Global invasion history and native decline of the common starling: insights through genetics

Few invasive birds are as globally successful as the Common or European Starling (Sturnus vulgaris). Native to the Palearctic, the starling has been intentionally introduced to North and South America, South Africa, Australia, and the Pacific Islands, enabling us to explore species traits that may contribute to its invasion success. Coupling the rich studies of life history and more recent explorations of genomic variation among invasions, we illustrate how eco-evolutionary dynamics shape the invasion success of this long-studied and widely distributed species. Especially informative is the comparison between Australian and North American invasions, because these populations colonized novel ranges concurrently and exhibit shared signals of selection despite distinct population histories. In this review, we describe population dynamics across the native and invasive ranges, identify putatively selected traits that may influence the starling’s spread, and suggest possible determinants of starling success world-wide. We also identify future opportunities to utilize this species as a model for avian invasion research, which will inform our understanding of species’ rapid evolution in response to environmental change.

Transcript- and annotation-guided genome assembly of the European starling

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.

Bird Welfare in Zoos and Aquariums: General Insights across Industries

Animal welfare is a priority across accredited zoological institutions; however, historically, research has been prioritized for mammals. Bird-focused studies accounted for less than 10% of welfare research in zoos and aquariums over the last ten years. Due to the lack of scientific publications on bird welfare, zoo scientists and animal practitioners can look to other industries such as agriculture, laboratories, and companion animal research for insight. This qualitative review highlights findings across industries to inform animal care staff and scientists on the welfare needs of birds within zoos and aquariums. Specifically, the review includes an overview of research on different topics and a summary of key findings across nine resources that affect bird welfare. We also highlight areas where additional research is necessary. Future welfare research in zoos and aquariums should prioritize studies that consider a diversity of bird species across topics and work to identify animal-based measures with empirical evidence. Moving forward, research from other industries can help develop innovative research on bird welfare within zoos and aquariums.

Beyond the Chicken: Alternative Avian Models for Developmental Physiological Research

Biomedical research focusing on physiological, morphological, behavioral, and other aspects of development has long depended upon the chicken (Gallus gallus domesticus) as a key animal model that is presumed to be typical of birds and generally applicable to mammals. Yet, the modern chicken in its many forms is the result of artificial selection more intense than almost any other domesticated animal. A consequence of great variation in genotype and phenotype is that some breeds have inherent aberrant physiological and morphological traits that may show up relatively early in development (e.g., hypertension, hyperglycemia, and limb defects in the broiler chickens). While such traits can be useful as models of specific diseases, this high degree of specialization can color general experimental results and affect their translational value. Against this background, in this review we first consider the characteristics that make an animal model attractive for developmental research (e.g., accessibility, ease of rearing, size, fecundity, development rates, genetic variation, etc.). We then explore opportunities presented by the embryo to adult continuum of alternative bird models, including quail, ratites, songbirds, birds of prey, and corvids. We conclude by indicating that expanding developmental studies beyond the chicken model to include additional avian groups will both validate the chicken model as well as potentially identify even more suitable avian models for answering questions applicable to both basic biology and the human condition.

Research-Relevant Background Lesions and Conditions in Common Avian and Aquatic Species

Non-mammalian vertebrates including birds, fish, and amphibians have a long history of contributing to ground-breaking scientific discoveries. Because these species offer several experimental advantages over higher vertebrates and share extensive anatomic and genetic homology with their mammalian counterparts, they remain popular animal models in a variety of fields such as developmental biology, physiology, toxicology, drug discovery, immunology, toxicology, and infectious disease. As with all animal models, familiarity with the anatomy, physiology, and spontaneous diseases of these species is necessary for ensuring animal welfare, as well as accurate interpretation and reporting of study findings. Working with avian and aquatic species can be especially challenging in this respect due to their rich diversity and array of unique adaptations. Here, we provide an overview of the research-relevant anatomic features, non-infectious conditions, and infectious diseases that impact research colonies of birds and aquatic animals, including fish and Xenopus species.

