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  Subjects -> BIOLOGY (Total: 2784 journals)
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    - BIOLOGY (1361 journals)
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BIOLOGY (1361 journals)            First | 3 4 5 6 7 8 9 10 | Last

International Agrophysics     Open Access   (Followers: 1)
International Aquatic Research     Open Access   (Followers: 3)
International Biodeterioration & Biodegradation     Hybrid Journal   (Followers: 1)
International Journal for Computational Biology     Open Access  
International Journal for Parasitology     Hybrid Journal   (Followers: 11)
International Journal for Parasitology : Drugs and Drug Resistance     Open Access   (Followers: 5)
International Journal of Acarology     Hybrid Journal   (Followers: 1)
International Journal of Applied Sciences and Biotechnology     Open Access   (Followers: 1)
International Journal of Aquatic Biology     Open Access   (Followers: 8)
International Journal of Basic, Applied and Innovative Research     Open Access  
International Journal of Bio-Inspired Computation     Hybrid Journal   (Followers: 1)
International Journal of Bioassays     Open Access   (Followers: 6)
International Journal of Biodiversity     Open Access   (Followers: 3)
International Journal of Biological and Chemical Sciences     Open Access   (Followers: 2)
International Journal of Biological Macromolecules     Hybrid Journal   (Followers: 1)
International Journal of Biological Sciences     Open Access   (Followers: 7)
International Journal of Biology     Open Access   (Followers: 3)
International Journal of Biomaterials     Open Access   (Followers: 4)
International Journal of Biomathematics     Hybrid Journal  
International Journal of Biomedical Engineering and Technology     Hybrid Journal   (Followers: 5)
International Journal of Biomedical Nanoscience and Nanotechnology     Hybrid Journal   (Followers: 7)
International Journal of Biometrics     Hybrid Journal   (Followers: 2)
International Journal of Brain Science     Open Access  
International Journal of Cell Biology     Open Access   (Followers: 6)
International Journal of Chemical and Life Sciences     Open Access   (Followers: 3)
International Journal of Computational Biology and Drug Design     Hybrid Journal   (Followers: 1)
International Journal of Design Engineering     Hybrid Journal   (Followers: 12)
International Journal of Ecological Economics and Statistics     Full-text available via subscription   (Followers: 1)
International Journal of Ecology & Development     Full-text available via subscription   (Followers: 2)
International Journal of Ecosystem     Open Access   (Followers: 1)
International Journal of Engineering Science     Hybrid Journal   (Followers: 5)
International Journal of Enteric Pathogens     Open Access  
International Journal of Evolution     Partially Free   (Followers: 2)
International Journal of Evolutionary Biology     Open Access   (Followers: 11)
International Journal of Experimental and Computational Biomechanics     Hybrid Journal   (Followers: 4)
International Journal of Genomics     Open Access   (Followers: 2)
International Journal of High Throughput Screening     Open Access   (Followers: 2)
International Journal of Impact Engineering     Hybrid Journal   (Followers: 7)
International Journal of Innovation and Applied Studies     Open Access   (Followers: 2)
International Journal of Insect Science     Open Access   (Followers: 5)
International Journal of Knowledge Discovery in Bioinformatics     Full-text available via subscription   (Followers: 2)
International Journal of Life Science and Medical Research     Open Access   (Followers: 4)
International Journal of Life Sciences     Open Access   (Followers: 1)
International Journal of Medical Informatics     Hybrid Journal   (Followers: 10)
International Journal of Myriapodology     Open Access  
International Journal of Nanoparticles     Hybrid Journal   (Followers: 6)
International Journal of Natural Sciences     Open Access   (Followers: 1)
International Journal of Peptide Research and Therapeutics     Partially Free   (Followers: 5)
International Journal of Peptides     Open Access   (Followers: 5)
International Journal of Pharmaceutical and Life Sciences     Open Access   (Followers: 5)
International Journal of Phytoremediation     Hybrid Journal   (Followers: 2)
International Journal of Plant Genomics     Open Access   (Followers: 2)
International Journal of Plant Research     Open Access   (Followers: 2)
International Journal of Primatology     Hybrid Journal   (Followers: 3)
International Journal of Proteomics     Open Access   (Followers: 1)
International Journal of Signs and Semiotic Systems     Full-text available via subscription   (Followers: 1)
International Journal of Speleology     Open Access   (Followers: 11)
International Journal of Systems Biology and Biomedical Technologies     Full-text available via subscription   (Followers: 2)
International Journal of Tropical Insect Science     Hybrid Journal   (Followers: 1)
International Journal of Tryptophan Research     Open Access  
International Review of Cell and Molecular Biology     Full-text available via subscription   (Followers: 5)
Intervirology     Full-text available via subscription  
IntraVital     Full-text available via subscription  
Invertebrate Biology     Hybrid Journal   (Followers: 6)
Invertebrate Neuroscience     Hybrid Journal   (Followers: 2)
Invertebrate Systematics     Hybrid Journal   (Followers: 5)
Iranian Journal of Parasitology     Open Access   (Followers: 2)
IRBM     Full-text available via subscription  
IRBM News     Full-text available via subscription  
Islets     Full-text available via subscription  
Israel Journal of Ecology and Evolution     Full-text available via subscription   (Followers: 2)
ITBM-RBM News     Full-text available via subscription   (Followers: 1)
IUBMB Life     Hybrid Journal   (Followers: 1)
IUFS Journal of Biology     Open Access  
Izvestiya Atmospheric and Oceanic Physics     Hybrid Journal   (Followers: 3)
Izvestiya, Physics of the Solid Earth     Hybrid Journal   (Followers: 4)
Japanese Journal of Applied Physics     Full-text available via subscription   (Followers: 4)
JCP : BioChemical Physics     Hybrid Journal   (Followers: 1)
JETP Letters     Hybrid Journal   (Followers: 3)
Journal of Bacteriology & Parasitology     Open Access   (Followers: 3)
Journal of Bioanalysis & Biomedicine     Open Access   (Followers: 1)
Journal of Bioequivalence & Bioavailability     Open Access  
Journal of Bioremediation & Biodegradation     Open Access   (Followers: 2)
Journal of Computer Science & Systems Biology     Open Access   (Followers: 2)
Journal of Proteomics & Bioinformatics     Open Access   (Followers: 6)
Journal of Advance Researches In Biological Sciences     Open Access   (Followers: 3)
Journal of Advances in Biology     Open Access   (Followers: 3)
Journal of Agricultural, Biological & Environmental Statistics     Hybrid Journal   (Followers: 8)
Journal of Amino Acids     Open Access   (Followers: 3)
Journal of AOAC International     Full-text available via subscription   (Followers: 8)
Journal of Applied Biobehavioral Research     Hybrid Journal  
Journal of Applied Bioinformatics & Computational Biology     Hybrid Journal   (Followers: 1)
Journal of Applied Biosciences     Open Access  
Journal of Applied Ichthyology     Hybrid Journal   (Followers: 6)
Journal of Applied Phycology     Hybrid Journal   (Followers: 9)
Journal of Applied Virology     Open Access   (Followers: 5)
Journal of Aquatic Sciences     Full-text available via subscription  
Journal of Arachnology     Full-text available via subscription  
Journal of Astrobiology & Outreach     Open Access  
Journal of Avian Biology     Hybrid Journal   (Followers: 17)

  First | 3 4 5 6 7 8 9 10 | Last

Journal Cover   Journal of Avian Biology
  [SJR: 1.201]   [H-I: 52]   [19 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  [1608 journals]
  • Impacts of nest predators and weather on reproductive success and
           population limitation in a long‐distance migratory songbird
    • Authors: Thomas W. Sherry; Scott Wilson, Sarah Hunter, Richard T. Holmes
      Abstract: Although avian nesting success is much studied, little is known about the relative importance of the factors that contribute to annual reproductive success and population limitation, especially for long‐distance migratory songbird species. We combined a field experiment limiting access to nests by mammalian predators with modeling of long‐term field data of American redstarts (Parulidae: Setophaga ruticilla) to assess the effects of multiple environmental variables on breeding success and population limitation. Experimental treatment (baffles placed around tree boles beneath active nests; N = 71) increased nesting success of this single‐brooded species significantly (77% vs. 50% in controls; N = 343), demonstrating that scansorial mammals, primarily red squirrels (Tamiasciurus hudsonicus) and Eastern chipmunks (Tamias striatus), reduced reproductive success. Based on unbaffled nests (N = 466), daily nest survival varied annually, and was positively influenced by May temperature and negatively by sciurid nest predator abundance. Daily nest survival was also influenced positively by June rainfall, and declined with nest age but not with calendar date. Since nest failure was overwhelmingly caused by nest predation, these significant climate and nest‐age effects in our models are indirect, likely influencing nest predator and/or nesting bird behaviors that in turn influenced nest predation. Redstart population density had no effect on nesting success, after accounting for other factors. Annual reproductive success accounted for 34% of the variability in annual population change in redstarts in our study area. Our findings document 1) breeding season population limitation in this species, 2) a link between tree masting and bird population dynamics via mammal population fluctuations, 3) the independent contributions of summer versus winter population processes in a migratory species, and 4) the potential complexity of climate‐biotic interactions. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-16T03:22:58.453242-05:
      DOI: 10.1111/jav.00536
       
  • Does fragmentation of wetlands affect gene flow in sympatric Acrocephalus
           warblers with different migration strategies?
    • Authors: Francesco Ceresa; Eduardo J. Belda, Laura Kvist, Hamid Rguibi‐Idrissi, Juan S. Monrós
      Abstract: Wetlands are naturally patchy habitats, but patchiness has been accentuated by the extensive wetlands loss due to human activities. In such a fragmented habitat, dispersal ability is especially important to maintain gene flow between populations. Here we studied population structure, genetic diversity and demographic history of Iberian and North African populations of two wetland passerines, the Eurasian reed warbler Acrocephalus scirpaceus and the moustached warbler Acrocephalus melanopogon. These species are closely related and sympatric in our study sites, but the reed warbler is a widespread long‐distance migrant while the moustached warbler's breeding range is patchier and it is resident or migrates over short distances. Using microsatellite and mtDNA data, we found higher differentiation in moustached than in reed warblers, indicating higher dispersal capability of the latter species. Our results also suggest that the sea limits dispersal in the moustached warbler. However, we found evidence of gene flow between the study sites in both species, indicating a capability to compensate for habitat fragmentation. In most cases, the gene flow was restricted, possibly because of the large distances between study sites (from c. 290 to 960 km) or breeding site fidelity. The reed warbler had higher haplotype diversity, likely due to dispersal from different populations, past admixture event and a larger population size. We found also signs of postglacial population growth for both species and evidence of a recent colonization or re‐colonization of the Mallorca Island by the moustached warbler. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-16T03:22:38.770315-05:
      DOI: 10.1111/jav.00589
       
