Bibliography: pages 251-265. / A population of Pale Chanting Goshawks Melierax canorus, some of which live in families, was studied during 1988-1992 for a total of 117 group-years near Calitzdorp, South Africa. The aims of the study were to identify ecological and social factors that might predispose individuals in the population to delay dispersal and become non-breeding or co-breeding members of Pale Chanting Goshawk families, and to determine why cobreeders breed cooperatively in polyandrous trios. In all vegetation types within the study area, non-breeders, as juvenile and adult offspring, delayed dispersal from their natal territories. However, co-breeding males occurred only in one vegetation type, Karroid Broken Veld. Co-breeding males participated in all reproductive activities, including copulation. Karroid Broken Veld also supported the largest known groups of Pale Chanting Goshawks and the highest frequency of groups with non-breeders, which resulted in some of the highest recorded single species raptor densities in the Afrotropics. Pale Chanting Goshawks in Karroid Broken Veld preyed primarily on two otomyinid rodents, Otomys unisulcatus (42-48 % of prey biomass) and Parotomys brantsii (18-32 % ). The habitat quality of Karroid Broken Veld for Pale Chanting Goshawks was high since, compared with other vegetation types, it incorporated: (1) optimal habitat for otomyinid prey, (2) a very high estimated biomass of otomyinids, almost twice that of other vegetation types, and (3) a hunting habitat with an optimum combination of prey visibility and perch availability that facilitated hunting efficiency. Territorial space was limited throughout the study area, constraining the number of nonbreeders per group to two and inhibiting new breeders from establishing territories. Juvenile non-breeders probably delayed dispersal to increase their probability of survival, and dispersed later as sexually mature adults, since they could not increase their fitness further by becoming helpers at the nest. During the nestling period, co-breeding beta males provided prey at an equal rate to dominant males, that enabled polyandrous trios to undertake more frequent and successful breeding attempts in years of high prey abundance. The help provided by co-breeders contributed more to this success than did density of dominant prey and territory size. In Karroid Broken Veld co-breeders delayed dispersal since their fitness as subordinate sibling males was probably higher than fitness achieved due from dispersing to a breeding vacancy in habitat of lower quality. I suggest that those ecological factors which contribute to habitat quality provided the proximate impetus, and the resulting saturation of the habitat the ultimate impetus, in promoting the establishment of Pale Chanting Goshawk family units. Once Pale Chanting Goshawk formed families, a range of secondary benefits evolved as birds adjusted their behaviour to benefit from the presence of other group members. For example, although breeders in high-quality habitat produced the highest number of offspring, the lack of territorial space probably forced more offspring to disperse. To increase offspring survival, breeders may have adjusted their reproductive strategy and allow non-breeders to partake and share in returns of cooperative hunts. Other secondary benefits included the possibility of inheriting a natal territory, budding-off onto territorial borders or helping close relatives as an experienced co-breeder.

Includes abstract. / Includes bibliographical references. / Waterfowl annual life history events in north-temperate regions are driven primarily by predictable seasonal variations in temperature. In contrast, the spatio-temporal availability of adequate resources to waterfowl in the semi-arid regions of southern Africa is determined by rainfall which is extremely variable in timing and intensity. I studied the environmental influences on flight-feather moult and movement strategies of southern African waterfowl. Six duck species that are fairly common in most parts of South Africa were selected for the study, namely; Egyptian Geese, Alopochen aegyptiaca, Spur-winged Geese, Plectropterus gambensis, South African Shelducks, Tadorna cana, Yellow-billed Ducks, Anas undulata, Red-billed Teals, A. erythrorhyncha and Southern Pochards, Netta erythrophthalma. I chose two study sites to represent the extremes of environmental conditions in southern African, namely Barberspan (summer-rainfall region) and Strandfontein (temperate winter-rainfall region). I investigated the underlying responses of Afrotropical waterfowl to stochastic varying environmental conditions in southern Africa and the life-history strategies they have evolved to cope with this variability. The study also compares and contrasts the life-history strategies of southern hemisphere waterfowl with those of the northern hemisphere.