The Impact of Acute Loud Noise on the Behavior of Laboratory Birds

Husbandry procedures and facility settings, such as low-frequency fire alarms, can produce noises in a laboratory environment that cause stress to animals used in research. However, most of the data demonstrating harmful effects that have, consequently, led to adaptations to management, have largely come from laboratory rodents with little known of the impacts on avian behavior and physiology. Here we examined whether exposure to a routine laboratory noise, a low-frequency fire alarm test, induced behavioral changes in laboratory zebra finches (Taeniopygia guttata). Twenty-four breeding pairs of zebra finches were randomly selected and exposed to the low-frequency fire alarm (sounding for 10-20 s) or no noise (control) on separate test days. All birds were filmed before and after the alarm sounded and on a control day (without the alarm). The zebra finches decreased their general activity and increased stationary and social behaviors after exposure to the alarm. Brief exposure to a low-frequency alarm disrupted the birds' behavior for at least 15 min. The induction of this behavioral stress response suggests that low-frequency sound alarms in laboratory facilities have the potential to compromise the welfare of laboratory birds.

Experimental traffic noise attracts birds during the breeding season

Understanding how anthropogenic disturbance affects animal behavior is challenging because observational studies often involve co-occurring disturbances (e.g., noise, lighting, and roadways), and laboratory experiments often lack ecological validity. During the 2016 and 2017 avian breeding seasons, we investigated the effects of anthropogenic noise and light on the singing and spatial behavior of wild birds by independently manipulating the presence of each type of disturbance at 89 sites in an otherwise undisturbed boreal forest in Labrador, Canada. Each treatment was surrounded by an eight-channel microphone array that recorded and localized avian vocalizations throughout the manipulation. We analyzed the effects of noise and light on the timing of the first vocalizations of each species at each array during the dawn chorus, and on the proximity of the vocalizing birds to the disturbance when those songs were produced. We analyzed all species combined, and then conducted separate analyses for the six most common species: boreal chickadee, dark-eyed junco, ruby-crowned kinglet, Swainson’s thrush, white-throated sparrow, and yellow-rumped warbler. When all species were analyzed together, we found that traffic noise attracted vocalizing birds. There was some evidence that light repelled birds, but this evidence was inconsistent. In our species-specific analyses, yellow-rumped warbler sang earlier in response to noise; Swainson’s thrush was attracted to noise and the combination of noise and light but repelled by light alone. Our study provides some of the first experimental evidence of the independent and combined effects of traffic noise and light on the vocal and spatial behavior of wild birds and suggests that breeding birds may be attracted to noisy roads where they could be exposed to additional forms of disturbance.

Could Greater Time Spent Displaying Waking Inactivity in the Home Environment Be a Marker for a Depression-Like State in the Domestic Dog?

Dogs exposed to aversive events can become inactive and unresponsive and are commonly referred to as being "depressed", but this association remains to be tested. We investigated whether shelter dogs spending greater time inactive "awake but motionless" (ABM) in their home-pen show anhedonia (the core reduction of pleasure reported in depression), as tested by reduced interest in, and consumption of, palatable food (KongTM test). We also explored whether dogs being qualitatively perceived by experts as disinterested in the food would spend greater time ABM (experts blind to actual inactivity levels). Following sample size estimations and qualitative behaviour analysis (n = 14 pilot dogs), forty-three dogs (6 shelters, 22F:21M) were included in the main study. Dogs relinquished by their owners spent more time ABM than strays or legal cases (F = 8.09, p = 0.032). One significant positive association was found between the KongTM measure for average length of KongTM bout and ABM, when length of stay in the shelter was accounted for as a confounder (F = 3.66, p = 0.035). Time spent ABM also correlated with scores for "depressed" and "bored" in the qualitative results, indirectly suggesting that experts associate greater waking inactivity with negative emotional states. The hypothesis that ABM reflects a depression-like syndrome is not supported; we discuss how results might tentatively support a "boredom-like" state and further research directions.