  • Re‐colonization by common eiders (Somateria mollissima) in the
           Aleutian Archipelago following removal of introduced arctic foxes (Vulpes
           lagopus)
    • Authors: Margaret R. Petersen; G. Vernon Byrd, Sarah A. Sonsthagen, Matthew G. Sexson
      Abstract: Islands provide refuges for populations of many species where they find safety from predators, but the introduction of predators frequently results in elimination or dramatic reductions in island‐dwelling organisms. When predators are removed, re‐colonization for some species occurs naturally, and inter‐island phylogeographic relationships and current movement patterns can illuminate processes of colonization. We studied a case of re‐colonization of common eiders (Somateria mollissima) following removal of introduced arctic foxes (Vulpes lagopus) in the Aleutian Archipelago, Alaska. We expected common eiders to resume nesting on islands cleared of foxes and to re‐colonize from nearby islets, islands, and island groups. We thus expected common eiders to show limited genetic structure indicative of extensive mixing among island populations. Satellite telemetry was used to record current movement patterns of female common eiders from six islands across three island groups. We collected genetic data from these and other nesting common eiders at 14 microsatellite loci and the mitochondrial DNA control region to examine population genetic structure, historical fluctuations in population demography, and gene flow. Our results suggest recent interchange among islands. Analysis of microsatellite data supports satellite telemetry data of increased dispersal of common eiders to nearby areas and little between island groups. Although evidence from mtDNA is suggestive of female dispersal among island groups, gene flow is insufficient to account for recolonization and rapid population growth. Instead, near‐by remnant populations of common eiders contributed substantially to population expansion, without which re‐colonization would have likely occurred at a much lower rate. Genetic and morphometric data of common eiders within one island group two and three decades after re‐colonization suggests reduced movement of eiders among islands and little movement between island groups after populations were re‐established. We predict that re‐colonization of an island group where all common eiders are extirpated could take decades. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-16T03:22:26.999708-05:
      DOI: 10.1111/jav.00626
       
  • No change in common cuckoo Cuculus canorus parasitism and great reed
           warblers' Acrocephalus arundinaceus egg rejection after seven decades
    • Authors: Anikó Zölei; Miklós Bán, Csaba Moskát
      Abstract: The coevolutionary process among avian brood parasites and their hosts involves stepwise changes induced by the antagonistic selection pressures of one on the other. As long‐term data on an evolutionary scale is almost impossible to obtain, most studies can only show snapshots of such processes. Information on host behaviour, such as changes in egg rejection rates and the methods of rejection are scarce. In Hungary there is an interesting case between the common cuckoo (Cuculus canorus) and the great reed warbler (Acrocephalus arundinaceus), where the level of parasitism is unusually high (around 50%). We compared host rejection rates and methods of rejection from within our own project to that of an early study carried out and published almost 70 years ago in the same region. Our comparisons revealed high and stable rates of parasitism (range: 52‐64%), and marked fluctuations in the ratio of multiply parasitized nests (range: 24‐52%). No difference was revealed in egg rejection rates after 7 decades (34‐39%). Linear mixed‐effects modelling revealed no year effect on the type host responses toward the parasitic egg(s) during the years of study (categorized as acceptance, ejection, burial, and nest desertion). Cuckoo egg rejection was primarily affected by the type of parasitism, as more cuckoo eggs were rejected during single parasitism than from multiply parasitized nests. Our comparison did not reveal any directional changes in this cuckoo‐host relationship, except a slight decrease in the frequency of multiple parasitism, which is likely to be independent from coevolutionary processes. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-16T03:22:13.910489-05:
      DOI: 10.1111/jav.00673
       
  • Evidence for strong genetic structure in European populations of the
           little owl Athene noctua
    • Authors: Irene Pellegrino; Alessandro Negri, Giovanni Boano, Marco Cucco, Torsten N. Kristensen, Cino Pertoldi, Ettore Randi, Martin Šálek, Nadia Mucci
      Abstract: The little owl Athene noctua is a widespread species in Europe. This mainly sedentary owl experienced reduction in population sizes in some areas due to habitat loss and modification of the landscape. To assess the genetic structure of the populations of western and central Europe, we analysed 333 specimens from 15 geographical areas at 13 microsatellite loci. Statistical analyses and Bayesian clustering procedures detected two major genetically distinct clusters, the first distributed from Portugal to the Czech Republic and the second from the Balkans to Italy. The second cluster was further split into three groups, located in Italy, Sardinia and the Balkans. These groups match four previously‐described mtDNA haplogroups, and probably originated from the isolation of little owl populations in Sardinia and in three glacial refugia (Iberia, south Italy and Balkans) during the ice ages. High genetic admixture was recorded in central and northern Europe, probably as a consequence of the expansion from the refugia during interglacial. The main colonization route originated from the Iberian Peninsula towards central and northern Europe. Contact zones with colonization events from Italy and the Balkans were detected respectively in northern Italy and central Europe. Genetic indices show the existence of moderate levels of genetic variability throughout Europe, although evidence of recent evolutionary bottlenecks was found in some populations. Estimation of migration rates and approximate Bayesian computations highlighted the most likely phylogeographical scenario for the current distribution of little owl populations.
      PubDate: 2015-04-10T05:57:42.9192-05:00
      DOI: 10.1111/jav.00679
       
  • Ecological niche variation in the Wilson's Warbler (Cardellina pusilla)
           complex
    • Authors: Angelina Ruiz‐Sánchez; Katherine Renton, Rosario Landgrave‐Ramírez, Eder F. Mora‐Aguilar, Octavio Rojas‐Soto
      Abstract: Wilson's Warbler comprises three subspecies separated into two geographic groups: C. p. pusilla that breeds in Eastern North America; and C. p. pileolata and C. p. chryseola that breed in Western North America. Given the differences between the groups in genetics, morphology, habitat use, and population decline, we tested for ecological niche similarity in both their breeding and wintering distribution using niche modeling based on temperature and precipitation data. We first conducted an inter‐prediction approach considering the percent of summer and winter localities of one group that are predicted by the potential distribution of the alternate group. We also applied a null model approach that compares self‐predictions and pseudoreplicates of each group to indicate similarity, divergence, or indeterminate niche overlap. Finally, we compared ecological distances between and within groups using the Gower similarity equation. We found that the Western group had an ecological niche of broader climatic conditions, while the Eastern group had a narrower ecological niche. The inter‐prediction approach showed that, for both summering and wintering ranges, ecological niche models of the Western group predicted ~50% of the observed distribution of the Eastern group, whereas Eastern group models predicted
      PubDate: 2015-04-10T05:57:26.447885-05:
      DOI: 10.1111/jav.00531
       
  • Stopover duration, movement patterns and temporary home ranges of fall
           migrant yellow‐rumped warblers Setophaga coronata in native and
           anthropogenic woodlands of the Northern Prairie region, USA
    • Authors: Ming Liu; David L. Swanson
      Abstract: Stopover behavior of migrant birds is influenced by their energetic condition, but also by extrinsic factors, including weather conditions and habitat attributes such as vegetation structure, microclimates, predation pressure, competition, and food availability. Anthropogenic habitats may differ from natural habitats in these attributes, which could promote differing stopover behaviors for migrants in the two habitat types and affect overall habitat suitability. We used radio‐telemetry to measure stopover behaviors of fall migrant yellow‐rumped warblers Setophaga coronata in native riparian corridor woodlands (corridors) and anthropogenic woodlots (woodlots) in the Northern Prairie region. We measured stopover duration, movement rate, and temporary home range size for birds in both habitat types by attaching radio‐transmitters and relocating birds to either corridor (n = 17) or woodlot (n = 16) study sites. We used AICC to rank null, global, and reduced models, which included habitat type, energetic condition, habitat size, year, date, and movement rate (for stopover duration analyses only) as explanatory variables. Model rankings showed that habitat type was not included in any of the top models (ΔAICC < 2) for movement behavior, temporary home range size, or stopover duration, which suggests similar functional habitat quality between the two habitat types. These data add similar behavioral responses for birds in the two habitat types to similar fattening rates and stress physiology, further confirming similar suitability of native and anthropogenic woodland habitats in this region as stopover habitat. We also applied logistic regression with a model selection approach, including cloud cover, tail wind component, temperature, and barometric pressure as independent variables, and departure decision as the dependent variable, to evaluate the effects of weather variables on departure. Model selection suggested that cloud cover is a prominent factor affecting departure decisions and the other variables may also influence departure decisions of yellow‐rumped warblers from inland stopover sites.
      PubDate: 2015-04-10T05:57:08.406263-05:
      DOI: 10.1111/jav.00672
       
  • Evidence of a link between survival and pair fidelity across multiple tit
           populations
    • Authors: Antica Culina; Shelly Lachish, Ben C. Sheldon
      Abstract: Although they have the potential to strongly influence individual fitness and the dynamics and productivity of populations, the survival consequences of pairing outcomes and the influence of current pairing outcomes on those in the future have rarely been addressed. Previously, we have shown that pair fidelity increases both survival and future pair fidelity in a population of great tits (Parus major). The aim of this study was to explore the generality of our previous findings by evaluating the influence of current paring outcomes on survival and on future pairing outcomes in two different species and in different populations. We addressed our aims within a multievent capture‐mark‐recapture (MECMR) statistical framework, which accounts for differences in recapture rates and uncertainty in the assignment of pair status (i.e. whether an individual is breeding with the same partner or not). We applied the framework to breeding records of two great tit populations and one blue tit (Cyanistes caeruleus) population. We detected survival benefits (i.e. increased survival) of pair fidelity in all three populations. These were similar in both great tit populations, but higher for male great tits than for male blue tits. We found that age‐dependence in the rate of pair fidelity was shared between different populations and species, but did not detect any influence of current pair status on future pair status. Our study highlights the importance of considering survival when studying the fitness benefits of pair fidelity. Some of the differences in pair fidelity rates and survival benefits of pair fidelity are likely the result of long‐term and short‐term demographic and environmental factors in the population. We advocate the use of the MECMR framework used here for further exploration of these differences. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-08T08:58:32.097969-05:
      DOI: 10.1111/jav.00661
       
  • Food availability modulates the effects of maternal antibodies on growth
           and immunity in young feral pigeons
    • Authors: A. Ismail; L. Jacquin, C. Haussy, S. Perret, J. Gasparini
      Abstract: It is now widely acknowledged that mothers can transfer their own immune experience to their progeny through the allocation of specific maternal antibodies (hereafter referred as MatAb) that can shape offspring phenotype and affect their fitness. However, the importance of environmental variability in modulating the effects of MatAb on offspring traits is still elusive. Using an experimental approach, we investigated how food availability interacted with MatAb to solve the trade‐off between humoral immunity and growth in young feral pigeons (Columba livia). Results show that the inhibitory effect of MatAb on the humoral response of chicks was detected regardless of the food treatment. In addition, body mass growth was higher in chicks receiving lower amounts of maternal antibodies but only in chicks of the ad libitum food treatment. This contradicts previous studies and suggests that the transfer of MatAb could entail some costs for chicks and reduce their growth. Taken together these results reinforce the idea that the maternal antibodies play a central role in shaping offspring life‐history traits but that their adaptive value is highly dependent on the environmental context in which they are transmitted by the mother. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-08T08:58:17.731771-05:
      DOI: 10.1111/jav.00698
       
