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BIOLOGY (1322 journals)            First | 3 4 5 6 7 8 9 10 | Last

International Journal of Biometrics     Hybrid Journal   (Followers: 2)
International Journal of Brain Science     Full-text available via subscription  
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: 11)
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: 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: 10)
International Journal of Experimental and Computational Biomechanics     Hybrid Journal   (Followers: 3)
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 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: 11)
International Journal of Myriapodology     Open Access  
International Journal of Nanoparticles     Hybrid Journal   (Followers: 5)
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: 3)
International Journal of Phytoremediation     Hybrid Journal   (Followers: 1)
International Journal of Plant Genomics     Open Access   (Followers: 2)
International Journal of Primatology     Hybrid Journal   (Followers: 2)
International Journal of Proteomics     Open Access   (Followers: 1)
International Journal of Speleology     Open Access   (Followers: 9)
International Journal of Tropical Insect Science     Hybrid Journal   (Followers: 1)
International Journal of Tryptophan Research     Open Access  
International Research Journal of Applied Life Sciences     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: 1)
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)
ISRN Bioinformatics     Open Access   (Followers: 2)
ISRN Biomarkers     Open Access  
ISRN Biomathematics     Open Access   (Followers: 1)
ISRN Computational Biology     Open Access   (Followers: 1)
ISRN Genomics     Open Access  
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: 3)
JCP : BioChemical Physics     Hybrid Journal  
JETP Letters     Hybrid Journal   (Followers: 3)
Journal of Bacteriology & Parasitology     Open Access   (Followers: 2)
Journal of Bioanalysis & Biomedicine     Open Access   (Followers: 1)
Journal of Bioequivalence & Bioavailability     Open Access  
Journal of Biometrics & Biostatistics     Open Access   (Followers: 1)
Journal of Bioremediation & Biodegradation     Open Access   (Followers: 2)
Journal of Biosensors & Bioelectronics     Open Access   (Followers: 1)
Journal of Bioterrorism & Biodefense     Open Access   (Followers: 1)
Journal of Cell Science & Therapy     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: 2)
Journal of Advances in Biology     Open Access   (Followers: 2)
Journal of Agricultural, Biological & Environmental Statistics     Hybrid Journal   (Followers: 7)
Journal of Amino Acids     Open Access   (Followers: 3)
Journal of Analytical & Bioanalytical Techniques     Open Access   (Followers: 4)
Journal of AOAC International     Full-text available via subscription   (Followers: 8)
Journal of Applied Biobehavioral Research     Hybrid Journal  
Journal of Applied Bioinformatics & Computational Biology     Partially Free  
Journal of Applied Biosciences     Open Access  
Journal of Applied Ichthyology     Hybrid Journal   (Followers: 6)
Journal of Applied Phycology     Hybrid Journal   (Followers: 7)
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 Avian Biology     Hybrid Journal   (Followers: 16)
Journal of Bacteriology     Full-text available via subscription   (Followers: 13)
Journal of Basic Microbiology     Hybrid Journal   (Followers: 3)
Journal of Bio-Science     Open Access  
Journal of Biobased Materials and Bioenergy     Full-text available via subscription  
Journal of Biodiversity Management & Forestry     Full-text available via subscription  
Journal of Bioenergetics and Biomembranes     Hybrid Journal  
Journal of Biogeography     Hybrid Journal   (Followers: 17)
Journal of Bioinformatics and Computational Biology     Hybrid Journal   (Followers: 11)
Journal of Biological and Information Sciences     Open Access   (Followers: 1)
Journal of Biological Dynamics     Open Access   (Followers: 1)
Journal of Biological Education     Hybrid Journal   (Followers: 1)
Journal of Biological Engineering     Open Access   (Followers: 3)
Journal of Biological Methods     Open Access  
Journal of Biological Physics     Hybrid Journal  
Journal of Biological Research - Thessaloniki     Open Access  
Journal of Biological Sciences     Open Access   (Followers: 4)

