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Noise pollution is expanding at an unprecedented rate and is increasingly associated with impaired reproduction and development across taxa. However, whether noise sound waves are intrinsically harmful for developing young—or merely disturb parents—and the fitness consequences of early exposure remain unknown. Here, by only manipulating the offspring, we show that sole exposure to noise in early life in zebra finches has fitness consequences and causes embryonic death during exposure. Exposure to pre- and postnatal traffic noise cumulatively impaired nestling growth and physiology and aggravated telomere shortening across life stages until adulthood. Consistent with a long-term somatic impact, early life noise exposure, especially prenatally, decreased individual offspring production throughout adulthood. Our findings suggest that the effects of noise pollution are more pervasive than previously realized. [ABSTRACT FROM AUTHOR]

The world of scientific publishing has undergone significant changes with the rise of open access (OA) initiatives. Emu Austral Ornithology has historically provided OA through a hybrid publishing model, but a recent agreement between Taylor and Francis and the Council of Australian University Librarians (CAUL) is expected to greatly enhance OA uptake within the journal. This agreement allows corresponding authors from participating institutions in Australia and New Zealand to publish their papers as open access without incurring individual costs. The growth of OA publishing has not led to reduced costs for researchers, and the costs associated with OA publishing vary across disciplines. The new CAUL agreement is expected to improve OA access for researchers in the environmental sciences, including ornithology, and promote greater dissemination of research findings. [Extracted from the article]

There is considerable research regarding measures of early reading but much less in early writing. Nevertheless, writing is a critical skill for success in school and early difficulties in writing are likely to persist without intervention. A necessary step toward identifying those students who need additional support is the use of screening tools. The purpose of this study was to identify tools used with emergent writers and summarize the current state of this empirical literature. A systematic review was conducted for publications between 1990 and 2022. A total of 59 studies focused on early writing for preschool or kindergarten students and met criteria for inclusion in the review. Results indicated the most used early writing measure was Name Writing followed by Letter Writing, and Spelling tasks with some studies using this specific combination of measures. Despite some consistency in the measures used, there was significant variation in the scoring approach. Review of technical adequacy indicated 65% of studies included reliability data while considerably fewer included validity. Future studies using consistent approaches to scoring early writing tasks and additional examinations of validity are needed to improve educators’ ability to identify and intervene in this skill area. [ABSTRACT FROM AUTHOR]

Biologists have long appreciated the critical role that energy turnover plays in understanding variation in performance and fitness among individuals. Whole-organism metabolic studies have provided key insights into fundamental ecological and evolutionary processes. However, constraints operating at subcellular levels, such as those operating within the mitochondria, can also play important roles in optimizing metabolism over different energetic demands and time scales. Herein, we explore how mitochondrial aerobic metabolism influences different aspects of organismal performance, such as through changing adenosine triphosphate (ATP) and reactive oxygen species (ROS) production. We consider how such insights have advanced our understanding of the mechanisms underpinning key ecological and evolutionary processes, from variation in life-history traits to adaptation to changing thermal conditions, and we highlight key areas for future research. The study of mitochondrial aerobic metabolism provides a promising avenue through which ecologists and evolutionary biologists can explore mechanistic sources of variation in metabolic and life-history phenotypes, with important consequences for organismal performance and fitness. Mitochondria vary not only in rate of respiration, but also in ATP production efficiency through OXPHOS, rate of ROS production, and amount of heat generated; the interplay among these factors underlies mechanistic trade-offs and constraints that can have cascading effects up to the level of organismal performance. Growing interest in mitochondrial biology within ecology and evolutionary biology, has enriched understanding of how metabolic rate, energy availability, and the byproducts of mitochondrial aerobic metabolism, may interact to shape different life-history strategies and how organisms adapt to their environment. [ABSTRACT FROM AUTHOR]

Developmental stressors are increasingly recognised for their pervasive influence on the ecology and evolution of animals. In particular, many studies have focused on how developmental stress can give rise to variation in adult behaviour, physiology, and performance. However, there remains a poor understanding of whether general patterns exist in the effects and magnitude of phenotypic responses across taxonomic groups. Furthermore, given the extensive phenotypic variation that arises from developmental stressors, it remains important to ascertain how multiple processes may explain these responses. We compiled data from 111 studies to examine and quantify the effect of developmental stress on animal phenotype and performance from juveniles to adulthood, including studies from birds, reptiles, fish, mammals, insects, arachnids, and amphibians. Using meta‐analytic approaches, we show that across all studies there is, on average, a moderate to large negative effect of developmental stress exposure (posterior mean effect: |d| = −0.51) on animal phenotype or performance. Additionally, we demonstrate that interactive effects of timing of stressor onset and the duration of exposure to stressors best explained variation in developmental stress responses. Animals exposed to stressors earlier in development had more‐positive responses than those with later onset, whereas longer duration of exposure to a stressor caused responses to be stronger in magnitude. However, the high amount of heterogeneity in our results, and the low degree of variance explained by fixed effects in both the meta‐analysis (R2 = 0.034) and top‐ranked meta‐regression model (R2 = 0.02), indicate that phenotypic responses to developmental stressors are likely highly idiosyncratic in nature and difficult to predict. Despite this, our analyses address a critical knowledge gap in understanding what effect developmental stress has on phenotypic variation in animals. Additionally, our results highlight important environmental and proximate factors that may influence phenotypic responses to developmental stressors. [ABSTRACT FROM AUTHOR]