  • Cover, not caging, influences chronic physiological stress in a
           ground‐nesting bird
    • Authors: Laura X. L. Tan; Katherine L. Buchanan, Grainne S. Maguire, Michael A. Weston
      Abstract: Predator exclosures (‘nest cages’) around nests are increasingly used to enhance hatching success of declining ground‐nesting birds. However, such exclosures are contentious and have been suggested to have detrimental effects on the species which they aim to protect. This study examines whether exclosures increase physiological stress of incubating birds, a hitherto unrecognised and untested potential drawback of exclosures. Red‐capped plover Charadrius ruficapillus hatching success was radically altered and significantly higher for nests with exclosures (96.2%) compared with those without (6.8%). Chronic physiological stress in parents (as measured by the heterophil/lymphocyte [H/L] ratio in blood) did not vary between nests with and without exclosures, or between the sexes. However the absence of vegetative cover at the nest site was associated with a 62.7% elevation in H/L ratio, indicating that incubating birds which place their nests in the open are subject to increased levels of chronic stress. The results from this study demonstrate the fundamental importance of predation for the nesting success of this species and confirm that chronic stress levels are not a detrimental side effect of exclosure use.
      PubDate: 2015-04-08T08:57:58.396807-05:
      DOI: 10.1111/jav.00625
       
  • Visual obstruction and vigilance: a natural experiment
    • Authors: Guy Beauchamp
      Abstract: Visual obstructions can cause an increase in antipredator vigilance in prey animals by making predator detection more difficult. However, visual obstructions can also skew the perception of group size and inter‐individual distances and impair the detection of alarm signals by conspecifics. These changes within the group alone can cause an increase in vigilance. To disentangle the contribution of these various factors to changes in vigilance, I documented vigilance in a gregarious species, the semipalmated sandpiper Calidris pusilla, foraging in a habitat where a naturally‐occurring visual barrier partially prevented predator detection without altering the transfer of information about predation risk within the group. I used a matched sampling design to collect vigilance data for birds using adjacent areas with and without the visual barrier. In the visually‐obstructed area, sandpipers maintained a higher level of vigilance, occurred farther away from cover and in smaller flocks, and preferentially scanned the area of danger with one eye in particular. All these changes suggest that visual obstruction increased perceived predation risk. I conclude that it is the inability to get a good view of any approaching predator, rather than changes in intra‐group communication that caused the increase in vigilance in the visually‐obstructed area.
      PubDate: 2015-04-08T08:57:42.197467-05:
      DOI: 10.1111/jav.00612
       
  • Nest‐dwelling ectoparasites influence the start and duration of the
           first pre‐basic moult in the European starling Sturnus vulgaris
    • Authors: Simone Pirrello; Andrea Pilastro, Lorenzo Serra
      Abstract: Nest‐dwelling ectoparasites represent an early stressor for birds as they impair the development of nestlings, which can adaptively respond by adjusting their growth rate to current conditions. While nest ectoparasites have long‐term effects on nesting adults, no study has examined if they also have an impact on the moult patterns of juveniles. Herein, we investigated whether the presence of ectoparasites in the nest influences the start and duration of the first pre‐basic moult in the European starling. To do so, we experimentally removed nest‐dwelling ectoparasites from a group of nests and used another group of unmanipulated (i.e. naturally infested) nests as the control. The moult began at an earlier age and lasted longer in birds from the ectoparasite‐free nests compared to their control counterparts. The timing of the moult was also affected by the hatching date (i.e. birds that fledged later had shorter moults) and the brood size (i.e. birds in larger broods started their moult at an older age). We also found evidence that the removal of nest ectoparasites influenced the condition of individuals during the course of the moult. In the control birds, we observed a decrease in hematocrit levels, but these were unaltered in the birds fledged from the ectoparasite‐free nests. Our study shows that nest‐dwelling ectoparasites adversely affected the timing of the moult and the individual condition of juvenile starlings, with possible major consequences for their subsequent life‐history events.
      PubDate: 2015-03-26T04:12:08.744294-05:
      DOI: 10.1111/jav.00565
       
  • Skipping‐type migration in a small Arctic wader, the Temminck's
           stint Calidris temminckii
    • Authors: Terje Lislevand; Steffen Hahn
      Abstract: By using morphometric data and geolocator tracking we investigated fuel loads and spatio‐temporal patterns of migration and non‐breeding in Temminck's stints Calidris temminckii. Body masses in stints captured at autumn stopover sites from Scandinavia to northern Africa were generally not much higher than during breeding and did not vary geographically. Thus, we expected migrating stints to make several stopovers and either circumventing the Sahara desert with low fuel loads or fuelling at north African stopover sites before desert crossing. Geolocation revealed that birds (n = 6) departed their Norwegian breeding site in the last part of July and all but one migrated south‐west over continental western Europe. A single bird headed south‐east to the Balkan Peninsula where the geolocator died. As predicted, southbound migration proceeded in a typical skipping manner with 1–4 relatively short stopovers (median 4 d) during 10–27 d of migration before reaching north‐west Africa. Here birds spent 11–20 d before crossing the Sahara. The non‐breeding sites were located at or near the Niger River in Mali and were occupied continuously for more than 215 d with no indications of itinerancy. Spring migration commenced in late April/early May when birds crossed the desert and used stopover sites in the western Mediterranean basin in a similar manner as during autumn. The lowest body masses were recorded in spring at islands in the central Mediterranean basin, indicating that crossing the Sahara and Mediterranean barriers is exhausting to these birds. Hence, the skipping‐type pattern of migration revealed by geolocators is likely to be natural in this species and not an effect of instrumentation.
      PubDate: 2015-03-23T04:41:33.491965-05:
      DOI: 10.1111/jav.00653
       
  • Strouhal number for flying and swimming in rhinoceros auklets Cerorhinca
           monocerata
    • Authors: Dale M. Kikuchi; Yutaka Watanuki, Nobuhiko Sato, Kenji Hoshina, Akinori Takahashi, Yuuki Y. Watanabe
      Abstract: Alcids propel themselves by flapping wings in air and water that have vastly different densities. We hypothesized that alcids change wing kinematics and maintain Strouhal numbers (St = fA/U, where f is wingbeat frequency, A is the wingbeat amplitude, and U is forward speed) within a certain range, to achieve efficient locomotion during both flying and swimming. We used acceleration and GPS loggers to measure the wingbeat frequency and forward speed of free‐ranging rhinoceros auklets Cerorhinca monocerata during both flying and swimming. We also measured wingbeat amplitude from video footage taken in the wild. On average, wingbeat frequency, forward speed, and wingbeat amplitude were 8.9 Hz, 15.3 m s−1, and 0.39 m, respectively, during flying, and 2.6 Hz, 1.3 m s−1, and 0.18 m, respectively, during swimming. The smaller wingbeat amplitude during swimming was achieved by partially folding the wings, while maintaining the dorso‐ventral wingbeat angle. Mean St was 0.23 during flying and 0.36 during swimming. The higher St value for swimming might be related to the higher thrust force required for propulsion in water. Our results suggest that rhinoceros auklets maintain St for both flying and swimming within the range (0.2–0.4) that propulsive efficiency is known to be high and St in both flying specialists and swimming specialists are known to converge.
      PubDate: 2015-03-23T04:41:05.662297-05:
      DOI: 10.1111/jav.00642
       
  • Uncommon paleodistribution patterns of Chrysolophus pheasants in East
           Asia: explanations and implications
    • Authors: Nan Lyu; Martin Päckert, Dieter Thomas Tietze, Yue‐Hua Sun
      Abstract: Some modeling studies indicated that the past distributions of species in East Asia during the Last Interglacial (LIG) and Last Glacial Maximum (LGM) periods differ from those of European and North American species and the deviant Asian distribution pattern is known under the term ‘pre‐LGM expansion’. It represents the unusually similar distribution patterns between the current and the LGM scenario. However, there is still no satisfying explanation for this phenomenon so far. Therefore, we took the two recently separated pheasant species of genus Chrysolophus in East Asia as an example to test the pattern by performing ecological niche models. The main findings of this study include: (1) the paleodistributions of these two pheasants also corresponded to the ‘pre–LGM expansion’ pattern; (2) climatic similarity results from Mobility‐Oriented Parity analysis also revealed similar pattern for both species; (3) climate regimes of East Asia showed patterns different from those in Europe and North America in a climate shift towards drier conditions and stronger seasonality and to more extreme temperatures of the coldest months particularly during the LIG; (4) the two Chrysolophus species occupied significantly different ecological niches according to current distribution. We suggest that ecological segregation established in allopatric glacial refugia should be the main determinants for the separation of two Chrysolophus species until they came into extant post–Pleistocene contact. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-23T04:20:19.229589-05:
      DOI: 10.1111/jav.00590
       
  • Landscape‐scale habitat availability, and not local geography,
           predicts migratory landbird stopover across the Gulf of Maine
    • Authors: Jennifer D. McCabe; Brian J. Olsen
      Abstract: While it is clear that many migratory behaviors are shared across taxa, generalizable models that predict the distribution and abundance of migrating taxa at the landscape scale are rare. In migratory landbirds, ephemeral concentrations of refueling birds indicate that individual behaviors sometimes produce large epiphenomena in particular geographic locations. Identifying landscape factors that predict the distribution and abundance of birds during migratory stopover will both improve our understanding of the migratory process and assist in broad, regionally relevant conservation. In this study we used autumnal passerine stopover data from a five‐year period and eleven stopover sites across coastal Maine, USA, to test four broad hypotheses of migrant distribution and abundance that have been supported in other regions: a) the community characteristics of the pool of potential migrants, b) a site's local geography, c) landscape composition and configuration measured at different spatial scales, and d) interactions between these factors. Our final model revealed that birds concentrate at ‘habitat islands’, sites that possess a disproportionate percentage of the vegetated habitat in the 4‐km surrounding landscape. The strength of this pattern, however, was inversely proportional to a species' remaining migratory distance. Our results corroborate several studies that emphasize the importance of land cover composition at finer spatial scales (< 80 km2) for predicting the stopover distribution and abundances of migratory birds. This suggests that different migrants likely assess stopover sites with similar mechanisms along their migratory route, and these commonalities may be broadly applied to identify stopover locations of conservation importance across the continent.
      PubDate: 2015-03-18T03:44:00.358813-05:
      DOI: 10.1111/jav.00598
       
  • Carry‐over effects of winter habitat quality on en route timing and
           condition of a migratory passerine during spring migration
    • Authors: Kristina L. Paxton; Frank R. Moore
      Abstract: We examined how conditions prior to migration influenced migration performance of two breeding populations of black‐and‐white warblers (Mniotilta varia) by linking information on the migrant's winter habitat quality, measured via stable carbon isotopes, with information on their breeding destination, measured via stable hydrogen isotopes. The quality of winter habitat strongly influenced the timing of migration when we accounted for differential timing of migration between breeding populations. Among birds migrating to the same breeding destination, males and females arriving early to the stopover site originated from more mesic habitat than later arriving birds, suggesting that the benefits of occupying high‐quality mesic habitat during the winter positively influence the timing of migration. However, male warblers arriving early to the stopover site were not in better migratory condition than later arriving conspecifics that originated from poor‐quality xeric winter habitat, regardless of breeding destination. The two breeding populations stopover at the study site during different time periods, suggesting that the lower migratory condition of early birds is not a function of the time of season, but potentially a migrant's migration strategy. Strong selection pressures to arrive early on the breeding grounds to secure high‐quality breeding territories may drive males from high‐quality winter habitat to minimize time at the expense of energy. This migration strategy would result in a smaller margin of safety to buffer the effects of adverse weather or scarcity of food, increasing the risk of mortality. The migratory condition of females was the same regardless of the timing of migration or breeding destination, suggesting that females adopt a strategy that conserves energy during migration. This study fills an important gap in our understanding of the linkages between winter habitat quality and factors that influence the performance of migration, the phase of the annual cycle thought to be limiting most migratory bird populations. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-17T07:46:20.974532-05:
      DOI: 10.1111/jav.00614
       
