Birds Research Articles

The global determinants of climate niche breadth in birds

Understanding why certain species occupy wider climate niches than others is a fundamental pursuit in ecology with important implications for conservation and management. However, existing synthesis on this topic has focused on the consequences rather than the causes of climate niche expansion, leading to significant gaps in our understanding of the possible evolutionary drivers of this important ecological property. Here we leverage species distribution models powered by millions of citizen science sightings of birds to determine how a comprehensive suite of parameters influences the breadth of climate niches. Our analyses show that migration and more central locations in climate space are directly associated with wider climate niches. Additionally, they indicate that larger brains, smaller bodies, and broader dietary requirements are indirectly associated with narrower niches, presumably because they enable the occupancy of geographically widespread habitats that occupy narrow areas in climate niche space. Through follow-up analyses we further clarify how the different factors considered in this study help shape niche breadth by affecting the colonization of more versus less frequently used habitats. Overall, our findings shed light on critical, yet highly underappreciated properties of climate niches, underscoring the complexity and interconnectivity of the factors that shaped their evolution among birds.

Atypical Presence of Interstitial Telomeric Sequences in Thamnophilus Species (Passeriformes: Thamnophilidae)

Introduction: Thamnophilidae (typical antbirds) are a diverse family of insectivorous passerine birds restricted to neotropical forests, encompassing 237 species, of which only five have been studied cytogenetically. Methods: To investigate the chromosomal evolution of this group, we applied classical and molecular cytogenetic techniques, including conventional staining, C-banding, and fluorescence in situ hybridization (FISH) with probes for repetitive telomeric sequences (TTAGGG)5 and 18S rDNA, in two representative species: Thamnophilus caerulescens and Thamnophilus ruficapillus. Results: The karyotypes of T. caerulescens and T. ruficapillus comprise 80 and 82 chromosomes, respectively. In addition to a possible fission in T. ruficapillus, morphological differences suggest the occurrence of pericentric inversions in the chromosomes of this species. The patterns of constitutive heterochromatin differed between the species: both showed centromeric markings and heterochromatin on the W chromosome, but T. ruficapillus also exhibited interstitial markings on seven chromosomal pairs. Both species presented interstitial telomeric sequences (ITSs) in the first seven pairs, which corresponded to constitutive heterochromatin in T. ruficapillus. The 18S rDNA probe hybridized to a single pair of microchromosomes in T. caerulescens and two pairs in T. ruficapillus. Conclusion: This study revealed novel patterns of constitutive heterochromatin in T. ruficapillus and ITSs in both species, which have not been previously observed in Passeriformes. The correspondence between constitutive heterochromatin and ITSs in T. ruficapillus suggests that these sequences are composed of repetitive DNA highly similar to telomeric sequences and/or are remnants of pericentric inversions, whereas in T. caerulescens, other mechanisms seem to be involved. The differences in observed patterns highlight distinct chromosomal evolution between these species, emphasizing the diversity within the family Thamnophilidae and the genus Thamnophilus, in contrast to the conserved patterns typically observed in the class Aves.

The anaerobic gut fungal community in ostriches ( Struthio camelus ).

Anaerobic gut fungi (AGF; Neocallimastigomycota ) are essential for plant biomass degradation in herbivores. While extensively studied in mammals, information regarding their occurrence, diversity, and community structure in non-mammalian hosts remains sparse. Here, we report on the AGF community in ostriches ( Struthio camelus ), herbivorous, flightless, hindgut fermenting members of the class Aves (birds). Culture-independent diversity surveys of fecal samples targeting the D2 region of the large ribosomal subunit (28S rRNA) revealed a uniform community with low alpha diversity. The community was mostly comprised of sequences potentially representing two novel species in the genus Piromyces, and a novel genus in the Neocallimastigomycota . Sequences affiliated with these novel taxa were absent or extremely rare in datasets derived from mammalian and tortoise samples, indicating a strong pattern of AGF-host association. One Piromyces strain (strain Ost1) was successfully isolated. Transcriptomics-enabled molecular dating analysis suggested a divergence time of ≈ 30 Mya, a time frame in line with current estimates for ostrich evolution. Comparative gene content analysis between strain Ost1 and other Piromyces species from mammalian sources revealed a high degree of similarity. Our findings expand the range of AGF animal hosts to include members of the birds (class Aves ), highlight a unique AGF community adapted to the ostrich alimentary tract, and demonstrate that - like mammals - coevolutionary phylosymbiosis (i.e. concurrent evolution of AGF and their animal hosts) plays a central role in explaining current AGF distribution patterns in Aves .

