Responses in the breeding parameters of the collared flycatcher to the changing climate.

Global climate change involves various aspects of climate, including precipitation changes and declining surface wind speeds, but studies investigating biological responses have often focused on the impacts of rising temperatures. Additionally, related long-term studies on bird reproduction tend to concentrate on breeding onset, even though other aspects of breeding could also be sensitive to the diverse weather aspects. This study aimed to explore how multiple aspects of breeding (breeding onset, hatching delay, breeding season length, clutch size, fledgling number) were associated with different weather components. We used an almost four-decade-long dataset to investigate the various aspects of breeding parameters of a collared flycatcher (Ficedula albicollis) population in the Carpathian Basin. Analyses revealed some considerable associations, for example, breeding seasons lengthened with the amount of daily precipitation, and clutch size increased with the number of cool days. Parallel and opposing changes in the correlated pairs of breeding and weather parameters were also observed. The phenological mismatch between prey availability and breeding time slightly increased, and fledgling number strongly decreased with increasing mistiming. Our results highlighted the intricate interplay between climate change and the reproductive patterns of migratory birds, emphasizing the need for a holistic approach. The results also underscored the potential threats posed by climate change to bird populations and the importance of adaptive responses to changing environmental conditions.

Density dependence of songbird demographics in grazed sagebrush steppe.

Sagebrush steppe is one of the most threatened ecosystems in North America. Adult density of songbirds within sagebrush steppe is a metric used to evaluate conservation actions. However, relying on only adult density to guide conservation may be misleading. Information on how conservation actions influence the nest density and nest survival of songbird species, in addition to adult density, are needed. We evaluated the relationships between nest density, nest survival, and adult density of Brewer's sparrow (Spizella breweri) and vesper sparrow (Pooecetes gramineus) over 3 breeding seasons in central Montana. Our findings suggest that adult pairs of both species were often present in higher numbers than nests, and this relationship was most prominent for Brewer's sparrows. However, our results do not support density dependence when considering nest survival. This discrepancy suggests that songbirds may not breed every year and that density dependence may be operating on nest densities within these populations differently than we examined. This study provides information on relationships between population demographics for 2 songbird species in grazed sagebrush steppe that will improve monitoring and management activities of conservation efforts.

Photoperiod-driven concurrent changes in hypothalamic and brainstem transcription of sleep and immune genes in migratory redheaded bunting.

The molecular regulation of sleep in avian migrants is still obscure. We thus investigated this in migratory redheaded buntings, where four life-history states (LHS; i.e. non-migratory, pre-migratory, migratory and refractory states) were induced. There was increased night-time activity (i.e. Zugunruhe) during the migratory state with reduced daytime activity. The recordings of the sleep-wake cycle in buntings showed increased night-time active wakefulness coupled with drastically reduced front and back sleep during migratory phase. Interestingly, we found the buntings to feed and drink even after lights-off during migration. Gene expression studies revealed increased hypothalamic expression of glucocorticoid receptor (nr3c1), and pro-inflammatory cytokines (il1b and il6) in pre-migratory and migratory states, respectively, whereas in brainstem Ca2+/calmodulin-dependent protein kinase 2 (camk2) was upregulated during the migratory state. This suggested a heightened pro-inflammatory state during migration which is a feature of chronic sleep loss, and a possible role of Ca2+ signalling in promoting wakefulness. In both the hypothalamus and brainstem, the expression of melatonin receptors (mel1a and mel1b) was increased in the pre-migratory state, and growth hormone-releasing hormone (ghrh, known to induce sleep) was reduced during the migratory state. The current results demonstrate key molecules involved in the regulation of sleep-wake cycle across LHS in migratory songbirds.

Prenatal thyroid hormones accelerate postnatal growth and telomere shortening in wild great tits.

