This investigation examined the social structure of four species of small mammals (Perognathus parvus (Peale), Reithrodontomys megalotis (Baird), Peromyscus maniculatus (Wagner), and Dipodomys ordi (Woodhouse) at the National Reactor Testing Station (NRTS) in Idaho. An understanding of the social structure provides ecological clues concerning the integration of interactions, reproduction, distributions, densities, and diel activities for not only one animal and species, but for a complex of animals interacting with each other.

The study was initially a long term study of the ecology of small mammals at Mlawula Nature Reserve in the eastern part of Swaziland. Due to the drought and dwindling numbers of rodents in the reserve the study was redirected to determining the factors resulting in the low numbers. The impacts of food and cover and grazing by the larger ungulates were studied. In addition, the age class distribution and gastro-intestinal parasites of small mammals were studied. A study of the small mammals in the Siphiso Valley of Mlawula Nature Reserve was conducted over four years from August 2000. The population density, biomass and composition of the small mammal community in the area were studied. The community comprised of Mus minutoides A. Smith, 1834, Mastomys natalensis (A. Smith, 1834), Lemniscomys rosalia (Thomas, 1904), Crocidura hirta Peters, 1952, Steatomys pratensis Peters, 1846 and Graphiurus murinus (Desmarest, 1822). Mus minutoides was the dominant species with pregnant females caught from November to May. Species richness varied significantly with the time of the year. The biomass, density and numbers of small mammals were low and by the end of the second year of the study, small mammal density was close to zero. Mastomys natalensis from a Middleveld study site, Luyengo, Swaziland were used to study the age structure of the population by means of eye lenses. The eye lens to age (in days) curve determined by Leirs (1994) was applied. A large percentage of M. natalensis in winter (June) were 2 months old while in spring/summer (October to March) the population consisted mainly of 3 month old specimens. A very low number of specimens were older than 4 months. This suggests a high mortality/removal rate of the young especially in the winter months. The impact of grazing pressure and rainfall on small mammal densities were investigated. High grazing pressure by ungulates rendered the habitat unsuitable for small mammals as it removed cover and encouraged colonization by alien invasive plant species. This effect was exacerbated by diminishing and unpredictable rains, such that mild grazing pressure negatively impacted on small mammal communities and on individual species. When the small mammals disappeared from the study site, M. natalensis was reintroduced to determine the factors that led to the disappearance. Supplementary food resulted in the longest persistence of the reintroduced mice while the impact of additional cover was small. Predation was likely responsible for the rapid decline of the reintroduced mice. Small mammals were examined for ectoparasites and gut parasites as these were thought to negatively impact on their physiology and reproduction. Ectoparasites collected included the ticks Ixodes sp. and Boophilus sp., the mite Allodermanyssus sp. and another species of mite. The gastrointestinal tracts contained the helminths Syphacia sp., Heligmonina sp., Trichuris sp., Protospirura sp., two unidentified nematode species and different cestode species. A new species of heligmosomoid nematode is described and named. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.

In this study I examine the effect of seasonal resource limitation on the behaviour and population dynamics of white-eared kob, Kobus kob leucotis, in the Boma region of the southern Sudan. This population, numbering over 800,000, migrates seasonally between savannah grasslands in areas with low rainfall and ephemerally swamped grasslands in areas with high rainfall. The aims of the study were: (1) to examine whether kob migration tracks ephemeral distributions of food or water resources, (2) to test the hypothesis that the Boma kob population is limited by food availability, (3) to determine if calf production is cued to seasonal peaks in food abundance, and (4) to evaluate the effect of breeding synchrony on lekking behavior and male competition. Seasonal climatic changes produced pronounced changes in the distribution and abundance of both green forage and water supplies. Dry season migration primarily tracked limited supplies of water. Within the dry season range, kob aggregated at high densities (over 1,000 per km²) in low-lying meadows that supported grass re-growth when little green grass was available elsewhere in the ecosystem. However, southerly movements in the wet season were not explainable by the resource hypothesis, since both food and water were widely distributed during the wet season. I suggest that kob may move southward in order to avoid surface flooding during the wet season. Kob mortality during the dry seasons of 1982 and 1983 was considerably higher than estimated mortality during the wet season. Unusual rainfall during the dry season of 1982 provided a "natural experiment" to test the food limitation hypothesis. Adult mortality was significantly lower during the dry season of 1982 than during the more typical dry season of 1983. Calf mortality did not vary significantly between years. Adult mortality rates were related to dry season duration. Dry season mortality was related to sub-maintenance food intake and declining fat reserves. The age structure of the kob population in 1983 suggests that large-scale mortality (ca. 40%) occurred in the 1980 drought that immediately preceded this study. These findings support the food limitation hypothesis. Kob exhibited a 4 month period of calf production during the late wet season, when food availability was highest. As a consequence, females continued lactation through the dry season period of food scarcity. I suggest that kob reproductive phenology may result from an obligatory delay during which females restore their fat reserves prior to calving or selection pressures imposed by predation during the vulnerable post-partum period. Synchronous breeding in the Boma kob was related to increased rates of aggression between males and increased color dimorphism, in comparison to the asynchronous breeding Uganda kob, Kobus kob thomasi. Male aggression served not only to establish dominance relations between males on leks, but also disrupted the mating activities of neighboring males. Young adult males suffered higher age-specific mortality than females, possibly resulting from injuries incurred during strenuous fighting on leks. In order to analyze the age structure of the kob population, I devised a new method for estimating age-specific mortality rates that is free of the restrictive assumptions that underlie most conventional techniques. The proposed method has somewhat greater sampling variation, but is considerably more robust, than two current methods. Moreover, the proposed method permits calculation of age-specific mortality at frequent intervals during periods of population fluctuation and, under some circumstances, population numerical trends may be directly determined from age structure. / Science, Faculty of / Zoology, Department of / Graduate

