Rozprawy doktorskie na temat „White-backed”

In Sweden, intense human land use, especially forestry, has led to profound changes in the landscape over time, especially within the forest ecosystems. A consequence of this is that several specialist species have become endangered. One group of specialists is the woodpeckers. The middle spotted woodpecker became extinct in Sweden in 1982 and the white-backed woodpecker is today Sweden’s most critically endangered forest-living bird. The white-backed woodpecker is dependent on old deciduous forests, rich in dead wood. The woodpecker is areademanding and hence one of the best indicators or umbrella species for biodiversity in this region. A long-term goal within the conservation of the species is to be able to make more accurate predictions of what is needed in the species habitat to establish a viable population, both in terms of composition of landscape and breeding territories. In addition to earlier studies better tools are needed for measuring the distribution of suitable and potential habitats and finding faster ways of creating optimal habitats. In an attempt to secure the future existence of the white-backed woodpecker in Sweden, restocking of birds are carried out. This presupposes availability of suitable habitats as well as strong enough landscape. Due to intense forestry the presumption for the species is, as stated above, alarming. Comparing the different populations around the Baltic Sea and Norway, great differences but also similarities can be seen, in landscape as well as in territory composition. It seems that fragmentation of foraging patches as well as amount of dead deciduous wood within the breeding territory is critical matters. Grey alder stands in Sweden should have high priority in conservation of habitat for the species.

Funding agency: Swedish Society for Nature Conservation (SSNC)

African White-backed Vultures have recently been uplisted to Critically Endangered by the IUCN due to declines across their range mainly linked to high levels of poisoning. Botswana likely supports significant numbers of this species, but as yet there is no published information on their population trends or their breeding success in this country. However, in recent years within Botswana and neighbouring countries there have been multiple incidents of mass poisonings, which have resulted in the deaths of thousands of White-backed Vultures. I therefore expected that nesting numbers of this species may have declined in this region, with potential additional negative impacts to breeding success. I used information from aerial surveys conducted between 2006 and 2017 in Khwai and Linyanti, two of the most important breeding areas for this species in northern Botswana to examine changes in nesting numbers and breeding success. The results showed a 53.5% decline in nesting numbers from these colonies, from 99 pairs in 2007 to 46 in 2017; with a greater decline in Linyanti than in Khwai. In both areas breeding success was significantly lower in 2017 than it was ten years ago. Current breeding success rates were generally lower than for other populations in South Africa. A population viability analysis suggested that if the productivity levels detected in 2017 were a true indication of current levels of productivity for this population, and if recent poisoning rates continue, this population has a high probability of extinction in the next 5 to 13 years.

Saving the white-backed woodpecker (Dendrocopos leucotos) from extinction in Sweden has been an ongoing struggle for decades. Despite this, there have been remarkably few studies on the species ecology in Sweden, especially in the north. The aim of this study was to investigate if the white-backed woodpeckers living in the Umeå region show a preference regarding what kind of trees they use for foraging, based on the factors tree species, tree condition (dead/alive), and tree size. Data were gathered at three sites in the vicinity of the lower Umeå River region and was made up of holes left by the woodpeckers from excavating trees for food. By comparing the trees carrying these traces with a representative sample of remaining trees at the sites, a test for preference could be performed. The results from this study indicate that the local white-backed woodpeckers strongly favour trees of the Salix genus when deep-boring, and that they also have a preference for dead trees independent of species. No significant effect of tree size on foraging choice could be found, although this would ideally require further studies. These findings provide knowledge on the local behaviour of the white-backed woodpecker that could potentially be of importance for implementing precise conservation efforts for this area-demanding species.