Adaptive evolution of cytochrome b in songbirds.

The mitochondrial bc1 complex catalyzes the oxidation of ubiquinol by reducing cytochrome c. Cytochrome b, the catalytic core of bc1, generates superoxide during the oxidation of ubiquinol. Excessive superoxide production is known to accelerate aging and neurodegeneration. Songbirds (oscine, Passeri) exhibit lower production of mitochondrial ROS and greatly accelerated evolution of cytochrome b, relative to all other modern birds, suggesting adaptive selection for lower generation of ROS. Here we identified songbirds-specific substitutions in modern bird's cytochrome b amino-acids sequences and examined the high-resolution structures of the chicken bc1 complex in an effort to predict the effect of these substitutions on the function of bc1. Many of the songbirds-specific substitution cluster around sites that are critical for the function of bc1. One cluster of substitutions interacts with heme BH. A second cluster of substitutions interacts with residues in the ubiquinone reduction site, Qi. Both groups of substitution may affect the rate of reduction of ubiquinone at the Qi site. Another cluster of cytochrome b substitutions interacts with the hinge region of the Rieske protein that transfers electron from cytochrome b to cytochrome c1. These songbirds-specific substitutions appear to be selected to modulate the rate of both ubiquinol oxidation at the Qo site and ubiquinone reduction at the Qi site thereby modulating the rate of superoxide production. These findings are compatible with the hypothesis that cytochrome b evolution in songbirds was driven by selection of substitutions that reduce the rate of superoxide production thereby increasing songbird lifespan and cognitive abilities.

Drivers of avian genomic change revealed by evolutionary rate decomposition.

Modern birds have diversified into a striking array of forms, behaviours and ecological roles. Analyses of molecular evolutionary rates can reveal the links between genomic and phenotypic change1-4, but disentangling the drivers of rate variation at the whole-genome scale has been difficult. Using comprehensive estimates of traits and evolutionary rates across a family-level phylogeny of birds5,6, we find that genome-wide mutation rates across lineages are predominantly explained by clutch size and generation length, whereas rate variation across genes is driven by the content of guanine and cytosine. Here, to find the subsets of genes and lineages that dominate evolutionary rate variation in birds, we estimated the influence of individual lineages on decomposed axes of gene-specific evolutionary rates. We find that most of the rate variation occurs along recent branches of the tree, associated with present-day families of birds. Additional tests on axes of rate variation show rapid changes in microchromosomes immediately after the Cretaceous-Palaeogene transition. These apparent pulses of evolution are consistent with major changes in the genetic machineries for meiosis, heart performance, andRNA splicing, surveillance and translation, and correlate with the ecological diversity reflected in increased tarsus length. Collectively, our analyses paint a nuanced picture of avian evolution, revealing that the ancestors of the most diverse lineages of birds underwent major genomic changes related to mutation, gene usage and niche expansion in the early Palaeogene period.

