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  Subjects -> BIOLOGY (Total: 3003 journals)
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BIOLOGY (1427 journals)            First | 1 2 3 4 5 6 7 8 | Last

Showing 1201 - 1400 of 1720 Journals sorted alphabetically
Quantitative Biology     Hybrid Journal   (Followers: 2)
Quarterly Review of Biology     Full-text available via subscription   (Followers: 15)
Radiation Research     Full-text available via subscription   (Followers: 3)
Rajshahi University Journal of Life & Earth and Agricultural Sciences     Open Access  
Redox Biology     Open Access   (Followers: 1)
Redox Report     Hybrid Journal  
Regeneration     Open Access   (Followers: 2)
Regulatory Peptides     Hybrid Journal   (Followers: 9)
Reinwardtia : A Journal on Taxonomy Botany, Plant Sociology and Ecology     Open Access   (Followers: 1)
Reports in Parasitology     Open Access   (Followers: 2)
Reports on Mathematical Physics     Full-text available via subscription   (Followers: 1)
Reports on Progress in Physics     Full-text available via subscription   (Followers: 3)
Reproductive Biology     Full-text available via subscription   (Followers: 1)
Reproductive Biology Insights     Open Access   (Followers: 2)
Reproductive Biomedicine & Society Online     Open Access  
Reproductive Toxicology     Hybrid Journal   (Followers: 15)
Research & Reviews : Journal of Computational Biology     Full-text available via subscription   (Followers: 4)
Research & Reviews : Journal of Ecology     Full-text available via subscription   (Followers: 1)
Research and Reports in Biodiversity Studies     Open Access  
Research and Reports in Biology     Open Access  
Research in Engineering Design     Hybrid Journal   (Followers: 11)
Research Journal of Parasitology     Open Access   (Followers: 3)
Research Journal of Seed Science     Open Access   (Followers: 3)
Research Journal of Soil Biology     Open Access   (Followers: 2)
Research Journal of Toxins     Open Access  
Resources     Open Access  
Retrovirology     Open Access   (Followers: 1)
Reviews in Fish Biology and Fisheries     Hybrid Journal   (Followers: 31)
Reviews of Modern Physics     Full-text available via subscription   (Followers: 28)
Revista Argentina de Antropología Biológica     Open Access  
Revista Brasileira de Biociencias     Open Access  
Revista Brasileira de Biologia     Open Access  
Revista Brasileira de Fisiologia Vegetal     Open Access  
Revista CENIC. Ciencias Biológicas     Open Access  
Revista Ceres     Open Access  
Revista Ciencias Marinas y Costeras     Open Access  
Revista Cubana de Investigaciones Biomédicas     Open Access   (Followers: 1)
Revista de Biología Tropical     Open Access   (Followers: 2)
Revista de Ciencia y Tecnología     Open Access  
Revista de Educación en Biología     Open Access  
Revista de Investigaciones Altoandinas - Journal of High Andean Research     Open Access  
Revista de la Ciencia del Suelo y Nutricion Vegetal     Open Access  
Revista de Protección Vegetal     Open Access  
Revista Eletrônica de Biologia     Open Access  
Revista Eletrônica TECCEN     Open Access  
Revista Fitotecnia Mexicana     Open Access  
Revista Iberoamericana de Bioética     Open Access  
Revista Iberoamericana de las Ciencias Biológicas y Agropecuarias     Open Access  
Revista Iberoamericana de Micología     Full-text available via subscription  
Revista Mexicana de Biodiversidad     Open Access  
Revista Mexicana de Micologí­a     Open Access  
Revista Peruana de Biología     Open Access  
Revue de primatologie     Open Access   (Followers: 1)
Revue d’ethnoécologie     Open Access   (Followers: 1)
Rhodora     Full-text available via subscription  
Rice     Open Access   (Followers: 4)
Rice Science     Open Access   (Followers: 2)
Risk Analysis     Hybrid Journal   (Followers: 35)
RNA     Hybrid Journal   (Followers: 9)
RNA & Disease     Open Access   (Followers: 1)
RNA Biology     Full-text available via subscription   (Followers: 4)
RURALS: Review of Undergraduate Research in Agricultural and Life Sciences     Open Access   (Followers: 1)
Russian Journal of Biological Invasions     Hybrid Journal   (Followers: 1)
Russian Journal of Developmental Biology     Hybrid Journal   (Followers: 2)
Russian Journal of Marine Biology     Hybrid Journal   (Followers: 3)
Russian Journal of Mathematical Physics     Hybrid Journal  
Russian Physics Journal     Hybrid Journal   (Followers: 1)
Rwanda Journal     Full-text available via subscription  
Sainstek : Jurnal Sains dan Teknologi     Open Access  
Sainteknol : Jurnal Sains dan Teknologi     Open Access  
Saudi Journal of Biological Sciences     Open Access   (Followers: 2)
Science and Engineering Ethics     Hybrid Journal   (Followers: 9)
Science Bulletin     Hybrid Journal  
Science China Life Sciences     Open Access  
Science Signaling     Full-text available via subscription   (Followers: 22)
Science Technology & Society     Hybrid Journal   (Followers: 4)
Scientific Journal of Biological Sciences     Open Access   (Followers: 1)
Scientific Papers Animal Science and Biotechnologies     Open Access  
Scientific Reports     Open Access   (Followers: 53)
Scientific Research Journal     Open Access  
Scientifica     Open Access  
Seed Science and Technology     Full-text available via subscription   (Followers: 2)
Selection     Full-text available via subscription  
Self/Nonself - Immune Recognition and Signaling     Full-text available via subscription   (Followers: 2)
Selforganizology     Open Access  
Semiconductor Science and Technology     Open Access   (Followers: 1)
Seminars in Cancer Biology     Hybrid Journal   (Followers: 3)
Seminars in Cell & Developmental Biology     Hybrid Journal   (Followers: 7)
Seminars in Hematology     Hybrid Journal   (Followers: 11)
Sensing and Bio-Sensing Research     Open Access  
Sensors     Open Access   (Followers: 19)
Sexual Development     Full-text available via subscription   (Followers: 2)
Sierra Leone Journal of Biomedical Research     Open Access  
Signal Transduction and Targeted Therapy     Open Access  
Signal Transduction Insights     Open Access   (Followers: 2)
SINET : Ethiopian Journal of Science     Open Access   (Followers: 6)
Small     Hybrid Journal   (Followers: 10)
Small GTPases     Full-text available via subscription   (Followers: 1)
Social and Natural Sciences Journal     Open Access   (Followers: 1)
Sociobiology     Open Access  
Somatic Cell and Molecular Genetics     Hybrid Journal   (Followers: 2)
Somatosensory and Motor Research     Hybrid Journal   (Followers: 1)
Source Code for Biology and Medicine     Open Access  
South African Journal of Enology and Viticulture     Open Access  
South African Journal of Science     Open Access   (Followers: 3)
South Asian Journal of Experimental Biology     Open Access   (Followers: 1)
South Australian Naturalist, The     Full-text available via subscription  
Spatial Vision     Hybrid Journal   (Followers: 2)
Sri Lankan Journal of Biology     Open Access  
Standards in Genomic Sciences     Open Access  
Statistics in Biosciences     Hybrid Journal   (Followers: 3)
Stem Cell and Translational Investigation     Open Access   (Followers: 2)
Stem Cell Biology and Research     Open Access   (Followers: 5)
Stem Cell Discovery     Open Access   (Followers: 4)
Stem Cell Epigenetics     Open Access   (Followers: 3)
Stem Cell Reports     Open Access   (Followers: 11)
Stem Cell Research     Open Access   (Followers: 16)
Stem Cell Reviews and Reports     Hybrid Journal   (Followers: 8)
Stem Cells     Hybrid Journal   (Followers: 8)
Stem Cells and Cloning: Advances and Applications     Open Access   (Followers: 2)
Stem Cells International     Open Access   (Followers: 2)
Steroids     Hybrid Journal  
Studies in Mycology     Open Access   (Followers: 2)
Studies on Neotropical Fauna and Environment     Hybrid Journal   (Followers: 1)
Subterranean Biology     Open Access  
Sugar Tech     Hybrid Journal   (Followers: 1)
Summa Phytopathologica     Open Access  
Sunsari Technical College Journal     Open Access  
Surface Science Reports     Full-text available via subscription   (Followers: 20)
Sustainability : The Journal of Record     Hybrid Journal   (Followers: 6)
Symbiosis     Hybrid Journal   (Followers: 3)
Synthesis Lectures on Biomedical Engineering     Full-text available via subscription  
Synthetic Biology     Full-text available via subscription  
Systematic Biology     Hybrid Journal   (Followers: 15)
Systematics and Biodiversity     Hybrid Journal   (Followers: 10)
Systems and Synthetic Biology     Hybrid Journal   (Followers: 11)
Systems Biology in Reproductive Medicine     Hybrid Journal  
Taprobanica : The Journal of Asian Biodiversity     Open Access  
Taxon     Full-text available via subscription   (Followers: 5)
Telomere and Telomerase     Open Access  
Terrestrial Arthropod Reviews     Hybrid Journal   (Followers: 1)
The Anatomical Record : Advances in Integrative Anatomy and Evolutionary Biology     Hybrid Journal   (Followers: 3)
The Botulinum J.     Hybrid Journal  
The Breast Journal     Hybrid Journal   (Followers: 10)
The Bryologist     Full-text available via subscription   (Followers: 8)
The Cerebellum     Hybrid Journal   (Followers: 2)
The Coleopterists Bulletin     Full-text available via subscription   (Followers: 1)
The Condor     Full-text available via subscription   (Followers: 28)
The Enzymes     Full-text available via subscription   (Followers: 2)
The FASEB Journal     Full-text available via subscription   (Followers: 25)
The Herpetological Journal     Full-text available via subscription   (Followers: 8)
The International Journal of Advanced Manufacturing Technology     Hybrid Journal   (Followers: 6)
The Journal of Technology Transfer     Hybrid Journal   (Followers: 9)
The Knee     Hybrid Journal   (Followers: 15)
The Nucleus     Hybrid Journal   (Followers: 1)
The Physics of Metals and Metallography     Hybrid Journal   (Followers: 17)
The Plant Cell     Full-text available via subscription   (Followers: 26)
The Protein Journal     Hybrid Journal   (Followers: 8)
Theoretical Biology and Medical Modelling     Open Access   (Followers: 2)
Theoretical Population Biology     Hybrid Journal   (Followers: 8)
Tissue and Cell     Hybrid Journal   (Followers: 2)
Tissue Engineering and Regenerative Medicine     Hybrid Journal   (Followers: 11)
Tissue Engineering Part A     Hybrid Journal   (Followers: 11)
Tissue Engineering Part B: Reviews     Hybrid Journal   (Followers: 9)
Tissue Engineering Part C: Methods     Hybrid Journal   (Followers: 9)
Toxicology in Vitro     Hybrid Journal   (Followers: 11)
Traffic     Hybrid Journal   (Followers: 7)
Transactions of the Royal Society of South Australia     Hybrid Journal  
Transcription     Full-text available via subscription   (Followers: 2)
Transgenic Research     Hybrid Journal   (Followers: 3)
Translational Psychiatry     Open Access   (Followers: 10)
Transportation Planning and Technology     Hybrid Journal   (Followers: 8)
Tree Genetics & Genomes     Hybrid Journal   (Followers: 3)
Tree-Ring Research     Full-text available via subscription  
Trees     Hybrid Journal   (Followers: 5)
Trends in Bacteriology     Open Access   (Followers: 3)
Trends in Bioinformatics     Open Access   (Followers: 21)
Trends in Biotechnology     Full-text available via subscription   (Followers: 137)
Trends in Cell Biology     Full-text available via subscription   (Followers: 35)
Trends in Evolutionary Biology     Open Access   (Followers: 13)