A Bird's-Eye View of Regulatory, Animal Care, and Training Considerations Regarding Avian Flight Research

A thorough understanding of how animals fly is a central goal of many scientific disciplines. Birds are a commonly used model organism for flight research. The success of this model requires studying healthy and naturally flying birds in a laboratory setting. This use of a nontraditional laboratory animal species presents unique challenges to animal care staff and researchers alike. Here we review regulatory, animal care, and training considerations associated with avian flight research.

Enclosure design for flock-level, chronic exposure of birds to air contaminant mixtures

The objective of this study was to design an enclosure suitable for studying the ecotoxicological effects of vehicle emissions on groups of wild birds without compromising welfare. Two, adjacent enclosures sheltered from sunlight, wind and rain, were bird-proofed and wrapped with thick polyethylene sheeting. Emissions were directed into the treatment enclosure from the exhaust of a light-duty gasoline truck, using flexible, heat-proof pipe, with joins sealed to prevent leakage. During active exposure, the engine was idled for 5 h/day, 6 days/week for 4 weeks. Fans maintained positive pressure (controls) and negative pressure (treatment), preventing cross-contamination of enclosures and protecting investigators. Four sets of passive, badge-type samplers were distributed across each enclosure, measuring nitrogen dioxide, sulfur dioxide and volatile organic compounds (NO₂, SO₂ and VOCs, respectively), and were complemented by active monitors measuring VOCs and particulate matter (2.5 µm diameter, PM_2.5). We found that the concentrations of NO₂, SO₂ and PM_2.5 were not different between treatment and control enclosures. Volatile organic compounds (e.g. benzene, toluene, ethylbenzene and xylenes) were approximately six times higher in the treatment enclosure than control (13.23 and 2.13 µg m^-1, respectively). In conclusion, this represents a successful, practical design for studying the effects of sub-chronic to chronic exposure to realistic mixtures of vehicle exhaust contaminants, in groups of birds. Recommended modifications for future research include a chassis dynamometer (vehicle treadmill), to better replicate driving conditions including acceleration and deceleration.

Biomarker Sensitivity to Vehicle Exhaust in Experimentally Exposed European Starlings

The effects of vehicle-related emissions on health has been a long-standing question in human health sciences; however, the toxicology of chronic exposure to environmentally relevant concentrations of these complex mixtures has not been characterized in wild birds. Adult European starlings (Sturnus vulgaris) were exposed to vehicle emissions, with combined benzene, toluene, ethylbenzene, and xylenes (BTEX) concentrations totaling 13.3 μg/m³ over 20 days of exposure for 5 h per day. Exposed birds had significantly lower cell-mediated immunity (measured using phytohaemagglutinin skin test, p < 0.0001), thyroxine (T4, p = 0.042), and glutathione (GSH, p = 0.034) concentrations than control birds. There was no difference in body condition, antibody response to vaccination, triiodothyronine (T3), hepatic biotransformation (7-ethoxyresorufin-O-deethylase activity), or oxidative stress (thiobarbituric acid-reactive substances and ratios of reduced to oxidized GSH) or organ masses between exposed and control birds. This study supports findings of previous studies examining wild birds exposed to these air contaminants and raises concern that environmentally relevant concentrations of common urban volatile pollutants may have measurable effects on health.

Commonly Used Animal Models

This chapter provides an introduction to animals that are commonly used for research. It presents information on basic care topics such as biology, behavior, housing, feeding, sexing, and breeding of these animals. The chapter provides some insight into the reasons why these animals are used in research. It also gives an overview of techniques that can be utilized to collect blood or to administer drugs or medicine. Each section concludes with a brief description of how to recognize abnormal signs, in addition to lists of various diseases.