Wildlife and wellbeing: Wildlife immersion experiences in veterans with PTSD

Abstract Animal-assisted interventions (AAI) involve interactions between humans and other species aimed at improving human psychological and/or physical health. Post-traumatic stress disorder (PTSD) is a condition in which AAI may be helpful. Most AAI research has been conducted with domestic animals. Few studies have been conducted with wildlife. This study used a modified crossover design to evaluate the feasibility and human response to a nature/wildlife immersion program for US veterans with PTSD/ PTSD symptoms. A total of 19 veterans participated in the study over a mean of 15.1 weeks. The intervention included a baseline forest walk, assisting with wildlife care in a rehabilitation center, observation of wildlife in a sanctuary, and bird watching. Each activity was conducted twice and included didactic education. Bird feeders were provided for sustainable connection to wildlife following the study. The study was guided by the realms of human/beyond-human animal interaction model within the theory of transcendent pluralism, which is grounded in mutual human/beyond-human dignity. Evaluation incorporated observation, post-activity surveys, psychological instruments, physiological measures, focus groups, and follow-up interviews. Qualitative findings included five themes within the larger theme, “To see the animals up close”: connection and caring, feeling better, personal growth, understanding our place in the natural world, and wildlife in everyday living. Quantitative findings were in the predicted direction for several measures including a statistically significant reduction in anxiety. Findings suggested greater improvement in scores in the wildlife settings over a baseline forest walk. Transcendent feelings of animal valuation appeared to mediate a reduction in depression and enhance mental wellbeing. In sum, the response of veterans with PTSD to wildlife immersion experiences suggests improved psychological symptoms as well as connection to nature/ wildlife and increased understanding and concern for animal welfare and conservation-related issues. Nature-based interventions are dynamic and require a flexible design, which may be addressed through immersion experiences.

Observations and dispersal of black-billed gulls (tarāpuka, Chroicocephalus bulleri) banded at North Canterbury, New Zealand, 1958–1974 and 1983

A total of 15,694 black-billed gulls (tarāpuka, Chroicocephalus bulleri) chicks were banded at six braided gravel-bed rivers in North Canterbury, New Zealand, from 1958 to 1983, and at least 1,754 later sightings of dead or alive birds were reported to the Banding Office. The main banding sites were the Ashley River and its major tributary, the Ōkūkū River; other banding was carried out on the Kowhai River near Kaikoura, Conway River, Waiau River, Waipara River, and Waimakariri River. Colonies typically shifted location between years, as flooding and weed growth affected the habitat and suitability for nesting. Up to 6 colonies were found on the Ashley River system in a season. Average size of all colonies was about 230 nests, with the largest reaching about 800 nests. Some birds were found at rivers apart from their natal rivers. Birds bred when as young as 2-years-old. The furthest sighting was at Firth of Thames, 736 km NE of the banding site; the southernmost was at Waipahi, Otago, 412 km SW of the banding site; and the oldest recovery was 22.1 years after banding. Band loss likely affected recovery rates, as the oldest bird found with an aluminium band was only 10.9 years-old.

Origin and diversification of Dicrocoeliidae (Neodermata, Trematoda) with the description of a new species of Euparadistomum, a parasite of Tropidurus torquatus (Squamata, Tropiduridae) in South America.

Origin and diversification of Dicrocoeliidae (Neodermata, Trematoda) with the description of a new species of Euparadistomum, a parasite of Tropidurus torquatus (Squamata, Tropiduridae) in South America.

A comparative developmental study of the avian syrinx: Insights into the homology of the sound-producing muscles in birds.

The anatomical innovation of sound-producing organs, which gives rise to a wide variety of sound signals, is one of the most fundamental factors leading to the explosive speciation of modern birds. Despite being a key clue to resolving the homology of sound-controlling muscles among birds, only few studies have explored the embryonic development of syringeal muscles. Using serial histological sections and immunohistochemistry, we described the three-dimensional anatomy and development of the cartilage, muscle, and innervation pattern of the tracheobronchi in three avian species: domestic fowls, cockatiels, and zebra finches. Crucially, the muscle primordia of the syringeal and tracheobronchial muscles develop from the caudal end of the lateral tracheal muscle in cockatiels and zebra finches. Furthermore, the tracheobronchial and syringeal muscle primordia of the zebra finches are subsequently split during embryonic development. Based on our findings on the identity of muscle primordia development and innervation pattern of the hypoglossal nerve between the cockatiels and zebra finches, we suggest that the muscle component traditionally documented as the superficial syringeal muscle in parrots is homologous to the tracheobronchial and ventral syringeal muscles of the zebra finches. These facts not only orchestrate the terminological discrepancies among previous studies, but also suggest that the syringeal muscles were acquired by the anatomical innovation of the lateral tracheal muscles in the common ancestor of the parrots and passerines, and further compartmentalized in the passerines, perhaps leading to a wide song repertoire for acoustic communication.

