Responses to flooding and drying in seedlings of a common Australian desert floodplain shrub : Muehlenbeckia florulenta Meisn. (tangled lignum)

We investigated the effects of flooding and drying over 6 months on growth and biomass allocation in seedlings of Muehlenbeckia florulenta Meisn. (tangled lignum), a common and widely distributed shrub of Australia's desert floodplains. We sought to determine if lignum seedlings respond to flooding or drying by altering traits or allocation patterns or instead display fixed patterns of development. Since desert floodplains are highly unpredictable and heterogeneous environments, we hypothesised that adaptive phenotypic plasticity is unlikely to have developed or be advantageous in seedlings of this species as environmental state changes are highly variable in their timing and duration and plants risk being caught out of kilter with environmental conditions. To test this, we conducted a glasshouse experiment in which lignum seedlings, grown in both clay and sandy sediments, were subjected to a range of hydrological conditions over a period of 6 months. Lignum seedlings exhibited considerable tolerance of both flooding and drying in our experiment and no mortality was observed. Growth was significantly reduced by flooding, however, and seedlings displayed extremely delayed development rather than plasticity in overall biomass allocation or any of the specific morphological variables we measured. Lignum seedlings were considerably more tolerant of drying than flooding and responded plastically by reducing leaf area ratios through reductions in specific leaf areas and leaf production and expansion. Sediment type had little effect on seedling development. Our results indicate that surface water hydrology is likely to be a major determinant of recruitment patterns in this ecologically significant species.

FEA simulation of contact and wear between non-metallic materials for accelerated new product development

The conventional approach ie laboratory life testing to examine the reliability of products takes long time and involves tremendous cost as samples are tested till failures. The accelerated life test (ALT) has recently been used as an alternative method. Although ALT reduces the cost of reliability testing through applying more severe environmental conditions than the normal ones, it is no longer sufficient as it does not describe the process of products’ failure explicitly and it is still highly dependent on physical testing. Consequently, novel practices need to be developed for better understanding of the products’ reliability. A novel Finite Element Analysis (FEA) model incorporating mathematical wear equations is developed in the current work and applied to polymer materials. Wear rate, a key parameter, is calculated by using a combinatorial formula that combines a conventional linear equation with a recently published exponential equation. The local wear is firstly calculated and then integrated over the sliding distance. The FEA simulation works in a loop and performs a series of simulation with updated surface geometries. The simulation is in good agreement with the physical testing result.

Animal visual systems and the evolution of color patterns; sensory processing illuminates signal evolution

Animal color pattern phenotypes evolve rapidly. What influences their evolution? Because color patterns are used in communication, selection for signal efficacy, relative to the intended receiver's visual system, may explain and predict the direction of evolution. We investigated this in bowerbirds, whose color patterns consist of plumage, bower structure, and ornaments and whose visual displays are presented under predictable visual conditions. We used data on avian vision, environmental conditions, color pattern properties, and an estimate of the bowerbird phylogeny to test hypotheses about evolutionary effects of visual processing. Different components of the color pattern evolve differently. Plumage sexual dimorphism increased and then decreased, while overall (plumage plus bower) visual contrast increased. The use of bowers allows relative crypsis of the bird but increased efficacy of the signal as a whole. Ornaments do not elaborate existing plumage features but instead are innovations (new color schemes) that increase signal efficacy. Isolation between species could be facilitated by plumage but not ornaments, because we observed character displacement only in plumage. Bowerbird color pattern evolution is at least partially predictable from the function of the visual system and from knowledge of different functions of different components of the color patterns. This provides clues to how more constrained visual signaling systems may evolve.