Developmental telomere attrition predicts impulsive decision-making in adult starlings

Animals in a poor biological state face reduced life expectancy, and as a consequence should make decisions that prioritize immediate survival and reproduction over long-term benefits. We tested the prediction that if, as has been suggested, developmental telomere attrition is a biomarker of state and future life expectancy, then individuals who have undergone greater developmental telomere attrition should display greater choice impulsivity as adults. We measured impulsive decision-making in a cohort of European starlings (Sturnus vulgaris) in which we had previously manipulated developmental telomere attrition by cross-fostering sibling chicks into broods of different sizes. We show that as predicted by state-dependent optimality models, individuals who had sustained greater developmental telomere attrition and who had shorter current telomeres made more impulsive foraging decisions as adults, valuing smaller, sooner food rewards more highly than birds with less attrition and longer telomeres. Our findings shed light on the biological embedding of early adversity and support a functional explanation for its consequences that could be applicable to other species, including humans.

Opposite Effects of Early-Life Competition and Developmental Telomere Attrition on Cognitive Biases in Juvenile European Starlings

Moods are enduring affective states that we hypothesise should be affected by an individual's developmental experience and its current somatic state. We tested whether early-life adversity, induced by manipulating brood size, subsequently altered juvenile European starlings' (Sturnus vulgaris) decisions in a judgment bias task designed to provide a cognitive measure of mood. We predicted that starlings from larger broods, specifically those that had experienced more nest competitors larger than themselves would exhibit reduced expectation of reward, indicative of a 'pessimistic', depression-like mood. We used a go/no-go task, in which 30 starlings were trained to probe a grey card disc associated with a palatable mealworm hidden underneath and avoid a different shade of grey card disc associated with a noxious quinine-injected mealworm hidden underneath. Birds' response latencies to the trained stimuli and also to novel, ambiguous stimuli intermediate between these were subsequently tested. Birds that had experienced greater competition in the nest were faster to probe trained stimuli, and it was therefore necessary to control statistically for this difference in subsequent analyses of the birds' responses to the ambiguous stimuli. As predicted, birds with more, larger nest competitors showed relatively longer latencies to probe ambiguous stimuli, suggesting reduced expectation of reward and a 'pessimistic', depression-like mood. However, birds with greater developmental telomere attrition--a measure of cellular aging associated with increased morbidity and reduced life-expectancy that we argue could be used as a measure of somatic state--showed shorter latencies to probe ambiguous stimuli. This would usually be interpreted as evidence for a more positive or 'optimistic' affective state. Thus, increased competition in the nest and poor current somatic state appear to have opposite effects on cognitive biases. Our results lead us to question whether increased expectation of reward when presented with ambiguous stimuli always indicates a more positive affective state. We discuss the possibility that birds in poor current somatic state may adopt a 'hungry' cognitive phenotype that could drive behaviour commonly interpreted as 'optimism' in food-rewarded cognitive bias tasks.

Developmental Exposure to Aroclor 1254 Alters Migratory Behavior in Juvenile European Starlings (Sturnus vulgaris)

Birds exposed to endocrine disrupting chemicals during development could be susceptible to neurological and other physiological changes affecting migratory behaviors. We investigated the effects of ecologically relevant levels of Aroclor 1254, a polychlorinated biphenyl (PCB) mixture, on moult, fattening, migratory activity, and orientation in juvenile European starlings (Sturnus vulgaris). Birds were orally administered 0 (control), 0.35 (low), 0.70 (intermediate), or 1.05 (high) μg Aroclor 1254/g-body weight by gavage from 1 through 18 days posthatch and later exposed in captivity to a photoperiod shift simulating an autumn migration. Migratory activity and orientation were examined using Emlen funnel trials. Across treatments, we found significant increases in mass, fat, and moulting and decreasing plasma thyroid hormones over time. We observed a significant increase in activity as photoperiod was shifted from 13L:11D (light:dark) to 12L:12D, demonstrating that migratory condition was induced in captivity. At 12L:12D, control birds oriented to 155.95° (South-Southeast), while high-dosed birds did not. High-dosed birds showed a delayed orientation to 197.48° (South-Southwest) under 10L:14D, concomitant with apparent delays in moult. These findings demonstrate how subtle contaminant-induced alterations during development could lead to longer-scale effects, including changes in migratory activity and orientation, which could potentially result in deleterious effects on fitness and survival.