  • Breeding season weather determines long‐tailed tit reproductive
           success through impacts on recruitment
    • Authors: Philippa R. Gullett; Ben J. Hatchwell, Robert A. Robinson, Karl L. Evans
      Abstract: Productivity is a key demographic trait that can be influenced by climate change, but there are substantial gaps in our understanding of the impact of weather on productivity and recruitment in birds. Weather is known to influence reproductive success in numerous species, although such effects have not been reported in all studies, perhaps because they are masked by high nest predation rates or buffered by density dependence. Here, we use a 19‐year study of a population of individually marked Long‐tailed Tits Aegithalos caudatus to quantify the impacts of weather on productivity in the nest (from eggs to fledging) and subsequent recruitment, while taking nest predation rates and density dependence into account. We find that weather has negligible effects on clutch size, hatching success, brood size, probability of fledging and number of fledglings. Annual variation in nest predation rates is a strong predictor of productivity, but we find no evidence that the magnitude of nest predation is determined by weather. Recruitment was strongly associated with breeding season weather, even when taking density dependence effects into account. This contrasts with the conventional view that first year survival of temperate passerines is primarily determined by winter weather. Recruitment was reduced when March temperatures were high, perhaps caused by earlier peaks in caterpillar abundance and thus reduced food availability at the time of fledging. Recruitment increased following high May temperatures, perhaps due to an improved thermo‐regulatory environment for young fledglings. These opposing effects of warm March and May temperatures highlight the importance of considering asymmetrical rates of warming in different months when predicting climate change impacts. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-16T14:21:33.117658-05:
      DOI: 10.1111/jav.00560
       
  • First archaeogenetic results verify the mid‐Holocene occurrence of
           Dalmatian pelican Pelecanus crispus far out of present range
    • Authors: Elena A. Nikulina; Ulrich Schmölcke
      Abstract: The paper presents an evaluation of subfossil bird bones from archaeological and geological sites in Europe that shows that birds of the genus Pelecanus occurred far out of their present range between 7.4 and 5.0 ka BP in the Danish archipelago. Additionally, from other northwestern European regions mid‐Holocene records of pelicans are known. However, due to morphological similarities there are difficulties in species identification. In this paper ancient DNA barcoding techniques were used to clarify the species assignment of one of these records for the first time. Our results show that the bone derives from Dalmatian pelican Pelecanus crispus, a species that today breeds in 15 colonies in the eastern Mediterranean. This species identification is especially remarkable since the Dalmatian pelican is known to be less migratory. We demonstrate that the appearance and disappearance of pelicans in northwestern Europe coincide with climate parameters, since all records fall within warm periods. This applies for the larger group of Danish records during the Holocene thermal maximum in northern Europe as well as for two more groups of records from central Europe and Britain dating to 1.9 and 0.8 ka ago. Recent ecological research on the Dalmatian pelican shows that the species seems to profit from the modern climate changes and is starting to expand its range. Our paper documents that under special circumstances short‐distance migrant birds are also able to expand their ranges to areas far outside of the former distribution areas. Finally, the Dalmatian pelican is presented as an indicator species reflecting special climate conditions. The present study demonstrates not only the possibility to recover avian DNA from at least 7 ka old bones, but the relevance of such genetic analysis in combination with archaeological data, particularly if bones could not be assigned to species level by morphological features. In such cases, aDNA is shown as a valuable tool for the reconstruction of the avifauna of the past.
      PubDate: 2015-03-16T11:46:04.707069-05:
      DOI: 10.1111/jav.00652
       
  • Delayed timing of breeding as a cost of reproduction
    • Authors: Matthew Low; Debora Arlt, Tomas Pärt, Meit Öberg
      Abstract: Timing of breeding is a trait with considerable individual variation, often closely linked to fitness because of seasonal declines in reproduction. The drivers of this variation have received much attention, but how reproductive costs may influence the timing of subsequent breeding has been largely unexplored. We examined a population of northern wheatears Oenanthe oenanthe to compare three groups of individuals that differed in their timing of breeding termination and reproductive effort to investigate how these factors may carry over to influence reproductive timing and reproductive output in the following season. Compared to females that bred successfully, females that put in less effort and terminated breeding early due to nest failure tended to arrive and breed earlier in year 2 (mean advancement = 2.2 and 3.3 d respectively). Females that spent potentially more effort and terminated breeding later due to production of a replacement clutch after nest failure, arrived later than other females in year 2. Reproductive output (number of fledglings) in year 2 differed between the three groups as a result of group‐level differences in the timing of breeding in combination with the general seasonal decline in reproductive output. Our study shows that the main cost of reproduction was apparent in the timing of arrival and breeding in this migratory species. Hence, reproductive costs can arise through altered timing of breeding since future reproductive success (including adult survival) is often dependent on the timing of breeding in seasonal systems.
      PubDate: 2015-03-16T11:44:01.30124-05:0
      DOI: 10.1111/jav.00623
       
  • Local variation in weather conditions influences incubation behavior and
           temperature in a passerine bird
    • Authors: Brittney H. Coe; Michelle L. Beck, Stephanie Y. Chin, Catherine M. B. Jachowski, William A. Hopkins
      Abstract: Incubation is an important component of avian parental care and slight changes in incubation temperature can affect offspring phenotype. Although many extrinsic and intrinsic factors may generate variation in incubation temperature, they remain underexplored under natural conditions. Using a robust data set encompassing 55 nests, 22 816 behavioral observations, and > 1 million paired ambient and egg temperatures, we describe the relationships among abiotic factors, female incubation behavior, incubation temperature, and incubation period for tree swallows Tachycineta bicolor. We report a large amount of individual variation in incubation behaviors and average incubation temperatures for our study population. The average on‐bout incubation temperature was 34.1°C, with daily egg temperatures ranging from 18.0–39.2°C. Females modulated the number of times they left the nest and the amount of time they stayed off the nest according to interactions between precipitation and temperature patterns. Models generated from our observations predicted that the number of female off‐bouts was the lowest under warm and dry conditions while more off‐bouts were taken under cold and dry or warm and wet conditions. During cold and dry conditions, females stayed off their nest ∼4 times longer than under warm and dry conditions. However, this pattern was reversed under periods of rainfall; females tended to take shorter off‐bouts when it was rainy and cold compared to longer off‐bouts during warmer rain events. Furthermore, variation in female behavior was associated with differences in overall incubation temperature such that females that maintained greater incubation constancy produced higher incubation temperatures at a given ambient temperature than those that displayed lower incubation constancy. Our results provide perspective on the timing of breeding, as some of the advantages of breeding early may be countered by cooler, early season temperatures and precipitation that cause reproducing females to favor self‐maintenance at a potential cost to optimal incubation temperatures for offspring development.
      PubDate: 2015-03-04T05:57:43.118812-05:
      DOI: 10.1111/jav.00581
       
  • Seasonal mortality and sequential density dependence in a migratory bird
    • Authors: Eldar Rakhimberdiev; Piet J. van den Hout, Maarten Brugge, Bernard Spaans, Theunis Piersma
      Abstract: Migratory bird populations may be limited during one or more seasons, and thus at one or more places, but there is a dearth of empirical examples of this possibility. We analyse seasonal survival in a migratory shellfish‐eating shorebird (red knot Calidris canutus islandica) during a series of years of intense food limitation on the nonbreeding grounds (due to overfishing of shellfish stocks), followed by a relaxation period when destructive harvesting had stopped and food stocks for red knots recovered. For the estimation of seasonal survival from the 15 yr‐long near‐continuous capture–resight dataset, we introduce a ‘rolling window’ approach for data exploration, followed by selection of the best season definition. The average annual apparent survival over all the years was 0.81 yr−1. During the limitation period, survival probability of adult red knots was low in winter (0.78 yr−1), but this was compensated by high survival in summer (0.91 yr−1). During the relaxation period survival rate levelled out with a winter value of 0.81 yr−1 and a summer survival of 0.82 yr−1. The fact that during the cockle‐dredging period the dip in survival in winter was completely compensated by higher survival later in the annual cycle suggests sequential density dependence. We conclude that seasonal compensation in local survival (in concert with movements to areas apparently below carrying capacity) allowed the islandica population as a whole to cope, in 1998–2003, with the loss of half of the suitable feeding habitat in part of the nonbreeding range, the western Dutch Wadden Sea. As a more general point, we see no reason why inter‐seasonal density dependence should not be ubiquitous in wildlife populations, though its limits and magnitude will depend on the specific ecological contexts. We elaborate the possibility that with time, and in stable environments, seasonal mortality evolves so that differences in mortality rates between seasons would become erased.
      PubDate: 2015-02-25T09:26:50.866032-05:
      DOI: 10.1111/jav.00701
       
  • Loss of sexual dimorphism is associated with loss of lekking behavior in
           the green manakin Xenopipo holochora
    • Authors: Renata Durães Ribeiro; John E. McCormack, Hernán G. Álvarez, Luis Carrasco, Gregory F. Grether, Patricio Mena‐Olmedo, Raul Sedano, Thomas B. Smith, Jordan Karubian
      Abstract: Manakins (Pipridae) are well know for elaborate male sexual displays and ornate plumage coloration, both of which are thought to have evolved as a consequence of lekking breeding, the prevalent mating system in the family. Less attention has been paid to a handful of ‘drab’ manakin species, in which sexual dimorphism appears to be reduced or absent. Using character reconstruction, we show that these ‘exceptions to the rule’ represent phylogenetically independent cases of losses in sexual dimorphism, and as such could provide a focal group to investigate the link between changes in morphology and in life history (e.g. mating system). We take a first step in this direction by focusing on two subspecies of the putatively monomorphic green manakin Xenopipo holochlora to formally confirm that the species is sexually monomorphic in size and plumage color and test the prediction that sexual monomorphism is associated with the loss of lekking behavior in this species. Our results show that size dimorphism is present but limited in the green manakin, with substantial overlap in male and female morphometric measures, and that sexes are largely monochromatic (including from an avian perspective), despite marked coloration differences between subspecies. Behavioral observations indicate that males do not form leks and do not engage in elaborate sexual displays, that there is no stable pair bond formation, and that females provide parental care alone. These findings are consistent with the idea that changes in mating behavior may have driven changes in morphology in Pipridae, and we encourage similar studies on other drab manakins to better understand this relationship.
      PubDate: 2015-02-19T06:26:19.76241-05:0
      DOI: 10.1111/jav.00545
       