Insights into the early evolution of modern avian physiology from fossilized soft tissues from the Mesozoic.

Modern birds (Neornithes) are the mostly highly modified group of amniotes, bearing little resemblance to other extant sauropsids. Archaeopteryx, with its nearly modern wings but plesiomorphic skeleton, demonstrated more than 160 years ago that soft tissue specializations preceded skeletal modifications for flight. Soft tissues are thus of great importance for understanding the early evolution of modern avian physiology. Most commonly, traces of the integumentary system are preserved; exceptional discoveries include remnants of organs. Together, these have helped to elucidate the evolution of the lungs, ovaries, plumage and beak in early diverging birds. These fossils reveal that many important adaptations for efficient digestion, high oxygen intake, reduced body mass and improved wing structure, all of which serve to improve aerial capabilities and/or meet the energetic demands of this costly form of locomotion, evolved within the first 20-30 Myr of avian evolution. Soft tissue preservation also provides important clues for understanding the ecology of early diverging birds and may even elucidate the extinction of certain groups. However, the current fossil record of Mesozoic avian soft tissues is almost entirely limited to the Early Cretaceous and thus, discoveries from the Late Cretaceous have the potential to drastically transform our interpretation of the available data.This article is part of the theme issue 'The biology of the avian respiratory system'.

The avian respiratory system: implications for anaesthesia.

Anaesthesia is not a natural state for any animal, including birds. The unique anatomic and physiological attributes of the class Aves that have made it possible for birds to inhabit every continent on this planet and to live in a variety of environments, some considered challenging if not inhospitable to mammals, pose challenges to their anaesthetic management. Indeed, it is more challenging than the anaesthetic management of mammals, a reality substantiated by the fact that the risk of anaesthesia-related death of birds is up to 20 times higher than for dogs and cats. This article highlights those anatomic (respiratory system, renal-portal system), physiological (gas exchange, respiratory control mechanisms in respiratory brainstem and peripheral chemoreceptor areas, including intrapulmonary chemoreceptors) and pharmacological attributes (pharmacokinetics and pharmacodynamics) that make anaesthetic management, both inhalant and injectable anaesthesia, of birds challenging, and how those challenges are managed.This article is part of the theme issue 'The biology of the avian respiratory system'.

Evaluating household dynamics of wildlife preferences using toys

ABSTRACT An understanding of public preference for species is critical for conservation efforts because successful conservation action often requires human intervention. In this study, we introduce a novel research approach using toy models to assess wildlife preference and perceived masculinity/femininity among children and adults in multi-generation households across a spectrum of socio-demographic and household-level characteristics. The golden retriever, gray wolf, monarch butterfly, and lion were the most preferred species for both children and adults. The lion, bull shark, wild boar, gray wolf, and black bear were ranked by parents as the most masculine and the monarch butterfly and flamingo most feminine. We observed differences in preference based on gender, race, ownership of pets, and household participation in hunting or bird watching. These findings suggest significant preference overlap between children and adults and the possibility of intergenerational transfer of gendered preferences for wildlife species.

Polling the Public to Select Flagship Species for Tourism and Conservation-A 'Big Five' for the Peruvian Amazon?