Flowering ecology of a Box-Ironbark Eucalyptus community

Box-Ironbark forests occur on the inland hills of the Great Dividing Range in Australia, from western Victoria to southern Queensland. These dry, open forests are characteristically dominated by Eucalyptus species such as Red Ironbark E. tricarpa, Mugga Ironbark E. sideroxylon and Grey Box E. microcarpa. Within these forests, several Eucalyptus species are a major source of nectar for the blossom-feeding birds and marsupials that form a distinctive component of the fauna. In Victoria, approximately 83% of the original pre - European forests of the Box-Ironbark region have been cleared, and the remaining fragmented forests have been heavily exploited for gold and timber. This exploitation has lead to a change in the structure of these forests, from one dominated by large 80-100 cm diameter, widely -spaced trees to mostly small (≥40 cm DBH), more densely - spaced trees. This thesis examines the flowering ecology of seven Eucalyptus species within a Box-Ironbark community. These species are characteristic of Victorian Box-Ironbark forests; River Red Gum E. camaldulensis, Yellow Gum E. leucoxylon, Red Stringybark E. macrorhyncha, Yellow Box E. melliodora, Grey Box E. microcarpa, Red Box E. polyanthemos and Red Ironbark E. tricarpa. Specifically, the topics examined in this thesis are: (1) the floral character traits of species, and the extent to which these traits can be associated with syndromes of bird or insect pollination; (2) the timing, frequency, duration, intensity, and synchrony of flowering of populations and individual trees; (3) the factors that may explain variation in flowering patterns of individual trees through examination of the relationships between flowering and tree-specific factors of individually marked trees; (4) the influence of tree size on the flowering patterns of individually marked trees, and (5) the spatial and temporal distribution of the floral resources of a dominant species, E. tricarpa. The results are discussed in relation to the evolutionary processes that may have lead to the flowering patterns, and the likely effects of these flowering patterns on blossom-feeding fauna of the Box-Ironbark region. Flowering observations were made for approximately 100 individually marked trees for each species (a total of 754 trees). The flower cover of each tree was assessed at a mean interval of 22 (+ 0.6) days for three years; 1997, 1998 and 1999. The seven species of eucalypt each had characteristic flowering seasons, the timing of which was similar each year. In particular, the timing of peak flowering intensity was consistent between years. Other spatial and temporal aspects of flowering patterns for each species, including the percentage of trees that flowered, frequency of flowering, intensity of flowering and duration of flowering, displayed significant variation between years, between forest stands (sites) and between individual trees within sites. All seven species displayed similar trends in flowering phenology over the study, such that 1997 was a relatively 'poor' flowering year, 1998 a 'good' year and 1999 an 'average' year in this study area. The floral character traits and flowering seasons of the seven Eucalyptus species suggest that each species has traits that can be broadly associated with particular pollinator types. Differences between species in floral traits were most apparent between 'summer' and 'winter' flowering species. Winter - flowering species displayed pollination syndromes associated with bird pollination and summer -flowering species displayed syndromes more associated with insect pollination. Winter - flowering E. tricarpa and E. leucoxylon flowers, for example, were significantly larger, and contained significantly greater volumes of nectar, than those of the summer flowering species, such as E. camaldulensis and E. melliodom. An examination of environmental and tree-specific factors was undertaken to investigate relationships between flowering patterns of individually marked trees of E. microcarpa and E. tricarpa and a range of measures that may influence the observed patterns. A positive association with tree-size was the most consistent explanatory variable for variation between trees in the frequency and intensity of flowering. Competition from near-neighbours, tree health and the number of shrubs within the canopy area were also explanatory variables. The relationship between tree size and flowering phenology was further examined by using the marked trees of all seven species, selected to represent five size-classes. Larger trees (≥40 cm DBH) flowered more frequently, more intensely, and for a greater duration than smaller trees. Larger trees provide more abundant floral resources than smaller trees because they have more flowers per unit area of canopy, they have larger canopies in which more flowers can be supported, and they provide a greater abundance of floral resources over the duration of the flowering season. Heterogeneity in the distribution of floral resources was further highlighted by the study of flowering patterns of E. tricarpa at several spatial and temporal scales. A total of approximately 5,500 trees of different size classes were sampled for flower cover along transects in major forest blocks at each of five sample dates. The abundance of flowers varied between forest blocks, between transects and among tree size - classes. Nectar volumes in flowers of E. tricarpa were sampled. The volume of nectar varied significantly among flowers, between trees, and between forest stands. Mean nectar volume per flower was similar on each sample date. The study of large numbers of individual trees for each of seven species was useful in obtaining quantitative data on flowering patterns of species' populations and individual trees. The timing of flowering for a species is likely to be a result of evolutionary selective forces tempered by environmental conditions. The seven species' populations showed a similar pattern in the frequency and intensity of flowering between years (e.g. 1998 was a 'good' year for most species) suggesting that there is some underlying environmental influence acting on these aspects of flowering. For individual trees, the timing of flowering may be influenced by tree-specific factors that affect the ability of each tree to access soil moisture and nutrients. In turn, local weather patterns, edaphic and biotic associations are likely to influence the available soil moisture. The relationships between the timing of flowering and environmental conditions are likely to be complex. There was no evidence that competition for pollinators has a strong selective influence on the timing of flowering. However, as there is year-round flowering in this community, particular types of pollinators may be differentiated along a temporal gradient (e.g. insects in summer, birds in winter). This type of differentiation may have resulted in the co-evolution of floral traits and pollinator types, with flowers displaying adaptations that match the morphologies and energy requirements of the most abundant pollinators in any particular season. Spatial variation in flowering patterns was evident at several levels. This is likely to occur because of variation in climate, weather patterns, soil types, degrees of disturbance and biotic associations, which vary across the Box-Ironbark region. There was no consistency among sites between years in flowering patterns suggesting that factors affecting flowering at this level are complex. Blossom-feeding animals are confronted with a highly spatially and temporally patchy resource. This patchiness has been increased with human exploitation of these forests leading to a much greater abundance of small trees and fewer large trees. Blossom-feeding birds are likely to respond to this variation in different ways, depending upon diet-breadth, mobility and morphological and behavioural characteristics. Future conservation of the blossom-feeding fauna of Box-Ironbark forests would benefit from the retention of a greater number of large trees, the protection and enhancement of existing remnants, and revegetation with key species, such as E. leucoxylon, E. microcarpa and E. tricarpa. The selective clearing of summer flowering species, which occur on the more fertile areas, may have negatively affected the year-round abundance and distribution of floral resources. The unpredictability of the spatial distribution of flowering patches within the region means that all remnants are likely to be important foraging areas in some years.