  • Always together: mate guarding or predator avoidance as determinants of
           group cohesion in white‐breasted mesites'
    • Authors: Anna Gamero; Peter M. Kappeler
      Abstract: Being a member of a cohesive group can have fitness benefits such as decreased predation risk, increased feeding efficiency as well as enhanced access to social information and mates. However, competition and the risk of parasite transmission exert centrifugal forces on group‐living. Thus, the actual degree of cohesion is expected to vary as a function of the relative importance of several social and ecological factors. White‐breasted mesites Mesitornis variegata are medium‐sized ground‐dwelling birds endemic to the dry deciduous forests of western Madagascar. They live in stable breeding pairs or small family groups, mate monogamously and often form temporary heterospecific associations with canopy‐dwelling bird species that give alarm calls to which mesites respond with anti‐predator behaviours. We investigated the potential effects of predation risk and mate defence on mesite group cohesion by analysing inter‐individual distances of 20 groups as a function of mesite social organization, alarm call events, the size of associated heterospecific flocks, and the adults' reproductive state. Mesite social units were very cohesive, particularly in families, when associated with smaller heterospecific flocks, and after an alarm call event. Adult reproductive state did not influence breeding partners' cohesion. Therefore, the pronounced group cohesion in mesites seems to be mainly a response to the high predation risk typically associated with a terrestrial life‐style, and not to mate‐guarding. However, we suggest that high group cohesion due to predation risk could limit opportunities for solitary extra‐territorial forays to obtain extra‐pair copulations, thereby contributing to a strictly monogamous system in this species.
      PubDate: 2015-02-19T06:26:02.056871-05:
      DOI: 10.1111/jav.00544
       
  • Ecological and environmental factors related to variation in egg size of
           New World flycatchers
    • Authors: Neander M. Heming; Miguel Â. Marini
      Abstract: Geographical variation in egg size is well documented for several taxa, but remains insufficiently described for birds in spite of a well‐known latitudinal gradient in clutch size. Several hypotheses have been proposed to explain avian egg size variation; however, they were not tested on a continental scale. Egg size is a key component of reproductive investment that influences offspring fitness. It is thought to vary geographically as one of a set of correlated life‐history traits that are under selection from varying ecological conditions. We completed a comprehensive literature review and calculated egg sizes for the most widespread clade within tyrant flycatchers, describing for the first time the geographical variation in egg size on a continental scale. We examined the relative support for ecological and environmental variables in explaining egg size variation using multi‐model inference and linear mixed models controlled for phylogenetic autocorrelation among species. We tested five hypotheses and found that: larger eggs occur in colder sites, which is consistent with the embryonic temperature hypothesis; medium/long‐distance migrants had smaller eggs than resident species while short‐distance migrants had the largest eggs; neither species clutch size, nor species nest type, nor evapotranspiration seasonality influenced egg size. Avian egg size is larger in Austral and Neotropical America (ANA), where species are resident or short‐distance migrants, and smaller across the medium/long‐distance migrants of the Nearctic region. In addition, while clutch size increases towards higher northern latitudes and is almost invariable across ANA species, egg sizes vary largely across ANA sites, increasing with southern latitudes and higher elevations and being influenced by summer temperature. While the embryonic temperature hypothesis has been usually linked to parental nest attentiveness, we highlight that environmental temperatures also have strong effects in shaping investment in egg size.
      PubDate: 2015-02-12T07:49:44.460374-05:
      DOI: 10.1111/jav.00629
       
  • Nest desertion cannot be considered an egg‐rejection mechanism in a
           medium‐sized host: an experimental study with the common blackbird
           Turdus merula
    • Authors: Manuel Soler; Francisco Ruiz‐Raya, Gianluca Roncalli, Juan Diego Ibáñez‐Álamo
      Abstract: Two main mechanisms of egg rejection, the main defence of hosts against brood parasites, have been described: ejection and desertion. Desertion of the parasitized nest is much more costly and is usually exhibited by small‐sized host species unable to remove the parasitic egg. However, nest desertion is frequently assumed to be an anti‐parasite strategy even in medium or large‐sized host species. This assumption should be considered with caution because: 1) large‐sized hosts able to eject the parasitic egg should eject it rather than desert the nest, and 2) breeding birds may desert their nests in response to different disturbances other than brood parasitism. This problem is especially important in the common blackbird Turdus merula because this is a medium‐sized species, potential host of the common cuckoo Cuculus canorus, in which desertion has been frequently reported as a response to cuckoo egg models. Here, we seek to determine whether nest desertion can be considered a response unequivocally directed to the parasitic egg in medium‐sized hosts using the blackbird as the study species. In an experimental study in which we have manipulated levels of mimicry and size of experimental eggs, we have found that both colour (mimetic and non‐mimetic; at least for human vision) and size (small, medium, and large) significantly affected ejection rates but not nest desertion rates. In fact, although large eggs disproportionally provoked nest desertion more frequently than did small or medium‐sized eggs, cuckoo‐sized parasitic eggs were not deserted allowing us to conclude that desertion is unlikely to be an adaptive response to brood parasitism at least for this species.
      PubDate: 2015-02-02T06:40:12.544161-05:
      DOI: 10.1111/jav.00571
       
  • Exploration and exploitation of foraging patches by desert sparrows:
           environmental indicators and local evaluation of spatially correlated
           costs and benefits
    • Authors: Fernando A. Milesi; Luis Marone
      Abstract: Conventional evolutionary and behavioral reasoning expects foragers to show strong spatial preferences in environments with heterogeneous resource distribution. Moreover, consumers should benefit from exploiting the information embedded in environmental features that indicate resource abundance. In desert soils seed abundance associates strong and reliably with vegetation and litter cover at small spatial scales. However, other spatially correlated factors (substrate complexity, temperature, predation risk) may affect foraging costs, benefits and decisions by ground‐feeding granivores. We used a sequence of three semi‐controlled field experiments of binary spatial choice within a portable aviary to identify the main cause of foraging microhabitat selection by the most abundant postdispersal granivorous bird in the central Monte desert (Argentina). In the first experiment we placed the aviary at field to offer pairs of adjacent microhabitats of unmodified, naturally‐contrasting substrates and environmental conditions to single, untrained rufous‐collared sparrows Zonotrichia capensis. Birds selected covered microhabitats in winter and summer, ruling out substrate complexity or thermoregulation as main single causes of patch selection. The other two experiments dissociated seed abundance, tree cover and litter to reveal their effects on patch selection. The results indicate that 1) sparrows do not restrict microhabitat exploration relying on environmental indicators, 2) distance to tree cover influences the order of patch exploration, probably in association with apprehension or risk‐assessment behavior, and 3) patch exploitation is determined by short‐term local estimation of seed abundance. The integration of these with previous results obtained under variable degrees of realism and experimental control allows for a better explanation of the spatial component of postdispersal granivory and its consequences on plants. The unconstrained selective foraging strategy of these sparrows would allow them to detect sporadic or ephemeral rich patches with structural characteristics indicating ‘low‐quality’, should promote the spatial homogenization of the palatable seed bank, and would favor indirect interactions between plants.
      PubDate: 2015-02-02T06:39:56.899313-05:
      DOI: 10.1111/jav.00388
       
  • Low‐budget ready‐to‐fly unmanned aerial vehicles: an
           effective tool for evaluating the nesting status of canopy‐breeding
           bird species
    • Authors: M. H. Weissensteiner; J. W. Poelstra, J. B. W. Wolf
      Abstract: Remotely controlled, unmanned aerial vehicles (UAVs) promise to be of high potential for a variety of applications in ecological and behavioural research. Off‐the‐shelf solutions have recently become available for civil use at steeply decreasing costs. In this study, we explored the utility of an UAV equipped with an on‐board camera (14 megapixel photo and 1920 × 1080 pixel video resolution) in assessing the breeding status, offspring number and age of a canopy‐breeding bird species, the hooded crow Corvus [corone] cornix. We further quantified performance and potential time savings using the UAV versus inspection with alternative approaches (optical instruments, camera on a telescopic rod, tree climbing). Nesting status, number and approximate age of nestlings could be assessed with good success in all 24 attempts using the UAV. Eighty‐five percent of the time required for inspection by climbing could be saved. Disturbance was moderate and lower than caused by climbing or using a camera on a telescopic rod. Additionally, UAV usage avoided tree damage and circumvented health risks associated with tree‐climbing.
      PubDate: 2015-01-23T08:51:19.183193-05:
      DOI: 10.1111/jav.00619
       
  • Plain wrens Cantorchilus modestus zeledoni adjust their singing tempo
           based on self and partner's cues to perform precisely coordinated duets
    • Authors: Karla D. Rivera‐Cáceres
      Abstract: Precise coordination appears to be an important signal in several duetting species. However, little attention has been directed to the proximate mechanisms that might drive this behavior. To perform highly coordinated duets, individuals can either have an intrinsic fixed singing tempo or modify their singing tempo based on cues in their own and their partner's songs. In this study I determined whether autogenous and/or heterogenous factors are associated with duet coordination in plain wrens Cantorchilus modestus zeledoni by analyzing recorded duets from 8 territorial pairs in the field. Previous research has determined that plain wrens perform highly coordinated antiphonal duets with almost no overlap. I found that to achieve such precise coordination individuals perform phrase‐by‐phrase modifications to the duration between two consecutive phrases (inter‐phrase interval) based on a) whether their song is answered, b) the phrase type used in the duet and c) the position of the inter‐phrase interval within the duet. Moreover, there are several sex differences in how individuals use these cues to modify their inter‐phrase intervals. Females produce longer inter‐phrase intervals when their mates do not answer a phrase, whereas males produce shorter inter‐phrase intervals when their mates do not answer. Females modify their inter‐phrase intervals based only on the phrase type their mates sing, whereas males modify their inter‐phrase intervals based on both the phrase that they sing and the phrase the females use to answer. Both males and females produce longer inter‐phrase intervals for longer phrase types sung by their partners, but males do so with more precision than do females. Finally both sexes increase their inter‐phrase intervals as the duet progresses. That precise coordination is achieved by a complex and dynamic process supports the idea that this behavior could signal pair bond strength.
      PubDate: 2015-01-23T08:51:04.333372-05:
      DOI: 10.1111/jav.00575
       
  • Malaria infection status predicts extra‐pair paternity in the blue
           tit
    • Authors: Edyta Podmokła; Anna Dubiec, Aneta Arct, Szymon M. Drobniak, Lars Gustafsson, Mariusz Cichoń
      Abstract: Extra‐pair matings comprise a common reproductive strategy among socially monogamous bird species. However, it remains unclear why females decide to mate with extra‐pair males. Indirect benefits in terms of improving offspring genetic quality are usually invoked to explain this phenomenon. Parasite resistance genes are often considered as a female target of seeking extra‐pair matings, but the direct test of this hypothesis is generally lacking. Here, we report on a relationship between the status of infection with malaria parasites (Plasmodium and Haemoproteus) and occurrence of extra‐pair paternity in a wild population of the blue tit Cyanistes caeruleus inhabiting Gotland (Sweden). We found that the probability of extra‐pair paternity is significantly related to the infection status of social parents. Infected males showed higher probability of being cuckolded than uninfected ones. However, this was observed only among males mated to uninfected females. Thus, avian malaria may potentially contribute to explanation of extra‐pair mating behaviour.
      PubDate: 2015-01-23T03:44:58.634191-05:
      DOI: 10.1111/jav.00599
       
