Aerobic power and flight capacity in birds: a phylogenetic test of heart-size hypothesis

Flight capacity is one of the most important innovations in animal evolution; it only evolved in insects, birds, mammals and the extinct pterodactyls. Given that powered flight represents a demanding aerobic activity, an efficient cardiovascular system is essential for the continuous delivery of oxygen to the pectoral muscles during flight. It is well known that the limiting step in the circulation is stroke volume (the volume of blood pumped from the ventricle to the body during each beat), which is determined by the size of the ventricle. Thus, the fresh mass of the heart represents a simple and repeatable anatomical measure of the aerobic power of an animal. Although several authors have compared heart masses across bird species, a phylogenetic comparative analysis is still lacking. By compiling heart sizes for 915 species and applying several statistical procedures controlling for body size and/or testing for adaptive trends in the dataset (e.g. model selection approaches, phylogenetic generalized linear models), we found that (residuals of) heart size is consistently associated with four categories of flight capacity. In general, our results indicate that species exhibiting continuous hovering flight (i.e. hummingbirds) have substantially larger hearts than other groups, species that use flapping flight and gliding show intermediate values, and that species categorized as poor flyers show the smallest values. Our study reveals that on a broad scale, routine flight modes seem to have shaped the energetic requirements of birds sufficiently to be anatomically detected at the comparative level

Multiple metals exposure and neurotoxic risk in bald eagles ( Haliaeetus leucocephalus ) from two Great Lakes states

In the present study, the authors determined concentrations of several elements (As, Cd, Co, Cu, Cr, Mn, Pb, Sb, Zn) in the brains and livers of 46 bald eagles ( Haliaeetus leucocephalus ) from two Great Lakes states, Michigan and Minnesota. To explore whether exposures are of neurological concern, the authors assessed their associations with neurochemical receptors ( N ‐methyl‐ D ‐aspartate [NMDA] and γ‐aminobutyric acid A [GABA(A)]) and enzymes (glutamine synthetase [GS] and glutamic acid decarboxylase [GAD]) that play critical roles in vertebrate neurobehavior and reproduction. For most elements, levels in the livers and brains did not differ between region and gender. Hepatic Pb levels averaged 33.1 ppm (dry wt), 30.4% of all carcasses exceeded proposed avian Pb thresholds (>26.4 ppm), and in 30.8% of the birds examined evidence of Pb pellets or fragments was found. Significant changes in the activities of GS and GAD were related to brain concentrations of several metals (Pb, Cd, Co, Cu, Zn). No relationships were found among any of the nine elements and NMDA or GABA(A) receptor levels. When combined with the authors' previous study on these same eagles that showed Hg‐associated alterations in GS, GAD, and NMDA receptor levels, the present research suggests that bald eagles are exposed to various elements, especially Pb and Hg, that are capable of causing changes in GABAergic and glutamatergic neurotransmission. The functional significance of these neurochemical changes warrants attention. Environ. Toxicol. Chem. 2012;31:623–631. © 2011 SETACPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90053/1/1712_ftp.pd