Non-invasive techniques for measuring glucocorticoids (GCs) have become more prevalent, due to the advantage of eliminating the effects of animal disturbance on GC levels and their potential to provide an integrated, historic estimate of circulating GC levels. In the case of birds, corticosterone (CORT) is deposited in feathers, and may reflect a bird’s GC status over the period of feather synthesis. This technique thus permits a retrospective view of the average circulating GC levels during the moult period. While it is generally assumed that differences in feather CORT content (CORT f ) between individuals reflects their different stress histories during either natural or induced moult, it is not clear how much of this variation is due to extrinsic versus intrinsic factors. We examined this question by determining CORT f in free-living house sparrows ( Passer domesticus ) from two populations, one urban and the other rural, that were plucked before and after exposure to different plasma CORT levels while held captive. We experimentally manipulated plasma CORT by implanting birds with either a corticosterone-filled, metyrapone-filled, or empty (‘sham’) silastic capsule as replacement feathers first emerged. The pattern of post-treatment CORT f was consistent with our expectations, based on plasma CORT levels of an experimentally implanted reference group. However, there was no statistically significant difference in CORT f between these treatment groups unless sex, population origin, and CORT f of original feathers for each individual were included in a model. Thus, birds with higher CORT f in feathers removed for this experiment tended to have higher CORT f in post-treatment replacement feathers, irrespective of treatment. In addition, we found that feather fault bar scores were significantly higher in CORT-treated birds than in the other two treatment groups, but did not vary directly with CORT f level. Our study therefore broadly confirms the use of feathers as a non-invasive tool to estimate plasma CORT during moult in birds, but importantly demonstrates the potential for intrinsic differences in stress characteristics between populations and individuals to obscure the effects extrinsic stressors might have on CORT f . [ABSTRACT FROM AUTHOR]

The arid and semi-arid zones of Australia are characterized by highly variable and unpredictable environmental conditions which affect resources for flora and fauna. Environments which are highly unpredictable in terms of both resource access and distribution are likely to select for a variety of adaptive behavioral strategies, intrinsically linked to the physiological control of behavior. How unpredictable resource distribution has affected the coevolution of behavioral strategies and physiology has rarely been quantified, particularly not in Australian birds. We used a captive population of wild-derived zebra finches to test the relationships between behavioral strategies relating to food access and physiological responses to stress and body condition. We found that individuals that were in poorer body condition and had higher peak corticosterone levels entered baited feeders earlier in the trapping sequence of birds within the colony. We also found that individuals in poorer body condition fed in smaller social groups. Our data show that the foraging decisions which individuals make represent not only a trade-off between food access and risk of exposure, but their underlying physiological response to stress. Our data also suggest fundamental links between social networks and physiological parameters, which largely remain untested. These data demonstrate the fundamental importance of physiological mechanisms in controlling adaptive behavioral strategies and the dynamic interplay between physiological control of behavior and life-history evolution. [ABSTRACT FROM AUTHOR]

Bacteria have had a fundamental impact on vertebrate evolution not only by affecting the evolution of the immune system, but also generating complex interactions with behavior and physiology. Advances in molecular techniques have started to reveal the intricate ways in which bacteria and vertebrates have coevolved. Here, we focus on birds as an example system for understanding the fundamental impact bacteria have had on the evolution of avian immune defenses, behavior, physiology, reproduction and life histories. The avian egg has multiple characteristics that have evolved to enable effective defense against pathogenic attack. Microbial risk of pathogenic infection is hypothesized to vary with life stage, with early life risk being maximal at either hatching or fledging. For adult birds, microbial infection risk is also proposed to vary with habitat and life stage, with molt inducing a period of increased vulnerability. Bacteria not only play an important role in shaping the immune system as well as trade-offs with other physiological systems, but also for determining digestive efficiency and nutrient uptake. The relevance of avian microbiomes for avian ecology, physiology and behavior is highly topical and will likely impact on our understanding of avian welfare, conservation, captive breeding as well as for our understanding of the nature of host-microbe coevolution. [ABSTRACT FROM AUTHOR]

Up to 80% of all bird species are socially monogamous. Divorce (switching partners) or pair disruption (due to the death of a partner) has been associated with decreased reproductive success, suggesting social monogamy is a strategy that may maximize fitness via coordination between partners. Previous studies have demonstrated the effects of divorce and pair disruption on immediate reproductive success. Here, we used a paired experimental design in the zebra finch ( Taeniopygia guttata ) to examine the hormonal mechanisms that modulate parental behavior and reproductive success in response to a partnership change (hereafter divorce). Specifically, we examined the effects of divorce on the avian stress hormone corticosterone (CORT) in both parents and nestlings, parental behaviors (incubation and nestling provisioning), prolactin (PRL), and reproductive success. We found that divorce resulted in delayed clutch initiation, reduced clutch mass, and an increase in nestling CORT response to a standardized stressor. These effects on reproductive investment and chick CORT response were not clearly determined by parental endocrine responses. Divorce had no effect on the level of parental CORT. PRL levels were highly correlated within a pair regardless of treatment, were negatively related to the investment that males made in incubation, and increased in experimental males as a result of pair disruption. This study demonstrates the fundamental impact which divorce has not only on reproduction, but also the physiological stress responses of offspring and suggests that in socially monogamous animals the maintenance of a stable partnership over time could be advantageous for long term fitness. [ABSTRACT FROM AUTHOR]

This article is part of a Special Issue "SBN 2014". Photoperiod and the hormonal response it triggers are key determinants of reproductive timing in birds. However, other cues and physiological traits may permit flexibility in the timing of breeding and perhaps facilitate adaptation to global change. Opportunistic breeders are excellent models to study the adaptive significance of this flexibility, especially at the individual level. Here, we sought to quantify whether particular male physiological and behavioral traits were linked to reproductive timing and output in wild-derived zebra finches. We repeatedly assessed male stress-induced corticosterone levels (CORT), basal metabolic rate (BMR), and activity before releasing them into outdoor aviaries and quantifying each pair's breeding timing, investment, and output over a seven-month period. Despite unlimited access to food and water, the colony breeding activity occurred in waves, probably due to interpair social stimulations. Pairs adjusted their inter-clutch interval and clutch size to social and temperature cues, respectively, but only after successful breeding attempts, suggesting a facultative response to external cues. When these effects were controlled for statistically or experimentally, breeding intervals were repeatable within individuals across reproductive attempts. In addition, males' first laying date and total offspring production varied with complex interactions between pre-breeding CORT, BMR and activity levels. These results suggest that no one trait is under selection but that, instead, correlational selection acts on hormone levels, metabolism, and behavior. Together our results suggest that studying inter-individual variation in breeding strategy and their multiple physiological and behavioral underpinnings may greatly improve our understanding of the mechanisms underlying the evolution of breeding decisions. [ABSTRACT FROM AUTHOR]