  • Avian compass systems: do all migratory species possess all three'
    • Authors: Nikita Chernetsov
      PubDate: 2015-01-23T03:44:05.280492-05:
      DOI: 10.1111/jav.00593
       
  • Evolution of island warblers: beyond bills and masses
    • Authors: Bernd Leisler; Hans Winkler
      Abstract: In this paper, we take a closer look into the evolution of Acrocephalus warblers on islands in the Atlantic, Indian and Pacific Oceans. The shape‐related morphological evolution of island species is characterized by changes in the hind limb, flight, and feeding apparatus. Birds on islands converged to a morphology with strong legs, shorter rictal bristles, and rounder, more slotted and broader wings. Because of their high variance among islands, body size and bill dimensions did not contribute to the separation of continental and island forms, although bills tend to be longer on islands. The wings of island birds hardly vary among islands, unsurprisingly due to a lack of the adaptive features associated with long distance flights. The tendency towards shorter rictal bristles in the island warblers can be explained by the diminished role of aerial feeding, and closer contact with various substrates in the course of extractive foraging. The shift towards stronger legs in several insular species is remarkable because reed warblers on continents have even stronger legs than other passerines of comparable size. This trait correlates with diverse, acrobatic feeding techniques that are typically associated with broad habitat use. Bills reach extreme lengths on some islands. However, short bills occur as frequently, rendering this character highly variable among islands. Short bills indicate gleaning feeding techniques, whereas long bills are typical for species that pursue hidden and difficult‐to‐access prey. Body sizes differ greatly from island to island. On average, the sizes of island birds do not differ from continental ones, however. We suggest that vegetation clutter is the major driving force for this variation. The main conclusion following from our results is that evolution on islands pertains to all functional complexes, and not only the hitherto studied body size and bill dimensions.
      PubDate: 2015-01-20T06:25:37.981622-05:
      DOI: 10.1111/jav.00509
       
  • Are European birds leaving traditional wintering grounds in the
           Mediterranean'
    • Authors: José Luis Tellería; Álvaro Ramírez, José Ignacio Aguirre
      Abstract: Climate warming and other environmental changes seem to be causing a shift in the wintering grounds of European birds northwards. We tested this hypothesis by exploring whether the abundance of 14 common migratory passerines (Passeriformes) wintering in Spain has decreased during recent decades. We used data on ringed birds provided by the European Union for Bird Ringing (EURING) with a capture per unit of effort approach to detect whether the number of foreign ring recoveries controlled by the total number of ringed birds has decreased during the last 60 yr. We also explored if trends of breeding populations, diet and body mass explained the observed patterns. Results show that the arrival of extra Iberian wintering birds has decreased since the 1980s. This tendency was weakly associated with the trends of breeding populations reported by the European Bird Census Council (EBCC). However, diet produced some suggestive patterns since frugivorous birds, a group adapted to tracking spatiotemporal changes in food availability, depicted sharper reductions in the number of wintering individuals. In addition, larger birds, less affected by winter thermoregulatory requirements, lessened their migratory movements to the south more than small birds. The results suggest a long‐term rearrangement of migratory movements of European birds in which the Mediterranean basin is losing its traditional role as primary wintering ground.
      PubDate: 2015-01-20T06:24:09.453841-05:
      DOI: 10.1111/jav.00588
       
  • Conspicuous calling near cryptic nests: a review of hypotheses and a field
           study on white‐browed scrubwrens
    • Authors: T. M. Haff; A. G. Horn, M. L. Leonard, R. D. Magrath
      Abstract: Predation is an important source of nest mortality in many bird species and calling near the nest can increase this risk, yet adults of many species regularly vocalize near their nests. Some of these calls serve clearly adaptive functions, such as alarm or provisioning calls. However, many species also give conspicuous ‘contact’ calls near the nest, which is puzzling because the function of these calls is unclear, and they might attract predators. Most studies of parental vocalizations near nests have focused on specific vocalizations and single hypotheses, yet there is a diversity of vocalization types and potential functions. We review the literature on the diversity and possible function of parental vocalizations near the nest, and then investigate the puzzle of conspicuous contact calling near nests by white‐browed scrubwrens Sericornis frontalis. In scrubwrens, ‘chip‐zz’ contact calls were almost always used when adults approached nests, and when they approached one another or changed location. Call composition also changed: the proportion of ‘chip’ elements increased as callers approached the nest or other adults. Neither adult sex nor nestling age affected calling. Thus, chip‐zz calls appear to be used as ongoing signals to other group members of the caller's activity and location, particularly relative to the nest. Nestlings appeared to use the calls as cues of adult arrival, and increased calling as adults approached nests. Further, adults called less after a predator was on the territory, suggesting that parents may be able to reduce the risk of chip‐zz calls betraying nest location, or possibly use the absence of calling as a signal of danger. This study thus demonstrates that calling near nests could inform both adults and nestlings about the caller's behaviour, and could serve multiple functions. Future studies will need to experimentally test these functions, as well as the other hypotheses reviewed here.
      PubDate: 2014-12-22T06:47:44.821645-05:
      DOI: 10.1111/jav.00622
       
  • Increased syllable rate during aggressive singing in a bird with complex
           and fast song
    • Authors: Caterina Funghi; Gonçalo C. Cardoso, Paulo G. Mota
      Abstract: Sexual signals can comprise traits with multiple functions, and species with extreme phenotypes offer an opportunity to link function with signal evolution. This is the case in the serin Serinus serinus, a songbird with extremely fast syllable rate compared to related finches, and high sound frequency for its body size. Previous work on receiver responses showed that playback of artificially increased syllable rate is avoided and inhibits vocal responses, suggesting it is perceived as aggressive, while, on the contrary, higher sound frequency appears preferred by females. We tested whether senders also change these traits during aggressive singing, with a field playback experiment. Serin males responding aggressively by approaching the playback loudspeaker also increased syllable rate, while males responding less aggressively did not change syllable rate. Together with work on receiver responses, this suggests that aggressive signalling may have been an important selective pressure for the evolution of extremely fast syllable rate in this species. It is noteworthy that aggressive male serins still increase syllable rate, despite of their already elevated natural syllable rate. We found no changes in sound frequency when singing aggressively, which agrees with previous work that instead showed a female preference for high song frequency. We conclude that the evolution of extreme traits in serin song is best explained by multiple functions.
      PubDate: 2014-12-22T06:47:31.254708-05:
      DOI: 10.1111/jav.00480
       
  • Incorporating site and year‐specific deuterium ratios (δ2H)
           from precipitation into geographic assignments of a migratory bird
    • Authors: Christopher M. Tonra; Christiaan Both, Peter P. Marra
      Abstract: The study of migratory connectivity is rapidly growing in ornithology, as is the technology used to measure it. While use of extrinsic markers, such as archival tags, is becoming more prevalent, for many small species the best tool available for tracking birds remains intrinsic markers, such as stable‐hydrogen isotope ratios (δ2H). Many researchers have raised concerns that spatial and temporal environmental variation introduces a large amount of error into isotope‐based assignments, limiting their utility. Here, using feathers, we sought to address these issues in developing δ2H base maps for assigning pied flycatchers Ficedula hypoleuca of known origin to 15 sites across the breeding range (approx. 4 020 800 km2). We evaluated the effects of including random site variation and year‐specific precipitation δ2H (δ2HP) maps on assignments, compared to using mean annual growing season δ2Hp and no site effects. We found a positive correlation between feather δ2H (δ2HF) and mean annual δ2HP, resulting from large scale geographic variation. Repeatability of feather δ2H for individuals sampled in multiple years was strong overall, but variable among populations. Annual variation in δ2HP explained 21% of within individual variation in δ2HF. Neither year‐ nor site‐specific methods improved assignment precision or accuracy. All three methods assigned flycatchers of unknown origin captured at an African overwintering site to similar breeding areas. However, methods using long‐term means of δ2Hp assigned birds more precisely than year‐specific methods. Our results suggest that annual variation in this system is primarily a result of food web or individual level processes and that random site effects are not strong enough to drastically impact accuracy. We conclude that improvements in isotope based geographic assignments will rely on the addition of prior information, such as relative abundance in a Bayesian framework, or additional intrinsic markers.
      PubDate: 2014-12-12T03:38:40.187105-05:
      DOI: 10.1111/jav.00553
       
  • Egg removal by cuckoos forces hosts to accept parasite eggs
    • Authors: Osamu K. Mikami; Nozomu J. Sato, Keisuke Ueda, Keita D. Tanaka
      Abstract: Many avian brood parasites remove one or more host eggs before laying their own eggs in the host nest. Various hypotheses have been proposed to explain the adaptive significance of this behaviour, but none of them provides an adequate explanation. Here we provide a new hypothesis for explaining why a parasite removes host eggs before laying its own. In this study, we attempted to answer this question by constructing a mathematical model that focused on the changes in host decision making according to reduced clutch size as a consequence of egg removal by parasites. We assume that a host selects one of the following two options to maximise the number of its own chicks: trying to eject a suspicious egg from the nest (trying‐to‐eject) or acceptance without trying to eject the egg (acceptance). The option selected depends on the number of eggs in the nest. Our model provides a new explanation for egg removal behaviour by showing that the host should select trying‐to‐eject if there is a large number of eggs in the nest but acceptance with a small number of eggs. This is because the relative payoff for a host that selects trying‐to‐eject decreases with the number of eggs in the nest. Therefore, parasites benefit by removing the host egg because this behaviour reduces the number of eggs in the nest, thereby increasing the probability of their own eggs being accepted. Thus, hosts have evolved egg ejection to combat brood parasites, but it may also have facilitated the evolution of egg removal by parasites. This hypothesis may also apply to brood parasitic species that do not eject host chicks. In addition, this hypothesis may explain other parasitic behaviours, such as egg damaging and egg puncturing, which lead to reductions in the host clutch size.
      PubDate: 2014-12-12T03:38:25.292508-05:
      DOI: 10.1111/jav.00410
       