The early-life environment is known to affect later-life health and disease, which could be mediated by the early-life programming of telomere length, a key hallmark of ageing. According to the fetal programming of telomere biology hypothesis, variation in prenatal exposure to hormones is likely to influence telomere length. Yet, the contribution of key metabolic hormones, i.e. thyroid hormones (THs), has been largely ignored. We recently showed that in contrast to predictions, exposure to elevated prenatal THs increased postnatal telomere length in wild collared flycatchers, but the generality of such effect, the underlying proximate mechanisms and consequences for survival have not been investigated. We therefore conducted a comprehensive study evaluating the impact of THs on potential drivers of telomere dynamics (growth, post-natal THs, mitochondria and oxidative stress), telomere length and medium-term survival using wild great tits as a model system. While prenatal THs did not significantly affect telomere length a week after hatching (i.e. day 7), they influenced postnatal telomere shortening (i.e. shorter telomeres at day 14 and the following winter) but not apparent survival. Circulating THs, mitochondrial density or oxidative stress biomarkers were not significantly influenced, whereas the TH-supplemented group showed accelerated growth, which may explain the observed delayed effect on telomeres. We discuss several alternative hypotheses that may explain the contrast with our previous findings in flycatchers. Given that shorter telomeres in early life tend to be carried until adulthood and are often associated with decreased survival prospects, the effects of prenatal THs on telomeres may have long-lasting effects on senescence.

Hypothalamic molecular correlates of photoperiod-induced spring migration in intact and castrated male redheaded buntings.

This study investigated the molecular changes associated with neural plasticity in photoperiodic induction of spring migration in intact and castrated redheaded bunting, Emberiza bruniceps. We measured the hypothalamic mRNA expression of genes in birds that were photostimulated into winter non-migratory and spring (vernal) migratory phenotypes under short and long photoperiods, respectively. These included genes associated with the appetitive phase of reproduction (spring migration drive, th and ddc genes encoding for tyrosine hydroxylase and dopamine decarboxylase enzymes, respectively), sleep/awake state (pmch gene encoding for pro-melanin concentrating hormone; hcrt and hcrtr2 encoding for the hypocretin/orexin and its receptor, respectively) and neurogenesis (dcx and neuN coding for doublecortin and neuronal nuclear proteins, respectively). Higher th mRNA levels suggested an upregulated dopamine synthesis in the hypothalamus of spring migrants. Similarly, elevated hcrt and hcrtr2 mRNA levels suggested an increased wakefulness, and those of dcx and neuN genes suggested an enhanced neurogenesis during the spring migration state. Further, compared to intact birds, the lower th and pmch, and higher hcrtr2 and neuN mRNA levels in castrates suggested a role of testicular steroids in modulation of the appetitive phase of reproduction, sleep and awake states, and neurogenesis during spring migration period. These results provide insights into molecular changes linked with important hypothalamic molecular pathways and steroidal influence in the photoperiodic induction of spring migration in obligate migratory songbirds.

Mindful larks and lonely owls: The relationship between chronotype, mental health, sleep quality, and social support in young adults.

Chronotype is related to mental health, with evening chronotypes being more susceptible to psychological disorders than intermediate and morning types. The present study investigated the relationship between chronotype, mental health, sleep quality, and social support in Canadian young adults. We surveyed 3160 university students aged 18-35 years. Participants completed the Morningness-Eveningness Questionnaire, the Hospital Anxiety and Depression Scale, the Mindful Attention Awareness Scale, the Pittsburgh Sleep Quality Index, and the Medical Outcomes Study - Social Support Survey. We conducted Bonferroni-corrected one-way analyses of covariance with post hoc paired comparisons to determine the relationship between the aforementioned variables, with age and sex as covariates. We further looked at the moderation of social support on the relationship between chronotype and sleep quality. Overall, 55%, 36% and 9% of participants were classified as intermediate, evening and morning types, respectively. There was a significant difference between chronotype on levels of depression, anxiety, and sleep quality, with evening types reporting more severe symptomology than morning-types and intermediate types. Morning types reported greater levels of overall social support and mindfulness. Evening types reported the lowest levels of all types of social support. Social support did not moderate the relationship between chronotype and sleep quality. This study further demonstrates the association between worse psychological well-being and eveningness and between more social support, and mindfulness in morning chronotype young adults. Education and intervention are warranted to help evening chronotypes manage the potential negative features of their circadian rhythm, as well as to cultivate a greater sense of social support and mindfulness.