Predator exclosures ('nest cages') around nests are increasingly used to enhance hatching success of declining ground-nesting birds. However, such exclosures are contentious and have been suggested to have detrimental effects on the species which they aim to protect. This study examines whether exclosures increase physiological stress of incubating birds, a hitherto unrecognised and untested potential drawback of exclosures. Red-capped plover Charadrius ruficapillus hatching success was radically altered and significantly higher for nests with exclosures (96.2%) compared with those without (6.8%). Chronic physiological stress in parents (as measured by the heterophil/lymphocyte [H/L] ratio in blood) did not vary between nests with and without exclosures, or between the sexes. However the absence of vegetative cover at the nest site was associated with a 62.7% elevation in H/L ratio, indicating that incubating birds which place their nests in the open are subject to increased levels of chronic stress. The results from this study demonstrate the fundamental importance of predation for the nesting success of this species and confirm that chronic stress levels are not a detrimental side effect of exclosure use. [ABSTRACT FROM AUTHOR]

The article presents information on several papers on ornithology that were published on December 12, 2014. Topics discussed in the papers include the response of birds to global climate change, the evolution of sex chromosomes in birds, and DNA sequences in birds. The papers also focus on mutations of protein-coding genes in birds, and the effect of gene expression on singing behaviour in oscine songbirds.

The article discusses the journals evolution towards electronic communication and international accessibility in favour of online electronic access to encourage growth of open access publishing, which shifts the publication costs from the subscriber to the author.

Birdsong is a classic example of a learned trait with cultural inheritance, with selection acting on trait expression. To understand how song responds to selection, it is vital to determine the extent to which variation in song learning and neuroanatomy is attributable to genetic variation, environmental conditions, or their interactions. Using a partial cross fostering design with an experimental stressor, we quantified the heritability of song structure and key brain nuclei in the song control system of the zebra finch and the genotype-by-environment (G × E) interactions. Neuroanatomy and song structure both showed low levels of heritability and are unlikely to be under selection as indicators of genetic quality. HVC, in particular, was almost entirely under environmental control. G × E interaction was important for brain development and may provide a mechanism by which additive genetic variation is maintained, which in turn may promote sexual selection through female choice. Our study suggests that selection may act on the genes determining vocal learning, rather than directly on the underlying neuroanatomy, and emphasizes the fundamental importance of environmental conditions for vocal learning and neural development in songbirds. [ABSTRACT FROM AUTHOR]

An introduction to the journal is presented which discusses various papers published within the issue, including one on a phylogenetic and phylogeographic analyses of the Maluridae, one on the prevalence of nest parasitism of Maluridae members by cuckoos, and another on factors underlying selection on female plumage traits in Malurus.

Across taxa, both neural growth and cognitive function show considerable developmental plasticity. Data from studies of decision making, learning, and discrimination demonstrate that early life conditions have an impact on subsequent neural growth, maintenance, and cognition, with important ecological and evolutionary implications. Here, we provide a synthesis of the evidence that spatial and vocal learning are condition dependent, addressing what is known about their physiological control and the functional explanations. Neural investment is predicted to be affected by environmental conditions, but the shape of the response should depend on the fitness benefits of the cognitive traits under control. From an evolutionary perspective, traits promoting resistance to environmental perturbations should be favored when the cognitive trait is a crucial determinant of fitness. [ABSTRACT FROM AUTHOR]

Contact zones between subspecies or closely related species offer valuable insights into speciation processes. A typical feature of such zones is the presence of clinal variation in multiple traits. The nature of these traits and the concordance among clines are expected to influence whether and how quickly speciation will proceed. Learned signals, such as vocalizations in species having vocal learning (e.g. humans, many birds, bats and cetaceans), can exhibit rapid change and may accelerate reproductive isolation between populations. Therefore, particularly strong concordance among clines in learned signals and population genetic structure may be expected, even among continuous populations in the early stages of speciation. However, empirical evidence for this pattern is often limited because differences in vocalisations between populations are driven by habitat differences or have evolved in allopatry. We tested for this pattern in a unique system where we may be able to separate effects of habitat and evolutionary history. We studied geographic variation in the vocalizations of the crimson rosella (Platycercus elegans) parrot species complex. Parrots are well known for their life-long vocal learning and cognitive abilities. We analysed contact calls across a ca 1300 km transect encompassing populations that differed in neutral genetic markers and plumage colour. We found steep clinal changes in two acoustic variables (fundamental frequency and peak frequency position). The positions of the two clines in vocal traits were concordant with a steep cline in microsatellite-based genetic variation, but were discordant with the steep clines in mtDNA, plumage and habitat. Our study provides new evidence that vocal variation, in a species with vocal learning, can coincide with areas of restricted gene flow across geographically continuous populations. Our results suggest that traits that evolve culturally can be strongly associated with reduced gene flow between populations, and therefore may promote speciation, even in the absence of other barriers. [ABSTRACT FROM AUTHOR]