Trends in Microbiology     Full-text available via subscription   (Followers: 37)
Trends in Molecular Sciences     Open Access   (Followers: 5)
Trends in Parasitology     Full-text available via subscription   (Followers: 10)
Trends in Plant Science     Full-text available via subscription   (Followers: 25)
Trends in Vector Research and Parasitology     Open Access  
Tropical Freshwater Biology     Full-text available via subscription  
Tumor Biology     Open Access   (Followers: 3)
Tumor Microenvironment and Therapy     Open Access  
Tunnelling and Underground Space Technology     Hybrid Journal   (Followers: 9)
Turtle and Tortoise Newsletter     Full-text available via subscription   (Followers: 1)
Ukrainian Journal of Ecology     Open Access   (Followers: 1)
Ultrasound in Medicine & Biology     Full-text available via subscription   (Followers: 8)
Uniciencia     Open Access  
Universal Journal of Biomedical Engineering     Open Access  
Unnes Journal of Biology Education     Open Access   (Followers: 1)
Vakuum in Forschung und Praxis     Hybrid Journal   (Followers: 2)
Vascular Cell     Open Access  
Victorian Naturalist, The     Full-text available via subscription   (Followers: 3)
Virchows Archiv     Hybrid Journal   (Followers: 1)
Virologica Sinica     Hybrid Journal  

  First | 1 2 3 4 5 6 7 8 | Last

Journal Cover Journal of Avian Biology
  [SJR: 1.296]   [H-I: 59]   [25 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0908-8857 - ISSN (Online) 1600-048X
   Published by John Wiley and Sons Homepage  [1579 journals]
  • The evolutionary origin of variation in song length and frequency in the
           avian family Cettiidae
    • Authors: Chentao Wei; Trevor D. Price, Jiayu Liu, Per Alström, Yanyun Zhang
      Abstract: Aspects of bird song have been shown to correlate with morphological and ecological features, including beak and body size, and habitat. Here we study evolution of song length and song frequency among 30 species belonging to the Cettiidae. Frequency is negatively correlated with body size, and song length increases with latitude. Although migration distance correlates with latitude, the association of song length with latitude is only present within the non-migratory species, implying the association is not a consequence of migration. We place these correlations in a historical framework to show that the body size-frequency association arose early in the group, but the latitude-song length association is more evolutionarily labile. We suggest that latitudinal correlates of song length may reflect increased importance of sexual selection by female choice.This article is protected by copyright. All rights reserved.
      PubDate: 2017-04-12T04:26:15.186599-05:
      DOI: 10.1111/jav.01366
  • Evaluating the reliability of species distribution models with an indirect
           measure of bird reproductive performance
    • Authors: Olatz Aizpurua; Lisette Cantú-Salazar, Gilles San Martin, Francesc Sardà-Palomera, Gabriel Gargallo, Sergi Herrando, Lluís Brotons, Nicolas Titeux
      Abstract: Measures of fitness such as reproductive performance are considered reliable indicators of habitat quality for a species. Such measures are, however, only available in a restricted number of sites, which prevents them from being used to quantify habitat quality across landscapes or regions. Alternatively, species presence records can be used along with environmental variables to build models that predict the distribution of species across larger spatial extents. Model predictions are often used for management purposes as they are assumed to describe the quality of the habitats to support a species. Yet, given that species are often present both in optimal and suboptimal areas, the use of data collected during the breeding season to build these models may potentially result in misleading predictions of habitat quality for the reproduction of the species, with potentially significant conservation consequences. In this study we analysed the relationship between fitness parameters informing on habitat quality for reproduction and predictions of species distribution models at multiple spatial scales using two independent sets of data. For 19 passerine bird species, we compared an indirect measure of reproductive performance (ratio of juveniles-to-adults) – obtained from Constant Effort Sites (CES) mist-netting data in Catalonia – with the predictions of models based on bird presence records collected during the Catalan Breeding Bird Atlas (CBBA). A positive relationship between the predictions derived from species distribution models and the reproductive performance of the species was found for half of the species at one or more spatial scales. This result suggests that species distribution models may help to predict habitat quality for some species over some extents. However, caution is needed as this is not consistent for all species at all scales. Further work based on species- and scale-specific approaches is now required to understand in which situations species distribution models provide predictions that are in line with reproductive performance.This article is protected by copyright. All rights reserved.
      PubDate: 2017-03-07T09:30:27.248048-05:
      DOI: 10.1111/jav.01218
  • Evaluating interspecific niche overlaps in environmental and geographic
           spaces to assess the value of umbrella species
    • Authors: Yoan Fourcade; Aurélien G. Besnard, Jean Secondi
      Abstract: The concept of umbrella species assumes that concentrating resources on the protection of a single species contributes to the conservation of a suite of species and ecological processes belonging to the same ecosystem. The environmental requirements and geographical distribution of the umbrella species should thus overlap those of the group of targeted species. In western France, the conservation of several large grassland floodplains relies on agri-environmental schemes targeting one single bird species, the corncrake Crex crex. It is considered as an umbrella species but no real assessment of its effectiveness has been carried out so far. We used a two-step methodology to assess the potential of the corncrake to act as an umbrella species by estimating niche overlap in the environmental and geographic space between the main ground-nesting species of the bird community in these grasslands, including the corncrake and four passerines. The five species showed substantial differences in their ecological niches so that their distributions did not perfectly overlap. Overlaps in predicted distributions between pairs of species depended on the threshold used to convert suitability to binary maps. Moreover, the number of species that could be protected by a candidate umbrella species was affected by the overlap criterion of success. Although the corncrake may be used as an umbrella species, it would be outperformed by several passerine species. Our study highlights the potential of using niche overlap to select umbrella species. It also reveals the importance of analysing the sensitivity of outputs when changing thresholds and overlap criteria.
      PubDate: 2017-02-21T06:31:04.1398-05:00
      DOI: 10.1111/jav.01153
  • Habitat suitability and the constraints of migration in New World warblers
    • Authors: David P. L. Toews
      Abstract: Identifying the factors that influence geographic range limits can illustrate the various ecological, physiological, and evolutionary constraints imposed on a species. The range limits of migratory birds are particularly challenging to study as they occur in disjunct regions at different times of the year, which can impose different constraints. Travel between breeding and wintering regions poses a significant energetic and navigational challenge to birds, although it is not clear how these movements influence breeding dispersal and range expansion. Here I ask whether the possible costs of migration limit the breeding ranges of wood warblers, a group of birds with an extensive history of ecological and evolutionary studies. I used occurrence records for multiple wood warbler species, breeding primarily in the boreal forest of North America, to generate environmental niche models. I tested for over-prediction of habitat suitability into the western boreal forest, where most these species do not have occurrence records but where there is presumably suitable habitat. I found that some of these vagile taxa, primarily found east of the Rocky Mountains, also have predicted habitat suitability that extends into the north and west, where they have little to no occurrence records. I discuss several possible explanations for this discordance. In particular, the patterns are consistent with the costs of a long-distance migration limiting the benefits of range expansion, as migration may become too onerous as the distance between breeding and wintering areas increases. These results speak to the process of niche filling more generally and call attention to an under-appreciated explanation for why migratory species may not fully occupy their fundamental niche.This article is protected by copyright. All rights reserved.
      PubDate: 2017-02-10T05:50:52.183644-05:
      DOI: 10.1111/jav.01157
  • Climate determinants of breeding and wintering ranges of lesser kestrels
           in Italy and predicted impacts of climate change
    • Authors: Michelangelo Morganti; Damiano Preatoni, Maurizio Sarà
      Abstract: Climate warming would theoretically create conditions for the breeding range expansion of pseudo-steppe Mediterranean and long-distance migrant species and provide the possibility for these to overwinter in the same breeding areas. However, contemporary changes in rainfall regimes might have negative effects on the climate suitability and in turn, shrink species potential range. The lesser kestrel, Falco naumanni, is highly sensitive to rainfall oscillations and has recently extended its Italian breeding range towards northern latitudes and increasing its wintering records. We modelled the effects of temperature and rainfall on current and future climate suitability for lesser kestrels in both the breeding and wintering periods by using MaxEnt. Models were based on the distribution of 298 colonies and 45 wintering records. Future climate suitability was assessed under eight different scenarios.Spring rainfall amount resulted as the main determinant of breeding climate suitability, so its predicted reduction will determine a shrinkage in suitable areas (-42.10% in 2050; -32.07% in 2070). Specifically, the 66.05% of Italian colonies will be outside the climatically suitable area by 2050. However wide areas, suitable under current climate conditions, are still not occupied by lesser kestrel and allow the potential expansion of its Italian breeding range in the short term. Temperature seasonality mainly determined the species’ winter climate suitability, which is overall predicted to boost in the next decades (+145.03% in 2050; and +123.91% in 2070). All but one future scenarios predicted a northward shift of about 40 km for both breeding and wintering climate suitability. Despite its recent expansion, we have found that climate change will pose conservation concerns for the Italian breeding population of lesser kestrels. Indeed, changes in non-climate factors will also outline the future suitability of the Italian range for lesser kestrels in both seasons with effects that might both strengthen or mitigate climate effects.This article is protected by copyright. All rights reserved.