Exploring the perceptual inabilities of Eurasian jays (Garrulus glandarius) using magic effects.

In recent years, scientists have begun to use magic effects to investigate the blind spots in our attention and perception [G. Kuhn, Experiencing the Impossible: The Science of Magic (2019); S. Macknik, S. Martinez-Conde, S. Blakeslee, Sleights of Mind: What the Neuroscience of Magic Reveals about Our Everyday Deceptions (2010)]. Recently, we suggested that similar techniques could be transferred to nonhuman animal observers and that such an endeavor would provide insight into the inherent commonalities and discrepancies in attention and perception in human and nonhuman animals [E. Garcia-Pelegrin, A. K. Schnell, C. Wilkins, N. S. Clayton, Science 369, 1424-1426 (2020)]. Here, we performed three different magic effects (palming, French drop, and fast pass) to a sample of six Eurasian jays (Garrulus glandarius). These magic effects were specifically chosen as they utilize different cues and expectations that mislead the spectator into thinking one object has or has not been transferred from one hand to the other. Results from palming and French drop experiments suggest that Eurasian jays have different expectations from humans when observing some of these effects. Specifically, Eurasian jays were not deceived by effects that required them to expect an object to move between hands when observing human hand manipulations. However, similar to humans, Eurasian jays were misled by magic effects that utilize fast movements as a deceptive action. This study investigates how another taxon perceives the magician's techniques of deception that commonly deceive humans.

Unexpectedly low paternal diversity is associated with infrequent pollinator visitation for a bird-pollinated plant.

The behaviour of pollinators has important consequences for plant mating. Nectar-feeding birds often display behaviour that results in more pollen carryover than insect pollinators, which is predicted to result in frequent outcrossing and high paternal diversity for bird-pollinated plants. We tested this prediction by quantifying mating system parameters and bird visitation in three populations of an understory bird-pollinated herb, Anigozanthos humilis (Haemodoraceae). Microsatellite markers were used to genotype 131 adult plants, and 211 seeds from 23 maternal plants, from three populations. While outcrossing rates were high, estimates of paternal diversity were surprisingly low compared with other bird-pollinated plants. Despite nectar-feeding birds being common at the study sites, visits to A. humilis flowers were infrequent (62 visits over 21,552 recording hours from motion-triggered cameras, or equivalent to one visit per flower every 10 days), and the majority (76%) were by a single species, the western spinebill Acanthorhynchus superciliosus (Meliphagidae). Pollen counts from 30 captured honeyeaters revealed that A. humilis comprised just 0.3% of the total pollen load. For 10 western spinebills, A. humilis pollen comprised only 4.1% of the pollen load, which equated to an average of 3.9 A. humilis pollen grains per bird. Taken together, our findings suggest that low visitation rates and low pollen loads of floral visitors have led to the low paternal diversity observed in this understory bird-pollinated herb. As such, we shed new light on the conditions that can lead to departures from high paternal diversity for plants competing for the pollination services of generalist nectar-feeding birds.

The effect of toxic pyridine-alkaloid secondary metabolites on the sunbird gut microbiome.