Songbird vocal learning is a popular model for understanding the evolution of complex communication. When multiple tutors are available, juvenile songbirds prefer to learn vocalizations from some tutors over others, their preferences partly guided by postnatal acoustic experience and social interactions. The potential for prenatal sound to also influence song tutor choice remains largely untested, despite recent evidence that prenatal sound affects other aspects of songbird development. Previously, we showed that Australian zebra finches, Taeniopygia castanotis , learnt more song syllables from nonpaternal tutors if they had previously experienced 'heat calls' (parental vocalizations produced at high ambient temperatures) as embryos. This suggests that heat call exposure may trigger changes in offsprings' social behaviour or learning strategy as juveniles, thereby indirectly affecting their song tutor preferences. In this study, we tested this hypothesis by prenatally exposing male zebra finches to either heat calls (treatment) or contact calls (control) and then assessing their song preferences as adults. Song preferences were measured in a four-way choice apparatus in response to playback from four different individuals: their social father (paternal song), an unrelated conspecific (nonpaternal song) and two heterospecifics (both male canaries, Serinus canaria). As expected, subjects were more attracted to conspecific songs than to canary songs, regardless of their prenatal sound exposure. In addition, prenatal sound experience altered subjects' conspecific song preferences: treatment birds preferred nonpaternal conspecific song over their social father's song while control birds showed no preference. That prenatal sound produced long-lasting differences in individual song preferences, which are typically reflective of vocal tutor choice, has implications for understanding both the flexibility of vocal learning and the influence of prenatal soundscapes on individual phenotypes. • Avian song preferences are potentially influenced by the prenatal sound environment. • We exposed Australian zebra finch embryos to either heat calls or contact calls. • Regardless of their prenatal experience, adult birds preferred conspecific song. • Prenatal sound affected birds' relative preference for paternal vs nonpaternal song. [ABSTRACT FROM AUTHOR]

Secondary sexual signals are thought to indicate individual quality. In order to understand the evolutionary pressures that give rise to such traits it is important to understand the physiological mechanisms underlying their production. The black bib of the house sparrow Passer domesticus is known to function as a badge of social status in males. Past studies have found that the size of the bib in older males is determined, at least partly, by the androgen testosterone. The immunocompetence handicap hypothesis suggests that testosterone has a key role in maintaining honest signalling - it is both involved in the development or expression of sexual signals and is immunosuppressive. In this paper we test experimentally two hypo theses relating to bib size development, whether 1) testosterone is only immunosuppressive in conditions where the natural feedback loop from the testes has been removed, and 2) testosterone is, in addition to influencing the bib size of older males, responsible for the size of the bib in juvenile sparrows. In the first experiment we found that exogenous testosterone administered to intact males during the winter (when LH and FSH levels are very low and were not artificially increased by castration) caused significant immunosuppression, albeit in interaction with the stress hormone corticosterone. Second, we found that exogenous testosterone administration in castrated fledgling male house sparrows had no effect on subsequent post-juvenile moult bib size relative to controls. Our results suggest that in some circumstances testosterone can be immunosuppressive, but that its role in bib size determination is age-dependent. [ABSTRACT FROM AUTHOR]

Individuals within species differ in their behavioural reactions to the environment. Consistent individual differences in these behaviours (personality traits) are often correlated and known to be under natural selection. These differences are frequently associated with variation in physiological traits, such as endocrine profiles. For example, variation in circulating testosterone levels is associated with variation in several personality traits and has been hypothesized to be a marker for personality in humans and rodents. The importance of testosterone in controlling both behavioural strategies and individual physiological differences suggests that direct selection on personality traits might cause pleiotropic selection on the physiological mechanisms underlying these traits. To test this hypothesis, we quantified levels of plasma testosterone levels and measured phytohaemagglutinin (PHA)-induced immune responses of male great tits, Parus major, in lines artificially selected for diverging levels of avian personality (‘fast’ and ‘slow’ exploratory behaviour). We found that testosterone levels were highly repeatable within individuals and fluctuated predictably over the season. Contrary to our expectations, ‘slow’ explorers had consistently higher levels of baseline testosterone and higher immune responses than ‘fast’ explorers. These results show that phenotypic selection for variation in personality traits corresponds to consistent differences in hormone profile and immune function, but that higher aggression levels do not need to be associated with higher baseline testosterone levels. Our results confirm that personality traits have evolved as a result of selection on both the underlying controlling physiological mechanisms and the phenotypic traits. [ABSTRACT FROM AUTHOR]

In many species, embryos can perceive and learn external sounds. Yet, the possibility that parents may use these embryonic capacities to alter their offspring’s developmental trajectories has not been considered. Here, we demonstrate that zebra finch parents acoustically signal high ambient temperatures (above 26°C) to their embryos. We show that exposure of embryos to these acoustic cues alone adaptively alters subsequent nestling begging and growth in response to nest temperature and influences individuals’ reproductive success and thermal preferences as adults. These findings have implications for our understanding of maternal effects, phenotypic plasticity, developmental programming, and the adaptation of endothermic species to a warming world. [ABSTRACT FROM AUTHOR]

The immunocompetence handicap hypothesis (ICHH) suggests that the male sex hormone testosterone has a dual effect; it controls the development and expression of male sexually selected signals, and it suppresses the immune system. Therefore only high quality males are able to fully express secondary sexual traits because only they can tolerate the immunosuppressive qualities of testosterone. A modified version of the ICHH suggests that testosterone causes immunosuppression indirectly by increasing the stress hormone corticosterone (COAT). Lines of Japanese quail (Coturnix japonica) selected for divergent responses in levels of plasma COAT were used to test these hypotheses. Within each COAT response line (as well as in a control stock) we manipulated levels of testosterone in castrated quail by treatment with zero (sham), low or high testosterone implants, before testing the birds' humoral immunity and phytohaemagglutinin (PHA)-induced immune response, as well as body condition. The PHA-induced response was not significantly affected by COAT selected line, testosterone treatment or their interaction. There was, however, a significant effect of COAT line on humoral immunity in that the control birds exhibited the greatest antibody production, but there was no significant effect of testosterone manipulation on humoral immunity. The males in the sham implant treatment group had significantly greater mass than the males in the high testosterone group, suggesting a negative effect of high testosterone on general body condition. We discuss these results in the context of current hypotheses in the field of sexual selection. [ABSTRACT FROM AUTHOR]

