Academic literature on the topic 'Gymnorhina tibicen'

Recent advances in tracking technology have enabled devices such as Global Positioning Systems (GPS) loggers to be used on a wide variety of birds. Although there are established ethical considerations to these processes, different species may react differently to particular devices and attachments. Thus, pilot studies are still of utmost importance in this field. Here, we describe one such study trialling a novel harness design for GPS tracking devices on Australian Magpies Gymnorhina tibicen. Despite previous testing demonstrating the strength and durability of the harness, devices were removed within minutes to hours of initial fitting. Notably, removal was observed to involve one bird snapping another bird’s harness at the only weak point, such that the tracker was released. This behaviour demonstrates both cooperation and a moderate level of problem solving, providing potential further evidence of the cognitive abilities of this species. To our knowledge, this is the first study to report the conspecific removal of GPS trackers, and should be considered when planning future tracking studies especially on highly social species.

With the advent of efficient and affordable sequencing technology, it has become increasingly viable to generate whole or reduced-representation genome sequence data for non-model organisms. The surfeit of genetic information contained in these datasets can be used in a wide range of studies. These include the assessment of genetic structure and diversity among contemporary populations, the investigation of past divergence events and demographic history, and the identification of variants or loci involved in adaptation. Not only do these insights afford us a greater understanding of the evolutionary history and likely future trajectory of a species, but they also allow us to inform conservation and wildlife management programs by identifying at-risk subpopulations and gauge the ability of a species to respond to environmental changes resulting from climate change or habitat loss. In this thesis, I investigate aspects of the population genetic structure and diversity of Gymnorhina tibicen, the Australian magpie, as well as phylogeographic relationships within the species and the impact that weather conditions have on the species’ ability to recruit new individuals. G. tibicen is an iconic member of the Australian avifauna, a medium-sized generalist passerine known for its characteristic ‘fluting’ call, stark black and white plumage, and aggressively territorial behaviour. Its distribution covers most of mainland Australia and Tasmania, as well as parts of Papua New Guinea, and has been recorded as an invasive species in New Zealand. Currently, the phylogeography & demography of the Australian magpie has been examined using a single mitochondrial gene & a small number of microsatellite loci. In Chapter 2, I use III genomic data to explore the structure, diversity, and biogeography of southern populations of Gymnorhina tibicen. I utilize restriction site-associated (RAD) sequencing to generate a dataset consisting of over 29,000 single nucleotide polymorphisms (SNPs) distributed over more than 15,000 loci. I detail the process of preparing the RADseq dataset, including the testing of parameters that influence the assembly of loci from raw reads. I then use the dataset to examine several hypotheses: that due to the influence of major biogeographic barriers across mainland Australia and Tasmania, reduced-representation genomic data would reveal clear structuring between eastern, western and Tasmanian populations of the Australian magpie, that the western group would be more structured and exhibit a more stable demographic history while the eastern would show signs of population expansion due to the more widespread temperate climate. I use ten populations of G. tibicen distributed across south-eastern and south-western Australia, including two populations from Tasmania. Tests for genetic clustering and fine-scale genetic structure among populations revealed a clear distinction between eastern, western and Tasmanian populations, with Tasmanian samples more closely related to the eastern mainland than western. Western populations also appear more differentiated from one another than those in the eastern cluster, supporting my initial hypothesis. Demographic analyses also suggested a greater rate of expansion in eastern mainland Australia, compared to the relatively stable western mainland. Previous phylogeographic studies of Gymnorhina tibicen made use of a single mitochondrial gene, but recent advances in sequencing technology make it possible to investigate phylogeographic relationships across entire mitogenomes to verify earlier results and increase the genetic resolution at which inferences are made. In Chapter 3, my goal was to assemble 60 whole mitochondrial genomes from specimens of G. tibicen across its distribution, and compare phylogenetic trees constructed from individual genes and complete + near-complete IV mitogenomes. Previously, a single attempt had been made to assemble a complete G. tibicen mitogenome from a museum eggshell specimen, which produced a near-complete sequence minus a repetitive area of the control region. In my study, five complete mitogenomes were assembled, with the remainder assembled into partial but near-complete sequences. Analysis of the mitogenomes assembled here revealed the same broad patterns of divergence between western and eastern halves of the Australian mainland, and closer relationship of the Tasmanian cluster to the eastern group than the western. This study incorporates new sampling locations into our understanding of the phylogeography of G. tibicen, and most notably suggests that the ‘eastern’ group may extend further west across the arid interior than previously identified. The results here also demonstrate the efficacy and improved resolution of phylogeographic analyses when whole mitogenomes are used in lieu of single genes. Long-term ecological datasets are often difficult to produce, but are invaluable when estimating the impact of changing environmental conditions on native wildlife. In Chapter 4, I analyse recruitment data collected over 25 years as part of a long-term territory monitoring study. Birds from over 200 territories were banded and monitored twice yearly, with a range of observations and biological samples taken. I have taken one aspect of the collected data, the number of new juveniles observed in each territory annually, and investigated how recruitment is influenced by variation in local weather conditions over the course of the year preceding the breeding season. I conclude that Gymnorhina tibicen appears relatively robust in the face of annual variation in weather and adverse conditions such as drought, though lower levels of precipitation in the leadup to the breeding season are linked to lower numbers of juveniles recruited per territory. I tentatively suggest that this is result of reduced 85 invertebrate abundance and therefore reduced foraging opportunities, impacting the reproductive health of individuals. Overall, genomic studies of the Australian magpie still have much to offer, particularly in the investigation of demographic history and the identification of regions under selection. Principal recommendations for building on the questions covered in this study are a more thorough sampling regime, both in total number of samples and their spatial resolution across G. tibicen’s distribution.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
Full Text