The zebra finch, Taeniopygia guttata: an avian model for investigating the neurobiological basis of vocal learning

Songbirds are capable of learning their vocalizations by copying a singing adult. This vocal learning ability requires juveniles to hear and memorize the sound of the adult song, and later to imitate it through a process involving sensorimotor integration. Vocal learning is a trait that songbirds share with humans, where it forms the basis of spoken language acquisition, with other avian groups (parrots and hummingbirds), and with a few other mammals (cetaceans, bats). It is however absent in traditional model organisms such as rodents and nonhuman primates. Zebra finches, a songbird species from Australia, are popular pets and are easy to breed. They also sing a relatively simple and stereotyped song that is amenable to quantitative analysis. Zebra finches have thus emerged as a choice model organism for investigating the neurobiological basis of vocal learning. A number of tools and methodologies have been developed to characterize the bioacoustics properties of their song, analyze the degree of accurate copying during vocal learning, map the brain circuits that control singing and song learning, and investigate the physiology of these circuits. Such studies have led to a large base of knowledge on song production and learning, and their underlying neural substrate. Several molecular resources have recently become available, including brain cDNA/EST databases, microarrays, BAC libraries, a molecular brain atlas, a complete genome assembly, and the ability to perform transgenesis. The recent availability of many other avian genomes provides unique opportunities for comparative analysis in the search for features unique to vocal learning organisms.

Proper care, husbandry, and breeding guidelines for the zebra finch, Taeniopygia guttata

The zebra finch Taeniopygia guttata castanotis is a songbird commonly used in the laboratory, particularly for studies of vocal learning, neurobiology, and physiology. Within the laboratory, it is important to adopt careful husbandry practices that allow for normal development of the birds. For example, their song is a learned trait, passed culturally from adult males to juveniles, and thus its learning can be influenced by the health and social conditions of the birds present in the laboratory. Here we present guidelines for the successful maintenance and breeding of captive zebra finches.

Reference genes for quantitative gene expression studies in multiple avian species

Quantitative real-time PCR (qPCR) rapidly and reliably quantifies gene expression levels across different experimental conditions. Selection of suitable reference genes is essential for meaningful normalization and thus correct interpretation of data. In recent years, an increasing number of avian species other than the chicken has been investigated molecularly, highlighting the need for an experimentally validated pan-avian primer set for reference genes. Here we report testing a set for 14 candidate reference genes (18S, ABL, GAPDH, GUSB, HMBS, HPRT, PGK1, RPL13, RPL19, RPS7, SDHA, TFRC, VIM, YWHAZ) on different tissues of the mallard (Anas platyrhynchos), domestic chicken (Gallus gallus domesticus), common crane (Grus grus), white-tailed eagle (Haliaeetus albicilla), domestic turkey (Meleagris gallopavo f. domestica), cockatiel (Nymphicus hollandicus), Humboldt penguin (Sphenicus humboldti), ostrich (Struthio camelus) and zebra finch (Taeniopygia guttata), spanning a broad range of the phylogenetic tree of birds. Primer pairs for six to 11 genes were successfully established for each of the nine species. As a proof of principle, we analyzed expression levels of 10 candidate reference genes as well as FOXP2 and the immediate early genes, EGR1 and CFOS, known to be rapidly induced by singing in the avian basal ganglia. We extracted RNA from microbiopsies of the striatal song nucleus Area X of adult male zebra finches after they had sang or remained silent. Using three different statistical algorithms, we identified five genes (18S, PGK1, RPS7, TFRC, YWHAZ) that were stably expressed within each group and also between the singing and silent conditions, establishing them as suitable reference genes. In conclusion, the newly developed pan-avian primer set allows accurate normalization and quantification of gene expression levels in multiple avian species.