RETO CIUDAD NATURALEZA LA PAZ: UMA EXPERIÊNCIA DE OBSERVAÇÃO E REGISTO DA BIODIVERSIDADE URBANA

Citizen science encourages people to participate in scientific research projects. One of the best-known initiatives is the City Nature Challenge contest, aimed at recording biodiversity in cities through the iNaturalist application. The metropolitan region of La Paz, Bolivia, participated in this contest in 2019 and 2022 under the name Reto Ciudad Naturaleza, promoted by the Wildlife Conservation Society (WCS) Bolivia, the Biology Department and the Ecology Institute of the Universidad Mayor de San Andrés (UMSA), and the National Museum of Natural History (MNHN), who together formed an Organizing Committee. The objective was to strengthen the links between the urban population and nature so that they can contribute in improving knowledge about biodiversity and help to conserve Nature. The activities were based on the promotion and dissemination of the contest, training events in the use of iNaturalist, photographic registration, taxonomic identification events, and delivery of certificates to participants. In 2019, La Paz competed with 158 cities and achieved eighth place in number of species (3,005), third place in number of participants (1,500) and second place in number of observations (46,931). In 2022, 447 cities participated. La Paz led in all three categories of the contest, with 137,345 observations, 5,320 species and 4,296 participants. Beyond these results, the outstanding commitment of La Paz citizens to their biodiversity is resulting in an increasingly close link between the urban population and their natural environment.La ciencia ciudadana incentiva la participación de las personas en proyectos de investigación científica. Una de las iniciativas más conocidas es el concurso City Nature Challenge, dirigida a registrar la biodiversidad en las ciudades mediante la aplicación iNaturalist. La región metropolitana de La Paz, Bolivia, participó de este concurso en 2019 y 2022 con el nombre de Reto Ciudad Naturaleza, gracias al impulso de Wildlife Conservation Society (WCS) Bolivia, la Carrera de Biología y el Instituto de Ecología de la Universidad Mayor de San Andrés (UMSA), y el Museo Nacional de Historia Natural (MNHN), que conformaron un Comité Organizador. El objetivo fue fortalecer los vínculos de la población urbana con la naturaleza para generar datos sobre el conocimiento y conservación de la biodiversidad. Las actividades se basaron en la promoción y difusión del concurso, eventos de capacitación en el manejo de aplicación iNaturalist, registro fotográfico, identificación taxonómica y entrega de certificados a los participantes. En 2019, La Paz compitió con 158 ciudades y consiguió el octavo lugar en número de especies (3.005), el tercer lugar en número de participantes (1.500) y el segundo en número de observaciones (46.931). En 2022, participaron 447 ciudades. La Paz lideró en las tres categorías del concurso, con 137.345 observaciones, 5.320 especies y 4.296 participantes. Más allá de estos resultados, destaca el compromiso de la ciudadanía paceña con su biodiversidad, lo que repercute en un vínculo cada vez más estrecho entre la población urbana y su entorno natural.A ciência cidadã encoraja às pessoas a participar em projetos de pesquisa científica. Uma das iniciativas mais conhecidas é o concurso City Nature Challenge, destinado a registrar a biodiversidade nas cidades através do aplicativo iNaturalist. A região metropolitana de La Paz, Bolívia, participou neste concurso em 2019 e 2022 sob o nome City Nature Challenge, com o impulso da Wildlife Conservation Society (WCS) Bolívia, do Departamento de Biologia e do Instituto de Ecologia da Universidad Mayor de San Andrés (UMSA), e do Museu Nacional de História Natural (MNHN), que formou uma Comissão Organizadora. O objectivo foi reforçar os laços entre a população urbana e a natureza, para que possam contribuir para o conhecimento e conservação da biodiversidade. As atividades basearam-se na promoção e divulgação do concurso, sessões  de formação na utilização do iNaturalist, registro fotográfico, identificação taxonómica e na entrega de certificados aos participantes. Em 2019, La Paz concorreu com 158 cidades atingindo o oitavo lugar em número de espécies (3.005), o terceiro lugar em número de participantes (1.500) e o segundo lugar em número de observações (46.931). Em 2022, participaram 447 cidades. La Paz liderou nas três categorias do concurso com 137.345 observações, 5.320 espécies e 4.296 participantes. Para além destes resultados, destaca-se o compromisso dos cidadãos de La Paz com a sua biodiversidade, tendo como resultado uma ligação cada vez mais estreita entre a população urbana e o seu ambiente natural.&nbsp

Reto Ciudad Naturaleza, La Paz: una experiencia de observación y registro de la biodiversidad urbana

Citizen science encourages people to participate in scientific research projects. One of the best-known initiatives is the City Nature Challenge contest, aimed at recording biodiversity in cities through the iNaturalist app. The metropolitan region of La Paz, Bolivia, participated in this contest in 2019 and 2022 under the name Reto Ciudad Naturaleza, thanks to the promotion of the Wildlife Conservation Society (WCS) Bolivia, the Biology Department and the Ecology Institute of Universidad Mayor de San Andrés (UMSA), and the National Museum of Natural History (MNHN), who formed an organizing committee. The objective was to strengthen the bond between the urban population and nature, with the aim to generate data on the knowledge and preservation of biodiversity. The activities consisted of the promotion and dissemination of the contest, training events regarding the use of iNaturalist, photographic records, taxonomic identification, and the delivery of certificates to participants. In 2019, La Paz competed with 158 cities and ranked eighth in number of species (3005), third in number of participants (1500), and second in number of observations (46 931). In 2022, 447 cities participated, and La Paz led in all three categories of the contest, with 137 345 observations, 5320 species, and 4296 participants. Beyond these results, the commitment of La Paz citizens to their biodiversity stands out, which results in an increasingly strong bond between the urban population and their natural environment.La ciencia ciudadana incentiva la participación de las personas en proyectos de investigación científica. Una de las iniciativas más conocidas es el concurso City Nature Challenge, dirigido a registrar la biodiversidad en las ciudades mediante la aplicación iNaturalist. La región metropolitana de La Paz, Bolivia, participó en este concurso en 2019 y 2022 bajo el nombre Reto Ciudad Naturaleza, gracias al impulso de Wildlife Conservation Society (WCS) Bolivia, la Carrera de Biología y el Instituto de Ecología de la Universidad Mayor de San Andrés (UMSA) y el Museo Nacional de Historia Natural (MNHN), los cuales conformaron un comité organizador. El objetivo fue fortalecer los vínculos de la población urbana con la naturaleza, en aras de generar datos sobre el conocimiento y la conservación de la biodiversidad. Las actividades consistieron en la promoción y difusión del concurso, eventos de capacitación en el manejo de iNaturalist, registros fotográficos, identificación taxonómica y entrega de certificados a los participantes. En 2019, La Paz compitió con 158 ciudades y consiguió el octavo lugar en número de especies (3005), el tercer lugar en número de participantes (1500) y el segundo en número de observaciones (46 931). En 2022 participaron 447 ciudades, y La Paz lideró en las tres categorías del concurso, con 137 345 observaciones, 5320 especies y 4296 participantes. Más allá de estos resultados, se destaca el compromiso de la ciudadanía paceña con su biodiversidad, lo que repercute en un vínculo cada vez más estrecho entre la población urbana y su entorno natural