Bibliography: leaves 168-187. / viii, a-f, 187, [51] leaves, [12] leaves of plates : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Investigates the environmental control of seasonal reproduction and the role of the pineal in the transmission of multiple environmental signals to the reproductive axis. The principle species studied was the highly seasonal native Australian bush rat, Rattus fuscipes greyi. / Thesis (Ph.D.)--University of Adelaide, Dept. of Obstetrics and Gynaecology, 1994

This study presents the results of a study on introduced giraffe diet and feeding effects within the Eastern Cape Province of South Africa. Five sites were selected over a moisture gradient from the mesic east to the arid west of the Eastern Cape to describe giraffe diet and provide baseline data for feeding effect experiments. At each site faecal samples were collected seasonally and diet composition determined by microhistological analysis. Plant species availability was measured using the point intersect method in order to compare plant availability to plant consumption to determine diet preferences. Giraffe diet across the sites showed a unimodal response to rainfall by utilising fewer species in drier areas where plant availability is low and increasing the number of species consumed as the rainfall increases. In higher rainfall areas, giraffe reduced the number of plant species fed upon because of the high availability of important species that reduces the need for a varied diet. Across all sites, plant availability was dominated by woody plant species (more than 90 percent at each site). A total of 57 plants species were recorded as being eaten across the five sites. Several PDI (Principle Diet Items) plant species (Acacia karroo, Schotia afra, Pappea capensis and Euclea undulata) were eaten across sites. Over all the sites, significantly preferred species were Asparagus striatus, Schotia latifolia, Asparagus suaveolens, Commelina benghalensis, Viscum rotundifolium, and Acacia cyclops. Acacia karroo, Schotia afra, Pappea capensis, Rhus crenata, A. tetracantha, and Grewia robusta were utilised in proportion to their availability. Euclea undulata, Rhus longispina and Putterlickia pyracantha were avoided. Feeding effects were tested by erecting exclosures around trees, covering one half of each tree. Ten trees were selected for these manipulative experiments which ran from September 2003 to February 2005. The number of branches, number of leaves, branch orders, branch diameter, branch length, leaf length and leaf width were measured for ten samples per side (enclosed vs. exposed) and analysed using a Wilcoxon matched pairs test and tested for effect size using Cohen’s d. Although no significant differences were detected between the sides measured, the effect size indicated differences in all measurements between sides ranging from low to moderate. Leaf length was greater on the outside of exclosures and showed a moderate difference between the sides in terms of the d-value with the p-value (0.059) tending towards significance. Although leaf width was higher on the inside of exclosures, it only showed a moderate difference for d with no statistical significance. Leaf area was higher on the inside of exclosures and tended to significance (p = 0.059) and similarly the d value indicated moderate differences between the sides in terms of effect size. Similarly branch length was higher on the inside of exclosures although not significantly, the p-value (0.07) approached significance. The effect size for branch length also showed a moderate difference between the sides. The number of branches and the number of leaves showed no statistical differences between the sides although the p-value (0.059) for the number of branches, as well as number of leaves (p = 0.07) approached significance. For both these variables, effect size showed a moderate difference. Giraffe showed diversity in their diet selection across sites but mainly fed upon available species. Some preferred species were however less available and this preference could possibly result in increased pressure on the selected plant species Exclosure experiments showed no significant differences in leaf and shoot characteristics although all measurements showed differences in terms of effect size meriting further investigation. It is concluded that giraffe impact on sites may be reduced if populations are properly managed however, high densities of giraffe could lead to similar vegetation impacts as observed in other areas where giraffe have been introduced and potentially change vegetation structure and plant community composition.