Flagship species are used to promote conservation and tourism. Africa's famous 'Big five' have become marketing flagships that fundraisers and tourism promoters emulate globally. Species can be selected systematically for marketing using characteristics such as colour, size or behaviour, but this approach can overlook unique animals or homogenise selections. Alternatively, polling the public can reveal existing preferences for animals directly. We used questionnaires with tourists in the Peruvian Amazon to identify existing biases for species and rank them for suitability for tourism and conservation marketing. Polling revealed several species that would not be considered good flagship candidates using systematic methods based on species characteristics. 'Free listing' tourists expressed preferences at inconsistent taxonomic levels. The response 'monkeys' (infraorder Simiiformes) was highest ranked, followed by 'jaguar' (Panthera onca), 'Amazon dolphin' (Inia geoffrensis), 'sloths' (suborder Folivora), and 'caiman' (subfamily Caimaninae) and 'birds' (class Aves). When ranking from a preselected shortlist, jaguar, Amazon dolphins and sloths (represented by Bradypus variegatus) remained popular, while vote splitting within higher taxonomic levels, in particular monkeys, made room for green-winged macaw (Ara chloropterus) and anaconda (Eunectes murinus). When asked about their willingness to pay for excursions or donate to conservation, tourists were overwhelmingly more likely to quote larger figures for jaguars than any other species, but results for other species were more homogenous. Some popular taxonomic groups are diverse in Amazonia; up to 14 monkey species may be present at some sites Amazonia, alongside several hundred bird species. A Big five strategy obscures this diversity. Using physical characteristics as selection criteria underplays diversity and overlooks popular taxa-notably sloths for the Amazon. A strategy of polling the public to select popular species as flagships more directly identifies salient species for marketing and efficiently considers existing biases. However, diversity will trump a Big five approach in megadiverse areas.

Ancient relative of geese is the earliest known modern bird

Ancient relative of geese is the earliest known modern bird

The three-dimensional structure of medullary bone: Novel criteria for the identification of avian sex-specific bone tissue.

The three-dimensional structure of medullary bone: Novel criteria for the identification of avian sex-specific bone tissue.

The return of raptors to Scotland's skies: Investigating the diets of reintroduced red kites and white-tailed eagles using stable isotopes.

Species reintroductions are increasingly seen as important methods of biodiversity restoration. Reintroductions of red kites Milvus milvus and white-tailed eagles Halieaeetus albicilla to Britain, which were extirpated in the late 19th and early 20th centuries, represent major conservation successes. Here, we measured stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) in feather keratin and bone collagen of museum specimens of red kites and white-tailed eagles, which were collected from across Scotland between the 1800s and 2010s. Our objectives were to investigate dietary differences between species and between the pre- and post- reintroduction periods. Among reintroduced birds, δ13C values were significantly less negative and δ15N values higher in feather keratin and bone collagen of white-tailed eagles compared to red kites, likely reflecting a greater reliance on marine resources by the former. Our stable isotope data showed a wide range, confirming the dietary diversity observed in conventional diet studies of both taxa, with white-tailed eagles, in particular, having wide dietary niches and a considerable degree of inter-individual variability. Isotopic data from pre-introduction red kites mostly fell within the range of post-reintroduction birds, suggesting they had similar diets to the pre-reintroduction birds, or the prey base for modern birds is isotopically indistinguishable from that of their historic counterparts. For white-tailed eagles, several pre-reintroduction birds were isotopically distinct from the post-reintroduction population. These differences may indicate a changing prey base, although these conclusions are complicated by shifting distributions and small population samples. Overall, our study demonstrates the utility of natural history collections in examining changes in diet, environment, and interactions with humans in reintroduced species compared with pre-extirpation indigenous populations.

Availability of pesticide-treated seeds and bird occurrence in freshly drilled onion and carrot fields in Brazil.

Agricultural landscapes in Brazil provide habitat to various bird species, which may be exposed to pesticide-treated seeds that have not been incorporated into the soil during drilling. Understanding the dynamics and interactions between birds and drilled fields is crucial for developing sustainable farming practices that balance agricultural food production with wildlife conservation. This study focused on the attractivity of freshly drilled onion and carrot fields to birds and the potential exposure of birds to the pesticide-treated onion and carrot seeds available on the soil surface after drilling in Minas Gerais, Brazil. Bird surveys were conducted using scan sampling and point count methods to assess diversity and behavior before, on the day of drilling, and after drilling. Carrot fields showed a decrease in observed species and individuals on the day of drilling, with an increase in bird sightings after drilling. Similar trends were observed in onion fields, with the species composition changing after drilling and a significant decrease in abundance on the day of drilling. None of the species found foraging in the field after drilling were granivorous or omnivorous. Seed exposure was assessed by counting available seeds on the soil surface at different time points after drilling. Seed exposure was higher in the field border than in the field center. These findings indicate that carrot and onion fields offer limited food sources for granivore bird species probably due to low seed availability and intensive seedbed preparation. The research also suggests that freshly drilled carrot and onion crops are unattractive to foraging birds, with low seed exposure and a reduced likelihood of contact with pesticides applied as a seed treatment.