      PubDate: 2017-02-08T05:05:37.380048-05:
      DOI: 10.1111/jav.01179
  • Integrating demography, dispersal and interspecific interactions into bird
           distribution models
    • Authors: Damaris Zurell
      Abstract: Species’ ranges are primarily limited by the physiological (abiotic) tolerance of the species, described by their fundamental niche. Additionally, demographic processes, dispersal, and interspecific interactions with other species are shaping species distributions, resulting in the realised niche. Understanding the complex interplay between these drivers is vital for making robust biodiversity predictions to novel environments. Correlative species distribution models have been widely used to predict biodiversity response but also remain criticised, as they are not able to properly disentangle the abiotic and biotic drivers shaping species’ niches. Recent developments have thus focussed on (i) integrating demography and dispersal into species distribution models, and on (ii) integrating interspecific interactions. Here, I review recent demographic and multi-species modelling approaches and discuss critical aspects of these models that remain underexplored in general and in respect to birds, for example, the complex life histories of birds and other animals as well as the scale dependence of interspecific interactions. I conclude by formulating modelling guidelines for integrating the abiotic and biotic processes that limit species’ ranges, which will help to disentangle the complex roles of demography, dispersal and interspecific interactions in shaping species niches. Throughout, I pinpoint complexities of avian life cycles that are critical for consideration in the models and identify data requirements for operationalizing the different modelling steps.This article is protected by copyright. All rights reserved.
      PubDate: 2017-02-02T09:10:49.271627-05:
      DOI: 10.1111/jav.01225
  • Influence of device accuracy and choice of algorithm for species
           distribution modelling of seabirds: A case study using black-browed
    • Authors: Petra Quillfeldt; Jan O. Engler, Janet R.D. Silk, Richard A. Phillips
      Abstract: Species distribution models (SDM) based on tracking data from different devices are used increasingly to explain and predict seabird distributions. However, different tracking methods provide different data resolutions, ranging from < 10m to>100km. To better understand the implications of this variation, we modeled the potential distribution of black-browed albatrosses Thalassarche melanophris from South Georgia that were simultaneously equipped with a Platform Terminal Transmitter (PTT) (high resolution) and a Global Location Sensor (GLS) logger (coarse resolution), and measured the overlap of the respective potential distribution for a total of nine different SDM algorithms. We found slightly better model fits for the PTT than for GLS data (AUC values 0.958±0.048 vs. 0.95±0.05) across all algorithms. The overlaps of the predicted distributions were higher between device types for the same algorithm, than among algorithms for either device type. Uncertainty arising from coarse-resolution location data is therefore lower than that associated with the modeling technique. Consequently, the choice of an appropriate algorithm appears to be more important than device type when applying SDMs to seabird tracking data. Despite their low accuracy, GLS data appear to be effective for analyzing the habitat preferences and distribution patterns of pelagic species.This article is protected by copyright. All rights reserved.
      PubDate: 2017-01-16T00:10:26.097813-05:
      DOI: 10.1111/jav.01238
  • Outdoor recreation causes effective habitat reduction in Capercaillie
           Tetrao urogallus: a major threat for geographically restricted populations
    • Authors: Joy Coppes; Judith Ehrlacher, Rudi Suchant, Veronika Braunisch
      Abstract: Outdoor recreation inflicts a wide array of impacts on individual animals, many of them reflected in the avoidance of disturbed areas. The scale and spatial extent, however, at which wildlife populations are affected, are mostly unclear. Particularly in geographically isolated populations, where restricted habitat availability may preclude a relocation to undisturbed areas, effective habitat reduction may remain underestimated or even unnoticed, when animals stay in disturbed areas and only show small-scale responses. Based on telemetry data, we investigated the spatial and seasonal effects of outdoor recreation - in relation to landscape and vegetation conditions – on western capercaillie Tetrao urogallus, considering two scales, homerange and within-homerange habitat selection. We determined the distance-thresholds up to which recreation infrastructures were avoided and estimated the extent of affected habitat for the isolated Black Forest (Southwestern Germany) study population. While outdoor recreation did not affect homerange selection, strong effects on habitat use within the homerange were detected: Distance to recreation infrastructure (hiking and cross-country skiing trails, ski pistes) was the main determinant of habitat selection in winter; in summer, mountain bike trails and hiker's restaurants were avoided up to an average distance of 145m (CI: 60-1092m). Around winter-infrastructure, relative avoidance was recorded up to 320m (CI: 36-327m), it was reduced, however, when dense understory provided visual cover. Of the entire population area, between 8- 20% (summer) and 8- 40% (winter) were affected by outdoor recreation, mainly in the high altitudes. Even without evident large-scale shifts in species distribution, local-scale avoidance of outdoor recreation can substantially contribute to effective habitat reduction. Based on our results we recommend a general reduction in recreation infrastructure density in key habitats, the establishment of undisturbed wildlife refuges with a diameter of at least 800m, as well as enhancing visual protection by maintaining a strip of dense understory along trails.This article is protected by copyright. All rights reserved.
      PubDate: 2017-01-16T00:10:23.785218-05:
      DOI: 10.1111/jav.01239
  • A bridge between oceans: Overland migration of marine birds in a wind
           energy corridor
    • Abstract: Located at the shortest overland route between the Gulf of Mexico and the Pacific Ocean, Mexico's Tehuantepec Isthmus is a globally important migratory corridor for many terrestrial bird species. The Pacific coast of the Isthmus also contains a significant wetland complex that supports large multi‐species aggregations of non‐breeding waterbirds during the boreal winter. In recent years, extensive wind energy development has occurred in the plains bordering these wetlands, directly along the migratory flyway. Using recent studies of movement patterns of three marine‐associated bird species—reddish egrets (Egretta rufescens), brown pelicans (Pelecanus occidentalis), and red knots (Calidris canutus)—from the northern Gulf of Mexico, we assess the use of the isthmus as a migratory corridor. Our data provide evidence that marine birds from the Gulf region regularly overwinter along the Pacific coast of Mexico and use the isthmus as a migratory corridor, creating the potential for interaction with terrestrial wind farms during non‐breeding. This study is the first to describe migration by marine‐associated bird species between the Gulf of Mexico and Pacific coast. These data contribute new information toward ongoing efforts to understand the complex migration patterns of mobile marine species, with the goal of informing integrated conservation efforts for species whose year‐round habitat needs cross ecoregional and geopolitical boundaries.This article is protected by copyright. All rights reserved.
  • Vocal plasticity in mallards: multiple signal changes in noise and the
           evolution of the Lombard effect in birds
    • Abstract: Signal plasticity is a building block of complex animal communication systems. A particular form of signal plasticity is the Lombard effect, in which a signaler increases its vocal amplitude in response to an increase in the background noise. The Lombard effect is a basic mechanism for communication in noise that is well‐studied in human speech and which has also been reported in other mammals and several bird species. Sometimes, but not always, the Lombard effect is accompanied by additional changes in signal parameters. However, the evolution of the Lombard effect and other related vocal adjustments in birds are still unclear because so far only three major avian clades have been studied. We report the first evidence for the Lombard effect in an anseriform bird, the mallard (Anas platyrhynchos). In association with the Lombard effect, the fifteen ducklings in our experiment also increased the peak frequency of their calls in noise. However, they did not change the duration of call syllables or their call rates as has been found in other bird species. Our findings support the notion that all extant birds use the Lombard effect to solve the common problem of maintaining communication in noise, i.e. it is an ancestral trait shared among all living avian taxa, which means that it has evolved more than 70 million years ago within that group. At the same time, our data suggest that parameter changes associated with the Lombard effect follow more complex patterns, with marked differences between taxa, some of which might be related to proximate constraints.This article is protected by copyright. All rights reserved.
  • Effect of light‐level geolocators on apparent survival of two highly
           aerial swift species
    • Abstract: Light‐level geolocators are currently widely used to track the migration of small‐sized birds, but their potentially detrimental effects on survival of highly aerial species have been poorly investigated so far. We recorded capture‐recapture histories of 283 common swifts Apus apus and 107 pallid swifts Apus pallidus breeding in 14 colonies in Italy, Spain, Sweden and Switzerland that were deployed with 10 different types of geolocators (‘geolocator birds’), and compared their survival with that of, respectively, 215 common and 101 pallid swifts not equipped with geolocators (‘control birds’). We performed both traditional GLMM using return rate as a proxy for survival and mark‐recapture models to estimate survival while accounting for recapture probability. In all the analyses, geolocator birds showed reduced apparent survival compared to controls. The extent of the negative effect on survival differed between the species but the direction of the difference between species was opposite in either type of analysis. Geolocator weight was always lower 3% of body mass or less, and did not affect survival per se. Geolocators with a light‐stalk, which is used in some geolocator models to reduce light sensor shading by feathers, decreased apparent survival more than models without light‐stalk. Apparent survival of geolocator birds significantly varied among sites, being much higher in northern Europe. Despite in our analyses we could only partly account for variable recapture probabilities among sites and for inter‐annual variability in survival, our results generally showed that equipping swifts with geolocators decreased their survival prospects, but also that the magnitude of this effect may depend on species‐specific traits. These conclusions are in line with those of other studies on aerial foragers. We suggest that future studies tracking the movements of aerial insectivorous birds should use devices designed to minimize drag.This article is protected by copyright. All rights reserved.
  • Effects of food limitation on the intensity of blue‐green and brown
           eggshell coloration: an experimental study with the canary
    • Abstract: Variation in blue‐green and brown coloration of avian eggshells could be affected by several factors, including environmental nutritional constraints. Better availability of nutrients could influence the synthesis and deposition of pigments into the eggshell, so we may expect a link between the food availability during egg formation, the body condition of the female and intensity of eggshell coloration. This hypothesis has received mixed support so far: in some bird species a positive correlation between female body condition and eggshell blue‐green coloration could be demonstrated, but other studies failed to find a significant link. In this study, we experimentally limited the food availability for domestic canaries (Serinus canaria) prior to and during egg laying, and examined its effects on the biliverdin‐ and protoporphyrin‐based eggshell coloration. Treatment had no significant effect on eggshell blue‐green chroma and biliverdin concentration. However, we found a significant positive relationship between female body condition and eggshell background blue‐green chroma in the control group, but not in the food restricted group. Females possibly experiencing a decline in antioxidant capacity due to food limitation may not be able to produce a blue‐green eggshell colour intensity reliably indicating their body condition. Furthermore, food‐restricted canary females laid eggs with significantly higher eggshell brown chroma, spot intensity, and protoporphyrin concentration. Therefore, our results suggest that limitation in actual nutrient availability increases deposition of protoporphyrin into the eggshell, and it may also modify the association between female body condition and intensity of blue‐green eggshell coloration.