The complex song of the male sedge warbler functions mainly in sexual attraction and the evolution of repertoire size is driven primarily by female choice. As male song ceases upon pairing, male–male singing interactions are relatively brief and have not been studied to our knowledge. This study shows that young males in their first breeding season shared significantly more syllables with their nearest neighbour than with their fathers or more distant males. Moreover, daily recordings revealed that rapid learning and modification of syllable repertoires occurred, resulting in a progressive increase in sharing within just a few days. This does not lead to a gradual increase in repertoire size as some syllables are dropped and new ones are acquired. This turnover process allows males to share syllables with their neighbours, whilst repertoire size, known to be important in female choice, remains relatively constant in any one year. Individual males were followed for several years and also showed considerable syllable turnover between years. However, in this case, repertoire size was found to increase between years, the largest increase occurring between the first and second years. We obtained a significant positive correlation between repertoire size and age, suggesting that females choosing males with larger repertoires may gain indirect (genetic) benefits for their offspring, such as good genes for viability. Whilst these results reveal a more flexible picture of repertoire turnover than previously suspected, the relative stability of repertoire size within a season and the increase with age suggests that repertoire size remains a likely target for sexual selection by female choice. [Copyright &y& Elsevier]

Although 90% of passerine birds live in socially monogamous pair bonds, molecular studies have revealed that genetic polygamy occurs in 86% of surveyed passerines, because individuals engage in copulations outside the pair bond (extrapair copulations; EPCs). Most explanations for the occurrence of EPCs involve female gaining indirect benefits from the extrapair male. The sedge warbler is a socially monogamous species in which some offspring result from EPCs (8% in this study). Complex song is a sexually selected male trait used by females which select mates based on a variety of male qualities. We used microsatellite DNA profiling to detect extrapair young and assign paternity. ‘Good genes’ theory predicts that females should engage in EPCs with males of higher quality than their social mate, with resulting fitness benefits. Extrapair males had smaller song repertoires and smaller territories than the social mate. This apparent preference for small-repertoire males as extrapair mates conflicts with the predictions from previous studies of this species. Sudden cessation of song after pairing may mean that song cues are unavailable for later extrapair matings and females may switch to other cues. Such behaviour may lead to different patterns of female choice during social and extrapair mating in the sedge warbler. We conclude that multiple reasons underlie patterns of female choice in this species. [Copyright &y& Elsevier]

Abstract: The original immunocompetence handicap hypothesis (ICHH) suggested that testosterone has a handicapping effect in males by both promoting the development of sexual signals and suppressing immune function. A modified version, the stress-linked ICHH, has recently proposed that testosterone is immunosuppressive indirectly by increasing production of corticosterone. To test both the original and stress-mediated versions of the ICHH, we implanted male zebra finches taken from lines selected for divergent maximum stress-induced levels of corticosterone (high, low and control) with either empty or testosterone-filled implants. Their humoral and cell-mediated immune responses were then assessed by challenge with diphtheria:tetanus vaccine and phytohemagglutinin respectively. We found no effect of the hormone manipulations on either PHA or tetanus antibody responses, but found a significant interaction between titers of both testosterone and corticosterone on diphtheria secondary antibody response; antibody response was greatest in individuals with high levels of both hormones. There was also a significant interactive effect between testosterone treatment group and corticosterone titer on body mass; the body mass of males in the elevated testosterone treatment group decreased with increasing corticosterone titer. These results suggest that, contrary to the assumption of the stress-mediated version of the ICHH, high plasma levels of corticosterone are not immunosuppressive, but are in fact immuno-enhancing in the presence of high levels of plasma testosterone. Equally, the central assumption of the ICHH that testosterone is obligately immunosuppressive is also not supported. The same individuals with the highest levels of both hormones and consequently the most robust antibody response also possessed the lowest body mass. [Copyright &y& Elsevier]

The utilization of a fuzzy aspect within data analysis attempts to move from a quantitative to a more qualitative investigative environment. As such, this may allow the more non-quantitative researchers results they can use, based on sets of linguistic terms. In this paper an inductive fuzzy decision tree approach is utilized to construct a fuzzy-rule-based system for the first time in a biological setting. The specific biological problem considered attempts to identify the antecedents (conditions in the fuzzy decision rules) which characterize the length of song flight of the male sedge warbler when attempting to attract a mate. Hence, for a non-quantitative investigator the resultant set of fuzzy rules allows an insight into the linguistic interpretation on the relationship between associated characteristics and the respective song flight duration. [ABSTRACT FROM AUTHOR]

• We quantified a temporal window for avian maternal corticosterone yolk deposition. • Oral dosing at ovulation elevated both maternal plasma and egg yolk corticosterone. • Elevated maternal corticosterone did not affect maternal reproductive outputs. • Yolk corticosterone concentrations did not differ with egg order or yolk layers. • Maternal corticosterone variations at ovulation may impact offspring development. Maternally-derived hormones affect offspring physiological and behavioural phenotype, plausibly as an adaptive response to maternal environmental conditions. Corticosterone (CORT), the principal avian glucocorticoid produced in response to stress, is recognised as a potential mediator of such maternal reproductive effects. Maternally-derived yolk CORT is implicated in mediating offspring growth and hatchling begging behaviour. However, determining the potential for maternal effects in opportunistic breeders subject to variable environments relies on understanding whether natural variation in maternal circulating hormones may directly impact the embryo during development. Therefore, we tested whether elevated maternal CORT concentrations increase yolk CORT concentrations in zebra finch (Taeniopygia guttata) eggs. We remotely dosed breeding females with biologically-relevant doses of CORT, or the oil vehicle, 0–3 h prior to the predicted time of ovulation, and allowed pairs to produce two clutches, one under each treatment, in a crosswise, balanced design. CORT dosing elevated maternal plasma CORT and increased mean yolk CORT by a factor of 1.75 compared to the egg yolks of control mothers. Importantly, CORT concentrations did not differ between inner and outer layers of yolk. We found no egg lay order effect and maternal CORT dosing did not influence reproductive outputs (clutch initiation date, clutch size or egg mass). Our results confirm the direct impact of biologically-relevant increases in maternal CORT on yolk CORT, providing evidence that maternal CORT concentrations during yolk deposition to the follicle alters embryonic exogenous CORT exposure. Further research is required to determine the impact of maternal CORT on embryonic developmental programming. [ABSTRACT FROM AUTHOR]