  • The effects of spatial and temporal ecological variation on fatty acid
           compositions of wild great tits Parus major
    • Authors: Caroline Isaksson; Mark A. Hanson, Graham C. Burdge
      Abstract: In birds, fatty acids (FA) have three main functions; they are structural components of cell membranes, metabolic fuel, and inflammatory molecules. Environmental factors, such as diet and ambient temperature, affect FA composition, thereby function and ultimately fitness. Thus, variation in FA compositions can be the underlying mechanism for varying performance of birds in different habitats. Here we examine variation in plasma FA composition in nestling and adult great tits Parus major, between 1) deciduous and coniferous, and 2) sun‐exposed and shaded habitats. The main results revealed that nestlings had a higher proportion of α‐linolenic acid (α‐LNA) in deciduous habitats and arachidonic acid in coniferous habitats. This reflects a difference in caterpillar availability between habitats with the deciduous habitat being caterpillar‐rich, whereas the coniferous habitats are rich in spiders. In addition, α‐LNA increased with nestling body condition in the coniferous habitat, supporting the importance of caterpillars for fledging success in this species. In line with dietary intake, the proportion of the essential α‐LNA and linoleic acid (LA) increased over the course of the day for all birds. In the deciduous habitat, adult females showed a positive association between LA and body condition. Furthermore, habitat sun‐exposure showed significant interactions with body condition for polyunsaturated FAs in nestlings, and with saturated FA in adult males, which is in accordance with the homeoviscous hypothesis stating that the proportion of saturated FA should decrease with decreasing ambient temperature. Taken together, small‐scale heterogeneity in habitat structure significantly influences FA compositions of great tits. Many of the results can be linked to dietary, and possibly, ambient temperature differences between habitats. These habitat effects on FA compositions can lead to different capacities of individual birds to deal with infections and low temperatures, two stressors that cause major mortality among wild birds.
      PubDate: 2014-12-12T03:38:12.374864-05:
      DOI: 10.1111/jav.00409
       
  • Timing of migration and residence areas during the non‐breeding
           
    • Authors: Felix Liechti; Chiara Scandolara, Diego Rubolini, Roberto Ambrosini, Fränzi Korner‐Nievergelt, Steffen Hahn, Roberto Lardelli, Maria Romano, Manuela Caprioli, Andrea Romano, Beatrice Sicurella, Nicola Saino
      Abstract: We investigated sex‐ and year‐dependent variation in the temporal and spatial movement pattern of barn swallows Hirundo rustica during the non‐breeding period. Hundred and three individuals equipped with miniaturized light‐level geolocators at three different breeding areas in southern Switzerland and northern Italy provided data for the analysis. We identified a region 1000 km in radius centred in Cameroon as the main non‐breeding residence area of these three geographical populations. Five residence areas of males only were in southern Africa, south of 19°S. Most individuals occupied a single site during their stay south of the Sahara. The timing of migration broadly overlapped between sexes and all geographical breeding populations. Between the two study years there was a distinct difference of 5 to 10 d in departure dates from and arrival at the breeding sites. Remarkably, the period of residence in sub‐Saharan Africa was very similar (157 d) in the two study years, but their positions in the first year (2010–2011) were about 400 km more to the north than in the second (2011–2012). Independent of the year, individuals with sub‐Saharan residence areas further north and east had a shorter pre‐breeding migration and arrived earlier than those staying further south and west. In addition, birds breeding in southern Switzerland arrived at their breeding colony 7–10 d later than those breeding only 100 km south, in the Po river plain. Our study provides new information on the variance in migration phenology and the distribution of residence areas in sub‐Saharan Africa in relation to sex, population and year. It supports the usefulness of light‐level geolocators for the study of annual routines of large samples of small birds.
      PubDate: 2014-12-01T03:16:42.856868-05:
      DOI: 10.1111/jav.00485
       
  • Wide ranging stopover movements and substantial fuelling in first year
           garden warblers at a northern stopover site
    • Authors: Robert Stach; Thord Fransson, Sven Jakobsson, Cecilia Kullberg
      Abstract: Migratory birds use stopovers to replenish their fuel reserves and they generally spend more time at stopover sites than they do in actual flight. When arriving at a new stopover site birds may need to search extensively to find a suitable feeding area and this search and settling period may affect the duration of stopover. Stopover behaviour can thus have profound effects on the migratory programme and studies on stopover behaviour are important to understand migratory strategies. We followed 51 first‐year garden warblers Sylvia borin with radio‐transmitters at an autumn stopover site on the island of Gotland in southern Sweden. Our aim was to determine the distance birds relocated from the coastal capture site when searching for an area to settle in, and also to establish the duration of stopover and put it in relation to refuelling rate by recapturing a subset of the radio‐tracked individuals. Sixteen birds made an extended stopover (> 2 d), relocated inland from the capture site and settled on average 5.6 km from the capture site, with the longest recorded relocation being fourteen kilometres. Birds that relocated nocturnally settled in areas further away than birds that relocated diurnally. Thirteen birds that continued migration after a short stop carried larger fuel stores than birds that stopped over longer and they remained close to the capture site until departure. Three birds were re‐trapped and showed high fuelling rates, between 0.3 and 1.1 g d–1. They left the stopover site with fuel loads between 40–56 percent of lean body mass, which possibly would have allowed them to reach the Mediterranean area without additional refuelling stops.
      PubDate: 2014-11-27T03:08:28.059439-05:
      DOI: 10.1111/jav.00492
       
  • Systematics and evolution of the Pan‐Alcidae (Aves, Charadriiformes)
    • Authors: N. Adam Smith; Julia A. Clarke
      Abstract: Puffins, auks and their allies in the wing‐propelled diving seabird clade Pan‐Alcidae (Charadriiformes) have been proposed to be key pelagic indicators of faunal shifts in Northern Hemisphere oceans. However, most previous phylogenetic analyses of the clade have focused only on the 23 extant alcid species. Here we undertake a combined phylogenetic analysis of all previously published molecular sequence data (∼ 12 kb) and morphological data (n = 353 characters) with dense species level sampling that also includes 28 extinct taxa. We present a new estimate of the patterns of diversification in the clade based on divergence time estimates that include a previously vetted set of twelve fossil calibrations. The resultant time trees are also used in the evaluation of previously hypothesized paleoclimatic drivers of pan‐alcid evolution. Our divergence dating results estimate the split of Alcidae from its sister taxon Stercorariidae during the late Eocene (∼ 35 Ma), an evolutionary hypothesis for clade origination that agrees with the fossil record and that does not require the inference of extensive ghost lineages. The extant dovekie Alle alle is identified as the sole extant member of a clade including four extinct Miocene species. Furthermore, whereas an Uria + Alle clade has been previously recovered from molecular analyses, the extinct diversity of closely related Miocepphus species yields morphological support for this clade. Our results suggest that extant alcid diversity is a function of Miocene diversification and differential extinction at the Pliocene–Pleistocene boundary. The relative timing of the Middle Miocene climatic optimum and the Pliocene–Pleistocene climatic transition and major diversification and extinction events in Pan‐Alcidae, respectively, are consistent with a potential link between major paleoclimatic events and pan‐alcid cladogenesis.
      PubDate: 2014-10-10T03:34:25.839682-05:
      DOI: 10.1111/jav.00487
       
  • Survival of Gunnison sage‐grouse Centrocercus minimus in Colorado,
           USA
    • Authors: Amy J. Davis; Michael L. Phillips, Paul F. Doherty
      Abstract: Gunnison sage‐grouse Centrocercus minimus has declined from their historic range and recent monitoring has provided evidence that some populations are continuing to decline. The evaluation of long‐term, population‐specific survival rates is important to assess population stability, and is necessary for conservation of this species of concern. We evaluated adult and yearling survival in two dynamically different populations of Gunnison sage‐grouse (a relatively large, more stable population and a small, declining population). Our goal was to examine the relationship between annual survival and population, and test hypotheses with regards to temporal effects (across years and within year) and individual effects (sex and age). We also evaluated the effects of snow depth on sage‐grouse survival. We tracked 214 radiomarked birds in the large population from 2005–2010 and 25 birds in the small population from 2007–2010. We found no evidence for a difference in survival between yearlings and adults nor did we find an influence of snow depth on survival. Males had the lowest survival during the lekking season (March–April); females had lower survival during the nesting and chick rearing season (May–July) and late‐summer and fall (August–October). The annual survival rate was 0.61 (SE 0.06) for females and 0.39 (SE 0.08) for males. Survival was constant across years and between the populations suggesting observed population changes during this time period are not a result of changes in adult survival.
      PubDate: 2014-10-10T03:33:56.653144-05:
      DOI: 10.1111/jav.00473
       
  • The decline of a peripheral population of the European robin Erithacus
           rubecula
    • Authors: José Luis Tellería
      Abstract: This paper examines the potential effect of some factors involved in the decline of a winter population of the European robin Erithacus rubecula in southern Spain. The area receives extra‐Iberian immigrants that come into contact with resident conspecifics. Given this interspersed distribution, three hypotheses were tested to explain the decline: a) the depletion of the carrying capacity of the area during winter, b) the decline of the resident population, and c) the reduction of foreign individuals in this wintering area. Winter robin and fruit (a main winter food) abundances were assessed at 43 sites from 1999 to 2014, and the abundance of breeding robins was evaluated from 1998 to 2012. Rainfall and temperatures were recorded throughout this period and changes in forests occupied by breeding robins were assessed in 1999 and 2013. Results showed a decline in winter temperatures and an increase in fruit availability. Given that food increases could buffer the thermoregulatory costs of colder conditions, the depletion of the carrying capacity of the area was discarded as a main driver of robin decline. Spring counts showed a reduction of 45% in the breeding population that was not explained by changes in forest management. However, a significant increase in summer temperatures could boost the pervasive effect of drought on robins inhabiting this marginal area of the species' range. Foreign immigrants, despite the increase in breeding populations in most of Europe, did not buffer the decline caused by the reduction of residents. In fact, an analysis of ring recoveries reported in this area depicted a sharp decrease in extra‐Iberian wintering individuals. These results may be related to the effect of global warming on migratory schedules (the northwards retreat of wintering areas) and on the suitability for robins of local habitats in this peripheral region of the Palaearctic.
      PubDate: 2014-10-10T03:32:32.672192-05:
      DOI: 10.1111/jav.00451
       
  • House sparrow Passer domesticus survival is not associated with
           MHC‐I diversity, but possibly with specific MHC‐I alleles
    • Authors: Maria Karlsson; Julia Schroeder, Shinichi Nakagawa, Henrik G. Smith, Terry Burke, Helena Westerdahl
      Abstract: The MHC (Major Histocompatibility Complex) plays an important role in the immune system of vertebrates. MHC genes are extremely polymorphic and this variation is considered to be maintained by selection from pathogens. We investigate whether MHC diversity (number of different alleles per individual) affects the survival and recruitment of nestling house sparrows. We hypothesize that individuals with higher MHC diversity can recognize and combat a wider range of pathogens, and therefore are more likely to survive and recruit into the breeding population. Additionally, we hypothesize that specific MHC class I alleles (MHC‐I) could be associated with survival and recruitment. We screened MHC‐I genotypes in 518 house sparrow chicks hatched on Lundy Island but we found no evidence for a relationship between nestling survival, post‐fledging survival or recruitment success with MHC diversity. Then we investigated effects of specific MHC‐I alleles in 195 individuals from a single cohort. Twenty‐one MHC‐I alleles were tested for relationships with nestling survival, post‐fledging survival and recruitment, and we detected associations with survival for three different alleles. This pattern was, however, not different to what would be expected from random, so we could not conclude that particular MHC‐I alleles are associated with survival in house sparrows on Lundy Island. Nonetheless, one of these alleles (1105) showed both a tendency for a higher probability of surviving in nestlings, and a significant association with survival in fledglings. We envision that allele 1105 could be an interesting candidate gene for testing associations with survival in house sparrows in the future.
      PubDate: 2014-10-10T03:32:18.953319-05:
      DOI: 10.1111/jav.00413
       