  • Males in seemingly female-like plumage do not mimic females: UV
           reflectance reveals temporal cryptic dimorphism in a manakin species
           exhibiting delayed plumage maturation
    • Abstract: Manakins (Pipridae) are neotropical birds that usually exhibit delayed plumage maturation (DPM). Thus, while plumage of most adult male manakins is brightly conspicuous, subadult males and females are basically dull-olive green. Although sexual dichromatism in some bird species may be evident only through UV reflectance, this phenomenon, known as hidden sexual dichromatism, has not been previously studied in manakins to compare subadult males and females. Within this framework, we carried out spectrophotometric analyses in searching for hidden sexual dichromatism in the white-bearded manakin Manacus manacus, through comparison of UV spectra in females and subadult males in green plumage. Our results revealed UV reflectance in both sexes in green plumage. Moreover, we found UV spectral differences in homologous color patches between sexes, particularly at belly. Since the observed differences may allow intraspecific sex recognition of individuals in green plumage, our results do not support the female-mimicry hypothesis to explain delayed plumage maturation in the white-bearded manakin. Although our findings dismiss the female mimicry hypothesis, we cannot state whether these results support the non-mutually exclusive cryptic and status signaling hypotheses. We propose then, that dull coloration of subadult males may serve both as a cryptic trait and to limit the energetic costs of acquiring the adult plumage before sexual maturity. Meanwhile, differential UV color traits between sexes in green plumage may allow adult males to avoid unnecessary energy expenditures in courtship displays in the presence of males near leks, and to selectively focus their the courtship displays on females. In accordance with the signaling status hypothesis, subadult males can be recognized both as males and subordinates and consequently may practice courtship displays without suffering aggressions by adult males. Our results highlight the importance to include a wider range of spectrophotometric information analyses for testing hypotheses regarding delayed plumage maturation.This article is protected by copyright. All rights reserved.
  • An Assessment of Tree Availability as a Possible Cause of Population
           Declines in Scavenging Raptors
    • Abstract: Lack of suitable nesting trees is an increasingly common issue for avian conservation given rampant habitat and tree destruction around the world. In the African savannah, habitat loss and particularly tree damage caused by elephants have been suggested as possible factors in the decline of large bird species. Given the recent declines of vultures and other scavenging raptors, it is critical to understand if nest availability is a limiting factor for these threatened populations. Loss of woodland, partially due to elephant populations, has been reported for the Mara-Serengeti ecosystem. Data on characteristics of trees used for nesting were collected for White-backed, Lappet-faced, White-headed vulture, and Tawny eagle nests in Masai Mara National Reserve, Kenya. Nest tree characteristics were compared with the distribution of a random subsample of trees to assess nest preferences and determine suitability of available trees. Nearest neighbor distances were estimated as well as availability of preferred nesting trees to determine if tree availability is a limiting factor for tree-nesting vultures. Tree availability was found to greatly exceed nesting needs for African vultures and Tawny eagles. We thus conclude that on a landscape scale, tree availability is not a limiting factor for any of the species considered here (White-backed, Lappet-faced, White-headed vultures, and Tawny eagles).This article is protected by copyright. All rights reserved.
  • Do environmental conditions experienced in early life affect recruitment
           age and performance at first breeding in common goldeneye females'
    • Abstract: Environmental conditions experienced early in life may have long-term impacts on life history traits and reproductive performance. We investigated whether ambient temperature experienced during the first two to four weeks of life and weather severity during the first two winters affected recruitment age and relative timing of breeding in the year of recruitment in female common goldeneyes (Bucephala clangula). Our sample consisted of 141 female recruits hatched in a study population in central Finland between 1985 and 2013 and captured later as breeders. About 56% of the recruited females bred for the first time when 2 years old (range 2-6 years). Individuals facing colder ambient temperatures during the first two to four weeks posthatch or more severe winter conditions during the first two winters did not recruit at an older age. Nor did maternal characteristics, relative hatch date or nest site availability affect recruitment age. For females that recruited at 2 years old, the date of first breeding was usually late relative to the population mean that year (mean difference 6.9 days, range -7 to 21 days). Our results suggest developmental buffering enables female goldeneye ducklings to mitigate the impacts of adverse environmental conditions experienced during the first weeks of life, at least in terms of first breeding.
  • Effect of composition on shape of bird eggs
    • Abstract: Numerous studies over the past 90 years have described the various bird egg shapes in mathematical terms but few studies have considered the underlying reasons for such interspecific egg shape variability. This study investigated how the size and composition, i.e. proportions of shell, yolk and albumen, were associated with egg shape. Geometric morphometrics were used to generate principal components, which were analysed in relation to taxonomy (i.e. avian order) and degree of neonatal developmental maturity, which correlates with egg composition. The analysis confirmed previous results that most of the variation in shape is associated with degree of elongation (i.e. length divided by breadth) and asymmetry (i.e. position of the broadest part of the egg away from the mid-point of the egg's length). Egg shape reflected avian order but not developmental maturity. The degree of elongation of an egg is related to absolute egg mass and the proportion of yolk. By contrast, the degree of asymmetry is related to the proportion of shell and the mass of the egg relative to female body mass. Although significant, the models explained little of the variation in egg shape and so it was concluded that other factors, such as pelvis size and shape, could be more important in determining egg shape in birds.
  • Crosstalk between growth and somatic maintenance in young animals
    • Abstract: Growing animals face allocation problems whenever receiving suboptimal amounts of resources in very stochastic natural environments, possibly through a trade-off between growth and somatic maintenance. However, the extent to which such a trade-off exists has remained an open question. We used an insulin-like growth factor 1 (IGF-1) injection treatment in free-living pied flycatcher (Ficedula hypoleuca) nestlings to see how IGF-1 levels mediate the development of an antioxidant phenotype via glutathione peroxidase (GPx). Our study showed that IGF-1 levels underlie variation in GPx activity and provides important information for understanding the mechanisms behind the growth variation of passerines.This article is protected by copyright. All rights reserved.
  • Predictable anthropogenic food subsidies, density-dependence and
           socio-economic factors influence breeding investment in a generalist
    • Abstract: Recent European policies on the ban of fishing discards and the closure of open-air landfills are expected to reduce predictable and abundant food resources for generalist seabirds. In order to forecast the consequences of this reduction on seabird breeding investment it is important to understand whether diverse anthropogenic foraging resources act synergistically or not and whether their influence is mediated by density-dependent mechanisms. To assess these effects at large spatio-temporal scale, we measured mean egg volume as a proxy of breeding investment in ca. 5,000 three-egg clutches of the Yellow-legged Gull (Larus michahellis) from 20 colonies of the Western Mediterranean, located both along European and African coasts. In European gull colonies, egg volume increased with the availability of fishing discards and landfills in the vicinity of the colony. However, the landfill effect was weaker than the effect of fishing discards, probably due to the lower quality of waste as food for gulls. In contrast, none of the anthropogenic food subsidies influenced egg volume in African colonies, likely due to socio-economic differences (i.e. a much lower availability and predictability of both discards and waste food. Finally, results showed that the positive association between fishing discards and open-air landfills on egg volume was mediated by negative density-dependent mechanisms probably related to an increase in competition for food.This article is protected by copyright. All rights reserved.
  • Fall migratory departure decisions and routes of Blackpoll Warblers
           Setophaga striata and Red-eyed Vireos Vireo olivaceus at a coastal barrier
           in the Gulf of Maine
    • Abstract: Each year, millions of songbirds concentrate in coastal areas during fall migration. The choices birds make at the coast about stopover habitat use and migratory route can influence both the success of their migratory journey and fitness in subsequent life stages. We made use of a regional-scale automated radio telemetry array to study stopover and migratory flights and migratory routes of Blackpoll Warblers Setophaga striata and Red-eyed Vireos Vireo olivaceus during fall migration in the Gulf of Maine, USA. We focused on differences between species, sexes, age groups, breeding origins, and time of year. Both species made within-stopover relocations (i.e. ‘stopover flights’) from the coastal capture site. Stopover flights were primarily oriented inland, and were more frequent for blackpolls (87%) than vireos (44%). By studying migratory behavior at a broad spatial scale, we demonstrated that most blackpolls and vireos took coastal and offshore routes through the Gulf of Maine, despite initially relocating inland from the capture site. Though we captured blackpolls and vireos from a broad breeding range, more than 70% of migratory flights from the capture site were oriented for coastal or offshore travel for both species, suggesting that birds actively chose coastal and offshore routes, and were not simply displaced by wind drift. Later vireos oriented offshore more frequently during migratory flights from the coast, indicating that they may be more inclined towards time-minimizing overwater flight routes and thus more exposed to coastal and offshore collision hazards than earlier conspecifics.This article is protected by copyright. All rights reserved.
  • Sex- and age-dependent morphology and selection on wing shape in the barn
           swallow (Hirundo rustica)
    • Abstract: Wings have evolved in phylogenetically distant organisms with morphologies that depend on the combined effects of diverse, potentially contrasting selective forces. In birds, long pointed wings boost speed and energetic efficiency during cruising flight but reduce manoeuvrability. Migratory behavior is believed to lead to the evolution of more pointed wings, but selection on pointedness has never been estimated. Because annual routines of migrants are tightly scheduled, wing pointedness may be selected for because it allows for earlier arrival to the breeding grounds. In long-distance migratory barn swallows (Hirundo rustica) we showed that selection via breeding date and thus annual fecundity operates on wing pointedness, but not on other wing traits, among yearling females but not among older females or males. Selection on wing pointedness specifically in yearling females may result from climatic effects, which favour earlier arrival from migration, and from yearling females being the sex-by-age class with the latest migration and the smallest wing pointedness. Wing morphology differed between sexes and age classes because of change in size of the outermost but not the innermost wing feathers. Hence, sex- and age-specific selection on wing pointedness operates in a species with sex- and age-dependent variation in phenology and wing morphology.This article is protected by copyright. All rights reserved.
  • Tasting novel foods and selecting nutrient content in a highly successful
           ecological invader, the common myna
    • Abstract: Invasion success is dependent on the ability of a species to discover and exploit novel food resources. Within this context, individuals must be willing to taste novel foods. They must also be capable of evaluating the nutritional content of new foods, and selecting their relative intake in order to fulfil their nutritional needs. Whereas the former capacity is well studied, little is known about the latter capacity. First, using the common myna as a model avian invader species, we quantified the willingness of mynas to taste novel foods relative to familiar ones. Mynas readily tasted high protein (HP) novel foods and consumed them in higher quantities compared to a familiar food. Data showed that at three different levels – mixes, ingredients and macronutrients – intake could not be explained by a random model. In experiment 2, we confirmed that mynas were making their selection based on protein (P) content rather than a selection for novelty per se. When given the choice of three equally unfamiliar foods, mynas again ate disproportionately from the high protein relative to high lipid and high carbohydrate foods. Analysis revealed that mynas consumed amounts of protein that were closer to the ones in their natural diet. Finally, in experiment 3, we measured inter-individual variation in innovation and exploration propensities, and examined associations with inter-individual variation in consumption of specific macronutrients. This analysis revealed that individuals that selected HP pellets were more exploratory and individuals that selected HC pellets were quicker to solve the innovative foraging task. These findings indicate that not only the willingness to taste novel foods, but also the capacity to evaluate their nutritional content, might be central to the myna's substantial ecological success.This article is protected by copyright. All rights reserved.