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

During the Pleistocene, fluctuating climates led to cycles of glacial/arid activity interspersed with pluvial periods across continents in both northern and southern hemispheres. Many studies in the northern hemisphere have used genetic analysis to document the important role that glacial activity has played in structuring avian populations at high latitudes. However, few have attempted to study the associated effect of aridification at low latitudes in the southern hemisphere. I investigated the past effects that cyclic aridification may have had on the population structure and history of a widespread endemic Australian bird species, the Australian magpie (Gymnorhina tibicen) and two species of obligate feather ectoparasites. 1166 samples from across the native range of G. tibicen were analysed for mitochondrial control region sequence variation and variation at six microsatellite loci. Analysis of mitochondrial control region sequence data indicated monophyletic clades that were geographically congruent with an eastern and western region. Analysis of mitochondrial variation at the sites sampled in this study suggested the contemporary distribution of eastern and western clades is non-overlapping but in close proximity. Analysis of microsatellite variation suggested that secondary contact may have occurred between eastern and western clades in north-western Australia. From AMOVA analysis and Bayesian analysis of population structure (BAPS) it was indicated that contemporary nuclear gene flow preceded mitochondrial gene flow from eastern populations through to north-western Australia. Most eastern, northern and north-western sites showed little geographic structure for microsatellite variation. BAPS analysis of microsatellite variation however, suggested there was as much structure among south-west populations as there was between eastern and western populations. For a majority of population comparisons, estimates of gene flow based on coalescent analyses (LAMARC) suggested higher gene flow rates for males than predicted by differences in effective population size of nuclear DNA compared to mitochondrial DNA. This result coupled with the spread of nuclear DNA preceding mitochondrial DNA supports earlier studies that suggest dispersal in magpies in male biased. Using the program IM, eastern and western mainland clades were estimated to have diverged in the Pleistocene around 36, 000 years ago. The island population of Tasmania was even more recent in origin, possibly since sea levels rose 16,000 years ago, inundating Bass Strait. The putative Carpentarian and possibly Canning barriers in the north and the Nullarbor-Eyrean arid barriers in the south appear to be associated with the divergence between eastern and western mainland populations. Nested clade analysis indicated a signature of range expansion in the eastern region suggesting movement possibly inland and northward subsequent to the last period of aridity. Although not significant, north-eastern and south-eastern populations appeared to show some evidence of a population expansion from mitochondrial DNA. Collectively, phylogeographic analyses suggested that increasing aridity during the Pleistocene played an important role in structuring the Australian magpie. The east to west pattern of mtDNA divergence that was identified contrasts with the striking north to south pattern in morphological (back colour) variation in magpies. Over a large proportion of northern Australia, magpies are black backed (BB) and over a smaller area in southern Australia, magpies are white backed (WB). Between BB’s and WB’s a contact zone is present where both parental forms and magpies with an intermediate black band occur. The discordance between back colour and mtDNA structure in magpies suggests recent history is not responsible for the morphological variation. Mitochondrial cytochrome oxidase I sequence variation was analysed for two species of feather lice associated with G. tibicen. Philopterus sp. has greater habitat specificity than Brueelia semiannulata and as predicted showed deeper divergences among populations than B. semiannulata. There was concordance between the distribution of mitochondrial clades for Philopterus sp. and magpies. The overlap of eastern magpie haplotypes and western Philopterus sp. haplotypes at one site suggested secondary contact among eastern and western clades in northern Australia. Two clades were also evident for B. semiannulata. However they were not congruent with geographic structure of the host or Philopterus sp. Rather, the two non-overlapping B. semiannulata clades were distributed in northern and southern Australia. The divergent clades of B. semiannulata may represent populations that diverged on magpies that were isolated prior to the last period of aridity. It was evident that gene flow occurs among populations of northern and southern B. semiannulata; therefore the contemporary maintenance of divergent clades may be due to selection. One possibility is that selection for thermal tolerance is maintaining current distributions of B. semiannulata.Overall microsatellite variation and mtDNA variation in host and lice suggest that increasing aridity and Pleistocene refugia played a role in structuring populations of the Australian magpie. Since the Pleistocene, the dispersal ability and generalist habitat requirements may have facilitated the movement of magpies into an almost contiguous modern distribution across the continent. This study supports the idea that Pleistocene aridification played an important role in structuring intraspecific variation in low latitudinal southern hemisphere avian species.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Australian School of Environmental Studies
Faculty of Environmental Studies
Full Text