The Australian magpie (Gymnorhina tibicen) is a large, sedentary, omnivorous passerine. In some populations, individuals live in groups, and some of these groups breed cooperatively. The white-backed magpie (G. t. tyrannica) from the south-eastern corner of the continent, has had relatively little study, and few details are known of its mating system, social structure, and method of parental care. I conducted an observational study on a population of white-backed magpies, recording details of their demography, dispersal, breeding system, and parental care. In conjunction, I conducted a genetic analysis of the population, to determine if the genetic mating system matched the observed social system, to detect instances of extra-group mating, and to sex juvenile birds. Extra-pair paternity (EPP) is a common feature of the mating systems of many birds. The rate of EPP may vary between species, races and populations. I made a comparison of extra-group paternity (EGP) rates between two races of the Australian magpie, to determine if similar mating systems were being employed. The two populations had similar social structure, but differed in group size and dispersal. I predicted that dispersal differences would have a profound effect on the rate of EGP between the populations, as the population with the lower rate of dispersal and higher chance of breeding with a close relative would engage in EGPs more frequently. Eight microsatellite loci were used to determine parentage in the white-backed Australian magpie. The rate of EGP was found to be 44%. Dispersal rates were estimated from observational data. Over half of the juvenile magpie cohort from the previous breeding season leave the territorial group. These results contrast sharply with the results found by other researchers in a population of western Australian magpies (G t. dorsalis). In this population, 82% EGP is recorded and dispersal of juveniles is close to nil. The results indicate that dispersal rate is a potentially important predictor of rates of extra-group fertilisations between populations of this species, and suggest that females maximise their reproductive output by avoiding breeding with close kin. The reproductive success of a male bird is often correlated with measurable traits that predict his intrinsic quality. Females are thought to select mates based on their quality to gain their 'good genes'. Male Australian magpies of the white-backed race were trapped in two breeding seasons. Measurements were taken of morphometric and other characteristics in order to discover whether particular traits of males were associated with: a) number of fledglings produced in the territory per season; b) percentage of offspring sired in the territory; and c) whether females select males for their 'good genes'. The only variable that was correlated with number of territorial offspring was feather lice load. Males with high numbers of lice were less likely to produce territorial fledglings in one season and across both seasons. Males of inferior quality may be subject to increased conspecific territorial intrusions, leading to more time spent on defence, more failed breeding attempts, less time allocated to grooming and thus high parasite loads. Males that produced many territorial fledglings were more likely to gain genetic paternity of at least some of them, although again this was significant for only one season. Also, across both seasons, a high number of females in the group was correlated with increased paternity within the group. The general lack of correlation between the variables and level of genetic paternity may be due to females engaging in extra-group mating primarily to avoid breeding with a close relative rather than to choose a quality male. In this scenario, males would not have to be 'high quality', but merely genetically different to the female's social mate. Extra-group paternity (EGP) can affect paternal effort. It may also influence the helping effort of auxiliary birds in cooperatively breeding species. If helping is driven by kin selection, helpers should decline to provision unrelated young. Relatedness becomes difficult to assess however, when females mate outside the group. Alternative rewards may then become important in helper decisions. In my study population of Australian magpies, 38% of fledglings were sired by males outside the territorial group. In a second population (G. t. dorsalis), 82% of fledglings were sired by extra-group males. I observed within-group male and helper feeding effort over three breeding seasons in the first population and obtained data recorded over a single season in the second population. In both populations, males provisioned young regardless of relatedness, as did helpers. Males provisioned less than the nesting female on average. Paternal effort did not reduce with an increase in the rate of EGP between populations. In the population with intermediate levels of EGP, the white-backed magpies, I observed helpers in about half of the sampled territories that produced fledglings. Helpers did not increase the production of young. In the population with high levels of EGP, western magpies, I detected helping behaviour in proportionally more territories. It appears that Australian magpie helpers provide help in order to pay 'rent' and remain on the natal territory. I discuss these results in light of the differences between the two races of magpie and the major theories regarding male parenting decisions and helper activity. Finally, I examine the relatively high rates of EGP's in the Australian magpie from a phylogenetic perspective. Although inbreeding avoidance is strongly supported by this study as the major reason EGP is so common in magpie populations, there may be an element of phylogenetic inertia that maintains the frequency of this behavioural trait. I comment upon the use of single-population estimates of species EGP rates in comparative analyses, given the intraspecific variation discovered between Australian magpie populations. Future directions for the study of mate choice in the Australian magpie are outlined with a proposal to study variation at the major histocompatibility complex between mated pairs.

