Land cover classifications are useful in a broad range of ecological applications, yet publicly available classifications are not always useful for the needs of specific projects. Custom classifications are always a possibility, however, they can be financially or computationally out of reach for many researchers. Here we present a custom 1m resolution land cover classification created using freely available imagery and a random forest classification approach. This classification detected shrub cover more accurately and at a finer resolution than previous classifications. With the creation of this map, we were then able to examine landscape factors influencing occupancy dynamics of the golden-winged warbler, a rapidly declining shrubland specialist, at two ecologically relevant scales. Our findings indicate that shrub cover is important in predicting warbler occupancy and persistence at scales relevant to nesting, while forest characteristics are important at scales relevant to foraging and fledgling dispersal.

Increasingly harsh and unpredictable climate regimes are affecting animal populations everywhere and understanding how species respond to current environmental variability is important for predicting vulnerability to climate change over longer timescales. Species living in characteristically harsh and unpredictable arid and semi-arid ecosystems are useful models for studying impacts of climate variability and change because these ecosystems are experiencing rapid increases in both average and maximum temperatures, as well as increased interannual rainfall variation, as a result of anthropogenic climate change. That animals living in highly variable environments are disproportionately more likely to engage in cooperative breeding implies that this strategy may buffer individuals against the negative effects of adverse climate conditions. An aspect of species' vulnerability to climate change that remains relatively unexplored is whether responses to environmental stressors might therefore be mitigated by sociality, particularly in those species in which group members are highly cooperative. In this thesis, I use behaviour, morphology, and physiology data that I collected over three consecutive austral summer field seasons (2016-2019) and A. Prof. Amanda Ridley's 15-year life history dataset (2003-2019, to which I contributed the last three years of data) for a cooperatively-breeding bird, the southern pied babbler Turdoides bicolor. I investigate the impacts of temperature, rainfall, and group size on interannual survival, behaviour, physiology, growth, and reproduction in southern pied babblers, taking a multidisciplinary approach combining behavioural ecology, life history, and ecophysiology. In order to avoid disturbance to the study population, I validated and implemented a non-invasive method for collecting physiological measurements (daily energy expenditure and water turnover). I also tested for the influence of interactions between weather and group size variables because the presence of significant interactions would provide evidence in support of a moderating effect of sociality. I found that exposure to high temperatures significantly constrained successful breeding and the interannual survival of both breeding adults and juvenile birds, and explored the mechanisms behind these observed relationships: adjustments in parental care behaviour, body mass loss, reduced nestling growth rates, and the physiological costs of care at high temperatures. Higher rainfall and larger groups sizes were generally associated with higher reproductive success and survival, but I found no evidence for an interaction between weather variables and group size: individuals across all group sizes experienced similar effects of conditions. I therefore conclude that 1) pied babblers will increasingly face challenges for population recovery and persistence in the near future as survival and reproduction are increasingly compromised by ever higher temperatures, and 2) a life history strategy that relies on the presence of helpers for successful breeding is unlikely to buffer individual group members against climatic variability and climate change in this cooperatively breeding species.

Predation is a widespread population process that has been shown to affect the distribution, abundance and dynamics of populations in ecosystems. This is the first study that used an experimental approach to assess the effect of nest predation on the population dynamics of the sociable weaver (Philetairus socius), a keystone species in the semi-arid savannas of the Kalahari and Namib regions. Snakes were excluded from five colonies for five breeding seasons and two colonies for three breeding seasons, with another eight colonies acting as the controls. Reproductive output, colony size, dispersal events and several environmental variables were measured between 2010 and 2015. This was done to determine (1) what effect nest predator exclusion had on reproductive output; (2) how this related to colony and population size trends by using a matrix-projection metapopulation model; (3) how protected colonies influence movement patterns; and (4) if nest predation had a compensatory or positive effect by reducing the intraspecific competition of a colony. The fourth aim was investigated by tracking the foraging paths of eight colonies of varying sizes, with foraging distance acting as a proxy for intraspecific competition. Colonies that were protected from snake predation produced, on average, more than double the number of fledglings per female per breeding season that were produced in unprotected colonies. However, the magnitude of this effect decreased with increasing colony size of protected colonies, most likely due to the negative effects that large colony sizes have on reproductive output. Increasing aridity was found to have a negative effect on reproductive output and warmer winter minimum temperatures were found to have a positive effect. My results suggested that protecting a subset of colonies in the metapopulation may be sufficient in preventing population declines under climate change conditions. The protected colonies played an important role in structuring and connecting the movement network of the metapopulation, whilst colony size explained the migration rates of colonies. However, predation was not found to have a compensatory effect in reducing the intraspecific competition (measured as foraging distance) of a colony. Instead, foraging distance was probably determined by the ability to thermoregulate under hot and humid conditions. To fully understand the effects of nest predation on sociable weaver population dynamics, future studies need to investigate the response of snake predators to sociable weaver behaviour and environmental conditions.