Sunbirds feed on tobacco tree nectar which contains toxic nicotine and anabasine secondary metabolites. Our aim was to understand the effect of nicotine and anabasine on the gut microbiota composition of sunbirds. Sixteen captive sunbirds were randomly assigned to two diets: artificial nectar either with (treatment) or without (control) added nicotine and anabasine. Excreta were collected at 0, 2, 4 and 7 weeks of treatment and samples were processed for bacterial culture and high-throughput amplicon sequencing of the 16S rRNA gene. The gut microbiome diversity of the treated and control birds changed differently along the seven-week experiment. While the diversity decreased in the control group along the first three samplings (0, 2 and 4 weeks), it increased in the treatment group. The microbiota composition analyses demonstrated that a diet with nicotine and anabasine, significantly changed the birds' gut microbiota composition compared to the control birds. The abundance of nicotine- and anabasine- degrading bacteria in the excreta of the treated birds, was significantly higher after four and seven weeks compared to the control group. Furthermore, analysis of culturable isolates, including Lactococcus, showed that sunbirds' gut-associated bacteria were capable of degrading nicotine and anabasine, consistent with their hypothesised role as detoxifying and nutritional symbionts.

Central prolactin binding site densities change seasonally in an adult male passerine bird (Junco hyemalis).

Seasonal reproduction is common across temperate zone avian species. In these species, physiological and behavioral adaptations have evolved to change according to day length (i.e., seasonally) in order to maximize reproductive output. The hormone prolactin regulates many aspects of parental care, a critical component of reproductive success. It's secretion in birds has been shown to be under photoperiodic control, with the highest levels measured in the spring and summer months, when birds breed and show parental care. However, to date, no study has tested whether the densities of central prolactin binding sites vary seasonally, which may also account for prolactin's effect on parental care. To test this, we collected brains from free-ranging adult male dark-eyed juncos, Junco hyemalis, a biparental songbird, in the spring, summer, and fall, and used quantitative in vitro autoradiography to compare the densities of specific prolactin binding sites across 20 different brain regions. Prolactin binding sites were found in regions that regulate parental behavior in other avian species. During the summer, several hypothalamic regions that regulate parental care, including the preoptic area and tuberal nucleus, contained lower densities of prolactin binding sites, suggesting exposure to higher endogenous prolactin levels, than at other times. This observation is consistent with the fact that circulating prolactin is highest during summer, when males would be providing care to young. Overall, these data suggest that prolactin binding sites are relatively conserved in the avian brain and that central prolactin activity supports parental care efforts in juncos and other avian species.

Examining the disconnect between prolactin and parental care in avian brood parasites.

Prolactin is often referred to as the "parental hormone" but there are examples in which prolactin and parental behavior are disconnected. One intriguing example is in avian obligate brood parasites; species exhibiting high circulating prolactin but no parental care. To understand this disconnect, we examined transcriptional and behavioral responses to prolactin in brown-headed (Molothrus ater) and bronzed (M aeneus) brood parasitic cowbirds. We first examine prolactin-dependent regulation of transcriptome wide gene expression in the preoptic area (POA), a brain region associated with parental care across vertebrates. We next examined prolactin-dependent abundance of seven parental care-related candidate genes in hypothalamic regions that are prolactin-responsive in other avian species. We found no evidence of prolactin sensitivity in cowbirds in either case. To understand this prolactin insensitivity, we compared prolactin receptor transcript abundance between parasitic and nonparasitic species and between prolactin treated and untreated cowbirds. We observed significantly lower prolactin receptor transcript abundance in brown-headed but not bronzed cowbird POA compared with a nonparasite and no prolactin-dependent changes in either parasitic species. Finally, estrogen-primed female brown-headed cowbirds with or without prolactin treatment exhibited significantly greater avoidance of nestling begging stimuli compared with untreated birds. Taken together, our results suggest that modified prolactin receptor distributions in the POA and surrounding hypothalamic regions disconnect prolactin from parental care in brood parasitic cowbirds.

Spatial variation in bird pollination and its mitigating effects on the genetic diversity of pollen pools accepted by Camellia japonica trees within a population at a landscape level.