Includes bibliographical references. / African Black Oystercatchers (Haematopus moquini) have a modal clutch size of two eggs but occasionally lay one or three eggs. It has been noted that an increase in frequency of larger threeand even four-egg clutches has occurred over the last few decades. By analysing extensive historical nest records dating back five decades I verified the occurrence of this increase in three-egg clutches over many of the sites within their breeding range. As African Black Oystercatchers are very territorial, co-operative polygyny was rejected as a sole cause (through observations). As eggs were found to be significantly similar (through intra-clutch egg shape comparisons) within clutches egg-dumping as a cause was also rejected. It was thus established that the increase in three-egg clutch frequency was indicating an increase in breeding effort. On further analysis of this increase, it was discovered that three-egg clutches offer no benefit to species fitness or breeding success as they do not result in an increased fledgling output to those of the smaller two-egg clutches. This is primarily due to inefficient incubation as a result of the extra egg, and the inability to maintain and feed a larger brood size. This study validates previous assertions that three-egg clutch frequency is increasing for African Black Oystercatchers.

Bibliography: leaves 58-61. / The rallid genus Dryolimnas is endemic to western Indian Ocean islands. Formerly widespread, it is now restricted to Aldabra Atoll (the Aldabra Rail D. cuvieri aldabranus) and Madagascar (the White-throated Rail D. c. cuvieri). Before this project began, the Aldabra Rail was restricted to Polymnie, Malabar and lIe aux Cedres, having been extirpated from Grande Terre and Picard by Domestic Cats Felis catus (still found on Grande Terre) and humans. In 1999, following IUCN guidelines, I captured 20 Aldabra Rails and brought them to now Cat-free Picard. Two Rails died in captivity, an indirect result of incorrect sexing based on a published field sexing method; a subsequent genetic sexing technique confirmed the unreliability of sexing Aldabra Rails in the field. All 18 remaining birds were released on Picard and survived beyond the first breeding season. Eight pairs had bonded and successfully reared a minimum of 13 chicks within five months of release. Eleven monitored pairs reared 20 chicks in 2000/2001, with one-year-old birds breeding successfully. Average chick production was significantly higher on Picard than on Malabar in both breeding seasons. The Picard population at the end of the 2000/2001 breeding season was at least 51, an increase of 283% in 18 months. There are excellent prospects for continued, exponential population growth until the population reaches carrying capacity (ca 1000 pairs), predicted to be between 2007 and 2009. Limited genetic data suggest some population structure between extant populations, and the Picard population is genetically healthy relative to that of Malabar. There has been no substantial change 111 the Aldabra Rail population since the 1960s. However, I have revised an earlier population estimate downwards to ca 3500 pairs. I also estimate the floating population on Malabar was around 1700 Rails in early 2000. A population model of the Malabar Rails predicts a likely minimum annual adult survival rate of 85 %, with a fluctuating floater population. It also shows the population to be very robust to the removal of territorial birds for other proposed reintroductions, but highly vulnerable to the establishment of a predator. The soft release protocol (including a period of acclimatisation before release and supplementary feeding, as required, after release) is believed to have played a crucial role in the success of the reintroduction by allowing individuals to acclimatise and providing an energetic cushion between release and self-sufficiency. A soft release is recommended as the conservative and precautionary method of choice for avian reintroductions and translocations.

Includes abstract. / This research demonstrated the dual utility of bio-loggers as a method for generating accurate, high-resolution oceanographic data. These data can be used in future studies, generating a cross disciplinary platform for research. The thesis augments our knowledge base of the African Penguins foraging ecology. African Penguins show flexibility in their foraging behaviour by adjusting their dive behaviour to subsurface thermal structures. Penguins also demonstrated foraging optimization by using temperature cues and behavioral switching to maximize the probability of locating prey patches on a fine temporal and spatial scale.