Presents a study on the sedge warbler which examines the phenotype-linked fertility hypothesis. What phenotype-linked fertility hypothesis states; Methods used in the study; Comparison of song measures, morphology and reproductive anatomy in a population of male sedge warblers.

It is of no news to the readership of I Emu Austral Ornithology i that birds are in trouble. It is in this environment I Emu Austral Ornithology i has instigated a new format of publication, the Ornithological Forum. The motivation for the Ornithological Forum is not solely to document conservation-related topics, but the current state of the world's birds may mean this forms a primary focus. [Extracted from the article]

It is possible that the reproductive strategy of the short-beaked echidna is related to seasonal changes in fat deposition and energy availability, regulated by seasonal changes in endocrine function. We predicted that circulating leptin levels would be directly proportional to adiposity during most of the year, but that a change in this relationship would occur during the pre-breeding season to allow increased fat deposition. To test this hypothesis, we made use of a captive colony of echidnas to describe and quantify changes in fat distribution and the adipostatic hormone leptin. First we assessed seasonal changes in circulating leptin levels, body mass and adiposity for three male and three female adult echidnas maintained on a standard diet. Second, we explored the relationship between circulating leptin levels and increased caloric intake for an additional five adult female echidnas that were provided with supplemented nutrition. Third we visualised fat distribution in male and female adult echidnas using magnetic resonance imaging (MRI) before and after the breeding season, to determine where fat is deposited in this species. For echidnas maintained on the standard diet, there were no seasonal changes in body mass, body fat or plasma leptin levels. However, female echidnas provided with supplemented nutrition had significantly elevated plasma leptin levels during the breeding season, compared to the pre-and post- breeding periods. MRI showed substantial subcutaneous fat depots extending dorso-laterally from the base of the skull to the base of the tail, in both sexes. Pre-breeding season, both sexes had considerable fat deposition in the pelvic/rump region, whilst the female echidna accumulated most fat in the abdominal region. This study shows that male and female echidnas accumulate body fat in the pelvic/rump and the abdominal regions, respectively and that circulating leptin may promote fattening in female echidnas during the breeding season by means of leptin resistance. However, further research is required to evaluate the precise relationship between seasonal changes in leptin and adiposity. [ABSTRACT FROM AUTHOR]

Cultural and genetic inheritance combine to enable rapid changes in trait expression, but their relative importance in determining trait expression across generations is not clear. Birdsong is a socially learned cognitive trait that is subject to both cultural and genetic inheritance, as well as being affected by early developmental conditions. We sought to test whether early-life conditions in one generation can affect song acquisition in the next generation. We exposed one generation (F1) of nestlings to elevated corticosterone (CORT) levels, allowed them to breed freely as adults, and quantified their son's (F2) ability to copy the song of their social father. We also quantified the neurogenetic response to song playback through immediate early gene (IEG) expression in the auditory forebrain. F2 males with only one corticosterone-treated parent copied their social father's song less accurately than males with two control parents. Expression of ARC in caudomedial nidopallium (NCM) correlated with father-son song similarity, and patterns of expression levels of several IEGs in caudomedial mesopallium (CMM) in response to father song playback differed between control F2 sons and those with a CORT-treated father only. This is the first study to demonstrate that developmental conditions can affect social learning and neurogenetic responses in a subsequent generation. [ABSTRACT FROM AUTHOR]

Conditions experienced prenatally, by modulating developmental processes, have lifelong effects on individual phenotypes and fitness, ultimately influencing population dynamics. In addition to maternal biochemical cues, prenatal sound is emerging as a potent alternative source of information to direct embryonic development. Recent evidence suggests that prenatal acoustic signals can program individual phenotypes for predicted postnatal environmental conditions, which improves fitness. Across taxonomic groups, embryos have now been shown to have immediate adaptive responses to external sounds and vibrations, and direct developmental effects of sound and noise are increasingly found. Establishing the full developmental, ecological, and evolutionary impact of early soundscapes will reveal how embryos interact with the external world, and potentially transform our understanding of developmental plasticity and adaptation to changing environments. Prenatal sounds and vibrations from parents, siblings, or the environment are used by embryos across taxonomic groups to obtain information on the external world and respond to risks and opportunities. Acoustic signals are used at transitions between life stages to optimize that transition (e.g., hatching time) or the postnatal phenotype. Prenatal sounds can directly alter developmental trajectories and provide accurate anticipatory cues to program offspring for particular postnatal environments. Acoustic developmental programming affects individual physiology and cognition through changes in brain connectivity, endocrinology, and gene expression. Acoustic signals differ from maternal nutritional and endocrine cues in multiple ways, and this has implications for conflict and coadaptation within the family, as well as for adaptation to rapidly changing environments. [ABSTRACT FROM AUTHOR]