  • Ratios, adaptations, and the differential metabolic capability of avian
           flight muscles
    • Authors: Joseph R. Jehl; Annette E. Henry, David L. Swanson
      First page: 119
      Abstract: The eared grebe Podiceps nigricollis shows seasonal variation in the relative size of the major flight muscles that lift and lower the wing: respectively, supracoracoideus (s) and pectoralis (p). S/p ratios are low (≈0.07–0.12) when grebes are in flying condition, higher (≈0.11–0.15) when staging and flightless, and extreme (to 0.29) when starving. Shifts were driven by changes in the protein content in the pectoralis; intramuscular fat had little effect. S/p ratios also vary seasonally in the red knot Calidris canutus and are higher in birds newly arrived in breeding areas than at other times. If that increase was an adaptive response to promote wing‐lifting in association with various breeding behaviors as suggested, one would expect it to result from an absolute increase in the post‐arrival size of the supracoracoideus, which was not observed. Instead, we propose that it is unrelated to enhancing the upstroke but results from a decrease in the size of the pectoralis, which is a consequence of the greater rate at which this muscle is catabolized in times of exertion and stress, as at the end of a long migration or during starvation. Fuller data on the size, morphology and physiology of individual muscles at various stages of the annual cycle and migration will help to clarify how ratio changes are achieved, and evaluate potential adaptive significance.
      PubDate: 2014-11-06T09:12:26.34457-05:0
      DOI: 10.1111/jav.00506
       
  • Breeding performance and survival in the peregrine falcon Falco peregrinus
           support an age‐related competence improvement hypothesis mediated
           via an age threshold
    • Authors: Jabi Zabala; Iñigo Zuberogoitia
      First page: 141
      Abstract: We studied the effects of age on breeding performance and survival probability in a peregrine falcon population, using data from a long term monitoring programme (carried out over 16 yr), in which we were able to identify individual birds. We compared the breeding performance and survival of yearling breeders, first‐time adult breeders and adult breeders. We found significant differences in breeding performance but not in survival. Yearling breeders had lower breeding success than older individuals but the breeding performance of inexperienced adults did not differ from that of experienced adults. We did not find changes in terminal breeding success since peregrines in their last year of life sustained the performance levels shown in previous years although with increasing variability. We found no evidence that attempting to breed affected survival probability in any age group. We argue that differences in breeding performance are related to age, not to breeding experience, and that there is an age threshold, coincident with the development of adult plumage, after which breeding performance is not affected either by age or experience. Peregrines that start breeding as yearlings are likely to have greater lifetime reproductive success than birds entering the breeding pool as adults. Consequently, such birds may represent a set of high quality individuals. Our results support the age‐related competence improvement hypothesis as being the relevant explanation for the increase in breeding performance with age.
      PubDate: 2014-11-06T09:12:32.782623-05:
      DOI: 10.1111/jav.00505
       
  • Neighbour recognition in two sister songbird species with a simple and
           complex repertoire – a playback study
    • Authors: Pavel Jaška; Pavel Linhart, Roman Fuchs
      First page: 151
      Abstract: The ability of individuals to recognize others based on vocalizations has been proven in many species of birds. However, we are still far from understanding important aspects of the discrimination process. For example, it is still not fully understood whether, and why, repertoire size hinders discrimination between individuals. Further, the strategies and vocal cues used for discrimination between individuals are largely unexplored. In this study, we tested the ability of chiffchaffs Phylloscopus collybita and willow warblers Phylloscopus trochilus, two closely related species with different repertoire sizes and song organization, to differentiate between their neighbours on the basis of a single song of a neighbouring male. We did playback experiments within the ‘dear enemy’ paradigm in which we tested resident males with a single song of a neighbour broadcast from the correct and opposite, incorrect territory border. Both species displayed a strong ability to discriminate between their neighbours representing further evidence that repertoire size per se has no negative impact on individual recognition in songbirds. Using a single song for playback allowed us to speculate about the nature of the possible cues used by males for recognition. Individual recognition in both species is most likely based on the modulation of syllables or on general voice characteristics. We suggest that specific changes in song organization, for example the tendency of individuals to insert a distinct phrase at the beginning of each song, may facilitate individual recognition and compensate for increased repertoire size in willow warblers.
      PubDate: 2014-09-30T06:56:40.800782-05:
      DOI: 10.1111/jav.00482
       
  • Testis asymmetry in birds: the influences of sexual and natural selection
    • Authors: Sara Calhim; Robert Montgomerie
      First page: 175
      Abstract: Gonad size and shape asymmetries are particularly common in birds. Although some obvious size and shape differences between the left and right testes in birds were first documented more than a century ago, little is known about what influences the variation across species in either the degree or the direction of these asymmetries. Here we show that a left bias in size is the most likely ancestral state in most orders and families, and that there is a weak but significant negative relation between the degree of size and shape asymmetries. In extant species, testis size and shape symmetries increase with the degree of sperm competition (relative testes mass), but those relations are significant only in those species with left bias in each of these traits. When space is particularly constrained on the left side of the body cavity due to a large gizzard (e.g. in granivores), the left testis is more elongated and the degree of size symmetry is larger. Despite significant patterns, relative testes mass and gizzard complexity together explain < 10% of the variation in testis asymmetry in species with left biases. Thus our analyses suggest that some other factor is largely responsible for the evolution of gonad asymmetry in birds: 1) that a left bias in testis size might be a correlated response to selection for a left bias in the development of a single (left) ovary in females of most bird species, and/or 2) that physiological efficiency due to the dramatic and rapid increase in testis size of most species during the breeding season might favour enlargement of one testis. Our conclusions highlight the need to rethink and improve our understanding of the physiological processes underlying the investment in gonads by male birds.
      PubDate: 2014-10-15T09:42:13.153406-05:
      DOI: 10.1111/jav.00503
       
  • Testing assumptions of central place foraging theory: a study of
           Adélie penguins Pygoscelis adeliae in the Ross Sea
    • Authors: R. Glenn Ford; David G. Ainley, Amelie Lescroël, Phil O'B. Lyver, Viola Toniolo, Grant Ballard
      First page: 193
      Abstract: We investigated central place foraging (CPF) in the context of optimal foraging theory in Adélie penguins Pygoscelis adeliae of the southern Ross Sea by using satellite tracking and time‐depth recorders to explore foraging at two spatio‐temporal scales: within the day‐to‐day (sub‐mesoscale: single foraging trip, 10s of km2) and the entire breeding season (mesoscale: trips by multiple individuals across the collective foraging area, 100s of km2). Specifically, we examine whether three basic assumptions of the Orians–Pearson CPF model, shown to occur in other CPF species, are met: 1) within a patch, the rate of prey acquisition declines with time spent in that patch; 2) food is distributed in discrete patches and is not available between those patches; and 3) CPF species have knowledge of the potential (or average, at least) feeding rate within their universe of patches, and use this knowledge to determine their foraging strategy when planning or engaging in a foraging trip. We found that prey consumption rates did not decline with time spent in patches, and penguins foraged to some degree most of the time when at sea. Food availability, as measured by foraging dive rate, appeared to be predictable within the same day at the same location, but predictability broke down after 2 d at distances > 10 km away. We conclude that the assumptions of the Orians–Pearson CPF model are not a good fit to the circumstances of Ross Sea penguins, which clearly are central place foragers.
      PubDate: 2014-11-27T03:07:36.871499-05:
      DOI: 10.1111/jav.00491
       
  • Pair bond characteristics and maintenance in free‐flying jackdaws
           Corvus monedula: effects of social context and season
    • Authors: Robin J. Kubitza; Thomas Bugnyar, Christine Schwab
      First page: 206
      Abstract: Most birds rely on cooperation between pair partners for breeding. In long‐term monogamous species, pair bonds are considered the basic units of social organization, albeit these birds often form foraging, roosting or breeding groups in which they repeatedly interact with numerous conspecifics. Focusing on jackdaws Corvus monedula, we here investigated 1) the interplay between pair bond and group dynamics in several social contexts and 2) how pair partners differ in individual effort of pair bond maintenance. Based on long‐term data on free‐flying birds, we quantified social interactions between group members within three positive contexts (spatial proximity, feeding and sociopositive interactions) for different periods of the year (non‐breeding, pre‐breeding, parental care). On the group level, we found that the number of interaction partners was highest in the spatial proximity context while in the feeding and sociopositive contexts the number of interaction partners was low and moderately low, respectively. Interactions were reciprocated within almost all contexts and periods. Investigating subgrouping within the flock, results showed that interactions were preferentially directed towards the respective pair partner compared to unmated adults. When determining pair partner effort, both sexes similarly invested most into mutual proximity during late winter, thereby refreshing their bond before the onset of breeding. Paired males fed their mates over the entire year at similar rates while paired females hardly fed their mates at all but engaged in sociopositive behaviors instead. We conclude that jackdaws actively seek out positive social ties to flock members (close proximity, sociopositive behavior), at certain times of the year. Thus, the group functions as a dynamic social unit, nested within are highly cooperative pair bonds. Both sexes invested into the bond with different social behaviors and different levels of effort, yet these are likely male and female proximate mechanisms aimed at maintaining and perpetuating the pair bond.
      PubDate: 2014-11-06T09:12:44.769876-05:
      DOI: 10.1111/jav.00508
       
  • Hawk mimicry in cuckoos and anti‐parasitic aggressive behavior of
           barn swallows in Denmark and China
    • Authors: Wei Liang; Anders Pape Møller
      First page: 216
      Abstract: Hosts of brood parasites defend their nests against parasitism by aggression and subsequently, if parasitized, by rejection of the parasite egg or nestling. Cuckoos have evolved plumage mimicry with convergence towards the phenotype of Accipiter hawks that are common predators of cuckoo hosts. Here we tested two alternative hypotheses 1) whether barn swallows Hirundo rustica have evolved less aggressive behavior towards cuckoos in areas of sympatry with more abundant Accipiter hawks; and 2) whether barn swallows have evolved more aggressive anti‐parasite behavior in areas with a single species of cuckoo. We presented dummies of common cuckoo Cuculus canorus, sparrowhawk Accipiter nisus and Oriental turtledove Streptopelia orientalis (a benign control) at the nests of barn swallows during breeding, while recording intensity of response and proximity of barn swallows to the dummy. We demonstrated that cuckoos moved away when attacked aggressively and approached more closely by barn swallows showing that barn swallow behavior was efficient at driving away cuckoos. Barn swallows were significantly more aggressive and approached cuckoo and sparrowhawk dummies more closely in Denmark than in China, despite sparrowhawks being relatively more common in Denmark. Responses towards cuckoo dummies differed from responses towards sparrowhawk dummies, showing that barn swallows distinguished between the two different causes of danger. These findings are inconsistent with a less aggressive response towards cuckoo dummies in areas of sympatry with more abundant Accipiter hawks, but consistent with the alternative hypothesis that barn swallows have evolved more aggressive behavior towards cuckoos in areas with a single species of brood parasite, but not in areas with multiple species of parasites, where it is harder for hosts to tell the difference.
      PubDate: 2014-11-06T09:13:00.676307-05:
      DOI: 10.1111/jav.00515
       
 
 
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