Thesis (B.Sc.Hons.) -- University of Adelaide, Department of Psychology, 1972.

The superior neocortex ratios in primates and their distinctive relationship with sociality among terrestrial mammals are well documented. However, there has been an absence of research into relative neocortex size, its evolution and correlates in marine mammals, such as cetaceans (dolphins, porpoises and whales). This study uses the advanced radiological techniques of computed tomography and magnetic resonance imaging to establish neocortex ratios in dolphins and to re-assess these values for humans. It was found that freezing and defrosting did not significantly alter the neocortex ratios of dolphins and thus extra material as included in the analysis. Furthermore, equations for the estimation of neocortex ratios from eT and MRI have been applied to the cranial volumes calculated for 19 toothed whale species, in order to extend the range of analysis. Using these techniques, it appears that dolphin neocortex ratios are higher than those of other mammals, except for primates. A notable finding is that dolphin values lie between human and other primates and are closer to human ratios at 4.1, than to non-human ratios reaching 3.2~ (Dunbar, 1992). The highest delphinid neocortex ratio from MRI was 3.94 for common dolphins, while the highest estimated neocortex ratio was at 3.95 for killer whales. To establish the correlates of such high neocortex ratios in dolphins, their scores were related to variables representing foraging ecology, sound and sociality. Although delphinid neocortex ratios do not appear to be related to foraging variables, they are significantly related with sound and sociality variables. Of these relationships, the most substantial finding exists with respect to the relationship of delphinid neocortex ratios and their mean group size. The capacity to predict group size from relative neocortex size has not been noted in non-primate species, and has formed the basis for current theories of social intelligence and mental evolution. The findings of this study are therefore of considerable interest and may have substantial implications. These may impact on current theories of primate-human mental evolution and therefore it is strongly recommended that the mental capacities of other mammals, such as dolphins, be examined in greater detail to support or refute these claims. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1998.

Lions are social, territorial animals that form prides of 2-18 individuals and hold territories ranging in size from 20 to 500 square km. My aim was to investigate the effect of ecological processes on lion spatial demography, specifically to determine the effect of habitat structure, prey availability, and rainfall (predictability and variability) on lion group dynamics. I worked with an extensive database of lion observations (approximately -+7000 over 29 years) from the Kruger National Park that had been recorded on monthly predator returns and in ranger diaries. I used the hypothesis of ideal free distribution to explain group dynamics across four physical habitat structures, namely, thickets, woodlands, mountainous areas and open tree savanna. There were larger groups of adults and more sightings than expected in the open tree savanna, while subadult and cub group sizes peaked in the woodlands. Using the resource dispersion hypothesis (RDH) as a base, I investigated lion group dynamics in relation to prey availability, I found agreement with the RDH, in that larger groups formed where their favoured prey species were in greatest abundance. Exclusively adult male and exclusively adult female group sizes increased with increasing buffalo abundance, while groups of adult males and adult females in mixed groups increased with increasing impala abundance. I used the mechanism of risk sensitive foraging to explain the influence of rainfall on lion group dynamics. While group dynamics did not differ significantly across averaged mean annual rainfall regions or across seasons, it did differ between variability regions and between two years of extreme rainfall. The lions exhibited risk-prone behaviour across variability regions, forming larger groups in more variable environments. Finally, I combined the three factors to determine the relative importance of each in determining lion group dynamics across seasons. Wildebeest were important to adult female group dynamics, impala and buffalo to adult males, while buffalo abundance influenced functional group size. In the wet season, larger functional groups occurred in the areas of medium rainfall variability regardless of buffalo abundance. In the dry season, more groups of females than solitary females occurred in more variable environments with this trend reversed for males. / Thesis (M.Sc.)-University of Natal, Durban, 2000.