The Australian magpie (Gymnorhina tibicen) is a large, sedentary, omnivorous passerine. In some populations, individuals live in groups, and some of these groups breed cooperatively. The white-backed magpie (G. t. tyrannica) from the south-eastern corner of the continent, has had relatively little study, and few details are known of its mating system, social structure, and method of parental care. I conducted an observational study on a population of white-backed magpies, recording details of their demography, dispersal, breeding system, and parental care. In conjunction, I conducted a genetic analysis of the population, to determine if the genetic mating system matched the observed social system, to detect instances of extra-group mating, and to sex juvenile birds. Extra-pair paternity (EPP) is a common feature of the mating systems of many birds. The rate of EPP may vary between species, races and populations. I made a comparison of extra-group paternity (EGP) rates between two races of the Australian magpie, to determine if similar mating systems were being employed. The two populations had similar social structure, but differed in group size and dispersal. I predicted that dispersal differences would have a profound effect on the rate of EGP between the populations, as the population with the lower rate of dispersal and higher chance of breeding with a close relative would engage in EGPs more frequently. Eight microsatellite loci were used to determine parentage in the white-backed Australian magpie. The rate of EGP was found to be 44%. Dispersal rates were estimated from observational data. Over half of the juvenile magpie cohort from the previous breeding season leave the territorial group. These results contrast sharply with the results found by other researchers in a population of western Australian magpies (G t. dorsalis). In this population, 82% EGP is recorded and dispersal of juveniles is close to nil. The results indicate that dispersal rate is a potentially important predictor of rates of extra-group fertilisations between populations of this species, and suggest that females maximise their reproductive output by avoiding breeding with close kin. The reproductive success of a male bird is often correlated with measurable traits that predict his intrinsic quality. Females are thought to select mates based on their quality to gain their 'good genes'. Male Australian magpies of the white-backed race were trapped in two breeding seasons. Measurements were taken of morphometric and other characteristics in order to discover whether particular traits of males were associated with: a) number of fledglings produced in the territory per season; b) percentage of offspring sired in the territory; and c) whether females select males for their 'good genes'. The only variable that was correlated with number of territorial offspring was feather lice load. Males with high numbers of lice were less likely to produce territorial fledglings in one season and across both seasons. Males of inferior quality may be subject to increased conspecific territorial intrusions, leading to more time spent on defence, more failed breeding attempts, less time allocated to grooming and thus high parasite loads. Males that produced many territorial fledglings were more likely to gain genetic paternity of at least some of them, although again this was significant for only one season. Also, across both seasons, a high number of females in the group was correlated with increased paternity within the group. The general lack of correlation between the variables and level of genetic paternity may be due to females engaging in extra-group mating primarily to avoid breeding with a close relative rather than to choose a quality male. In this scenario, males would not have to be 'high quality', but merely genetically different to the female's social mate. Extra-group paternity (EGP) can affect paternal effort. It may also influence the helping effort of auxiliary birds in cooperatively breeding species. If helping is driven by kin selection, helpers should decline to provision unrelated young. Relatedness becomes difficult to assess however, when females mate outside the group. Alternative rewards may then become important in helper decisions. In my study population of Australian magpies, 38% of fledglings were sired by males outside the territorial group. In a second population (G. t. dorsalis), 82% of fledglings were sired by extra-group males. I observed within-group male and helper feeding effort over three breeding seasons in the first population and obtained data recorded over a single season in the second population. In both populations, males provisioned young regardless of relatedness, as did helpers. Males provisioned less than the nesting female on average. Paternal effort did not reduce with an increase in the rate of EGP between populations. In the population with intermediate levels of EGP, the white-backed magpies, I observed helpers in about half of the sampled territories that produced fledglings. Helpers did not increase the production of young. In the population with high levels of EGP, western magpies, I detected helping behaviour in proportionally more territories. It appears that Australian magpie helpers provide help in order to pay 'rent' and remain on the natal territory. I discuss these results in light of the differences between the two races of magpie and the major theories regarding male parenting decisions and helper activity. Finally, I examine the relatively high rates of EGP's in the Australian magpie from a phylogenetic perspective. Although inbreeding avoidance is strongly supported by this study as the major reason EGP is so common in magpie populations, there may be an element of phylogenetic inertia that maintains the frequency of this behavioural trait. I comment upon the use of single-population estimates of species EGP rates in comparative analyses, given the intraspecific variation discovered between Australian magpie populations. Future directions for the study of mate choice in the Australian magpie are outlined with a proposal to study variation at the major histocompatibility complex between mated pairs.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Australian School of Environmental Studies
Full Text

Due to heavily managed forests in Sweden, there has been a rapid decline of deadwood and deciduous-rich areas since the 1950s. As a result of this, 2000 forest species are now red-listed of which 700 is in heavy need of deadwood. The white-backed woodpecker Dendrocopos leucotos, an umbrella species whose food choice consists of insects living in dead and decaying wood, has become critically endangered due to the lack of food and nesting areas. Preservation actions aimed towards saving the white-backed woodpecker are not only essential for itself but for 200 other species dependent on the same environmental requirements. The purpose of this study was to determine if the restoration for deciduous trees has favoured the white-backed woodpecker in four different areas: Ängsbacka, Degersjön, Ålidberget, and Kvillträsk in Västerbotten. By placing two different kinds of insect traps (window traps, and malaise traps) to analyze the different insects in restoration areas compared with control areas, I could investigate if there had been an increase in the number of insects preferred by the white-backed woodpecker. I could also investigate if there was a higher diversity of these preferred insects. There was no sign of an increase in numbers of preferred insects nor in numbers of preferred species. A higher diversity could neither be proven, however all four forests were deciduous-rich with high amount of dead-wood and has proven to show good potential for a future increase in saproxylic insects if restoration continues.