Bibliography: pages 144-153. / Biological extinction rates have escalated by as much as 1000 times the background extinction rate over the last 1500 years, causing concern over the long-term survival of many species. Avian extinctions since 1600 have been well documented relative to other taxa, as have current levels of avian threat. This study analyses avian extinctions post-1600 and current threats in an attempt to develop some predictive capacity about which avian taxa should be awarded the highest conservation priority. Analyses performed include examinations of the causes of avian extinction and threat, geographical location of extinct and threatened species, prehistoric and historical extinction rates, endemicity, migration, bird body size and phylogenetic diversity. An analysis dealing with historical and phylogenetic aspects of endangered and critically threatened species was performed, from which the world's most threatened species were identified. Factors which were the primary cause of historical extinctions are generally not the primary factors threatening today's extant avifauna. Whilst introduced predators and exploitation were primary causes of historical extinctions, habitat destruction poses the greatest threat to extant birds. Species predisposed to extinction typically have restricted ranges, and, compounded by habitat loss, these ranges are becoming more restricted. This has resulted in mainland-dwelling species becoming as prone to extinction as island-dwelling species have been historically. Introduced predators, however, do still threaten many of the world's most threatened species and their potential effects are highlighted in the phylogenetic analysis. Already, many extinctions may be inevitable over the next 25 years as a result of habitat loss. The magnitude of extinctions across all animal and plant species in the next few decades could be comparable with that of previous mass extinctions unless immediate conservation action is taken. However, future conservation efforts will have to be prioritized, and this study is intended as a contribution towards such a prioritization exercise.

Penguins are one of the largest consumers of marine resources in the Southern Ocean and spend most of their lives at sea. Although the last four decades have seen technological advancements that have considerably expanded our knowledge about their at-sea behaviour, there is still much to be learned. Given the rapid ongoing ecosystem changes in the Southern Ocean, it is vital to better understand, firstly, how penguins respond to environmental variability, and secondly, how such changes alter ecological relationships between sympatric species. Being flightless, travel is slower and more costly for penguins than flying seabirds. This constrains their ability to find resources, particularly during the breeding season when they must regularly return to the colony to provision offspring. As penguins are colonial nesters, high foraging pressure near the colony can limit available resources, enhancing potential intra- and interspecific competition. At many localities, ecologically similar penguin species breed sympatrically. In such cases, co-existence is only thought possible through ecological segregation in space, time and/or diet. At the Prince Edward Islands, approximately 302,000 pairs of macaroni Eudyptes chrysolophus and 80,000 pairs eastern rockhopper E. chrysocome filholi penguins breed sympatrically. These populations are closer to parity than at any other locations where two eudyptid species breed sympatrically. Populations of both species at the Prince Edward Islands have declined in the last two decades, but drivers of these declines are poorly understood. The primary aim of this thesis was to better understand the foraging strategies of macaroni and rockhopper penguins at the islands and identify aspects of their ecology that allow them to co-exist. The secondary focus was to investigate how each species responds to environmental variability and assess how ecological interactions between species might be altered in an era of rapid global change. To study the at-sea habitat use and diving behaviour of penguins during chick-rearing and pre-moult periods, I used GPS loggers and time-depth recorders. To track penguins during the winter I used geolocation loggers and satellite transmitters. Stable isotope analyses were used to investigate trophic ecology during late winter, summer and pre-moult periods. During the breeding season, both species primarily foraged in pelagic waters beyond the shelf break (> 3000 m), with macaroni penguins foraging slightly farther offshore on average. However, rockhopper penguins breeding adjacent to the inter-island shelf foraged in shallow waters (< 200 m) over the shelf. Both species dived to similar depths (40 to 60 m), but macaroni penguins dived deeper more often. The diet of both species was dominated by two krill species (Thysanoessa vicina and Euphausia vallentini). Diving behaviour varied between years, with both species diving deeper when the SAF was located farther away and geostrophic flow was reduced. During these conditions, macaroni penguins fed on a larger proportion of myctophids whereas rockhopper penguins resorted to less energy-dense nototheniids. This highlights contrasting responses to periods of low krill availability. During the pre-moult period, habitat preferences were similar between species, with penguins travelling up to 1000 km south to forage in Antarctic Zone waters (SST 3-4 °C). However, a three-week difference in departure dates minimised spatiotemporal overlap between species. Diving behaviour was similar between species, but macaroni penguins performed more deep dives and encountered thermoclines more often. Stable isotope analyses revealed that macaroni penguins fed on a greater proportion of fish than rockhopper penguins, and revealed species-specific spatial responses to changes in primary productivity, with macaroni penguins travelling farther south in less productive years. During the 6-month long winter sojourn, macaroni penguins generally foraged in cooler waters (SST ~ 3 °C) compared to rockhopper penguins (5-6 °C). However, stable isotope analyses revealed that trophic and spatial overlap were high during late winter. Both species associated with mesoscale eddies and submesoscale filaments, suggesting that these features play an important role in aggregating prey during the resource-limited winter months. In summary, it appears that subtle differences exist to minimise competitive overlap between macaroni and rockhopper penguins. The three-week difference in the onset of breeding is integral to minimising competitive overlap during late winter, brood-guard/crèche, pre-moult and immediately following the moult. This allochrony staggers the peak energy demands of rockhopper penguins to reduce overlap with macaroni penguins. The larger-bodied macaroni penguins are capable of diving deeper, for longer and more efficiently than rockhopper penguins, which increases their behavioural flexibility and fitness by minimising stresses associated with reduced krill availability. Such differences in diving behaviour may explain contrasting population trends at the islands and suggests that rockhopper penguins may continue to decline at a faster rate than macaroni penguins if ongoing climate change continues to reduce prey availability around the Prince Edward Islands.