Avian embryos develop in an egg composition which reflects both maternal condition and the recent environment of their mother. In birds, yolk corticosterone (CORT) influences development by impacting pre‐ and postnatal growth, as well as nestling stress responses and development. One possible mechanism through which maternal CORT may affect offspring development is via changes to offspring DNA methylation. We sought to investigate this, for the first time in birds, by quantifying the impact of manipulations to maternal CORT on offspring DNA methylation. We non‐invasively manipulated plasma CORT concentrations of egg‐laying female zebra finches (Taeniopygia castanotis) with an acute dose of CORT administered around the time of ovulation and collected their eggs. We then assessed DNA methylation in the resulting embryonic tissue and in their associated vitelline membrane blood vessels, during early development (5 days after lay), using two established methods – liquid chromatography–mass spectrometry (LC–MS) and methylation‐sensitive amplification fragment length polymorphism (MS‐AFLP). LC–MS analysis showed that global DNA methylation was lower in embryos from CORT‐treated mothers, compared to control embryos. In contrast, blood vessel DNA from eggs from CORT‐treated mothers showed global methylation increases, compared to control samples. There was a higher proportion of global DNA methylation in the embryonic DNA of second clutches, compared to first clutches. Locus‐specific analyses using MS‐AFLP did not reveal a treatment effect. Our results indicate that an acute elevation of maternal CORT around ovulation impacts DNA methylation patterns in their offspring. This could provide a mechanistic understanding of how a mother's experience can affect her offspring's phenotype. [ABSTRACT FROM AUTHOR]

Highlights • Developmental CORT reduces nestling body mass and body size. • Effects of developmental CORT treatment on body size last into adulthood. • Popular condition indices are not good predictors of nestling relative body fat. Abstract Animals exposed to stressful developmental conditions can experience sustained physiological, behavioral, and fitness effects. While extensive research shows how developmental stress affects development, few studies have examined the effects on body composition. To test the effects of developmental stress on nestling and adult body composition, we dosed nestling zebra finches (Taeniopygia guttata) with either a corticosterone (CORT) or control treatment. We calculated condition indices (scaled mass, residual mass, and ratio indices) from morphometric measurements and used quantitative magnetic resonance (QMR) to assess body composition during early development and adulthood. We compared these three traditionally-used condition indices to QMR-derived body composition measurements, to test how well they predict relative fat mass. Our results show that developmental stress decreases body mass, and has a dose-dependent effect on tarsus length in nestling birds. Furthermore, stress treatment during the nestling period had long-lasting effects on adult body mass, lean mass and tarsus length. None of the three condition indices were good indicators of relative fat mass in nestlings, but all indices were closely associated with relative fat mass in adults. The scaled mass index was more closely associated with relative fat mass than the other condition indices, when calculated from wing chord length in nestlings. In adults however, the residual mass index and the ratio index were better indicators of relative body fat than the scaled mass index, when calculated from tarsus length. Our data demonstrate the short and long-term impact of developmental stress on birds, and highlight important age-related factors to consider when using condition indices. [ABSTRACT FROM AUTHOR]

The author discusses how developmental stress hypothesis is compared with the evolution of condition-dependent sexual traits. According to her, the developmental stress hypothesis was proposed as a special case due to its mechanism. She states that some aspect of the hypothesis is that the mechanism can be defined and effects can be tested. K. A. Spencer and S. A. MacDougall-Shackleton made a comparison on the study of fluctuating asymmetry (FA) which has been considered as indicator of developmental stress.

A letter to the editor is presented in response to the article "Stress and sexual signaling: a systematic review and meta-analysis" by F. R. Moore and colleagues that was published in the previous issue.

A species' success during the invasion of new areas hinges on an interplay between the demographic processes common to invasions and the specific ecological context of the novel environment. Evolutionary genetic studies of invasive species can investigate how genetic bottlenecks and ecological conditions shape genetic variation in invasions, and our study pairs two invasive populations that are hypothesized to be from the same source population to compare how each population evolved during and after introduction. Invasive European starlings (Sturnus vulgaris) established populations in both Australia and North America in the 19th century. Here, we compare whole‐genome sequences among native and independently introduced European starling populations to determine how demographic processes interact with rapid evolution to generate similar genetic patterns in these recent and replicated invasions. Demographic models indicate that both invasive populations experienced genetic bottlenecks as expected based on invasion history, and we find that specific genomic regions have differentiated even on this short evolutionary timescale. Despite genetic bottlenecks, we suggest that genetic drift alone cannot explain differentiation in at least two of these regions. The demographic boom intrinsic to many invasions as well as potential inversions may have led to high population‐specific differentiation, although the patterns of genetic variation are also consistent with the hypothesis that this infamous and highly mobile invader adapted to novel selection (e.g., extrinsic factors). We use targeted sampling of replicated invasions to identify and evaluate support for multiple, interacting evolutionary mechanisms that lead to differentiation during the invasion process. [ABSTRACT FROM AUTHOR]

Opportunistic breeding is a strategy used to maximize reproductive success in unpredictable environments. Birds that breed opportunistically are thought to maintain partial activation of the reproductive axis in order to rapidly initiate breeding when environmental conditions become suitable. The physiological mechanisms that modulate reproduction in seasonally breeding birds have been well explored. In contrast, the physiological mechanisms that allow opportunistic breeding birds to maintain a continued state of reproductive readiness has not been well established. Here, we tested the hypothesis that reproductive readiness is modulated through condition-mediated effects on the hypothalamic–pituitaryadrenal (HPA) axis and its downstream effects on corticosterone (CORT) secretion in wild zebra finches ( Taeniopygia guttata ). We examined the variation in body condition, HPA-axis activity (endogenous and adrenocorticotropic hormone (ACTH)-induced responses), and hypothalamic-pituitary-gonadal (HPG) axis activity activity (baseline and gonadotropin-releasing hormone (GnRH) induced testosterone and estradiol levels) in zebra finches across five sites in the Northern Territory in Australia. We found that birds at the sites in the lowest condition had the highest level of baseline and peak CORT. Additionally, males at the sites in the lowest condition had the highest fold increase in testosterone following a GnRH challenge. Across sites, birds with low body condition had high baseline, peak, and ACTH-induced levels of CORT. Our data suggest that reproductive readiness in opportunistically breeding birds is modulated by condition-mediated trade-offs between the HPA- and the HPG-axes. Further work is needed to understand the environmental conditions that influence reproductive activation in opportunistically breeding birds. [ABSTRACT FROM AUTHOR]

