineering, 2000. / "Funding was provided by grants from WHOI's Rinehart Coastal Research Center and Ocean Ventures Fund, a National Science Foundation graduate fellowship, grant CC-S-611002-001-C from the Office of Naval Research, and broad financial support from WHOI's Education Department. Includes bibliographical references.

Vocalizations of the domestic chicken were recorded and analyzed by quantitative and qualitative methods in two experiments. In Experiment 1, recordings were made from males and females from two lines of White Leghorn chickens housed in individual battery cages. Five call types: crow, disturbance call, baaks, fear-squawks, and moans were distinguished. No significant differences were found between lines for any of the parameters measured. Crows consisted of four parts, with the combination of the durations of the various segments suggesting that they contribute to recognition among individuals. Both sexes emitted disturbance calls, baaks, fear-squawks, and moans. When comparisons were made between sexes for number of disturbance notes per second and length of fear-squawks no significant differences were found. Signal grading was shown by increased rates of disturbance notes and the addition of baaks as an individual became more upset. Three groups of eight-week old White Leghorn chickens subjected to different handling regimes emitted different vocalizations when held in the hand of the observer. Birds habituated to the handler gave mainly contentment calls while the other groups emitted peeps (distress calls), fear trills or alarm notes. A previously unreported melodic flock call was heard from White Rock chickens that were moved to a new pen at eight weeks of age. Experiment 2 consisted of comparisons between two commercial egg-laying stocks maintained under high-intensity battery cage housing. Data obtained at approximately 35 weeks of age from both stocks in the same house showed low frequencies of pecks and threats. Pullets from stock B had significantly more pushes and steps than those from stock A. The vocalizations emitted by stock B exhibited an increased range of frequencies in comparison to those by stock A. This difference was attributed to an increased number of disturbance calls and baaks and suggests that vocal behavior may be a means of assessing the social environment of chickens maintained in battery cages. / M.S.

Perceived predation risk has a large impact on how prey species utilise landscapes. In an effort to reduce predation risk, individuals tend to utilise safer areas more than unsafe areas. How perceived predation risk affects the utilisation of landscapes by animals is termed a “landscape of fear”. Vervet monkeys (Chlorocebus pygerythrus) have a landscape of fear that operates in both horizontal and vertical planes. Within this landscape, vervets perceive the safest area to be up in a tree, under the canopy. To reduce predation risk, vervets use various predator-specific alarm calls and have been found to eavesdrop on the alarm calls of other species (e.g. birds). In this study, I explored whether vervet monkeys were able to associate eavesdropped alarm calls with specific predator types (i.e. aerial and terrestrial) as they do with their own predator specific alarm calls. To do this, I first quantified the three-dimensional landscape of fear for vervet monkeys by measuring giving up densities in artificial patches. I then used playbacks of the vervets’ aerial and terrestrial predator alarm calls, the alarm call of a red-backed shrike, and a mixed-species flock mobbing call to manipulate perceived predation risk. By comparing changes in foraging intensity within the patches, I quantified the specific reactions of the vervet monkeys to aerial and terrestrial predators. In addition, I found that the monkeys did not eavesdrop on the red-backed shrike call. However, the vervets did eavesdrop on bird mobbing calls, and associated the calls with the location of the potential treat and reacted as if it was a particular predator type. Specifically, the vervets reacted to mobbing calls played from up in a tree the same way as they did if an aerial predator was present, and calls from the ground as if a terrestrial predator was present. Thus, this suggests that they were able to associate a non-functional referential call (i.e. the mobbing call) with specific information, gathered from the location of the calls, and interpreted it in a referential manner. Moreover, intensity of these reactions (as measured by total feeding effort) indicated that vervets saw aerial predators as a greater threat compared to terrestrial predators. Ultimately, my results suggest that vervets can associate eavesdropped calls with specific predators, and this likely provides a fitness benefit in a dangerous and unpredictable world. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.

Thesis (Ph. D.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references (p. 104-106).