Ecology of epifaunal caridean shrimps in the Hopkins River estuary, and the role of estuaries in the life history of the atyid "Paratya Australiensis" Kemp, 1917 in south-eastern Australia

This study examined the factors affecting the distribution and abundance of epifaunal caridean shrimps in seagrass meadows of the Hopkins River estuary in south-western Victoria, Australia, and investigated the life history patterns of the freshwater Parana australiensis, found for the first time in estuaries. Adult and sub-adult shrimps were surveyed in seagrass meadows along the estuary over two years, and their planktonic larvae were surveyed in adjacent waters. Three species were collected. The marine Palaemon serenus occurred only near the mouth, summer to autumn, in high salinities. The marine/estuarine Macrobrachium intermedium occurred throughout the estuary. Adults were most abundant in late autumn, and least abundant in summer (unlike trends reported in marine meadows). Densities were higher and less variable in downstream meadows. P. australiensis occurred in the upper estuary all year, most abundantly in spring, due to migration from the river after peak discharge. Ovigerous females dominated, while males, showing less migration into the estuary, dominated above estuarine influence. Adults disappeared from the estuary in summer as salinity rose. Breeding period for P. australiensis was briefer in the estuary (September-December) than upstream (July-April). M. intermedium began breeding later in the upper estuary (November/December-March) than in the lower estuary (October-March), probably reflecting a physiological response to lower salinity, rather than an interaction with P. australiensis. No ovigerous P. serenus were found in the estuary. Larvae of P. australiensis and M intermedium occurred abundantly throughout the estuary, but P. serenus larvae did not. P. australiensis was an early coloniser to the plankton after peak discharge (November-December). Larvae concentrated in the deep saline layer at the head of the intruding salt wedge, thus probably maintaining longitudinal position. Diurnal vertical migrations were evident within the salt wedge, and in a deep pool above tidal influence. M. intermedium larvae occurred October-May in the lower estuary and November-April in the upper estuary, peaking in abundance one to two months after P. australiensis. They were associated with low surface flows and surface salinities greater than 10, over an anoxic deeper layer. All three species exhibited extended development of euryhaline larvae in the laboratory. Tolerances and optimal salinities of larvae of the three species reflected their distributions. M. intermedium was the most euryhaline species. P. australiensis larvae were tolerant of higher salinities than juveniles of adults: capable of developing in salinity of at least 15. Most P. australiensis juveniles recruited to the estuary November-December, after which numbers declined dramatically. After settlement, most recruits probably migrated upstream out of the estuary. Two cohorts of M. intermedium recruited to the estuary from larvae in summer (December and February), but some juveniles also migrated from adjacent coastal waters. Post-larval migration was at least as important a determinant of abundance as direct recruitment from estuarine, planktonic larvae in all three species. Distributions among seagrass meadows along the estuary were determined primarily by physico-chemical patterns driven by hydrological changes. Seasonal variations in salinity and temperature were strongly associated with seasonal variations in shrimp abundance. Salinity tolerances of adults of the three species reflected their distribution patterns. Biotic interactions were more important in determining distributions within meadows. P. australiensis, when abundant, were associated with seagrass biomass. M. intermedium were also, but when seagrass was sparsest and least extensive. The two species apparently partitioned the seagrass meadow according to depth in early summer. Laboratory experiments suggested P. australiensis was displaced from deeper water by M. intermedium. Preference for vegetative complexity and competition for position within meadows suggest the underlying importance of predation in regulating shrimp populations. A survey of south-eastern Australian estuaries found P. australiensis larvae abundant in all stable, open, well-developed, salt-wedge estuaries where adults were abundant. Adults were most abundant in low salinities among submerged leafy macrophytes. Reproductive traits of P. australiensis were compared in estuarine and fresh reaches of three rivers. Early in the breeding season, egg size was smaller, and (size-specific) egg number larger in estuaries than upstream. A trade-off between egg size and egg number resulted in no difference in total (size-specific) reproductive investment between locations. Reproductive investment tended to decrease at some locations over the breeding season, and this decrease was a result of decreased egg size in most cases. The decrease in reproductive investment probably reflected reduced food availability for the adult, while the reduced egg size was probably a response to improved conditions for larval development. In the Hopkins River, larger egg size at upstream sites was reflected in larger early stage larvae. Later stage larvae were larger in the estuary, suggesting more favourable conditions for larval development. Allozyme electrophoresis showed the P. australiensis populations in each of the three rivers to be distinct. Allozyme frequencies were not different within the Hopkins River, but upstream and estuarine locations in the Curdies and Gellibrand were different. Although some variation in reproductive traits within catchments may have been due to genotypic differences, trade-offs between egg size and number, and decreases in egg size over summer were probably due to plastic responses to environmental cues. It is proposed P. australiensis inhabits and reproduces in both estuarine and freshwater environments by plastic response to environmental conditions. Recruitment to estuaries is dependent on the presence of suitable adult, littoral habitat, and a stable salt wedge for larval retention. Estuaries are important recruitment sites for P. australiensis, potentially allowing an extra brood each year before riverine recruitment. Estuarine broods could constitute a large part of the total fecundity of P. australiensis females. Euryhaline larvae and estuarine recruitment of P. australiensis suggest marine transport of larvae between estuaries as a possible dispersal mechanism for Paratya species.