Summary: Mean air temperatures and the frequency, intensity and duration of extreme weather events such as heatwaves are increasing due to climate change. Nest boxes experience more variable and extreme temperatures than natural cavities, which may reduce survival and reproductive success of the species which utilize them, but little is known about the factors which drive nest box temperature profiles. We quantified the potential for retrofitted insulation on nest boxes to modify internal temperatures and to mimic the thermal characteristics of natural cavities more closely. We tested three types of materials with insulative or reflective properties which were easy to retrofit to nest boxes: 3‐cm‐thick polystyrene, pleated foil batts and reflective paint. We found that polystyrene and foil batts reduced mean nest box temperatures during the day by 0.31 ± 0.01°C and 0.17 ± 0.01°C, respectively (but up to 5.84°C and 4.02°C). The effects of all insulation types were dependent on the time of day, and only polystyrene had a significant effect at night, with a greater capacity to retain heat (mean 0.21 ± 0.01°C warmer). Contrary to expectations, reflective paint caused a small increase in temperature during the late afternoon. In our study, the temperature modulation provided by insulation was able to match or exceed that due to variation in nest location and surrounding vegetation canopy cover. Our findings show that polystyrene and foil batts may offer effective and tractable means to mitigate the effects of extreme temperatures in nest boxes and thereby help achieve temperature profiles more similar to natural cavities. [ABSTRACT FROM AUTHOR]

The role of olfactory eavesdropping in interactions between mammalian predator and prey species is well established. Bird plumage can be odorous and consequently nest predators could use odor to identify and locate avian prey, and nest competitors could use odor to assess occupancy of nest cavities by birds. However, despite extensive research on avian nest predation and competition, the costs of olfactory eavesdropping on plumage odor by nest predators or competitors remain largely unknown. We used two experiments to investigate whether feather odor is detected by marsupial species which are competitors for nest hollows and predators of eggs and nestlings of crimson rosellas, Platycercus elegans. In the first experiment, odor presentation at nest boxes utilized by ringtail possums ( Pseudocheirus peregrinus) and rosellas showed that the latency of possums to enter the nest was shorter when crimson rosella odor was present compared to the controls. In the second experiment, carried out away from nest hollows, brushtail possums ( Trichosurus vulpecula) discriminated odors of two predators (dingo, Canis lupus dingo, and cat, Felis catus) from crimson rosella and control odors; however, they did not discriminate between crimson rosella odor and a control. We show that marsupials may use feather odor cues to assess nest hollow status, information which could aid their detection of avian prey or their vigilance at nest hollows (for which they compete with parrots). To our knowledge, our study is the first to show that wild mammalian predators and competitors of birds respond to plumage odor at nests and suggest that odor signaling may have hitherto unrecognized costs for birds. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "Male-to-Female Testosterone Ratios, Dimorphism and Life History--What Does It Really Tell Us?" by W. Goymann and J. C. Wingfield which appeared in the issue.

An introduction to this issue of "Emu: Austral Ornithology," is presented.

The article discusses aspects of the hybridisation and the future of austral ornithology. It notes that hybridisation is an evolutionary process by which two species combine to generate a different form, capturing the most successful traits of each parent, while displaying additional characteristics not found in the original two species. It talks about the hybridisation of the two leading ornithological conservation organisations in Australia, the Birds Australia and the Bird Observation and Conservation Australia (BOCA). It also tackles the history of both organisations the impact of its merger on the Australian ornithology.

An introduction to the journal is presented which discusses various papers published within the issue, including one on strategies for protecting shorebird populations along the Chinese Yellow Sea coast, one on geographic variation in shorebird population trends within Australia, and another on the decline in shorebird numbers in Saemangeum, Korea as a result of a seawall construction.

The European starling, Sturnus vulgaris, is an ecologically significant, globally invasive avian species that is also suffering from a major decline in its native range. Here, we present the genome assembly and long‐read transcriptome of an Australian‐sourced European starling (S. vulgaris vAU), and a second, North American, short‐read genome assembly (S. vulgaris vNA), as complementary reference genomes for population genetic and evolutionary characterization. S. vulgaris vAU combined 10× genomics linked‐reads, low‐coverage Nanopore sequencing, and PacBio Iso‐Seq full‐length transcript scaffolding to generate a 1050 Mb assembly on 6222 scaffolds (7.6 Mb scaffold N50, 94.6% busco completeness). Further scaffolding against the high‐quality zebra finch (Taeniopygia guttata) genome assigned 98.6% of the assembly to 32 putative nuclear chromosome scaffolds. Species‐specific transcript mapping and gene annotation revealed good gene‐level assembly and high functional completeness. Using S. vulgaris vAU, we demonstrate how the multifunctional use of PacBio Iso‐Seq transcript data and complementary homology‐based annotation of sequential assembly steps (assessed using a new tool, saaga) can be used to assess, inform, and validate assembly workflow decisions. We also highlight some counterintuitive behaviour in traditional busco metrics, and present buscomp, a complementary tool for assembly comparison designed to be robust to differences in assembly size and base‐calling quality. This work expands our knowledge of avian genomes and the available toolkit for assessing and improving genome quality. The new genomic resources presented will facilitate further global genomic and transcriptomic analysis on this ecologically important species. [ABSTRACT FROM AUTHOR]