Bottom of the heap: having heavier competitors accelerates early-life telomere loss in the European starling, Sturnus vulgaris

Early-life adversity is associated with poorer health and survival in adulthood in humans and other animals. One pathway by which early-life environmental stressors could affect the adult phenotype is via effects on telomere dynamics. Several studies have shown that early-life adversity is associated with relatively short telomeres, but these are often cross-sectional and usually correlational in design. Here, we present a novel experimental system for studying the relationship between early-life adversity and telomere dynamics using a wild bird, the European starling (Sturnus vulgaris). We used cross-fostering to experimentally assign sibling chicks to either small or large broods for twelve days of the growth period. We measured telomere length in red blood cells using quantitative PCR near the beginning of the experimental manipulation (4 days old), at the end of the experimental manipulation (15 days old), and once the birds were independent (55 days old). Being in a larger brood slowed growth and retarded wing development and the timing of fledging. We found no evidence that overall brood size affected telomere dynamics. However, the greater the number of competitors above the focal bird in the within-brood size hierarchy, the greater was the telomere loss during the period of the experimental manipulation. The number of competitors below the focal in the hierarchy had no effect. The effect of heavier competitors was still evident when we controlled for the weight of the focal bird at the end of the manipulation, suggesting it was not due to retarded growth per se. Moreover, the impact of early competition on telomeres was still evident at independence, suggesting persistence beyond early life. Our study provides experimental support for the hypothesis that social stress, in this case induced by the presence of a greater number of dominant competitors, accelerates the rate of telomere loss.

Hand rearing affects emotional responses but not basic cognitive performance in European starlings

Hand rearing is a common procedure in behavioural research on birds. While likely to produce tamer experimental animals, there is a risk that it could induce pathological changes in brain and behaviour similar to those seen in mammals that have experienced maternal separation. We explored the effects of hand rearing on the cognitive and behavioural development of European starlings, Sturnus vulgaris, to assess the generality of results obtained from hand-reared animals. Two groups of age-matched birds were created from the same wild population: one hand-reared from 10 days posthatch and one brought into the laboratory as independent juveniles. These groups were compared on a battery of neuropsychological tasks designed to probe different aspects of cognitive function including learning, perseverative cognition, interval timing, neophobia and impulsivity. There was no evidence for cognitive impairment in the hand-reared birds. They did not have reduced learning speed, impairments in accuracy or precision of interval timing or pathological perseverative cognition compared to the wild-caught birds. Additionally, there was no evidence that birds that developed stereotypies in laboratory cages (predominantly the wild-caught birds) had any cognitive impairments, although this may be because no birds had severe, crystallized stereotypies. There was some evidence that hand-reared birds were less neophobic and less impulsive than wild-caught birds, suggesting that hand rearing might alter emotionally mediated decision making in a direction usually associated with reduced developmental stress in mammals. This study therefore supports the use of hand rearing as an experimental procedure in behavioural research on passerine birds.

Circannual transitions in gene expression: lessons from seasonal adaptations

Circannual timing is important for the coordination of seasonal activities, particularly promoting the survival of individuals in adverse conditions through adaptive physiological and behavioral changes. This includes optimizing the survival of offspring by coordinating reproductive efforts at appropriate times. Thus, timing is very important for overall fitness. In this chapter, we provide several examples of circannually timed events, including mammalian hibernation, discussing the physiological changes that accompany these events, and some of the known genes and pathways underlying these changes. We then describe five candidate systems that are potentially involved in circannual timing. Finally, we discuss several recent advances in molecular biology and animal husbandry that have made the use of nonmodel organisms for research more feasible, which will hopefully promote and encourage further advancement in the knowledge of circannual timing.

Can starling eggs be useful as a biomonitoring tool to study organohalogenated contaminants on a worldwide scale?