Characterization of the moisture absorption and thermal ageing behaviour of polymeric composite systems using Raman spectroscopy

Advanced polymeric materials and their respective composites are fast becoming one of the world's most frequently used engineering materials. They find application in the manufacture of e.g. boat hulls, high performance motor vehicles, aircraft components and sports goods. Their high specific strength and specific stiffness give them the edge in applications where weight savings are critical, but their long-term durability is often questioned. These materials are susceptible to environmental conditions such as temperature and humidity. There is also a lack of relevant data, due to the long time-scales required for testing. In this study, the Raman technique has been used to monitor the degradation of two composite systems, namely: a rubber toughened vinylester material used in the marine industry and a high temperature bismaleimide/carbon fibre aerospace composite. Preliminary Raman studies show that the toughening rubber particles dispersed in the cured vinylester resin are leached out during hygrothermal ageing. The weight gain during ageing suggests that this leaching process occurs concurrently with the absorption of water molecules. An increase in the degree of cross-linking is observed when bismaleimide/carbon fibre composite is aged at high temperature. This cross- linking tendency decreases with increasing depth within the carbon fibre bundle.

Influence of disturbance on threatened fauna and associated habitat, Victoria

Results of fauna and vegetation surveys conducted around Portland Aluminium smelter between 1979 and 2004 found small mammal abundance and diversity had declined and changes in vegetation communities were related to changes in fire patterns, vegetation fragmentation and weed invasion. Small mammal numbers were greater in nearby National Parks.