Bird pollination can vary spatially in response to spatial fluctuations in flowering even within plant populations. In this study, we examined the hypothesis that the spatial variation in bird pollination may induce mitigating effects, which maintains or increases genetic diversity of pollen pools at local sites with low flowering densities. To test this hypothesis, we analyzed the landscape-level genetic effects within a population of Camellia japonica on the pollen pools accepted by individuals in two reproductive years by using genotypes at eight microsatellite loci of 1323 seeds from 19 seed parents. Regression analyses using the quadratic models of correlated paternity between pollen pools against spatial distances between the seed-parent pairs revealed not only local pollination but also some amount of long-distance pollen dispersal. The genetic diversity of pollen pools accepted by seed parents tended to be negatively related to the densities of flowering individuals near the seed parents during winter (when the effective pollination of C. japonica is mediated mostly by Zosterops japonica). We show that the low density of flowering individuals may induce the expansion of the foraging areas of Z. japonica and consequently increase the genetic diversity of pollen pools. This spatial variation in bird pollination may induce the mitigating effects on the C. japonica population. The comparisons between the two study years indicate that the overall pattern of bird pollination and the genetic effects described here, including the mitigating effects, may be stable over time.

Temperature alters the hypothalamic transcription of photoperiod responsive genes in induction of seasonal response in migratory redheaded buntings.

We investigated the temperature effects on hypothalamic transcription of genes involved in the induction of photoperiodic response in redheaded buntings. Birds were exposed at 22 and 38 °C to 13-h long photoperiods (LP), with controls at 22 °C on 8-h short photoperiods (SP). At 22 °C, compared to SP, we found higher tshb, eya3 and dio2 and low dio3 and gnih mRNA expressions after a week of LP; concomitant with testis recrudescence this confirmed buntings' responsiveness to LP-induced photostimulation. tshb, dio2 and gnrh mRNA levels were further increased by 2.5 weeks of LP at 38 °C. Temperature sensitive trpm8, but not trpv4, bdnf or adcyap1 also showed LP-induced expression at 22 °C. Concomitant changes in dnmt3b and tet2 mRNA expressions further suggested epigenetic modification of temperature influence on photoperiodic responses. These results demonstrate the role of temperature in hypothalamic molecular regulation of the photoperiodic gonadal response in seasonally breeding birds.

Plumage coloration and social context influence male investment in song.

Animals use multiple signals to attract mates, including elaborate song, brightly coloured ornaments and physical displays. Female birds often prefer both elaborate male song and intense carotenoid-based plumage coloration. This could lead less visually ornamented males to increase song production to maximize their attractiveness to females. We tested this possibility in the highly social and non-territorial house finch (Haemorhous mexicanus), in which females discriminate among males based on both song and on the intensity of red carotenoid-based plumage coloration. We manipulated male plumage coloration through carotenoid supplementation during moult, so that males were either red or yellow. Males were then housed under three social environments: (i) all red birds, (ii) all yellow birds or (iii) a mixture of red/yellow birds. We recorded song after presentation of a female. Red males produced more song than yellow males. But when yellow males were housed with red conspecifics, they produced more song relative to yellow males housed with equally unattractive yellow males. This study provides novel evidence that a male's plumage coloration and the plumage colour of his social competitors influence investment in song.

Scotostimulation of reproductive neural pathways and gonadal maturation are not correlated with hypothalamic expression of deiodinases in subtropical spotted munia.