Large-scale international monitoring studies are important to assess emission patterns and environmental distributions of organohalogenated contaminants (OHCs) on a worldwide scale. In this study, the presence of OHCs was investigated on three continents (Europe, North America and Australasia), using eggs of starlings (Sturnus vulgaris and Sturnus unicolor) to assess their suitability for large-scale monitoring studies. To the best of our knowledge, this is the first study using bird eggs of the same species as a biomonitor for OHCs on an intercontinental scale. We found significant differences in OHC concentrations of the eggs among sampling locations, except for hexachlorocyclohexanes (HCHs). Mean concentrations of sum polychlorinated biphenyls (PCBs) in eggs ranged from 78±26 ng/glipid weight (lw) in Australia to 2900±1300 ng/g lw in the United States. The PCB profile was dominated by CB 153 and CB 138 in all locations, except for New Zealand, where the contribution of CB 95, CB 101 and CB 149 was also high. The highest mean sum polybrominated diphenyl ether (PBDE) concentrations were found in Canada (4400±830 ng/g lw), while the lowest mean PBDE concentrations were measured in Spain (3.7±0.1 ng/g lw). The PBDE profile in starling eggs was dominated by BDE 47 and BDE 99 in all countries, but in Belgium, the higher brominated PBDEs had a higher contribution compared to other countries. For the organochlorine pesticides (OCPs), dichlorodiphenyltrichloroethanes (DDTs) ranged from 110±16 ng/g lw in France to 17,000±3400 ng/g lw in New Zealand, while HCHs and hexachlorobenzene were generally in low concentrations in all sampling locations. Chlordanes were remarkably high in eggs from the United States (2500±1300 ng/g lw). The OCP profile in all countries was largely dominated by p,p'-DDE. In general, the worldwide trends we observed in starling eggs were in accordance with the literature on human and environmental OHC data, which suggests that there is potential for using starling eggs as a biomonitoring tool on a large geographical scale.

The development of stereotypic behavior in caged European starlings, Sturnus vulgaris

Stereotypic behavior in captive animals has been hypothesized to emerge from thwarted natural behavior patterns and is thought to be more common in captive-reared animals. However, data on the early stages of developing stereotypies are currently scarce. We compared the development of stereotypic route-tracing and somersaulting in hand-reared and wild-caught starlings placed in individual cages for the first time. We found that wild-caught birds were less active but showed more escape motivation and more evidence of route-tracing behavior. Furthermore, somersaulting was only observed in wild-caught birds. Development of somersaulting was predicted by subtle differences in behavior during the first few days in cages and developed in individuals with low levels of route-tracing behavior. Our data suggest a role for escape motivation in the development of starling stereotypies and additionally that route-tracing and somersaulting may represent alternative outlets for thwarted escape. In contrast to observations from mammals, our results show that stereotypies are more common in wild-caught starlings.

Rapid and reliable sedation induced by diazepam and antagonized by flumazenil in zebra finches (Taeniopygia guttata)

Songbirds have emerged as attractive model systems in many areas of biological research. Notably, songbirds are used in studies of the neurobiological and neuroendocrine mechanisms that shape vocal communication, and zebra finches (Taeniopygia guttata) are the most commonly studied species. In these studies, some form of chemical restraint is often needed to facilitate procedures and to minimize the risk of injury during handling. To determine the minimum dose of the benzodiazepine diazepam that is adequate to achieve deep sedation across individual birds, a low dose (5 mg/kg) and a high dose (10 mg/kg) was administered intramuscularly to 20 zebra finches. Results showed that a 10 mg/kg dose of diazepam resulted in deep sedation, defined by dorsal recumbency, which was achieved in minutes and lasted for several hours. Sedation was induced without complication, because no birds displayed signs of distress during sedation or lethargy after recovery, and was adequate to permit minimally invasive surgical procedures. In addition, the duration of sedation was dose dependent, which provides additional information for researchers who seek to match the depth of sedation to their experimental requirements. Finally, complete recovery from the deeply sedated state was induced by a 0.3 mg/kg dose of the antagonist flumazenil, which enabled birds to more rapidly resume homeostatic behaviors to promote well-being and survival. Together, these results indicate that diazepam is a safe and reliable sedative for use in zebra finches and support specific recommendations to achieve rapid and reliable sedation and recovery.