South Africa is traditionally known to play host to two taxa of small Buteo, the endemic and uncommon Forest Buzzard B. trizonatus, and Steppe Buzzard B. b. vulpinus, an abundant Palearctic migrant. Since the late 1970s and early 1980s, a number of buzzards appearing unlike B. trizonatus have been found breeding in the south-west Cape, particularly on the Cape Peninsula and in and around the Elgin Valley, ca.60km east of Cape Town. Some of these buzzards resemble B. b. vulpinus, whilst others appear atypical of both B. trizonatus and B. b. vulpinus. This study conducted genetic and morphological analyses on a number of buzzards sampled in the south-west Cape, and compared them with three candidate taxa considered most likely to, in full or in part, explain the identity of these ‘mystery’ buzzards. The candidate taxa were: Steppe Buzzard B. b. vulpinus, Ménétries’s Buzzard B. b. menetriesi and Forest Buzzard B. trizonatus. Morphology data and genetic samples were collected from 23 buzzards through capture with a Bal-Chatri trap, from chicks in nests, from captive birds brought to rehabilitation centres or from birds found dead. The comparative morphology of the buzzards sampled in the Cape was determined by constructing a Discriminant Component Analysis using 9 morphometric characters which had previously been established as being important in the separation of Old World Buteo taxa (Kruckenhauser et al., 2004). Blood samples were then analysed using 18 polymorphic microsatellite loci designed for Buteo swainsoni (Hull et al., 2007), using the program STRUCTURE 2.3 to analyse the population assignment of the sampled buzzards. The majority of buzzards were found to most closely match B. trizonatus or B. b. vulpinus in their morphology (52%), and their genetic signature (65%). Additionally, two unidentified genetic signatures were evident. One of these signatures remains unresolved, because buzzards with this genetic signature lacked morphological data. The second signature, however, was displayed by buzzards with larger morphology than is known from both B. b. vulpinus and B. trizonatus. Based on previous research these larger buzzards lay most closely within the morphospace of B. b. menetriesi, being far removed from the morphospace of both B. b. vulpinus and B. trizonatus. Thus, it is conceivable that some of the birds belong to this taxon.

1. Eight burrowing petrel species were found nesting within the area studied in north-eastern Marion Island during April 1979 to May 1980. These were Salvin's Prion Pachyptila vittata salvini, Blue Petrel Halobaena caerulea, Greatwinged Petrel Pterodroma macroptera, Kerguelen Petrel Pterodroma brevirostris, Softplumaged Petrel Pterodroma mollis, Whitechinned Petrel Procellaria aequinoctialis, Grey Petrel Procellaria cinerea and South Georgian Divingpetrel Pelecanoides georgicus. Eighty-one percent of burrows found belonged to Salvin's Prions. 2. The nest site preferences of Salvin's Prion, Blue Petrel, Greatwinged Petrel, Kerguelen Petrel, Softplumaged Petrel and Whitechinned Petrel were investigated. These species had individual preferences with respect to soil depth, soil moisture content, slope angle or slope aspect. 3. The Kerguelen breeding biologies and diets of Greatwinged Petrels, Petrels and Softplumaged Petrels were studied. The species bred at different times of the year with non-overlapping chick-rearing periods. Incubation periods were similar but, relative to adult size, Kerguelen Petrel chicks grew fastest. All three species took mainly cephalopods although Kerguelen Petrels took the most crustaceans and fish. 4. Subantarctic Skuas Catharacta antarctica were important predators of petrels. They preyed upon whatever petrel species were most abundant in an area, although large petrels (Whitechinned Petrel) and those breeding in winter (Greatwinged Petrel) were seldom taken. 5. Similar petrel species had the bulk of their breeding populations spread over different habitats thus reducing any competition for nest space. At the same time, staggered timing of breeding, and particularly the non-overlapping chick-rearing periods of the three Pterodroma petrels, helped to minimize competition for food.

Bibliography: pages 111-119. / The thesis comprises four separate chapters dealing with various aspects of the ecology of the bald ibis Gerontiaus aalvus (Aves: Threskiornithinae) and fire in the South African grassland biome. The use of habitat by foraging bald tbises, and the reproductive performance of bald ibises during three consecutive breeding seasons (1978-80) at a single breeding colony in western Natal, South Africa, are discussed in relation to rainfall, grass-burning, domestic livestock grazing and agriculture. A review follows dealing with the ecology of fire in the South African grassland biome, with particular reference to the possible role of lightning in the origin, maintenance and distribution of open grassland in South Africa under the natural fire regime. The four chapters composing the thesis are prefaced by a general introduction and followed by a general summary and conclusion.

Thesis (M.S.)--Southern Oregon University, 2008. / Computer printout. Includes bibliographical references. Also available via Internet as PDF file through Southern Oregon Digital Archives: http://soda.sou.edu. Search Bioregion Collection.

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