Circannual rhythm regulates the annual timing of reproduction in spotted munia, with sex differences in its relationship with the external photoperiod environment. Interestingly, munia show an atypical photosensitivity and exhibit gonadal maturation when acutely exposed to an unnatural short photoperiod (eg 3 hours of light per day; ie a long scotoperiod). The proximate mechanisms regulating scotoperiod-induced hypothalamic-pituitary-gonadal (HPG) activation are unclear. Because thyroid hormone signalling plays a central role in photoperiodic induction, we hypothesised the involvement of similar mechanism, comprising alterations in hypothalamic deiodinases, under long scotoperiod-induced HPG activation. To test this, several endpoints of cellular and molecular correlates were assayed in male and female munias after 1 and 4 weeks of exposure to an 3:21 hour light/dark cycle (3L:21D), with controls on a 21:3 hour light/dark cycle (21L:3D). We measured the hypothalamic expression of mRNA and protein of light-sensitive (neuropsin, OPN5) and reproductive (vasoactive intestinal peptide [VIP], neuropeptide Y [NPY], gonadotrophin-releasing hormone [GnRH], gonadotrophin-inhibiting hormone [GnIH]) neuropeptides by quantitative polymerase chain reaction (PCR) and immunohistochemistry, respectively. In addition, we also measured mRNA expression of types 2 (DIO2) and 3 (DIO3) deiodinases that regulate triiodothyronine-mediated GnRH release and gonadal maturation in photoperiodic species. The quantitative PCR and immunohistochemistry results were consistent. Higher OPN5 levels under 21L:3D than under 3L:21D suggested its role in sensing the length of the light period. Similarly, low VIP and high NPY expression under 3L:21D than under 21L:3D were consistent with their roles as cellular correlates of photic and nonphotic environment, respectively. High GnRH-I/low GnIH levels and gonadal recrudescence under 3L:21D, and an inverse pattern under 21L:3D, confirmed the scotostimulation of HPG axis in spotted munia. However, DIO2 and DIO3 mRNA levels did not differ between 2 scotoperiods, in contrast to their reciprocal expression pattern found during long-day photostimulation. We demonstrate for the first time sex-dependent scotostimulation of reproductive neural pathways and suggest the involvement of molecules other than hypothalamic deiodinases in the regulation of gonad development cycle in 'nonphotoperiodic' seasonally breeding vertebrates.

Do parasites and antioxidant availability affect begging behaviour, growth rate and resistance to oxidative stress?

Early-life trade-offs faced by developing offspring can have long-term consequences for their future fitness. Young offspring use begging displays to solicit resources from their parents and have been selected to grow fast to maximize survival. However, growth and begging behaviour are generally traded off against self-maintenance. Oxidative stress, a physiological mediator of life-history trade-offs, may play a major role in this trade-off by constraining, or being costly to, growth and begging behaviour. Yet, despite implications for the evolution of life-history strategies and parent-offspring conflicts, the interplay between growth, begging behaviour and resistance to oxidative stress remains to be investigated. We experimentally challenged wild great tit (Parus major) offspring by infesting nests with a common ectoparasite, the hen flea (Ceratophyllus gallinae), and simultaneously tested for compensating effects of increased vitamin E availability, a common dietary antioxidant. We further quantified the experimental treatment effects on offspring growth, begging intensity and oxidative stress. Flea-infested nestlings of both sexes showed reduced body mass during the first half of the nestling phase, but this effect vanished short before fledging. Begging intensity and oxidative stress of both sexes were unaffected by both experimental treatments. Feeding rates were not affected by the experimental treatments, but parents of flea-infested nests fed nestlings with a higher proportion of caterpillars, the main source of antioxidants. Additionally, female nestlings begged significantly less than males in control nests, whereas both sexes begged at similar rates in vitamin E-supplemented nests. Our study shows that a parasite exposure does not necessarily affect oxidative stress levels or begging intensity, but suggests that parents can compensate for negative effects of parasitism by modifying food composition. Furthermore, our results indicate that the begging capacity of the less competitive sex is constrained by antioxidant availability.

Social information changes stress hormone receptor expression in the songbird brain.

Social information is used by many vertebrate taxa to inform decision-making, including resource-mediated movements, yet the mechanisms whereby social information is integrated physiologically to affect such decisions remain unknown. Social information is known to influence the physiological response to food reduction in captive songbirds. Red crossbills (Loxia curvirostra) that were food reduced for several days showed significant elevations in circulating corticosterone (a "stress" hormone often responsive to food limitation) only if their neighbors were similarly food restricted. Physiological responses to glucocorticoid hormones are enacted through two receptors that may be expressed differentially in target tissues. Therefore, we investigated the influence of social information on the expression of the mineralocorticoid receptor (MR) and glucocorticoid receptor (GR) mRNA in captive red crossbill brains. Although the role of MR and GR in the response to social information may be highly complex, we specifically predicted social information from food-restricted individuals would reduce MR and GR expression in two brain regions known to regulate hypothalamic-pituitary-adrenal (HPA) activity - given that reduced receptor expression may lessen the efficacy of negative feedback and release inhibitory tone on the HPA. Our results support these predictions - offering one potential mechanism whereby social cues could increase or sustain HPA-activity during stress. The data further suggest different mechanisms by which metabolic stress versus social information influence HPA activity and behavioral outcomes.