Fear and exploration in European starlings (Sturnus vulgaris): a comparison of hand-reared and wild-caught birds

The revision of EU legislation will ban the use of wild-caught animals in scientific procedures. This change is partially predicated on the assumption that captive-rearing produces animals with reduced fearfulness. Previously, we have shown that hand-reared starlings (Sturnus vulgaris) indeed exhibit reduced fear of humans compared to wild-caught conspecifics. Here, we asked whether this reduction in fear in hand-reared birds is limited to fear of humans or extends more generally to fear of novel environments and novel objects. Comparing 6-8 month old birds hand-reared in the lab with age-matched birds caught from the wild as fledged juveniles a minimum of 1 month previously, we examined the birds' initial reactions in a novel environment (a small cage) and found that wild-caught starlings were faster to initiate movement compared to the hand-reared birds. We interpret this difference as evidence for greater escape motivation in the wild-caught birds. In contrast, we found no differences between hand-reared and wild-caught birds when tested in novel object tests assumed to measure neophobia and exploratory behaviour. Moreover, we found no correlations between individual bird's responses in the different tests, supporting the idea that these measure different traits (e.g. fear and exploration). In summary, our data show that developmental origin affects one measure of response to novelty in young starlings, indicative of a difference in either fear or coping style in a stressful situation. Our data contribute to a growing literature demonstrating effects of early-life experience on later behaviour in a range of species. However, since we did not find consistent evidence for reduced fearfulness in hand-reared birds, we remain agnostic about the welfare benefits of hand-rearing as a method for sourcing wild birds for behavioural and physiological research.

Hand-rearing reduces fear of humans in European starlings, Sturnus vulgaris

Pending changes in European legislation ban the use of wild-caught animals in research. This change is partly justified on the assumption that captive-breeding (or hand-rearing) increases welfare of captive animals because these practices result in animals with reduced fear of humans. However, there are few actual data on the long-term behavioural effects of captive-breeding in non-domestic species, and these are urgently needed in order to understand the welfare and scientific consequences of adopting this practice. We compared the response of hand-reared and wild-caught starlings to the presence of a human in the laboratory. During human presence, all birds increased their general locomotor activity but the wild-caught birds moved away from the human and were less active than the hand-reared birds. After the human departed, the wild-caught birds were slower to decrease their activity back towards baseline levels, and showed a dramatic increase in time at the periphery of the cage compared with the hand-reared birds. We interpret these data as showing evidence of a greater fear response in wild-caught birds with initial withdrawal followed by a subsequent rebound of prolonged attempts to escape the cage. We found no effects of environmental enrichment. However, birds in cages on low shelves were less active than birds on upper shelves, and showed a greater increase in the time spent at the periphery of their cages after the human departed, perhaps indicating that the lower cages were more stressful. In demonstrating reduced fear of humans in hand-reared birds, our results support one of the proposed welfare benefits of this practice, but without further data on the possible welfare costs of hand-rearing, it is not yet possible to reach a general conclusion about its net welfare impact. However, our results confirm a clear scientific impact of both hand-rearing and cage position at the behavioural level.

An IACUC perspective on songbirds and their use in neurobiological research

Laboratory research using songbirds as a model system for investigating basic questions of neurobiological function has expanded rapidly and recently, with approximately 120 laboratories working with songbirds worldwide. In the United States alone, of the approximately 80 such laboratories nearly a third have been established in the past 10 years. Yet many animal facilities are not outfitted to manage these animals, and as a consequence laboratories often use alternative housing arrangements established by institutional animal care and use committees (IACUCs). These committees invariably differ in their expertise level with birds and thus guidelines also vary considerably from one institution to another. In this article I address a number of factors to consider for effective oversight of research involving songbirds.