As obligate scavengers Gyps vultures provide an important ecosystem service as the main consumers of ungulate carcasses in African savannas. Throughout the continent, however, multiple threats are causing vulture populations to decline, especially outside protected areas. Although the African white-backed vulture Gyps africanus is the most numerous and widely distributed Gyps species in Africa, its foraging ecology and land use preferences remain poorly understood. Furthermore, while protected areas are known to be important for vultures in East and West Africa, their role in South Africa has not been fully investigated. This study uses GPS-GSM tracking units to investigate the movement and land-use patterns of six immature African white-backed vultures that were caught at Mankwe Wildlife Reserve in the North West Province of South Africa. Immature individuals were chosen because they were expected to travel extensively and be exposed to the full range of threats. The tracking units recorded the GPS location, speed, altitude and direction of travel three times per day. The size and extent of the vultures‟ foraging ranges were estimated using three methods: minimum convex polygons (MCPs), fixed kernel density estimation (KDE) and grid cell range (GCR) estimation. The vultures‟ use of protected areas and areas of different cattle densities (zero, low, medium and high) was assessed to determine whether they were visited more or less than expected based on the area they occupied within the vultures‟ foraging ranges. The distances travelled by the vultures and their flight speeds and altitudes were also calculated, as well as the amount of time that they spent in the vicinity of supplementary feeding sites. The vultures were tracked for between 101 and 313 days and the GPS tracking units acquired 99.44% of expected GPS locations. The vultures ranged extensively and generally travelled in a nomadic manner. While three individuals occupied foraging ranges (mean 95% KDE contour area = 106,282.33 km2) either side of the South African borders between Botswana and Zimbabwe, the other three travelled more extensively through southern Africa, entering six different countries (mean 95% KDE contour area = 563,564.67 km2). The vultures rarely visited protected areas in South Africa but two of the vultures regularly used protected areas in northern Botswana and Zimbabwe. Areas of high cattle density were used less than expected by all vultures, but not at a significant level, while two of the vultures used areas with zero cattle density more than expected due to their regular use of supplementary feeding sites in those areas. Areas of medium cattle density were the most regularly used, containing an average of 30.72% of each vulture‟s stationary GPS locations. The vultures travelled an average of 33 km/day and a maximum of 267 km/day, flying at an average of 50 km/h (maximum = 107 km/h) at 561 m above ground level (maximum = 2,267 m). This study provides the first description of movement and land-use patterns of immature African white-backed vultures tracked continuously from South Africa. Their extensive foraging ranges and limited use of protected areas implies that the vultures could potentially encounter the full range of threats in the region, and it is clear that their future conservation will depend upon conservation strategies that extend across international borders. Copyright
Dissertation (MSc)--University of Pretoria, 2011.
Paraclinical Sciences
unrestricted

Studien har använt ny metod för att klassificera vitryggig hackspetts skogarförutsättningar för häckande revir. 287 hektar skog värdeklassades med minstav värdeklass 1 (42 ha) och mest av värdeklass 2 (195 ha). Död ved måste ökaför att populationen av vitryggig hackspett ska öka. De åtgärder som behövergöras är ringbarkning och att minska granvolymen för att värdeklasserna ska nånästa värdeklass. Resultatet tyder på att förutsättningarna för häckningsrevir ärgoda, dock måste vissa restaureringar göras för att vitryggig hackspett skaetablera sig i området.

