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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]

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]

Across multiple taxa, prenatal exposure to rhythmic sound can promote neural development and alter postnatal behavior. In recent studies using zebra finches, stimulating embryos with parental “heat calls” affected their begging behavior as nestlings and song learning as adults. This song learning effect is potentially mediated by broader changes to offspring behavior that affect how they interact with potential song tutors; however, the long-term behavioral effects of prenatal sound are still poorly understood. In this study, therefore, we used captive wild-derived zebra finches to experimentally test (1) whether prenatal sound experience affected long-term behavioral traits and (2) whether these traits were correlated with song learning outcomes. Offspring that had experienced heat calls (treatment) or contact calls (control) in the egg were raised after hatching in a colony environment. We then used four assays to quantify different aspects of their adult behavior, including food neophobia, detour reaching, and exploration in a novel environment. Treatment offspring were less food neophobic (quicker to eat a novel food item), adding to increasing evidence that prenatal sound can affect long-term behavior. However, levels of food neophobia did not, in turn, predict song learning. Differences in offspring song learning may instead be explained by exploration behavior, as fast-exploring males produced more syllables from non-paternal tutors. While our findings do not support the hypothesis that behavior mediates the effects of prenatal sound on song learning, they nevertheless bring us closer to understanding the behavioral mechanisms through which prenatal sound might affect postnatal outcomes. Significance statement: Sounds experienced inside the egg can influence an individual’s behavior after hatching. In the zebra finch, exposing embryos to a parental “heat call” altered their song learning later in life, but the mechanism driving this effect is unknown. In this study, we tested whether prenatal playback of heat calls affected a suite of adult behavioral traits and whether any of these traits were associated with song learning. Exposure to heat calls produced adult zebra finches that were less neophobic towards a novel food item, but this trait was not itself correlated with song learning. Overall, these findings highlight the importance of the prenatal sound environment for shaping future offspring behavior, which may in turn have unappreciated fitness consequences. [ABSTRACT FROM AUTHOR]

The developmental environment an animal experiences can have a pervasive and sustained effect on phenotype throughout its life. Animals exposed to suboptimal conditions during development can experience physiological trade-offs, leading to seemingly negative phenotypic changes in later life that have been hypothesised to have detrimental effects on fitness. However, few studies have investigated how exposure to suboptimal developmental conditions affects an animal's reproductive behavior and fitness. Here, we determine if elevated levels of corticosterone (CORT; the dominant avian stress hormone) during development affect fitness via changes in reproductive investment in adult zebra finches (Taeniopygia guttata). To do this, we exposed nestling zebra finches to either CORT supplemented or control treatments and assessed their mate selection and reproductive investment as adults, using free choice breeding experiments. We found that breeding pairs of birds from matched developmental treatments (CORT or control) had a shorter latency to lay clutches compared to pairs with mismatched developmental treatments. We found no indication that clutch size or egg mass were affected by developmental treatment. Also, we found no evidence that birds choose mates to match their own developmental treatment. Our results demonstrate that developmental experience may affect reproductive investment through changes to reproductive timing and add to the literature suggesting that pairs with similar developmental backgrounds can coordinate their reproduction more effectively. Significance statement: Developmental stress may reduce the fitness of a breeding pair as a result of its detrimental effect on phenotype and performance. Alternatively, individuals could use indicators of developmental stress to influence mate choice in order to compensate for a poor start to life. Previous studies suggest that birds do assortatively mate by developmental environment, but this has not been tested in a free choice mating context. Using a free choice breeding experiment, we show that pairs of breeding birds lay eggs faster when they have matching developmental environments, regardless of the quality of their developmental environment. This evidence suggests that assortatively mated pairs can potentially offset a bad start to life and maintain fitness in spite of the deleterious effects of developmental stress. [ABSTRACT FROM AUTHOR]

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An amendment to this paper has been published and can be accessed via a link at the top of the paper. [ABSTRACT FROM AUTHOR]