Bibliography: pages 192-208. / Patterns of distribution and diversity for African waterbirds are investigated at the continental, sub-continental, ecosystem and species levels. The focal species is the Great White Pelican Pelecanus onocrotalus, one of South Africa's 'Red Data' bird species. The 'focal' ecosystem is Rondevlei Bird Sanctuary (34°'04'S, 18°30'E), one of the few conserved areas in Africa set aside especially for waterbirds. Biogeographically, waterbirds partition Africa much more coarsely (into 8 vs 18 avifaunal zones) than do non-aquatic birds. Waterbird species diversity (number of species) and endemism are higher outside the tropics, and exhibit longitudinal gradients, with higher diversity in the east. Non-aquatic bird diversity is higher in the tropics and varies latitudinally. Spatia-temporal variation in habitat availability and quality are the primary factors which control waterbird distribution, and the dynamic nature of waterbird dispersion is an adaptation to dramatically fluctuating habitats. About 69% o£ the variance in African waterbird species diversity can be explained in terms of present-day environmental variation. Part of the unexplained variance is attributed to the effects of historical factors, with areas of unexpectedly high species possibly acting as refugia during dry climatic phases.

African Penguins (Spheniscus demersus) have undergone a dramatic decrease in their population since the turn of this century prompting the up-grading of their conservation status to 'endangered'. There is growing evidence that variation in the availability of their principle prey, pelagic shoaling fish, are driving this trend. This prey variability is driven by oceanographic factors as well as commercial purse-seine fishing operations. To isolate the direct impacts of fishing on the foraging performance of African Penguins, the primary oceanographic drivers of fish distribution and abundance were investigated by conducting fine-scale pelagic fish surveys around two of the largest breeding colonies of African Penguins in Algoa Bay, St Croix and Bird islands, between 2011 and 2014. Quantification of fish parameters were facilitated by a novel method using a recreational fishfinder and calibrating this instrument to a conventional scientific device. The specific types of fish assemblages selected for by African Penguins were then evaluated by looking at the correspondence in associations of fish and penguins recorded at sea using both counts and locations of foraging birds tracked simultaneously during a subset of fish surveys. Activity budgets of penguins calculated from these simultaneous deployments were modelled against the abundance of their prey to elucidate hypothesised functional relationships. Finally, the direct influence of purse-seine fishing on both targeted fish assemblages and penguin activity budgets were assessed by modelling interactions between known physical drivers of targeted fish assemblages and different levels of cumulative catches. Physical drivers of the three-dimensional distribution and abundance of fish varied between colonies with primary production playing the most important role around Bird Island but having little influence on fish around St Croix Island where factors associated with surface and sea-profile temperatures had a stronger influence. Results of both penguin count and track data highlight the importance of the vertical distribution of prey to the distribution of foraging African Penguins with the abundance of these assemblages having a significant influence on this species' activity budgets. Evidence for local depletion of pelagic fish was demonstrated for the waters around St Croix Island and the effects of purse-seine fishing on African Penguin foraging effort were significant when controlling for natural drivers of prey distribution. Results of this research should be applied to current conservation measures, most notably alleviating direct competition by purse-seine fishing operations during periods of reduced primary productivity and when the abundance of targeted fish aggregations are significantly diminished three months prior to and during the onset of the African Penguin breeding season.