Den vitryggiga hackspetten har sedan 1970 varit en starkt hotad art i Sverige tack vare förändrade habitat till följd av ett industrialiserat skogsbruk med stor fokus på barrträd vilket inte är ett optimalträd för den vitryggiga hackspetten. Idag finns det cirka 3 häckande par kvar i Sverige. I Finland och Lettland uppvisar den vitryggiga hackspetten en stark närvaro med en stor population då skogsbruket i dessa länder skiljer sig markant mot Sverige i form av typ av träd och hantering av död ved. Syftet med studien som utförts i den här rapporten är att bedöma om ett område vid sjön Erkens norra strand kallat Hasselhorn i Stockholms län uppnår de riktlinjer Naturvårdsverket har satt på minst 20m3/ha död lövved i trakten samt en medelålder på >80 år för att ett område ska anses vara ett optimalområde för den vitryggiga hackspetten. Fokustrakten identifierades med IR-bilder för att avgöra om området var rikt på lövträd och ett område på 110ha ritades in. Sextio stickprov slumpades ut i området där levande och döda träd mättes in med klave och höjdmätare för att beräkna m3/ha och ålder bedömdes visuellt för varje mätområde. Studien påvisar att Hasselhorn idag inte uppnår optimal status för alla parametrar som satts upp av Naturvårdsverket för att det ska utgöra ett lämpligt habitat för den vitryggiga hackspetten. Däremot uppnår området kravet på mer än 20m3/ha och mer än 75 % lövträd satta av Naturvårdsverket. Området uppnår dock inte medelåldern >80 år. Även artfördelningen i regionen av levande träd visar på mycket lite barrträd och stor tillgång på asp som anses vara det främsta trädet för födosök för den vitryggiga hackspetten som visar på att Hasselhorn kan uppnå god status inom ett fåtal år om särskilda naturvårdsåtgärder sker i området.
The white-backed woodpecker has been a highly threatened in Sweden since 1970 due to drastically changed habitats as a result from industrialized forestry methods with a high focus on conifers. Today there are only 2 known breeding pairs left at Dalälven in Sweden. Compared to Finland and Latvia the white-backed woodpecker exhibits a strong presence with large populations as the forestry industry in these countries differs from Sweden in terms of what type of trees they use and how they manage dead wood. The purpose of this study is to assess whether an area at lake Erken’s northern shore called Hasselhorn in Stockholm County achieves the guidelines determined by Naturvårdsverket. Naturvårdsverket has determined that the white-backed woodpecker at least need 20m3/ha dead deciduous trees in a habitat and an average age of >80 years to be considered as an optimal area for the white-backed woodpecker. The focus area was localized with IR-images to determine an area rich with deciduous trees and an area of 100ha was drafted. Sixty sample points were randomized in the area. All living and dead trees at each points were measured with a tree caliper and clinometer to determine the amount of wood in m3/ha. Age was determined visually for each sample point. The study showed that Hasselhorn currently does no achieve the optimal status for all parameters in the study to make it a suitable habitat for the white-backed woodpecker. On the other hand, the area does meet the guideline set by Naturvårdsverket of more than 20m3/ha dead deciduous wood and more than 75% deciduous trees in the area, however it does not show an average age of >80 years. Species distribution of living deciduous trees exhibits large volumes of aspen, which is considered to be a main source of food since they contain the type of bugs preferred by the white-backed woodpecker. With the right conservation methods, the study shows that Hasselhorn can become a viable habitat for the white-backed woodpecker in the near future.

Nature conservation is often seen as being primarily about shielding parts of nature from human intervention, e.g. by protecting areas. Over the last decades, however, intervention is increasingly being seen as necessary for nature to regain or retain its values, through ecological restoration and active management. This complicates simple assumptions that ‘nature knows best’ and raises dilemmas which are hotly debated in the scholarly literature around ecological restoration, protected area management, environmental ethics and green political theory. However, how these dilemmas are dealt with in actual policy struggles among the conservation professionals who make management decisions is less studied. This thesis explores how issues regarding active intervention in nature are represented, debated and institutionalized within Swedish nature conservation, and to what effect. The empirical focus lies on policy struggles around the designation and management of protected forests and around efforts to save a nationally threatened bird species, the white-backed woodpecker. My analytical framework is informed by Argumentative Discourse Analysis and Political Discourse Theory, to which I contribute a further elaboration of the notion of discourse institutionalization. Based on documents and interviews with conservation professionals, I identify competing articulations of the ends and means of conservation and relate these to scholarly debates around ecological restoration and interventionist conservation management. The analysis further focuses on how elements of the different policy discourses are institutionalized in rules, routines or official policy documents. Two main competing policy discourses are found: one focused on leaving pristine nature to develop freely, and one focused on active, adaptive management for biodiversity. While the former has previously been said to characterize the Swedish conservation bureaucracy, my analysis shows it is now widely seen as outdated. Arguments which in the scholarly literature are associated with an ethically informed defense of nature’s autonomy are here dismissed as emotional, aesthetic and thus unscientific concerns, delegitimizing them within the rational, science-based public administration for nature conservation. In contrast, biodiversity is broadly forwarded as a self-evident goal for active intervention, in line with both science and policy requirements. Adaptive management for biodiversity is in that sense the dominant discourse. Still, the older discourse is institutionalized in the purposes and management plans of existing nature reserves, and its defenders have also succeeded in strengthening that institutionalization through new and more restrictive guidelines. The findings suggest that this has been possible not only because of the gate-keeping role of a few centrally placed actors, but also because their restrictive stance resonates with the outside threat of exploitation which organizes the common order of discourse. Naturalness, a term described as irrelevant by some proponents of adaptive management for biodiversity, is also shown to remain a shared concern in several ways. The results thus highlight the importance of both entrenched common sense and institutionalization of certain logics or arguments in authoritative documents. The main theoretical contribution of the thesis consists in clarifying the effects of such discourse institutionalization — using the terms durability, legibility and leverage — and showing how the processes of negotiation, re-interpretation and modification of institutions are more dynamic than some accounts of discourse institutionalization suggest. Rather than trying to resolve (and thus remove) the dilemma of intervention, the thesis points to the importance of keeping open discussion of the ultimately unanswerable questions about intervention in nature alive in both theory and practice.
Ecosystem restoration in policy and practice: restore, develop, adapt (RESTORE)