Senescence is widespread in nature, often resulting in diminishing survival or reproduction with age, but its role in age-dependent variation in sexual traits is often poorly understood. One reason is that few studies of sexual traits consider non-linear relationships with age, or only consider a narrow range of years relative to the life span of the species. Birdsong has evolved to allow assessment of conspecific quality in numerous bird species. Whilst theory and empirical work suggests that song may become more elaborate with age, there are a paucity of long-term studies testing whether song is associated with age or longevity. In particular, the occurrence of song senescence has rarely been demonstrated. Using an exceptional long-term dataset for the Seychelles warbler (Acrocephalus sechellensis), we analysed relationships between male song, age, survival, and longevity. This species is a long-lived songbird with early life increases, followed by senescent declines, in survival and reproduction. The study population (Cousin Island, Seychelles) is a closed population, with no depredation of adults, providing an excellent opportunity to study senescence in free-living animals. We tested whether song traits were related to age at recording, future survival, longevity, and territory quality. We found age-dependent changes in five song traits (duration, maximum frequency, peak frequency of songs, and duration and frequency bandwidth of trills). Relationships with age were quadratic, indicating reversal in the expression of song coinciding with the onset of senescence in reproduction and survival in this species. One song trait (trill bandwidth) had a quadratic relationship with future survival, but no song traits were related to longevity, suggesting age-related patterns were not the result of selective disappearance. Our study provides one of the first examples of functional senescence in song, offering new insights into avian senescence. Late-life declines in avian song, and possibly other sexual traits, may be more common than currently known, and may play a fundamental role in age-dependent changes in reproductive success. [ABSTRACT FROM AUTHOR]

Animals thriving in hot deserts rely on extraordinary adaptations and thermoregulatory capacities to cope with heat. Uncovering such adaptations, and how they may be favoured by selection, is essential for predicting climate change impacts. Recently, the arid-adapted zebra finch was discovered to program their offspring's development for heat, by producing 'heat-calls' during incubation in hot conditions. Intriguingly, heat-calls always occur during panting; and, strikingly, avian evaporative cooling mechanisms typically involve vibrating an element of the respiratory tract, which could conceivably produce sound. Therefore, we tested whether heat-call emission results from a particular thermoregulatory mechanism increasing the parent's heat tolerance. We repeatedly measured resting metabolic rate, evaporative water loss (EWL) and heat tolerance in adult wild-derived captive zebra finches (n = 44) at increasing air temperatures up to 44 °C. We found high within-individual repeatability in thermoregulatory patterns, with heat-calling triggered at an individual-specific stage of panting. As expected for thermoregulatory mechanisms, both silent panting and heat-calling significantly increased EWL. However, only heat-calling resulted in greater heat tolerance, demonstrating that "vocal panting" brings a thermoregulatory benefit to the emitter. Our findings therefore not only improve our understanding of the evolution of passerine thermal adaptations, but also highlight a novel evolutionary precursor for acoustic signals. [ABSTRACT FROM AUTHOR]

Sound is arguably the external cue most accessible to embryos of many species, and as such may constitute an unrivalled source of early information. Recent evidence shows that prenatal sounds, similarly to maternal effects, may shape developmental trajectories. Establishing whether parental vocalisations are signals directed at embryos, or parental cues on which embryos eavesdrop, can elucidate whether parents or embryos control developmental outcomes. Prenatal exposure to a characteristic heat-related parental call was recently shown to alter zebra finch growth and fitness. Here, we test the ecological context of this behaviour in the wild, and assess the information value and specificity of this vocalisation for an embryonic audience. We show that wild zebra finches also produce this characteristic call, only at high temperatures. In addition, in the lab, we demonstrate experimentally that calling is specifically triggered by high air temperatures, can occur without an embryonic audience, and importantly, is predicted by individuals' body mass. Overall, our findings reveal a specialised heat vocalisation that enables embryonic eavesdropping, by indicating high ambient temperatures, and parents' capacity to cope with such conditions. This challenges the traditional view of embryos as passive agents of their development, and opens exciting research avenues on avian adaptation to extreme heat. [ABSTRACT FROM AUTHOR]

Songbirds are important models for understanding the mechanisms and fitness consequences of imitative vocal learning. Although the effects of early-life environmental and social conditions on song learning are well-established, the impact of early sound exposure has received surprisingly little attention. Yet recent evidence hints at auditory sensitivity in songbird embryos, including in the zebra finch (Taeniopygia guttata), a classic model species for song learning. Here, we tested whether prenatal exposure to incubation calls—highly rhythmic parental vocalisations produced on the nest—affected song learning in zebra finches. Embryos were exposed in the egg to either incubation (treatment) or contact (control) calls, and after hatching were reared in a large colony. The playback treatment did not affect song complexity nor the accuracy of song copying from the social father, but instead increased learning of non-paternal song syllables. This, in turn, improved males’ mounting success in mating trials. These effects may be attributable to changes in juvenile social behaviours, as playback also influenced male behaviour during mating trials. Our study provides the first experimental evidence that prenatal acoustic environment affects song learning and courtship behaviour in songbirds, thereby raising interesting questions on the role of innate versus acquired biases for vocal learning. [ABSTRACT FROM AUTHOR]