Developmental stress and female mate choice behaviour in the zebra finch

The potential effects of early environmental conditions on adult female mate choice have been largely neglected in studies of sexual selection. Our study tested whether developmental stress affects the mate choice behaviour of female zebra finches, Taeniopygia guttata, when choosing between potential mates. In an experiment manipulating developmental condition, female zebra finches were raised under nutritional stress or control conditions. In adulthood, female preferences were assessed using extensive four-stimulus mate choice trials. Nutritional stress affected growth rates during the period of stress, with experimentally stressed females lighter than controls. During mate choice trials stressed females were almost three times less active than controls and made fewer sampling visits to the stimulus males, although we found no evidence of a direct effect of developmental experience on which males were preferred. Thus, developmental experience had a clear effect on behavioural patterns in a mate choice context. To test whether this effect is specific to a mate choice context, we also investigated the effect of developmental stress on female activity rates in three social contexts: isolation, contact with a conspecific male (a potential mate) and contact with a conspecific female. Here, female activity did not differ between the experimental treatments in any of the social situations. Overall, our findings suggest that environmental conditions during early development can have long-term context-dependent consequences for adult female mate choice behaviour, mediated by changes in activity rates.

Temporal variation in reproductive characteristics of an introduced and abundant island population of koalas

Reproductive characteristics of a wildlife population are typically sensitive to changes in environmental conditions and intrinsic factors. Knowledge of these relationships is critical for understanding population dynamics and effective long-term management of a population. We examined temporal variation in reproductive parameters of an abundant, genetically compromised, and high-density population of koalas (Phascolarctos cinereus) on Kangaroo Island, South Australia, over 3 breeding seasons spanning 9 years: November–May of 1997–1998, 2005–2006, and 2006–2007. Timing of the breeding season was consistent between years, but fecundity, sex ratio of young, and the percentage of independent females (those not accompanying a lactating female) , 6 kg varied. Fecundity was lower than in other island populations, suggesting that the quality and distribution of food resources or inbreeding may be impacting the Kangaroo Island population. We did not test for Chlamydophila (synonym =Chlamydia), and clinical signs of this disease were not reported for any of the koalas in this study. However, historical evidence of Chlamydophila-infected koalas on Kangaroo Island exists, and the potential impact of this disease on fecundity warrants further investigation.

Solar thermal drying of canarium indicum nuts

Many situations exist in rural areas of developing countries where the help of simple technology can make substantial positive impacts on living conditions, finance, and in this case; sustainability. In the Melanesia region, there are numerous areas identified as needing improvement, including indigenous food preservation which will be addressed with a proposed solar thermal solution utilizing locally available materials as much as possible for low cost local construction. The current knowledge of the drying requirements for the product chosen in this study is quite limited. However, it is believed that solar thermal drying might be feasible for the remote sunny regions as in Melanesia. This paper describes the processes involved in determining the drying parameters of the Canarium indicum nut, and the proposed solar dryer designs that have been considered for the particular environmental conditions and product specifications. Through the selection process, a mixed mode, low-tunnel solar dryer was chosen as the best match to satisfy the different parameters.

Effect of CHO ingestion on exercise metabolism and performance in different ambient temperatures

Two series of experiments were conducted to examine the effect of ingesting beverages with differing carbohydrate (CHO) concentrations and osmolalities on metabolism and performance during prolonged exercise in different environmental conditions. In series 1, 12 subjects performed three cycling exercise trials to fatigue at 70% ·VO_2peak in either 33°C(N = 6) (HT1) or 5°C (N = 6) (CT). Subjects ingested either a 14% CHO solution (osmolality = 390 mosmol·l^-1) (HCHO); a 7% CHO solution (330 mosmol·l^-1) (NCHO) or a placebo (90 mosmol·l^-1) (CON1). In series 2, six subjects performed the same three trials at 33°C (HT2), while ingesting either NCHO, a 4.2% CHO solution (240 mosmol·l^-1) (LCHO) or a placebo) (240 mosmol·l^-1) (CON2). Plasma glucose was higher (P < 0.05) in HCHO than NCHO, which in turn was higher (P < 0.05) than CON1 in both CT and HT1. Plasma glucose was lower (P < 0.05) in CON2 compared with NCHO and LCHO in HT2. The fall in plasma volume was greater(P < 0.05) in HCHO than other trials in both CT and HT1 but was not different when comparing the three trials in HT2. Exercise time was not different when comparing the trials in either HT1 or HT2 but was longer(P < 0.05) in NCHO compared with HCHO, which, in turn, was longer(P < 0.05) than CON1 in CT. These data demonstrate that, during prolonged exercise in the heat, fatigue is related to factors other than CHO availability. In addition, during exercise in 5°C a 7% CHO solution is more beneficial for exercise performance than a 14% CHO solution.