  • Triploidy in a sexually dimorphic passerine provides new evidence for the
           effect of the W chromosome on secondary sexual traits in birds
    • Abstract: In birds, there are two main models for the determination of sex: the Z Dosage model in which the number, or dose, of Z chromosomes determines sex, and the Dominant W model which argues that a specific gene in the W chromosome may influence Z gene expression and determine sex. The best evidence for W determination of sex comes from birds with 2 copies of the Z chromosome paired with a single W (e.g. ZZW) which are nonetheless females. Here, we expand the species where such a mechanism may operate by reporting a case of a triploid Neotropical passerine bird with sexually dimorphic plumage, the São Paulo marsh antwren Formicivora paludicola. Evidence from 17 autosomal unlinked microsatellite loci, and CHD1 sex-linked locus, indicate that this individual is a 3n ZZW triploid with intermediate plumage pattern. This example expands our knowledge of sex determination mechanisms in birds by demonstrating that both the W and the two Z chromosomes affect the expression of morphological secondary sexual traits in a non-galliform bird.
  • Better nutritional condition changes the distribution of juvenile
           dispersal distances: an experiment with Spanish imperial eagles
    • Abstract: We investigated the distribution of juvenile dispersal distances of a territorial long-lived species with deferred maturity, the Spanish imperial eagle (Aquila adalberti). Here we used a reintroduction program as an experimental approach to test predictions of different hypotheses about the distribution of juvenile dispersal distances: competition and wandering behavior. We determined maximal juvenile dispersal distances of 59 young eagles; (i) 30 wild non-manipulated individuals, and (ii) 29 tranlocated young under an ad libitum feeding program, released with adults breeding in the area. The competitive displacement hypothesis predicts a leptokurtic distribution of distances in wild non-manipulated young as well as in released young. Under the ‘wandering’ hypothesis, however, a leptokurtic distribution is expected in wild young but a normal distribution would be expected in young released (with adults in the release area), owing to a general improvement in the nutritional status of released young that have been fed ad libitum, as is usual in reintroduction programs. Additionally, a negative relationship between hatching date and dispersal distances is expected in wild young but no relationship in released young under ad libitum feeding. Mean maximum dispersal distances for all the juvenile eagles was 142.8 Km. No differences between sexes were found, nor between populations or between wild and reintroduced young. Wild young distances were not normally distributed, being closer to a Poisson distribution. In contrast, released young with adults (under ad libitum feeding) showed a normal distribution. Wild birds showed a significant negative relationship between dispersal distance and hatching date, with young that hatched late in the season dispersing shorter distances. However, released young under ad libitum feeding showed no significant relationship between hatching date and dispersal distance. These results support the “wandering” hypothesis as the main driver of the distribution of dispersal distances.This article is protected by copyright. All rights reserved.
  • Egg mimicry by the pacific koel: mimicry of one host facilitates
           exploitation of other hosts with similar egg types
    • Abstract: When brood parasites exploit multiple host species, egg rejection by hosts may select for the evolution of host-specific races, where each race mimics a particular host's egg type. However, some brood parasites that exploit multiple hosts with the ability to reject foreign eggs appear to have only a single egg type. In these cases, it is unclear how the parasite egg escapes detection by its hosts. Three possible explanations are: (i) host-specific races are present, but differences in egg morphology are difficult for the human eye to detect; (ii) the brood parasite evolves a single egg type that is intermediate in appearance between the eggs of its hosts; (iii) or the parasite evolves mimicry of one of its hosts, which subsequently allows it to exploit other species with similar egg morphology. Here we test these possibilities by quantifying parameters of egg appearance of the brood-parasitic Pacific Koel (Eudynamys orientalis) and seven of its hosts. Koel eggs laid in the nests of different hosts did not show significant differences in colour or pattern, suggesting that koels have not evolved host-specific races. Koel eggs were similar in colour, luminance and pattern to the majority of hosts, but were significantly more similar in colour and luminance to one of the major hosts than to two other major hosts, supporting hypothesis (iii). Our findings suggest that mimicry of one host can allow a brood parasite to exploit new hosts with similar egg morphologies, which could inhibit the evolution of host defences in naïve hosts.This article is protected by copyright. All rights reserved.
  • Identifying demographic and environmental drivers of recruitment and
           population growth in a cavity-nesting sea duck population
    • Abstract: Traits with the greatest proportional effects on fitness are typically conserved (Stearns 1992), and traits with larger temporal variation frequently play a dominant role in population dynamics (Cooch et al. 2001). We examined recruitment patterns and population growth in Common Goldeneyes (Bucephala clangula; hereafter goldeneye), using Pradel mark-recapture models from a long-term nest box study (1997-2010). Our objectives were to estimate recruitment (f) and population growth (λ) relative to recruitment origin group (in-situ or unknown), investigate environmental and density dependent effects on these parameters, and evaluate potential immigration patterns. We detected group-specific differences for f (in-situ: 0.47± 0.13 SE, unknown: 0.31 ± 0.04), and the proportion of boxes occupied by goldeneyes the year prior to recruitment had a significant negative effect on recruitment for the in-situ group (β = -1.04; 85% CI -1.29, -0.78), and a positive effect for the unknown group (β = 0.45; 85% CI 0.30, 0.61). The negative box occupancy effect in the year prior to recruitment, when in-situ yearling goldeneyes prospect for potential nest sites, suggests that local nesting densities may limit recruitment of locally hatched females. We identified two competitive models for λ, which averaged 1.04 ± 0.03 and included interactions between recruitment origin group and a linear temporal trend, and the proportion of ducklings marked two years prior. By evaluating all levels of marking effort on λ, we determined that even if all hatched ducklings were marked in a given year, the resulting in-situ λ was consistently lower than all observed population-level λs during the study, indicating that individuals produced outside of study area nest boxes contributed to λ. Though female goldeneyes are considered highly philopatric, our results suggest that female natal and breeding dispersal may be more prevalent than previously thought, and the spatial scale at which these processes occur requires further investigation.This article is protected by copyright. All rights reserved.
  • Multi-functional crest display in Hoopoes (Upupa epops)
    • Abstract: Animals can engage in visual displays, which may target conspecifics, heterospecifics or both. Here we studied the function of the flamboyant crest-raising display of hoopoes (Upupa epops) in experiments performed with males in captivity. Males were exposed to sounds of a conspecific (male hoopoe song), a potential predator (human voice), and two controls (the song of a blackbird, Turdus merula, and background noise). These stimuli were presented to males in the presence and absence of females. Males raised the crest with a significantly higher probability when confronted with stimuli indicating potential threats (rival mate or predator) than with controls. The crest display was frequent when confronted with both kinds of threats independently of the presence of a female, suggesting that it was directed to the predator and the rival male. The probability of raising the crest was not related to body condition, and there was a marginally but not significant negative relationship between probability of raising the crest and the number of black spots on the crest feathers, which may suggest that crest display could be informing about male quality. Therefore, male hoopoes display the crest in a heterospecific context in response to detection of potential threats, which could be a deceptive or pursuit-deterrent signal. The results also support a role of the crest in sexual selection, suggesting that crest display in male hoopoes may serve multiple functions.This article is protected by copyright. All rights reserved.
  • Complex feeding behaviour by magpies in nests with great spotted cuckoo
    • Abstract: Parent decisions about food allocation are usually based on simple time-saving rules that optimize their own fitness; however, they can sometimes vary depending on the prevailing ecological conditions both outside and inside the nest. Parent-offspring interactions also become more complex when parents suffer from brood parasitism, which implies that they care for the parasite's eggs and unrelated young. The great spotted cuckoo (Clamator glandarius) is a specialist brood parasite that uses the magpie (Pica pica) as its primary host. Here, by filming food allocation by magpie parents in natural non-parasitized and experimentally parasitized and non-parasitized magpie nests, we have found that magpie provisioning behaviour is highly complex including two types of feedings apart from normal ones. First, false feedings, when the parent touched the chick's beak but did not leave any food, occurred more frequently when feeding a cuckoo than when feeding magpie nestlings. Second, two types of what we have called coax feedings: (2a) when magpie parents induce a nestling to beg by waking it up by touching it softly with the beak, and (2b) when parents disregard begging signals (always from brood parasitic great spotted cuckoos) while coaxing one non-begging nestling (always one of their own) to feed it. We suggest that brood parasitism, involving selfish excessively begging nestlings, could have acted as a selective pressure for both false and coax feedings to evolve, as both imply ignoring nestlings that beg too much. We also discuss that these parental responses could have evolved either by a discrimination without recognition mechanism, or, more probably, by a recognition-based discrimination mechanism.
  • A temporally explicit species distribution model for a long distance avian
           migrant, the common cuckoo
    • Abstract: Modelling the distribution of migratory species has rarely been extended beyond breeding and wintering ranges despite many species showing much more complex movement patterns with multiple stopovers. We aimed to create a temporally explicit species distribution model describing the full annual distribution cycle, and use it to model the complex seasonal shifts in distribution of the common cuckoo Cuculus canorus, a declining long-distance migrant. To do this we used full-year satellite telemetry occurrence data, with their associated temporal information, to inform a temporally explicit species distribution model using MaxEnt. The resulting full-year distribution model was highly predictive (AUC = 0.894) and appeared to have generality at the species-level despite being informed by data from a single breeding population. Comparison of our methodology with seasonal distribution models describing the breeding, winter and migration ranges separately showed that our full-year method provided more general and extensive predictions and performed better when tested with an independent dataset. When species distribution models based on a single season exclude environmental conditions experienced by birds in other parts of the annual cycle they risk underestimating niche breadth and neglecting the importance of stopover habitat. Conversely, models which simply average conditions across a season may miss the significance of finer scale within-season movements and overestimate niche breadth. In contrast, our framework for a full-year migrant distribution model successfully captures the finer-scale changes expected in seasonal environments and can be used to inform conservation management at every stage of migration. The full-year model framework appears to produce temporal distribution models generalised to the species-level from occurrence data limited to few individuals of a single population and may have particular utility when aiming to describe the distribution of species with complex migration patterns from telemetry data.
  • Investment in territorial defence relates to recent reproductive success
           in common loons (Gavia immer)
    • Abstract: As the value of a limited resource such as a territory increases, animals should invest more in the defence of that resource. Because reproductive success often depends on the quality of a breeding territory, reproductive success or failure may alter the perceived value of territory and affect an animal's investment in territorial defence. We used common loons (Gavia immer) to test the hypothesis that animals with recent breeding success would show stronger territorial defence than those with no recent breeding success. Surprisingly, successful loons responded less, not more, to a simulated intrusion. However, birds with success in the previous season also increased their territorial response as the breeding season progressed. In conjunction with past data showing that recently successful loons experience an increase in conspecific intrusions on their territories, we interpret our data to suggest that loons with recent success offset the cost of increased intrusions by adopting a more efficient strategy for territorial defence (e.g., limiting investment in resource defence until the time of the season when it is most critical).This article is protected by copyright. All rights reserved.