Natural Patterns in the Dawn and Dusk Choruses of a Neotropical Songbird in Relation to an Urban Sound Environment

Urbanization is one of the more important phenomena affecting biodiversity in the Anthropocene. Some organisms can cope with urban challenges, and changes in birds’ acoustic communication have been widely studied. Although changes in the timing of the daily organization of acoustic communication have been previously reported, there is a significant gap regarding possible variations in song structure between dawn and dusk choruses. Considering that urbanization imposes different soundscapes for dawn and dusk choruses, we postulate two hypotheses: (i) there are variations in song parameters between dawn and dusk choruses, and (ii) such parameters within the city will vary in response to urban noise. We studied urban and extra-urban populations of Chiguanco Thrush in La Paz, Bolivia, measuring in dawn and dusk choruses: song length; song sound pressure level; minimum, maximum, range and dominant frequency; and the number of songs per individual. The results support our two hypotheses: there were more songs, and songs were louder and had larger band widths at dawn than at dusk in urban and extra-urban populations. Urban Chiguanco Thrushes sing less, the frequency of the entire song rises, and the amplitude increases as compared with extra-urban Chiguanco Thrushes. Understanding variations between dawn and dusk choruses could allow for a better interpretation of how some bird species cope with urban challenges

Bird community responses to different urban conditions in La Paz, Bolivia

Our main objective was to contribute to a better knowledge of bird communities in La Paz, and to describe to some extent how they are affected by urbanization. We address the following questions: a) How are bird species richness and abundance influenced by different local habitat and urban development measures, and by different levels of urbanization?; b) How do these measures influence species composition?; and c) How much of the variation in species composition can be explained by these measures? For the first question, we predict that species richness and abundance will decline with increasing levels of urban development. For the second question, we predict that few bird species will be found in highly urbanized environments, compared to higher number of species in environments with low levels of urbanization. We expect the habitat and urban development measures to explain high percentages of variation in species composition.Urbanization alters ecosystems worldwide, but little is known about its effects in the Neotropical region. In the present research we examined the relative influence of different levels of urbanization and of some urban development measures on bird species richness, abundance and composition. We surveyed 104 observation stations at which we collected data on the relative abundance of bird species, and also data on seven environmental variables as measures of urban development and human activity. We registered 57 native bird species. Bird species richness and bird abundance increased with lower urbanization levels. Both variables were positively related to vegetation cover and native vegetation, and negatively to built-up cover, abundance of Rock Pigeon (Columa livia), pedestrian rate and car rate. A canonical correspondence analysis produced a significant model that explained 37% of the total variation in species data. This analysis segregated bird species along two important gradients: urbanization and elevation. The most urbanized areas were dominated by a few synanthropic species tolerant to human disturbance, such as Rufous-Collared Sparrow (Zonotrichia capensis), Eared Dove (Zenaida auriculata) or Chiguanco Thrush (Turdus chiguanco). Areas with lower urbanization levels had more species typically associated with native vegetation, such as Plain-Mantled Tit-Spinetail (Leptasthenura aegitaloides) or D’Orbigny’s Chat-Tyrant (Ochthoeca oenanthoides), among others. Elevation had a significant influence in structuring bird communities, with some species restricted to higher elevations and some to lower elevations. Although changes in elevation had an important influence, urbanization had a stronger effect on structuring bird communities. This study provides valuable information and an important baseline for future studies

Aerobic performance in tinamous is limited by their small heart. A novel hypothesis in the evolution of avian flight

Some biomechanical studies from fossil specimens suggest that sustained flapping flight of birds could have appeared in their Mesozoic ancestors. We challenge this idea because a suitable musculoskeletal anatomy is not the only requirement for sustained flapping flight. We propose the "heart to fly" hypothesis that states that sustained flapping flight in modern birds required an enlargement of the heart for the aerobic performance of the flight muscles and test it experimentally by studying tinamous, the living birds with the smallest hearts. The small ventricular size of tinamous reduces cardiac output without limiting perfusion pressures, but when challenged to fly, the heart is unable to support aerobic metabolism (quick exhaustion, larger lactates and post-exercise oxygen consumption and compromised thermoregulation). At the same time, cardiac growth shows a crocodilian-like pattern and is correlated with differential gene expression in MAPK kinases. We integrate this physiological evidence in a new evolutionary scenario in which the ground-up, short and not sustained flapping flight displayed by tinamous represents an intermediate step in the evolution of the aerobic sustained flapping flight of modern birds