Wing bone laminarity in Pterosaurs: insights into torsional adaptations for flight evolution.

Powered flight has evolved separately in three tetrapod clades: pterosaurs, birds (avian dinosaurs), and bats. To meet the challenges of powered flight, tetrapods acquired structural, mechanical, and physiological adaptations. Circumferential vascular canals, forming laminar bone, have been proposed to be an adaptation linked to withstanding torsional loading during flight in birds. However, whether laminarity serves as an indicator of biomechanical torsion in pterosaurs, remains to be elucidated. Through a comparative statistical approach, we investigate the association between cortical bone laminarity and skeletal stress in pterosaur flight. For the first time, the presence of laminarity in pterosaur bones was analyzed to observe torsion in bones associated with flight, using thirty-five thin sections of the tapejarid Caiuajara dobruskii, Anhangueridae, and Dsungaripteroidea pterosaurs. We conclude that adaptive relationships arise between bone microstructure and biomechanical function, with forelimb elements (humerus, ulna, and wing phalanges) exhibiting higher laminarity rates compared to hindlimb bones. Additionally, the results provide insights into the possible flight style of these pterosaurs through comparison with bird groups. The presence of laminarity in pterosaurs and birds, but not in bats, highlights that this feature, once considered exclusive to birds, may have convergently evolved in pterosaurs and birds.

Cursorial ecomorphology and temporal patterns in theropod dinosaur evolution during the mid-Cretaceous.

Coelurosauria, including modern birds, represents a successful group of theropod dinosaurs that established a high taxonomic diversity and significant morphological modifications. In the evolutionary history of this group, a specialized foot morphology, the arctometatarsus, evolved independently in several lineages and has been considered an adaptation for cursoriality. While its functional significance has been extensively studied, the temporal pattern of this parallel evolution, as well as its origin and influencing factors, remains largely unresolved. Here, we show the temporal evolution of cursorial traits, including the arctometatarsus and hind limb proportions. Our study reveals that the proportional elongation of distal hind limb segments preceded the evolution of the arctometatarsus in ornithomimosaurs and oviraptorosaurs. In contrast, in tyrannosauroids, alvarezsaurs and troodontids, the proportional elongation of the tibia and metatarsals occurred in parallel with the acquisition of the arctometatarsus. The evolutionary history of the arctometatarsus further highlights the presence of a phylogenetic constraint outside Coelurosauria, as this foot specialization is restricted to members of this group. Finally, our date estimation, based on compiled evolutionary patterns, demonstrates that these cursorial traits emerged during the mid-Cretaceous (93-120 Ma), suggesting selection on theropod locomotor performance throughout this interval.

Lyrical Stillness.

Description "Lyrical Stillness" is a poem I wrote during my radiation oncology rotation, during which I was provided the opportunity to learn more about multidisciplinary cancer care while delving deeper into radiotherapy. Cancer can be an overwhelming disease process physically, psychologically, and emotionally. Patients undergoing treatment often experience stress and anxiety with the uncertainty of their prognoses. In this poem, I describe a patient receiving radiation therapy whom I enjoyed speaking to about his favorite hobby: bird watching. During his subsequent radiation treatment sessions, I decided to play a CD of mockingbirds singing in a tropical forest, in the hopes it would remind him of fond memories and ease his anxiety with the treatment process. The poem emphasizes the importance of listening, having empathy, and treating others as whole human beings.