  • Uropygial gland volume and malaria infection are related to survival in
           migratory house martins
    • Abstract: Pathogens such as bacteria, fungi and malaria and related haemosporidians provoke negative effects on the fitness of their hosts. Animals have developed a range of defensive mechanisms to resist or eliminate these parasitic infections and their negative fitness costs. The uropygial gland secretion has been proposed to act as defensive barrier of skin and plumage in the fight against bacteria and fungi, and may prevent birds from acquiring haemosporidian infections. Thus, the secretion of uropygial glands of birds may favour survival of individuals. However, whether uropygial gland secretion influence survival remains unknown. Here we explore if the size of the uropygial gland and malaria infection influence survival of house martins Delichon urbica. We showed, for the first time, that the volume of the uropygial gland positively predicted survival prospects of malaria infected house martins. Malaria infected birds had the lowest probability of survival, with the effect of gland size on survival prospects depending on infection: Infected house martins with larger uropygial glands were better able to survive to the next breeding season, while infected birds with small uropygial glands were not. These results highlight the importance of uropygial gland secretion in the life history of wild birds.This article is protected by copyright. All rights reserved.
  • Determining the boundaries and plasticity of migratory bird flyways: a
           Bayesian model for Eurasian Teal Anas crecca in Western Europe
    • Abstract: Accurate flyway delineation is a prerequisite for effective conservation and management of migratory bird populations, yet such limits have so far mostly been set subjectively. We present a statistical method to infer population boundaries from the analysis of ring recoveries, using a Bayesian framework. The approach was applied to Eurasian Teal Anas crecca ringed in Camargue, southern France, and Abberton Reservoir, Essex, eastern England. The result presented show the boundaries of the two Teal flyways in Western Europe, with a zone of overlap, broadly matching those previously defined. The percentage of Teal switching flyways (abmigration rate) was 2.4-2.6%, greater in birds ringed as juveniles than as adults. Abmigrants ended up at sites within the other flyway where the density of local birds was lower than expected by chance, suggesting abmigration resulted from exploratory or aberrant behaviour. The methodology presented here can be used to infer flyway boundaries of any bird with an adequate ring-re-encounter dataset, which has crucial consequences for the evaluation of their trends in abundance and hence conservation status, and the management of sustainable harvests.This article is protected by copyright. All rights reserved.
  • Bluffing in the forest: Neotropical Neomorphus ground-cuckoos and
           peccaries in a possible case of acoustic mimicry
    • Abstract: Acoustic communication is particularly important in environments such as dense tropical forests, where the dim light constrains the efficacy of visual signals. In these environments, complex species interactions could promote the evolution of acoustic signals and result in intriguing patterns of mimicry and convergence. In the Neotropical region, Neomorphus ground-cuckoos frequently associate with herds of collared peccaries and white-lipped peccaries. Bill clacking behavior in ground-cuckoos closely resembles the sound of teeth clacking in peccaries and these acoustic signals are used in agonistic and foraging contexts in both species. Here we demonstrate that the acoustic characteristics of bill clacking in ground-cuckoos are more similar to teeth clacking of peccaries than to bill clacking of the more closely related Geococcyx roadrunner. We propose that two hypotheses may explain the evolution of the clacking behavior in these taxa. First, because peccaries are known to successfully ward off attacks from large predators to defend their herds, mimicking their clacking can deceive predators, either by triggering clacking from nearby peccaries, or making it appear to the predators that peccaries are present when they are not. Second, ground-cuckoos and peccaries could mutually benefit from the use of similar signals to alert each other of the presence of predators. In this context, ground-cuckoos could serve as sentinels while peccaries could confer protection. We also discuss alternative explanations for this striking acoustic resemblance. Ground-cuckoos and peccaries provide an interesting opportunity to study how an ecological association could foster the evolution of acoustic mimicry.This article is protected by copyright. All rights reserved.
  • Phylogenetic relatedness of co-occurring waterbird communities: a test of
           Darwin's competition-relatedness hypothesis
    • Abstract: The competition-relatedness hypothesis of Darwin (1859) states that competition is greater among species that are phylogenetically closely-related, and such species will tend to appear in separate communities (i.e. the species within communities will be phylogenetically overdispersed). Many studies have tested (and mainly refuted) this hypothesis for plant and bacterial communities. Results for the few studies with avian species are not conclusive. We tested Darwin's hypothesis for waterbirds using a set of open, artificial fish ponds in Doñana, south-western Spain, that provide relatively homogeneous habitat where competition is likely to be intense. Monthly counts of 38 ponds (for 11 months, i.e. 418 censuses) recorded 76 bird species. Darwin's hypothesis predicted that species appearing in the same pond would be less related phylogenetically than expected if species occurred randomly across ponds and months according to the structure of the overall community across the entire pond complex. However, the waterbird community did not show a predominantly overdispersed pattern, suggesting that interspecific competition among phylogenetically related species was not the main force structuring communities. In contrast, the proportion of clustered communities was higher than expected throughout the annual cycle, indicating that related waterbirds tend to co-occur on the same site, probably because they have similar microhabitat preferences. Clustering patterns were mainly driven by abundant and closely related duck species, and also by shorebirds. However, few individual pond communities remained significantly different from random after correction for multiple testing. Furthermore, the probability of co-occurrence of a given species pair was negatively related to the phylogenetic distance between them. In conclusion, our study shows waterbird communities are mainly phylogenetically clustered or random, and do not support the competition-relatedness hypothesis.
  • Decline of a montane Mediterranean Pied flycatcher Ficedula hypoleuca
           population in relation to climate
    • Abstract: Certain populations of long-distance migratory birds are suffering declines, which may be attributed to effects of climate change. In this article, we have analysed a long-term (1991-2015) data set on a Pied flycatcher (Ficedula hypoleuca) population breeding in nest-boxes in a Mediterranean montane oak forest, exploring the trends in population size due to changes in nestling recruitment, female survival and female immigration. We have related these changes in population parameters to local climate, winter NAO index and to breeding density. During the last 25 years the population has declined by half, mainly in association with a decrease in nestling mass and structural size which had repercussions on the probability of nestling recruitment to the population. Lower local nestling recruitment in certain years was linked to lower female immigration rate in the same years. On the other hand, the local survival of females remained stable throughout the study period. Laying date and breeding success were negatively affected by local temperatures while breeding, recruitment rate likewise by minimum temperature prior to breeding in April. As minimum April temperatures have increased across the study period, this may have affected recruitment and immigration rates negatively. On the other hand, tarsus length and body mass of nestlings were positively associated with winter NAO index, pointing to more global climatic links. Moreover, there was also a negative temporal trend in body mass of adults, implying increasingly difficult conditions for breeding. Declining recruit production in the study area could be attributed to a mismatch between the timing of arrival and breeding in the population, and the peak of food availability in this area.
  • Quantification of climatic niches in birds: adding the temporal dimension
    • Abstract: Quantification of the climatic niche from geographic occurrences is an increasingly important tool for studying species’ relationships to their environment, for example to predict responses to climate change. However, as the geographic distributions of birds are seasonally dynamic, they pose a challenge to carrying out comparable and appropriate quantification of climatic niches. In this review, we first assess how relevant seasonal dynamics are across birds as a whole by compiling a database of migratory behaviour for 10443 bird species. Second, we examine how studies have quantified climatic niches of birds. Finally, using Australia as a case study, we investigate how well existing distribution datasets represent temporal dynamics by comparing seasonal patterns of species richness obtained from point-occurrence data with those from range maps and assess the consequences for niche quantification. We provide a consistent classification of migratory behaviour across all birds, and find that a huge variety exists between and within species that should be considered when quantifying climatic niches. Despite this, our review of the literature revealed that seasonal dynamics have often not been accounted for. For future studies, we provide a framework for selecting appropriate occurrence data depending on migratory behaviour and data availability. Our comparison of seasonal species richness patterns obtained from extent-of-occurrence range maps and point-occurrence data suggests that range maps are less able to detect temporal dynamics of bird distributions than point-occurrence data. We conclude that seasonally explicit range maps combined with climatic data for the corresponding time period can be used to adequately quantify climatic niches for resident birds, but are not adequate to quantify the climatic niches of migratory and nomadic species. Therefore, consistent quantification of climatic niches across all birds requires temporally explicit occurrence points. As such, increasing the availability of occurrence data and methods correcting biases should be a priority.This article is protected by copyright. All rights reserved.
  • A pre-breeding immune challenge delays reproduction in the female
           dark-eyed junco (Junco hyemalis)
    • Abstract: Precise timing of life-history transitions in predictably changing environments is hypothesized to aid in individual survival and reproductive success, by appropriately matching an animal's physiology and behavior with prevailing environmental conditions. Therefore, it is imperative for individuals to time energetically costly life-history stages (i.e. reproduction) so they overlap with seasonal peaks in food abundance and quality. Female lifetime reproductive fitness is affected by several factors that influence energy balance, including arrival date, timing of egg production, and energetic condition. Therefore, any extra energetic costs during reproduction may negatively affect timing of egg production, and ultimately a female's fitness. For example, mounting an immunological response elicits a high energetic cost, and this transfer of resources towards cell and immune system maintenance could have direct negative effects on reproductive timing. In order to determine whether an immune challenge delays onset of breeding (i.e. egg production), we administered either a humoral immune challenge (keyhole limpet hemocyanin (KLH)) (treatment) or physiological saline (control) to free-living female dark-eyed juncos (Junco hyemalis) in the period immediately prior to egg-laying (~4 weeks). We found that KLH-injected females artificially delayed clutch initiation when compared to control females. These data help to refine our understanding of how free-living birds allocate resources between reproduction and self-maintenance processes during the critical pre-laying period of the annual cycle.This article is protected by copyright. All rights reserved.
  • A framework integrating physiology, dispersal and land-use to project
           species ranges under climate change
    • Abstract: To study the potential effects of climate change on species, one of the most popular approaches are species distribution models (SDMs). However, they usually fail to consider important species-specific biological traits, such as species’ physiological capacities or dispersal ability. Furthermore, there is consensus that climate change does not influence species distributions in isolation, but together with other anthropogenic impacts such as land-use change, even though studies investigating the relative impacts of different threats on species and their geographic ranges are still rare. Here we propose a novel integrative approach which produces refined future range projections by combining SDMs based on distribution, climate, and physiological tolerance data with empirical data on dispersal ability as well as current and future land-use. Range projections based on different combinations of these factors show strong variation in projected range size for our study species Emberiza hortulana. Using climate and physiological data alone, strong range gains are projected. However, when we account for land-use change and dispersal ability, future range-gain may even turn into a future range loss. Our study highlights the importance of accounting for biological traits and processes in species distribution models and of considering the additive effects of climate and land-use change to achieve more reliable range projections. Furthermore, with our approach we present a new tool to assess species’ vulnerability to climate change which can be easily applied to multiple species.This article is protected by copyright. All rights reserved.