The urbanised environment provides ecologists with unique situations in which to undertake ecological study. It has been said that urbanisation is like a natural experiment; we often have populations of animals that have gone from living in natural or semi-natural environments to living in a highly modified anthropogenic environment. These situations provide ideal settings to study the ecological and behavioural differences that may develop in populations located in different habitats. Urbanisation typically results in a minority of species dominating the fauna, and this thesis aimed to examine one such species, the Australian magpie. Despite the magpie being a common and well-liked suburban bird, the majority of previous research on this species has been undertaken within rural or exurban locations. This thesis aimed to examine what actually happens to the species when it lives in the suburban environment. In particular I focused on specific behavioural and ecological features, to see if there were any particular adaptations the suburban magpies showed and also if the suburban habitats provide certain resources favourable to the magpies and what ecological effects these may have. Comparisons of the territory structure and resources of rural and suburban magpies showed that although many features of the territory are similar between rural and suburban locations, notably the choice of native nest trees, magpie territories within suburban areas were smaller and contained more anthropogenic features. The reduced territory size may possibly be related to a greater abundance of key food resources also evident within suburban areas. Furthermore, suburban magpies are more successful in their foraging attempts, again possibly reflecting a more abundant food supply in suburbia and also the simplified nature of suburban foraging areas might facilitate more successful foraging. The increased foraging success is likely to explain the greater provisioning rate to nestling suburban magpies. Suburban magpies also utilised human provided foods. I quantified the extent of wildlife feeding within many of the suburban study sites of this thesis (through the use of questionnaire surveys). In each of the locations it was evident that at least one person (usually more) was providing a regular supply of food to wildlife and magpies appeared to be the main recipients of this food. Previous ecological studies suggest the provision of extra food to avian populations is likely to affect the breeding ecology, and this was so for magpies. The suburban populations initiated breeding significantly earlier than rural magpies. To test the influence of food, supplementary food was provided to rural magpies, not currently receiving any additional human provided foods. The fed rural magpies initiated breeding before control rural magpies (i.e. not receiving any additional food) but suburban magpies still initiated breeding before all other groups. This suggests additional factors present within suburbia, such as warmer temperatures, may also control the timing of breeding in magpies. Magpies in rural and suburban locations lived within different vertebrate communities. Within suburban magpie territories a greater number of intrusions were made by domestic animals, notably dogs (Canis lupus) and cats (Felis domesticus). The frequency of raptors entering the territorial areas occupied by magpies appears to suggest such events are more common in rural areas. The number of humans entering magpie territories was obviously greater in the more populated suburban areas and the majority of magpies responded neutrally to humans. However a group of magpies that previously exhibited extreme aggression towards humans were found to have a greater frequency of aggressive interactions with potential predatory intruders, which were primarily humans. Subsequent examination of the level of corticosterone from this aggressive group of magpies found that a high level of aggressive interactions with potential predators and humans is reflected in higher level of corticosterone, which may have implications for further behavioural and even physiological changes. An ability to habituate to human in urbanised areas is a key attribute of successful synanthropic species. Comparisons of magpies disturbance distances at different points along the urban gradient (the gradient that runs from the urbaised city to natural wildlands) found suburban magpies only responded to humans when they had approached to a close distance (often less than one metre) and many simply walked away to avoid the approaching human. Rural and exurban magpies responded to humans at greater distances than suburban magpies. The distance at which they responded to the human was usually 100 meters plus, and these magpies always flew away. A continuation of this investigation over a temporal scale again found the large difference in response to humans, with suburban magpies exhibiting a decreased response towards humans. However, a certain proportion of responses from suburban magpies were also aggressive. The examination of disturbance distance over the breeding season found that in suburban magpies the responses of most disturbance distance variables remained similar between breeding stages. Rural magpies, however, exhibited variation in their responses towards humans depending on the stage of breeding. It is suggested that the response of rural magpies may be a typical fear response towards an unusual potential threat. The studies presented in this thesis show that magpies have the behavioural capacity to take advantage of resources in suburban landscapes that are not available or are in lessor supply in rural landscapes, it is these abilities that facilitate the magpies synanthropy.