Thermoregulatory patterns, the use of rest-phase heterothermy, the energetic significance of clustering behaviour, and the role of sunning behaviour in thermoregulation were assessed in the white-backed mousebird Colius colius, an southern African arid zone species. I hypothesised that C. colius makes significant rest-phase energy savings by means of clustering behaviour, and has the ability to reduce diurnal energy costs by utilising solar radiation. I tested these hypotheses using indirect calorimetry and surgically implanted temperature-sensitive telemeters, and by simulating solar radiation in a constant-environment chamber. Rest-phase body temperature (T[b]s) was highly labile, with rest-phase T[b]s of down to 26 °C being recorded. During the rest-phase, T[b] was not regulated with respect to a setpoint temperature, as typically occurs in endotherms. Rather, rest-phase T[b] patterns were characterised by periods of linear decreases (passive cooling) at a rate dependent on ambient temperature and the number of individuals in a group. I did not observe any instances of torpor, as described in the literature. When T[b] depression did occur, it appeared to be the result of passive heat loss, and not the metabolic down-regulation which typically precedes a torpor bout. These findings, together with the phylogenetic position of the Coliidae, raise questions regarding the evolution of torpor. The inability of individual mousebirds to maintain a rest-phase setpoint T[b] suggests that in C. colius the physiological mechanism responsible for the defence of a rest-phase setpoint T[b] is replaced by a behavioural mechanism, namely clustering behaviour. The birds in this study showed a basal metabolic rate 40% below the predicted allometric values, and a circadian amplitude of body temperature (T[b]) of 5.2°C, 195% of the predicted value. The use of linear independent contrasts revealed that these deviations from the expected allometric values are not due to the phylogenetic relationships of the Coliiformes, and hence are likely to represent adaptation. These conservative metabolic traits offer opportunities for significant energy savings and are presumed to be adaptive in the unpredictable habitat of this species. The birds were able to make significant energy savings by means of huddling behaviour. At an ambient temperature of 15°C, the energy expenditure of birds in a group of six was 50% of that of single birds. The energy savings the birds were able to make were dependent on ambient temperature and the number of birds in the group. The ability to lower energy requirements by means of huddling behaviour is likely to be highly adaptive when dealing with low nocturnal temperatures in an environment where food supplies are spatially and temporally unpredictable. When allowed access to simulated solar radiation, individual mousebirds showed 15 - 30% reductions in their energy expenditure, while maintaining a constant body temperature. These reductions in energy expenditure hence represent thermoregulatory savings. My results support the hypothesis that solar radiation may be important in the energy budgets of some bird species. The ability to reduce food requirements by means of absorbing solar radiation is likely to be strongly selected for in the arid areas inhabited by C. colius, which are characterised by large circadian fluctuations in ambient temperature, in addition to resource unpredictability. Thermoregulation in C. colius appears to involve an interaction of behavioural patterns and physiological traits.
Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1998.

碩士
國立臺灣大學
國際企業學研究所
92
The benefits of credit card receivables-backed securities include less legal constraints and simpler cash flow than other kinds of MBS; therefore, they’re easier to issue. For financial institutions, credit card ABS can reduce the costs of raising funds and improve the financial structures. For investors, they also can increase the outlets for investments and have tax saving effects. Besides, many banking institutions urge consumer finance in recent years, and how to handle the increasing receivables will become a serious problem in the future. At the first of my essay, I give a brief introduction of credit card ABS, including the issuing process, participants, comparison of special purpose vehicles, types of amortization structures, and sources of risks. Since having separated the amortization structures into slow pay, rapid pay, controlled- amortization, and bullet-payment structures, we can see each representative formula for cash flow. Then, I concisely explain the Hull-White Interest Rate Model and the Dharan Forward Induction in order to use them calculate the price of securities. According to the preset data, we can conduct to some meaningful results through sensitivity analysis. Prices will be affected no matter under the variables that belong to credit card ABS or the interest rate model. Finally, wish this research can do some favor for credit card ABS in our country.