  • Broad-scale variation in sexual dichromatism in songbirds is not explained
           by sex differences in exposure to predators during incubation
    • Abstract: The evolution of sexual dichromatism provoked one of the greatest disagreements between Charles Darwin and Alfred Russel Wallace. According to Darwin the main driving force is sexual selection, whereby choosy females prefer showy males, leading to the evolution of conspicuous male plumage. On the other hand, Wallace suggested that dichromatism may arise because nest predation favors more cryptic females. To test the role of natural selection in the evolution of dichromatism we combined quantitative data on differences in parental share in nest attentiveness (representing the strength of natural selection on males vs. females) with spectrophotometric measurements of dichromatism in 412 species of songbirds from 69 families. We expected to find stronger dichromatism in open-nesting species with more divergent parental roles and in body parts exposed during incubation. Dichromatism was not related to the differences in parental share during incubation, but it was most pronounced in lekking species, migrants, and small species. Our results thus suggest that Wallace's hypothesis is not able to explain broad-scale variation in the dichromatism of songbirds, but point to a role for sexual selection, mutual mate choice, and migration strategy in shaping the extraordinary variation in dichromatism exhibited by songbirds.This article is protected by copyright. All rights reserved.
  • An experimental demonstration that house finches add cigarette butts in
           response to ectoparasites
    • Abstract: Urban species encounter resources that are uncommon in nature, such as materials found in city waste. Many studies have shown that these can be harmful to wildlife. In Mexico City, house finches bring cigarette butts to their nests, which reduces the amount of ectoparasites, but also induces genotoxic damage in chicks and parents. Yet, the reason for this behaviour is unknown. One possibility is that birds extract the cellulose fibres from discarded butts simply because they resemble feathers. Alternatively, disassembled cigarette butts may be brought to the nests because they repel ectoparasites. Here we tested the latter hypothesis by assessing whether house finches (C. mexicanus) increase the amount of cigarette butts in their nests in response to a raise in ectoparasite load. When present, fibres from butts are concentrated in the nest lining. By taking it away, we simultaneously removed most of the butt material and collected the bulk of the tick population infesting each nest, as these parasites cluster in the lining. We removed the bedding of nests when chicks had recently hatched, and randomly assigned each nests to one of the following treatments: 1) addition of live ticks, 2) addition of dead ticks and 3) simulation of tick addition. Females in the live ticks’ treatment added more butt fibres to their nests than parents in control treatments. Additionally, the amount of butt fibres in the original lining also predicted the amount of fibres added after the manipulation. It seems that the tendency to bring to the nest cigarette butts is at least partially a response to current, and perhaps also past, parasite load.This article is protected by copyright. All rights reserved.
  • Using citizen science monitoring data in species distribution models to
           inform isotopic assignment of migratory connectivity in wetland birds
    • Abstract: Stable isotopes have been used to estimate migratory connectivity in many species. Estimates are often greatly improved when coupled with species distribution models (SDMs), which temper estimates in relation to occurrence. SDMs can be constructed using from point locality data from a variety of sources including extensive monitoring data typically collected by citizen scientists. However, one potential issue with SDM is that these data oven have sampling bias. To avoid this potential bias, an approach using SDMs based on marsh bird monitoring program data collected by citizen scientists and other participants following protocols specifically designed to maximize detections of species of interest at locations representative of the species range. We then used the SDMs to refine isotopic assignments of breeding areas of autumn-migrating and wintering Sora (Porzana carolina), Virginia Rails (Rallus limicola), and Yellow Rails (Coturnicops noveboracensis) based on feathers collected from individuals caught at various locations in the United States from Minnesota south to Louisiana and South Carolina. Sora were assigned to an area that included much of the western U.S. and prairie Canada, covering parts of the Pacific, Central, and Mississippi Flyways. Yellow Rails were assigned to a broad area along Hudson and James Bay in northern Manitoba and Ontario, as well as smaller parts of Quebec, Minnesota, Wisconsin, and Michigan, including parts of the Mississippi and Atlantic Flyways. Virginia Rails were from several discrete areas, including parts of Colorado, New Mexico, the central valley of California, and southern Saskatchewan and Manitoba in the Pacific and Central Flyways. Our study demonstrates extensive data from organized citizen science monitoring programs are especially useful for improving isotopic assignments of migratory connectivity in birds, which can ultimately lead to better informed management decisions and conservation actions.This article is protected by copyright. All rights reserved.
  • High altitude flights by ruddy shelduck (Tadorna ferruginea) during
           Trans-Himalayan migrations
    • Abstract: Birds that migrate across high altitude mountain ranges are faced with the challenge of maintaining vigorous exercise in environments with limited oxygen. Ruddy shelducks are known to use wintering grounds south of the Tibetan Plateau at sea level and breeding grounds north of Himalayan mountain range. Therefore, it is likely these shelducks are preforming high altitude migrations. In this study we analyse satellite telemetry data collected from 15 ruddy shelduck from two populations wintering south of the Tibetan Plateau from 2007 to 2011. During north and south migrations ruddy shelduck travelled 1,481 km (range 548 – 2,671 km) and 1,238 km (range 548-2,689 km) respectively. We find mean maximum altitudes of birds in flight reached 5,590 m (range of means 4,755 – 6,800 m) and mean maximum climb rates of 0.45 m s-1 (range 0.23 - 0.74 m s-1). The ruddy shelduck is therefore an extreme high altitude migrant that has likely evolved a range of physiological adaptations in order to complete their migrations.This article is protected by copyright. All rights reserved.
  • Rock Wrens preferentially use song types that improve long distance signal
           transmission during natural singing bouts
    • Abstract: When animals are capable of producing variable signals they may preferentially use some signal types over others. Among songbirds, individuals are known to alter song type form and usage patterns in contest and mating situations, but studies have not examined how song choice improves signal efficacy during broadcast song. For this study we investigated rock wren (Salpinctes obsoletus) song type use rates during natural singing bouts. We tested three hypotheses for adaptive song use during broadcast song: 1) birds improve signal content by increasing the use of high quality songs, 2) birds optimize for signal propagation by preferentially using songs that transmit well, and 3) birds maintain energy by reducing the use of costly songs. The study included 19,058 songs sung by 12 individuals, each of which had a measured song repertoire of between 52 and 117 song types which were produced at highly variable rates. Results indicated that rock wrens did not preferentially sing song types with shorter durations or fewer frequency switches, as would be expected if they selected song types to minimize delivery costs. They also did not favor songs with more rapid trills or more frequency switches, as would be expected if they adjusted song use primarily to indicate quality. Focal birds did preferentially sing significantly longer songs with lower bandwidths, lower frequencies, and slower trill rates. Results suggest that natural broadcast singing patterns are shaped more by the benefits of long distance transmission than by the benefits of advertising performance ability or the costs of song production.This article is protected by copyright. All rights reserved.
  • The relationship between blood parasites and ornamentation depends on the
           level of analysis in the common yellowthroat
    • Abstract: The Hamilton-Zuk hypothesis predicts that ornament expression is a signal of the ability of individuals to resist parasite infection. Thus, across a population (i.e., between-individuals) more ornamented individuals should have lower levels of parasitism. Numerous studies have tested this prediction and the results are mixed. One reason for these conflicting results may be that many studies have examined this relationship at the between-individual level, which may be affected by confounding factors such as selective mortality. Using within-subject centering we examined the relationship between male ornamentation and avian blood parasites at both the between- and the within-individual level. These relationships focus on differences in genetically-based resistance to parasites and the trade-off in resource allocation between parasite resistance and ornament expression within an individual, respectively. We studied male common yellowthroats (Geothlypis trichas), which have two plumage ornaments, a yellow, carotenoid-based bib (throat and chest) and a black, melanin-based facial mask. Surprisingly, within-individuals, an increase in parasitism between years was associated with an increase in mask size and, potentially, greater concentration of carotenoids in the yellow feathers. This suggests that males may be able to tolerate an increase in parasitism and still increase ornament expression. In contrast, ornamentation was not related to parasitism at the between-individual level. Thus, our study revealed relationships between ornaments and parasitism at the within-individual level that were not present at the between-individual level. Our results highlight the importance of examining both within- and between-individual relationships as correlations between variables, such as ornaments and parasites, may depend on the level of analysis (i.e., within- or between- individuals).This article is protected by copyright. All rights reserved.
  • Spatial relationships and mechanisms of coexistence between dominant and
           subordinate top predators
    • Abstract: Most forest ecosystems contain a diverse community of top-level predators. How these predator species interact, and how their interactions influence their spatial distribution is still poorly understood.Here we studied interactions among top predators in a guild of diurnal forest raptors in order to test the hypothesis that predation among competing predators (intraguild predation) significantly affects the spatial distribution of predator species, causing subordinate species to nest farther away from the dominant ones.The study analyzed a guild in southwestern Europe comprising three raptor species. For 8 years we studied the spatial distribution of used nests, breeding phenology, intraguild predation, territory occupancy, and nest-builder species and subsequent nest-user species.The subordinate species (sparrowhawk, Accipiter nisus) nested farther away from the dominant species (goshawk, A. gentilis), which preyed on sparrowhawks but not on buzzards (Buteo buteo), and closer to buzzards, with which sparrowhawks do not share many common prey. This presumably reflects an effort to seek protection from goshawks. This potential positive effect of buzzards on sparrowhawks may be reciprocal, because buzzards benefit from old sparrowhawk nests, which buzzards used as a base for their nests, and from used sparrowhawk nests, from which buzzards stole prey. Buzzards occasionally occupied old goshawk nests.These results support our initial hypothesis that interspecific interactions within the raptor guild influence the spatial distribution of predator species in forest ecosystems, with intraguild predation as a key driver. We discuss several mechanisms that may promote the coexistence of subordinate and dominant predators and the spatial assembly of this raptor guild: spatial refuges, different breeding phenology, spatial avoidance, low territory occupancy between neighboring nesting territories, nest concealment and protection, and diet segregation.This article is protected by copyright. All rights reserved.
  • Exogenous and endogenous corticosterone in feathers
    • Abstract: In birds, the steroid hormone corticosterone (CORT) increases in response to real or perceived threats to homeostasis. A long-term record of CORT exposure is recorded in feathers when the hormone is incorporated into the keratinized tissue, and then preserved when the mature feather is cut off from the blood supply. The opportunity to retrospectively assess the exposure of an individual to stressors by measuring the amount of CORT in a feather has generated excitement amongst avian ecologists. However, this technique is relatively new and requires additional validations. In this study, we performed experiments in wild caught European starlings (Sturnus vulgaris) to test whether: 1) CORT deposition in the feather depends on time of day and 2) whether an ecologically relevant stressor (unpredictable food access) causes a change in feather CORT. We found that exogenous CORT was incorporated into feathers during the day and the night. However, there was no difference in feather CORT between birds with unpredictable access to food and those with continuous access, indicating that feather CORT might not always detect ecologically relevant stressors.This article is protected by copyright. All rights reserved.