Includes abstract. / Large terrestrial bird species, especially cranes and bustards, have adapted to low intensity agriculture to varying degrees, but large-scale industrial agriculture is in general inimical to these species. Cranes are charismatic and well studied, but bustards are retiring and in general cryptically coloured, and little is known of most species. Of South Africa's 10 bustard species, two are endemic and three subspecies are endemic or near-endemic. Six species are threatened or near-threatened. Three crane species occur in South Africa, one of which is near-endemic; all are threatened. This thesis used data from two long-term public participation bird monitoring projects to improve our understanding of six of these 13 species. The first and second Southern African Bird Atlas Projects (SABAP1, 1987-1992, and SABAP2, 2007-) provide two sets of presence/absence data which can be compared. The Coordinated Avifaunal Roadcounts (CAR; 1993-) project provides roadcount data spanning a similar period.

Includes bibliographical references / Sociality and cooperation are universal features of life, yet cooperative societies are highly vulnerable to conflicts-of-interests which may lead to societal collapse. Dominance may function as a central mechanism behind the maintenance of cooperative societies, because it may reduce conflict by the establishment of hierarchies, and may act in concert with kin selection, enforcement or signalling mechanisms to promote cooperation. Yet, the significance of dominance in the evolutionary routes that maintain cooperation remains poorly understood (Chapter 1). Sociable weavers Philetairus socius are highly social, cooperative passerines. The species is particularly prone to conflicts because of their year-round coloniality and thus year round sharing of resources. Using extensive field-data on individual behaviour, I examine in this thesis whether dominance may mitigate conflict and maintain cooperation, and how it may inform our understanding of the evolutionary mechanisms underlying cooperation. In Chapter2, I investigate whether hierarchies and phenotypic traits allowing the assessment of social status may have evolved to mediate conflicts. I show that weavers establish ordered hierarchies within colonies and that the size of a melanin-based plumage trait, the black bib, is correlated to social status. In Chapter 3, experimental manipulation supports my proposition of a status signalling function of the bib. In Chapter 4, I investigate the benefits of achieving high social status and whether these are shared with relatives through nepotism. Both dominants and their offspring gain enhanced access to resources. Dominants had more access to breeding positions, although this was not reflected by increased reproductive success. In Chapter 5, I explore how dominance and kinship predict individual cooperativeness to three tasks, nestling provisioning, nest construction and predator mobbing. I find that both explain variation in cooperativeness, yet some results follow opposite directions, revealing multiple routes to cooperation. Finally, in Chapter 6, I examine how dominance and kinship structure weavers' social network and whether network position are linked to cooperativeness. Social network analyses reveal that more central birds are more, related, dominant and cooperative. Chapter 7 concludes that dominance acts in concert with kinship to promote the societal lifestyle of sociable weavers highlighting the potential significance of dominance in the evolution of cooperation.

Agricultural transformation generally has a negative impact on biodiversity. Owing to landscape fragmentation and reduced prey availability, predators that inhabit transformed areas are usually forced to increase hunting effort or diversify their diet and this can have negative consequences for fitness or demographic parameters. Agricultural landscapes are therefore rarely considered important in the conservation of top predators. The Verreaux's eagle Aquila verreauxii has experienced loss of natural habitat due to agricultural transformation through much of its range. Despite the conspicuous nature and widespread distribution of Verreaux's eagles in sub- Saharan Africa, there is a paucity of information on the mechanism behind the recently observed population declines of this species, which have resulted in the recent re-classification as "Vulnerable" (from "Least Concern") in South Africa. This thesis aims to explore how land transformation influences changes in several key ecological components and demographic parameters, namely breeding performance, diet and movement ecology. In this thesis, I study two geographically adjacent populations of Verreaux's eagles; one located in a natural area (Cederberg) and one in an agriculturally transformed area (Sandveld), in the Western Cape Province, South Africa, from 2011-2014. I investigate the breeding performance of the two populations. In contrast to what was anticipated I found that breeding productivity was 2.7 times greater in the agricultural than in the natural area. Population modelling suggested that in isolation the Cederberg population is unlikely to be self-sustaining, whereas the eagles breeding in the Sandveld region are likely to be acting as a source population. However, I did not have any information about juvenile or adult survival in either area. Contrasting survival rates could distort these results and are in need of further research. Verreaux's eagles are generally regarded as dietary specialists. I therefore investigated the diet composition of eagles in the two study areas as a proxy to better understand prey availability and to look for evidence of behavioural flexibility to different availability of prey resources. The relationship between diet breadth and breeding performance was explored locally and regionally using data from previous studies. Eagles in the Sandveld were found to have a more diverse diet than eagles in the Cederberg, which rely on their traditional prey, rock hyrax Procavia capensis. Theory on specialist predators assumes that diet diversification will cause reduced breeding performance. In particular, individuals within a species with more diverse diets due to reduced availability of primary prey species can display reduced breeding performance. In direct contrast to this, eagles with broad diet did not exhibit trends for reduced breeding performance, both locally and across southern Africa.