Oxidative status in relation to metal pollution and calcium availability in pied flycatcher nestlings - A calcium manipulation experiment.

Metal exposure can produce oxidative stress by disrupting the prooxidant/antioxidant balance. It has been suggested that calcium (Ca) may provide protection against metal toxicity in the organism. The objective of this study is to explore the effects of Ca availability and metal pollution on oxidative stress biomarkers in pied flycatcher (Ficedula hypoleuca) nestlings. For this purpose, we performed a Ca-supplementation experiment with birds inhabiting a Ca-poor and metal-polluted area in SW Finland. An array of oxidative stress biomarkers (GSH, GSH:GSSG ratio, GPx, GST, CAT, SOD, lipid peroxidation and protein carbonylation) was measured in red blood cells. The effects of antioxidant molecules and oxidative damage on nestling size, growth, fledging success and fledgling number were evaluated. We observed an up-regulation of GST activity and increased protein carbonyl content in the polluted zone, probably related to a combination of higher metal exposure and reduced food quantity and quality in this area. As expected, birds from the unpolluted zone showed higher GSH:GSSG ratio but, unexpectedly, also showed signs of higher lipid peroxidation (not statistically significant, p = 0.056), both responses likely being related with the lower Ca availability. Our study suggests that different measures of oxidative damage are affected by different factors: while damage to proteins was the target of metal exposure/food limitation, poor Ca availability may enhance damage to lipids in growing birds. The intercorrelations found between Ca in plasma, metal exposure and the different oxidative stress biomarkers show that the antioxidant defense is finely regulated to cope with increased oxidative challenges. Finally, our results suggest that the antioxidant status during early development, conditioned by environmental pollution and Ca availability, is one factor affecting nestling survival and fledgling number.

INVESTIGATION OF THE PRESENCE OF ATOXOPLASMA SPP. IN BLUE-CROWNED LAUGHINGTHRUSH (DRYONASTES COURTOISI) ADULTS AND NEONATES.

Between 1996 and 2013, 71 blue-crowned laughingthrush (Dryonastes courtoisi) chicks, a small passerine bird endemic to China, were born at Mulhouse Zoo in northeast France. None of them survived past 1 yr, and 82% died between 0 and 6 days old of an unidentified cause and despite an attempt to establish an artificial breeding protocol. Atoxoplasma spp., causing a disease known as systemic isosporosis, is a coccidian parasite that can infect several species of birds. Mulhouse's adult birds were suspected to be infected with Atoxoplasma spp. and to transmit this parasite to their offspring. A treatment with toltrazuril (Baycox® 2.5%) was implemented in the four adult birds. Coprologic examinations were performed before, during, and after the treatment to quantify the parasite load in feces. Polymerase chain reaction (PCR) assays were used to test blood samples from the adult and liver, lung, gizzard, and kidney samples from 10 chicks to detect Atoxoplasma spp. Five of the 10 chicks had some tissue samples positive for Atoxoplasma spp. in at least one of the three repeats of the atoxoplasmosis PCR. An average of 181 Isospora spp. oocysts per gram of feces were found in the group of adults before treatment. This number was reduced to zero 1 wk after the beginning of the toltrazuril treatment. The PCR results suggest a transovarian transmission of Atoxoplasma spp., but further investigation is needed for confirmation. The treatment with toltrazuril appears to allow a significant reduction of the parasite excretion.