  • The relationship between plumage colouration, problem-solving and learning
           performance in great tits Parus major
    • Abstract: Recent studies suggest that individuals with better problem-solving and/or learning performance have greater reproductive success, and that individuals may thus benefit from choosing mates based on these performances. However, directly assessing these performances in candidate mates could be difficult. Instead, the use of indirect cues related to problem-solving and/or learning performance, such as condition-dependent phenotypic traits, might be favored. We investigated whether problem-solving and learning performance on a novel non-foraging task correlated with sexually selected plumage colouration in a natural population of great tits Parus major. We found that males successful in solving the task had darker blue-black crowns than non-solvers, and that males solving the task more rapidly over multiple attempts (i.e. learners) exhibited blue-black crowns with higher UV chroma and shorter-wavelength hues than non-learners. In contrast, we found no link between behavioural performance on the task and the yellow breast colouration in either sex. Our findings suggest that blue-black crown colouration could serve as a signal of problem-solving and learning performance in wild great tit males. Further research remains necessary to determine whether different sexually selected traits are used to signal cognitive performance for mate choice, either directly (i.e. cognitive performance influencing individual's health and ornamentation through diet for example) or indirectly (i.e. due to a correlation with a third factor such as individual quality or condition).This article is protected by copyright. All rights reserved.
  • Unmanned aircraft systems to unravel spatial and temporal factors
           affecting dynamics of colony formation and nesting success in birds
    • Abstract: Collecting information of ecological and behavioural processes often requires continuous field monitoring, however, reiterative human presence necessary to obtain monitoring data can disturb both the environment and the study species. An example of this phenomenon is the monitoring of the formation and dynamics of seabird colonies; one of the reasons for colony failure is disturbances caused by the presence of researchers or conservation managers during data collection. In this study, an Unmanned Aircraft System (UAS) was used throughout the breeding period to monitor the temporal and spatial dynamics of a black-headed gull colony in the interior of a difficult-to-access island. This methodology permitted weekly visits to the colony without disturbance, which allowed for the continuous collection of spatial and temporal data on the process of colony formation. We obtained detailed information about nesting success and its relation with the distance to the nearest incubating neighbour, as well as the colony boundary along breeding season. Thus, we successfully monitored the dynamics of a bird colony and identified factors affecting individual decision making in colony formation using a UAS.This article is protected by copyright. All rights reserved.
  • Study on the foraging behaviour of the European Nightjar Caprimulgus
           europaeus reveals the need for a change in conservation strategy in
    • Abstract: Effective nature conservation requires coherent actions based on the best available evidence concerning protected species. Recent studies have suggested that European nightjars Caprimulgus europaeus forage outside their recognized breeding habitats, yet, for Flanders (Northern Belgium) information on nightjar foraging behaviour and key foraging habitats is lacking . To assess whether the foraging ecology of nightjars in Flanders is similar to that observed in other parts of Europe, we studied the crepuscular behaviour of this species in Bosland (north-eastern Flanders) during a five-year radio telemetry study. Tracking of 48 individuals within a coniferous forest was standardized and home ranges were calculated using a kernel density estimator (fixed kernel). Habitat use was investigated by comparing kernel placement to available habitat. Average maximal foraging distance was 2603±1094m and home ranges extended up to 691ha. We identified the key foraging habitats to be extensively-cultivated grasslands and recreational areas, areas that were previously assumed unsuitable for Belgian nightjars. Our results indicate the importance of foraging sites outside the breeding territory, confirming the findings of previous studies performed elsewhere in Europe. Incorporating our findings into future conservation plans could, therefore, lead to improved efficiency of EU conservation measures, designed for the protection of this bird species in Flanders.This article is protected by copyright. All rights reserved.
  • Thermoregulation in free-ranging ground woodpeckers (Geocolaptes
           olivaceus): no evidence of torpor
    • Abstract: Heterothermic responses characterised by pronounced hypometabolism and reductions in body temperature (Tb) are one of the most effective ways in which small endotherms can offset the energetic cost of endothermic homeothermy. It remains unclear, therefore, why daily torpor and hibernation are restricted to only a subset of avian lineages. To further our understanding of the phylogenetic distribution of avian torpor, we investigated winter thermoregulation in the Southern African ground woodpecker (Geocolaptes olivaceus). We considered this species a good candidate for heterothermy, because it is resident year-round in mountainous regions with cold winters and reliant on small ectothermic prey. We recorded Tb patterns in free-ranging individuals and measured Tb and metabolic rates in captive individuals. Neither free-ranging nor captive woodpeckers showed any indication of daily torpor or even shallow rest-phase hypothermia. All birds maintained bimodally distributed Tb characteristic of classic endothemic homeothermy, with a mean rest-phase Tb of 37.9 ± 0.2 °C and no data below 37.0 °C. The mean circadian amplitude of Tb was 4.2 °C, equivalent to approximately twice the expected value. There was some evidence of seasonal acclimatisation in Tb, with a small decrease in rest-phase Tb with the onset of the austral winter. Captive birds showed patterns of resting metabolic rate and Tb consistent with the classic model of endothermic homeothermy. The apparent absence of torpor in G. olivaceus supports the notion that, unlike the case in mammals, many avian taxa that may a priori be expected to benefit from deep heterothermy do not use it.This article is protected by copyright. All rights reserved.
  • Plumage colour and the expression of stress-related genes in gull chicks
    • Abstract: In many bird populations, individuals show remarkable differences in feather colouration, which are often linked to individual differences in physiological traits, but the mechanisms maintaining this covariation are still unclear. Here, we investigate the variability of the melanic colouration in yellow-legged gull (Larus michahellis) chicks. In this species, hatchlings show high variability in the number and colour intensity of black spots in their plumage. In gulls, last-laid eggs receive less antioxidants but higher levels of androgens than first eggs. We first explored whether these remarkable differences within the clutch affect the feather melanisation during embryo development. Melanic colouration was not related to laying order, but nestling males were darker and had a larger spotted area than nestling females. In chicks hatching from first-laid eggs, the spot size and spot lightness were negatively correlated. We also explored the effect of the developmental environment, through a cross-fostering experiment, on the expression of five stress-related genes (SOD2, ALKBH3, HSPA8, NLRC5 and TRIAP1) and their link with melanic colouration. Post-hatching hierarchy did not affect the expression of any of the tested genes, but paler chicks showed reduced expression in some studied genes (SOD2, ALKBH3 and HSPA8) in comparison to darker chicks. Our results suggest that melanic chicks suffer less stress during development.This article is protected by copyright. All rights reserved.
  • Density-dependent increase in superpredation linked to food limitation in
           a recovering population of northern goshawks, Accipiter gentilis
    • Abstract: A better understanding of the mechanisms driving superpredation, the killing of smaller mesopredators by larger apex predators, is important because of the crucial role superpredation can play in structuring communities and because it often involves species of conservation concern. Here we document how the extent of superpredation changed over time, and assessed the impact of such temporal variation on local mesopredator populations using 40 years of dietary data collected from a recovering population of northern goshawks (Accipiter gentilis), an archetypical avian superpredator. We then assessed which mechanisms were driving variation in superpredation, e.g., was it opportunistic, a response to food becoming limited (due to declines in preferred prey) or to reduce competition. Raptors comprised 8% of goshawk diet on average in years when goshawk abundance was high, which is higher than reported elsewhere. Additionally, there was a per capita increase in superpredation as goshawks recovered, with the proportion of goshawk diet comprising raptors increasing from 2% to 8% as the number of goshawk home-ranges increased from ≤14 to ≥25. This increase in superpredation coincided with a population decline in the most commonly killed mesopredator, the Eurasian kestrel (Falco tinnunculus), which may represent the reversal of the “mesopredator release” process (i.e., mesopredator suppression) which occurred after goshawks and other large raptors declined or were extirpated. Food limitation was the most likely driver of superpredation in this system given: 1) the substantial decline of two main prey groups in goshawk diet, the increase in diet diversity and decrease in goshawk reproductive success are all consistent with the goshawk population becoming food-limited; 2) it's unlikely to be purely opportunistic as the increase in superpredation did not reflect changes in the availability of mesopredator species; and 3) the majority of mesopredators killed by goshawks do not compete with goshawks for food or nest sites.This article is protected by copyright. All rights reserved.
  • Elevational replacement of two Himalayan titmice: interspecific
           competition or habitat preference'
    • Abstract: Elevational species replacement is a widely documented pattern in montane species. Although interspecific competition has been shown to be important in setting species elevational limits in tropical habitats, its effect in species of temperate regions is poorly studied. We tested the role of interspecific competition for space in the breeding season and for food in the non-breeding season in mediating the distribution of two resident titmice species in the Himalayas. We show that high elevation green-backed tits (Parus monticolus) are behaviourally dominant over low elevation cinereous tits (Parus cinereus) in both song playback and feeder trials. Despite being subordinate, at their elevational upper limit, cinereous tits occur in sympatry in human modified habitats. Our study suggests that the loss of natural habitats in the sympatric zone, not interspecific competition, might be limiting the distribution of the high-elevation green-backed tits and facilitating an upward range shift through human association in cinereous tits.
  • Diurnal body temperature patterns in free-ranging populations of two
           southern African arid-zone nightjars
    • Abstract: Endotherms allocate large amounts of energy and water to the regulation of a precise body temperature (Tb), but can potentially reduce thermoregulatory costs by allowing Tb to deviate from normothermic levels. Many data on heterothermy at low air temperatures (Ta) exist for caprimulgids, whereas data on thermoregulation at high Ta are largely absent, despite members of this taxon frequently roosting and nesting in sites exposed to high operative temperatures. We investigated thermoregulation in free-ranging Rufous-cheeked Nightjars (Caprimulgus rufigena) and Freckled Nightjars (Caprimulgus tristigma) in the southern African arid zone. Individuals of both species showed labile Tb fluctuating around a single modal Tb (Tb-mod). Average Tb-mod was 39.7 °C for Rufous-cheeked Nightjars and 39.0 °C for Freckled Nightjars. In both species, diurnal Tb increased with increasing Ta. At Ta ≥ 38 °C, Rufous-cheeked Nightjar mean Tb increased to 42 °C, equivalent to 2.3 °C above Tb-mod. Under similar conditions, Freckled Nightjar Tb was on average only 1.1 °C above Tb-mod, with a mean Tb of 40.0 °C. Freckled Nightjars are one of the most heterothermic caprimulgids investigated to date, but our data suggest that during hot conditions this species maintains Tb within a narrow range above Tb-mod, possibly reflecting an evolutionary tradeoff between decreased thermal sensitivity to lower Tb but increased sensitivity to high Tb. These findings reveal how general thermoregulatory patterns at similar Ta can vary even among closely related species.This article is protected by copyright. All rights reserved.
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