Optimal management of a goose flyway : migrant management at minimum cost

1. We adopt a ‘whole flyway’ approach to modelling scenarios for protecting migratory birds, aiming at efficient and cost-effective conservation of flyway habitat.

2. We developed a model to minimize flyway management costs while safeguarding a migrating bird population. The model assumes that the intensity of the birds’ use of sites can be manipulated by varying management regimes (with concomitant costs) and that the birds make optimal use of the conditions created along their flyway.

3. We used dynamic programming to find the sequence of migratory decisions that maximizes the fitness of the migrants given a range of management scenarios, followed by a management cost estimate of all these scenarios and selection of those scenarios yielding an optimal solution from both an economic and the migrants’ perspective.

4. Using the population of pink-footed geese Anser brachyrhynchus that breed in Svalbard as an example, we calculated that the cheapest management scenario given current compensation payment rates at the various goose stopover sites yielded a 35% cost saving over current management. This cheapest scenario provides a migration itinerary that is very similar to the current itinerary used by the geese. This is fortuitous since changing environmental conditions may put the migrants at risk.

5. Synthesis and application. Given the global threats to migratory birds, developing a framework for efficient and effective conservation of flyway habitat is an urgent need. Such a framework may likewise be used to assist in controlling migrants causing conflict with agriculture, such as several goose species, in an economic and responsible fashion. Our suggested exemplified framework identified large unexplainable differences in management costs between regions. Differences in management costs between staging sites for birds make big differences to the optimal management of a flyway. Hence, to achieve efficient and effective management of migratory birds, we firstly need an objective assessment of the cost of management in different locations, followed by a modelling approach as here advocated, and followed up by a collaborative action of managers along the entire flyway.

Feast or famine : evidence for mixed capital–income breeding strategies in Weddell seals

Evolved patterns of resource expenditure for reproduction have resulted in a life history continuum across species. A strictly capital-breeding strategy relies extensively on stored energy for reproduction, whereas income breeding uses energy acquired throughout the reproductive period. However, facultative income breeding has been shown in some classically capital-breeding animals, and was originally thought to provide a nutritional refuge for smaller females incapable of securing sufficient reserves during pre-partum foraging. We examined milk composition and milk output for the Weddell seal to determine to what degree lactation was aided by food intake, and what factors contributed to its manifestation. Milk composition was independent of maternal post-partum mass and condition, but did change over lactation. Changes were most likely in response to energetic and nutritional demands of the pup at different stages of development. During early lactation, females fasted and devoted 54.9% of total energy loss to milk production. Later in lactation 30.5% more energy was devoted to milk production and evidence suggested that larger females fed more during lactation than smaller females. It appears that Weddell seals may exhibit a flexible strategy to adjust reproductive investment to local resource levels by taking advantage of periods when prey are occasionally abundant, although it is restricted to larger females possessing the physiological capacity to dive for longer and exploit different resources during lactation. This supports the assumption that although body mass and phylogenetic history explain most of the variation in lactation patterns (20–69%), the remaining variation has likely resulted from physiological adaptations to local environmental conditions. Our study confirms that Weddell seals use a mixed capital–income breeding strategy, and that considerable intraspecific variation exists. Questions remain as to the amount of energy gain derived from the income strategy, and the consequences for pup condition and survival.

Identifying crucial gaps in our knowledge of the life-history of avian influenza viruses - An Australian perspective

We review our current knowledge of the epidemiology and ecology of avian influenza viruses (AIVs) in Australia in relation to the ecology of their hosts. Understanding the transmission and maintenance of low-pathogenic avian influenza (LPAI) viruses deserves scientific scrutiny because some of these may evolve to a high-pathogenic AIV (HPAI) phenotype. That the HPAI H5N1 has not been detected in Australia is thought to be a result of the low level of migratory connectivity between Asia and Australia. Some AIV strains are endemic to Australia, with Australian birds acting as a reservoir for these viruses. However, given the phylogenetic relationships between Australian and Eurasian strains, both avian migrants and resident birds within the continent must play a role in the ecology and epidemiology of AIVs in Australia. The extent to which individual variation in susceptibility to infection, previous infections, and behavioural changes in response to infection determine AIV epidemiology is little understood. Prevalence of AIVs among Australian avifauna is apparently low but, given their specific ecology and Australian conditions, prevalence may be higher in little-researched species and under specific environmental conditions.