The urbanised environment provides ecologists with unique situations in which to undertake ecological study. It has been said that urbanisation is like a natural experiment; we often have populations of animals that have gone from living in natural or semi-natural environments to living in a highly modified anthropogenic environment. These situations provide ideal settings to study the ecological and behavioural differences that may develop in populations located in different habitats. Urbanisation typically results in a minority of species dominating the fauna, and this thesis aimed to examine one such species, the Australian magpie. Despite the magpie being a common and well-liked suburban bird, the majority of previous research on this species has been undertaken within rural or exurban locations. This thesis aimed to examine what actually happens to the species when it lives in the suburban environment. In particular I focused on specific behavioural and ecological features, to see if there were any particular adaptations the suburban magpies showed and also if the suburban habitats provide certain resources favourable to the magpies and what ecological effects these may have. Comparisons of the territory structure and resources of rural and suburban magpies showed that although many features of the territory are similar between rural and suburban locations, notably the choice of native nest trees, magpie territories within suburban areas were smaller and contained more anthropogenic features. The reduced territory size may possibly be related to a greater abundance of key food resources also evident within suburban areas. Furthermore, suburban magpies are more successful in their foraging attempts, again possibly reflecting a more abundant food supply in suburbia and also the simplified nature of suburban foraging areas might facilitate more successful foraging. The increased foraging success is likely to explain the greater provisioning rate to nestling suburban magpies. Suburban magpies also utilised human provided foods. I quantified the extent of wildlife feeding within many of the suburban study sites of this thesis (through the use of questionnaire surveys). In each of the locations it was evident that at least one person (usually more) was providing a regular supply of food to wildlife and magpies appeared to be the main recipients of this food. Previous ecological studies suggest the provision of extra food to avian populations is likely to affect the breeding ecology, and this was so for magpies. The suburban populations initiated breeding significantly earlier than rural magpies. To test the influence of food, supplementary food was provided to rural magpies, not currently receiving any additional human provided foods. The fed rural magpies initiated breeding before control rural magpies (i.e. not receiving any additional food) but suburban magpies still initiated breeding before all other groups. This suggests additional factors present within suburbia, such as warmer temperatures, may also control the timing of breeding in magpies. Magpies in rural and suburban locations lived within different vertebrate communities. Within suburban magpie territories a greater number of intrusions were made by domestic animals, notably dogs (Canis lupus) and cats (Felis domesticus). The frequency of raptors entering the territorial areas occupied by magpies appears to suggest such events are more common in rural areas. The number of humans entering magpie territories was obviously greater in the more populated suburban areas and the majority of magpies responded neutrally to humans. However a group of magpies that previously exhibited extreme aggression towards humans were found to have a greater frequency of aggressive interactions with potential predatory intruders, which were primarily humans. Subsequent examination of the level of corticosterone from this aggressive group of magpies found that a high level of aggressive interactions with potential predators and humans is reflected in higher level of corticosterone, which may have implications for further behavioural and even physiological changes. An ability to habituate to human in urbanised areas is a key attribute of successful synanthropic species. Comparisons of magpies disturbance distances at different points along the urban gradient (the gradient that runs from the urbaised city to natural wildlands) found suburban magpies only responded to humans when they had approached to a close distance (often less than one metre) and many simply walked away to avoid the approaching human. Rural and exurban magpies responded to humans at greater distances than suburban magpies. The distance at which they responded to the human was usually 100 meters plus, and these magpies always flew away. A continuation of this investigation over a temporal scale again found the large difference in response to humans, with suburban magpies exhibiting a decreased response towards humans. However, a certain proportion of responses from suburban magpies were also aggressive. The examination of disturbance distance over the breeding season found that in suburban magpies the responses of most disturbance distance variables remained similar between breeding stages. Rural magpies, however, exhibited variation in their responses towards humans depending on the stage of breeding. It is suggested that the response of rural magpies may be a typical fear response towards an unusual potential threat. The studies presented in this thesis show that magpies have the behavioural capacity to take advantage of resources in suburban landscapes that are not available or are in lessor supply in rural landscapes, it is these abilities that facilitate the magpies synanthropy.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Australian School of Environmental Studies
Full Text

Abstract This chapter describes the common terminologies, taxonomy, morphology, geographical distribution, physiology, diet, behaviour, reproduction, habitats, ecology, invasion pathways, environmental impact, control and human use of the Australian magpie (Gymnorhina tibicen).