Increased afforestation and protective legislation in the latter half of the 20th Century allowed the British pine marten Martes martes population to recover from near extinction. Although still largely confined to northern Scotland, the marten population is expanding its size and range by utlising coniferous plantation forests which have become increasingly available. However, little is known about the marten’s ecology in plantation forestry, and less about how they may adapt to changing silvicultural trends. This study investigated aspects of pine marten ecology within Morangie forest, a managed plantation in NE Scotland, with the ultimate aim of formulating management guidelines for modern plantation forests. During the course of the study 11 pine marten were radiotracked and their home ranges mapped to examine marten-habitat associations at several spatial scales. Compositional analysis of habitat based on dominant vegetation type showed that martens established their home ranges in areas dominated by mature forest, whilst showing relative avoidance for open heath moor and grazed pasture. Within home ranges, foraging martens utilised patches of graminoid vegetation, such as those typically associated with Microtus voles, in areas with little or no tree canopy cover. These findings provide unequivocal evidence that fine-scale patches of non-forested habitat provide crucial foraging resources for marten, and therefore ought to be provisioned for in forest management plans. To assist the implementation of these requirements in forest planning, a model was developed to predict the fine scale distribution of Microtus-rich foraging habitat for marten using GIS-based habitat variables that are routinely available to forest managers: topographic wetness index, stand tree height and stand basal area. Management recommendations of ways to improve wind-firm plantation forests as habitats for pine marten are provided. To augment the investigation of marten spatial ecology, the diet of martens was examined seasonally through the analysis of contents from c. 2450 scats, 86 % of which were genetically identified as being pine marten in origin. Marten diets displayed marked seasonality, but small mammals, berries and small birds were the principal foods consumed based on both frequency of occurrence and estimated weight of biomass ingested. Comparison of the relative composition of small mammal species in the diet with those available in the environment revealed that marten displayed an indisputable preference for Microtus voles. Such habits demonstrate that the niche of Scottish martens has diverged from those in mainland populations which predominantly prey upon Clethrionomys voles. A comparison of the marten’s winter diet with those found in studies at similar latitudes (58°N) demonstrated that the Scottish diet was more similar to diets at more southerly latitudes as they contained more fruit and fewer large mammals than typically boreal diets. Investigation of inter-annual variation of the marten’s spring diet from five successive years revealed that Microtus were consistently the most important prey species in the diet each year. Indirect evidence of the relative abundance of Microtus suggested that Microtus populations were non-cyclic. Findings are discussed with reference to the unique ecological circumstances confronting marten in the Scotland; typical of insular populations the UK has a depauperate native fauna in comparison with mainland Europe, in addition to this, mild climatic conditions, particularly over winter, and a historically fragmented landscape appear to have allowed the niche of the Scottish marten to diverge from that considered typical elsewhere in its range. The Scottish marten is dependent on both forested and open habitats, and is both a Microtus specialist and trophic generalist.

Elephants (Loxodonta africana, Blumenbach) are recognised as keystone herbivores and ecosystem engineers in African ecosystems due to the noticeable impact they have on plant communities. This impact can influence other animal taxa and ecosystem processes, especially within enclosed systems. I investigated the effects of elephants in four vegetation types and the cascade effect on three associated taxa and two ecosystem processes at five sites with elephants and five paired sites without elephants in the Eastern Cape Province, South Africa, between April 2005 and July 2007. In grassland habitats, the physical structure of the vegetation was neither enhanced nor degraded in the presence of elephants. Within the locally important Thicket Biome, elephant browsing transformed relatively homogeneous stands of vegetation into more heterogeneous units. However, although seeds from thicket plant species were recorded in elephant dung, elephants did not promote the viability and germination success of these plants. In addition, elephant foraging on aloes caused declines in their populations. By contrast, the size of bushclumps was not reduced in the presence of elephants in bushclump savanna. The associated insect, bird and mammal communities appeared to benefit from elephant foraging in all vegetation types assessed, whereas vegetation patch dynamics and soil surface processes were neither enhanced nor degraded in the presence of elephants. I conclude that, at current densities, elephants do not (in most cases) negatively affect plant and animal communities or ecosystem processes in enclosed reserves. However, elephants have only been present at each site for a relatively short period and it is likely that their impact will be cumulative, increasing over time in these closed systems. Thus, future research along a continuum of elephant density and time since re-introduction is recommended.