碩士
國立高雄第一科技大學
金融營運系碩士班
89
The effect of a valuation of mortgage-backed security includes the uncertainly of the risk of default and prepayment. Previous researches on the valuation of mortgage-backed securities, have been focused on the one-factor security valuation framework, that the borrower will prepay when the mortgage’s coupon rate exceeds refinancing rate. This article provides two-factor security valuation framework, considering the fluctuation of interest rate（Hull-White）and mortgaged house values. The two factors are interest and mortgaged house values. Assuming that interest rate follows Hull and White model and the mortgaged house values follows lognormal model. We use the method of valuation procedures that Hilliard, Kau, and Slawson（1998）jointly developed and the equations of forward induction that Dharan（1991）introduced to value MBS in lattice. Finally, we summarize our valuation results as follow： 1.The higher the house values volatility emerges, the lower the value of MBS appears. 2.The higher the interest rate volatility emerges, the higher the value of MBS appears. 3.The higher the mean-reverting parameter emerges, the higher the value of MBS appears. 4.The larger the speed-of-prepayment parameter emerges, the lower the value of MBS appears.

A dissertation submitted to the Faculty of Science, University of Witwatersrand, in fulfilment of the requirements for the degree of Master of Science Johannesburg, South Africa March 2016
This study examined the movements of white-backed (Gyps africanus) and Cape vultures (G. coprotheres) to assess their habitat preferences, measure seasonal changes in foraging behaviour, and examine where vultures are at risk of electrocution by and collision with power lines. White-backed and Cape vultures are two Old World vulture species found in southern Africa. They are listed as Critically Endangered and Endangered respectively, with massive population declines over the past three decades. These declines are due to poisoning, habitat loss, lack of food, use in traditional medicine, and electrical infrastructure mortality. Vultures provide key ecosystem services such as reducing disease transmission, cycling nutrients, and attracting tourists and therefore, a loss of vultures could cost the continent millions of US dollars. Thirteen vultures (five white-backed and eight Cape vultures) were tracked using either DUCK-4A or BUBO-4A GPS-GSM trackers (Ecotone Telemetry, Sopot, Poland). Birds were tracked between April 2013 and October 2014. These data were used to examine the habitat suitability of both species using MaxEnt habitat suitability modelling. Key drivers of country-wide habitat suitability for white-backed vultures were mean temperature (30.9% contribution), precipitation seasonality (22.0% contribution), and biome (19.5% contribution), while key drivers for Cape vultures were distance to artificial feeding station (24.8% contribution), and precipitation seasonality (50.5% contribution). Anthropological variables (land use, cattle density, and population density) contributed very little to the models. Using the same tracking data, seasonal changes in foraging movements were examined, particularly in relation to hypothetical food availability. Data were categorised by seasons (winter, spring, summer, and autumn) using weather data over the past decade. There was little evidence for seasonal movement in white-backed or Cape vultures which may be because food availability is not the limiting factor regardless of time of year. Lastly, a model was constructed in MaxEnt using the Endangered Wildlife Trust’s Wildlife and Energy Programme dataset of white-backed and Cape vulture electrocutions by and collisions with power lines. Voltage was a major contributor to risk in every model for both collision and electrocution. This is likely to be related to the type and height of the power line structures rather than actual voltage. Either land use or population density also contributed to all four models. Slope contributed to white-backed vulture models while feeding station and elevation contributed to Cape vulture models. Each of these variables probably relates not only to the likelihood of vulture presence but also how vultures behave in the area (e.g. flying lower in natural or low population areas to forage more effectively therefore putting them at higher risk of collision). This study suggests that management initiatives should include carefully placing vulture feeding stations to change foraging patterns and provide safe, uncontaminated carrion, and proactive retrofitting of high risk power lines to reduce the high unnatural mortality in white-backed and Cape vultures in South Africa. It is important to continue to improve these models using more tracking data from more populations of white-backed and Cape vultures, and more electrocution and collision data gathered from regular, randomly selected power line surveys.
M T 2016

Of the seven pelican species found world wide, only the Great White Pelican (Pelecanus onocrotalus) and the Pink-backed Pelican (P. rufescens) are found in Africa. The KwaZulu-Natal province of South Africa supports only one breeding site for each of these species, and both sites represent the southern most breeding colonies for the two species in the eastern region of Africa. These nesting sites fall within the Greater St Lucia Wetland Park, and are afforded a degree of protection, but the same is not true for their foraging and dispersal ranges, and this is a cause for concern. Considerable amounts of data have been collected relating to the status, distribution and breeding efforts of these two species in north eastern KwaZulu-Natal. These data have been collected in a variety of ways by a large number of people. Part of this work represents an attempt to collate and summarise these data to produce an estimation of the status, distribution and breeding success of these species, and to evaluate any trends in their demography. For this south eastern region of Africa I estimated the population for the Great White Pelican to range between 6000 and 9000 individuals, and the Pink-backed Pelican to range between 600 and 900 individuals. Pelicans are highly mobile birds, and this allows them to move considerable distances when they forage, disperse or migrate. They are also long-lived birds with few natural predators. The two pelican species in south eastern Africa have been poorly studied and little is known about their movements, population dynamics and causes of mortality. Habitat change poses a potential threat to pelicans in north eastern KwaZulu-Natal, and habitat loss could drive these species out this region to areas north of South Africa. Much of this north eastern region of KwaZulu-Natal is under threat, mainly through the actions of man. Many areas are naturally unsuitable for pelican foraging, while others are vital to the survival of both species. This study includes an attempt to assess the movements of these two species in south eastern Africa, and to assess the relative importance and condition of the potential pelican habitat in the north eastern KwaZulu-Natal region, focusing particularly on Lake St Lucia and the Pongolo River floodplain. All this is necessary to produce a baseline from which long term predictions of potential pelican species survival can be made. In the absence of documented life tables and environmental variability data, a range of parameters was modelled to generate population viability analyses to simulate possible scenarios. These extinction models show the outcomes of both the deterministic and the stochastic processes. An attempt was also made to identify the factors that impact most severely on the persistence of these two species. The models were most sensitive to variation in survivorship in the first year of life and to the frequency of catastrophes. Changes in these parameters had the greatest effect on extinction risk. In January 2004 Lake St Lucia was reduced to a fraction of its normal capacity as a result of a severe drought in this region of KwaZulu-Natal. After rains in the area the lake level rose and then fluctuated considerably over the next 24 months. During this time the mouth of the estuary into the sea was closed. Great White Pelican numbers and lake levels were monitored throughout this period. This part of the study relates the changes in population numbers to the lake conditions, and highlights the importance of the lake to this avian species. It uses lake levels as a proxy for the conditions of wetlands in the Lake St Lucia region. It also addresses the implications of these relationships to the management strategy of the lake and the conservation of some avifauna. To identify conservation concerns for the Great White and Pink-backed Pelicans it was necessary to generate these baseline estimations. Although much of this information is uncertain for these two species, an attempt has been made here to predict the persistence of these species in north eastern KwaZulu-Natal and to highlight the conservation issues related to their future.
Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006

碩士
國立臺灣大學
森林學系
85
I studied the foraging ecology of the White-backed Woodpecker （Picoides leucotos） in the Quercus zone of Da- Hsuen-Shan Mountain Area, Taiwan, from October 1995 to November 1996. The study focused on foraging habitat selection and intersexual and interseasonal foraging resource partitioning. During 180 observations of White-backed Woodpecker foraging they were observed utilizing 25 tree species in the study area. The foraging habitat of White-backed Woodpecker contained stands with characters of old-growth forest. The White-backed Woodpeckers prefered stands with more partially dead trees, and prefered trees which are Fagaceae, partially dead, Meso- or Mega- phanerophytes. Males and females differed in their foraging behavior, the dbh of trees and the diameter at foraging site selected for foraging. Males foraged on trees 25-75cm dbh, larger than 100cm dbh more than females and foraged on trees smaller than 25cm dbh, 75-100cm dbh less than females. In addition, male White-backed Woodpeckers foraged on trunks or branches greater than 10cm diameter more than females and on trunks or branches smaller than 10cm diameter less than females. Males used probing behavior more than females, and used scaling behavior less than females. Males used foraging resources more evenly than females. It is not known if this difference is associated with sexual dimorphism or intrapair dominance. The foraging behavior, the height at foraging site and condition of trees used by White-backed Woodpeckers during the breeding and non-breeding seasons differ. During the breeding season partially dead trees and snags are used more, and live trees less, than during the non-breeding season. During the breeding season the height at foraging site increases with more foraging above 15m and less foraging below 15m. Finally, White-backed Woodpeckers used scaling behavior more, and probing behavior less, during the breeding season than at other times. This is probably due to seasonal changes in food availability or endogenous physiological requirements of White-backed Woodpecker. Further studies are needed on the White-backed Woodpecker diet and foraging to understand the intersexual and interseasonal resource partitioning observed during this study.