  First | 3 4 5 6 7 8 9 10 | Last

Journal Cover Journal of Avian Biology
   [18 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  [1603 journals]   [SJR: 1.066]   [H-I: 50]
  • Irruptive movements and breeding dispersal of snowy owls: a specialized
           predator exploiting a pulsed resource
    • Authors: J.-F. Therrien; G. Gauthier, D. Pinaud, J. Bêty
      Abstract: Mobility and irruptive movements have been proposed as mechanisms that could allow some diet specialists to inhabit and breed in environments with highly unpredictable resources, like the arctic tundra. The snowy owl, one of the main avian predators of the tundra, is known to specialize on lemmings during the breeding season. These small mammals are also well known for their tremendous spatial and temporal variations in abundance. We examined the spring (pre‐breeding, from March to June) movements of snowy owls by tracking 9 breeding females in the Canadian Arctic for up to 3 yr with satellite transmitters. We used state‐space modeling to assess searching behavior and measure breeding dispersal distances. We also ascertain lemming abundance at some of the sites used by the marked owls. Tracked owls displayed searching movements for extended periods (up to 108 d) and traveled over large distances (up to 4093 km) each spring. The distance between furthest apart searching areas in a given year averaged 828 km (range 220 to 2433 km). Settlement date, distance between searching areas, traveled distance and the duration of prospecting movements were longer in the year where density of lemmings recorded in the eastern High‐Arctic (Bylot Island) was lowest. Nonetheless, snowy owls settled in areas where local lemming abundance was relatively high. Individual breeding dispersal distance between consecutive years averaged 725 km (range 18 to 2224). Overall, the high mobility of female snowy owls allowed these diet specialists to behave as irruptive migrants and to sustain their reproductive activities during consecutive years even under highly fluctuating resources.
      PubDate: 2014-06-02T04:55:37.815494-05:
      DOI: 10.1111/jav.00426
  • Geographical and environmental factors affecting the distribution of
           wintering black storks Ciconia nigra in the Iberian Peninsula
    • Authors: Luis Santiago Cano; Carlos Pacheco, Pablo Refoyo, José Luis Tellería
      Abstract: Here we explore the environmental and geographical factors affecting the winter distribution of the black stork Ciconia nigra in the Iberian Peninsula, where an increasing number of individuals have remained to winter in the last two decades. We recorded 179 locations of 54 ringed individuals between 1988 and 2011 to map the species habitat suitability with MaxEnt, a machine‐learning technique based on the principle of maximum entropy. The migratory movements of 25 birds equipped with satellite transmitters were used to define the autumnal migratory flyway used by most storks crossing the Peninsula as well as to define the wintering period. The aim was to test if the number of wintering storks was positively correlated to habitat suitability and negatively correlated to the flyway distance. Data provided by an extensive count across Portugal and Spain during the 2012–2013 winter supported the findings that black storks were more abundant in areas of high habitat suitability close to the migratory flyway. This agrees with previous evidence on the role of migratory flyways in determining the distribution of some wintering birds in Iberia. A gap analysis reflected that just 12.3% of the suitable areas and 18.8% of individuals recorded during the 2012–2013 winter were included within the Special Protection Areas network of Portugal and Spain. Most of these birds were crowded in unprotected areas covered by rice fields (68% of individuals), a key habitat for the species.
      PubDate: 2014-06-02T04:50:26.561406-05:
      DOI: 10.1111/jav.00391
  • Age‐dependent song changes in a closed‐ended vocal learner:
           elevation of song performance after song crystallization
    • Authors: Nao Ota; Masayo Soma
      Abstract: Birdsong is a sexual signal that serves as an indicator of male quality. There is already abundant evidence that song elaboration reflects early life‐history because early developmental stress affects neural development of song control systems, and leaves irreversible adverse effects on song phenotypes. Especially in closed‐ended vocal learners, song features crystallized early in life are less subject to changes in adulthood. This is why less attention has been paid to lifelong song changes in closed‐ended learners. However, in the eyes of female birds that gain benefits from choosing mates based on male songs, not only past but also current conditions encoded in songs would be meaningful, given that even crystallized songs in closed‐ended learners would not be identical in the long term. In this study, we examine within‐individual song changes in the Java sparrow Lonchura oryzivora, with the aim of shedding light on the relationship between song and long‐term life history. Specifically, we compared song length, tempo, and song complexity measures between the point just after song crystallization and around 1 yr later, and also compared those traits between fathers and sons to clarify the effect of vocal learning. While it is not surprising that song complexity did not differ depending on age or between fathers and sons, we found that song length and tempo increased with age. Follow‐up analyses have revealed that frequency bandwidth and peak frequency of song notes also elevated with age. Our results show that song performance related to motor skills can be improved even after song crystallization. We also suggest that song performance in closed‐ended vocal learners gives a reliable clue for mate choice by reflecting male quality with aging.
      PubDate: 2014-06-02T04:50:21.615686-05:
      DOI: 10.1111/jav.00383
  • South temperate birds have higher apparent adult survival than tropical
           birds in Africa
    • Authors: Penn Lloyd; Fitsum Abadi, Res Altwegg, Thomas E. Martin
      Abstract: Life history theory predicts an inverse relationship between annual adult survival and fecundity. Globally, clutch size shows a latitudinal gradient among birds, with south temperate species laying smaller clutches than north temperate species, but larger clutches than tropical species. Tropical birds often have higher adult survival than north temperate birds associated with their smaller clutches. However, the prediction that tropical birds should also have higher adult survival than south temperate birds because of smaller clutch sizes remains largely untested. We measured clutch size and apparent annual breeding adult survival for 17 south temperate African species to test two main predictions. First, we found strong support for a predicted inverse relationship between adult survival and clutch size among the south temperate species, consistent with life‐history theory. Second, we compared our clutch size and survival estimates with published estimates for congeneric tropical African species to test the prediction of larger clutch size and lower adult survival among south temperate than related tropical species. We found that south‐temperate species laid larger clutches, as predicted, but had higher, rather than lower, apparent adult survival than related tropical species. The latter result may be an artefact of different approaches to measuring survival, but the results suggest that adult survival is generally high in the south temperate region and raises questions about the importance of the cost of reproduction to adult survival.
      PubDate: 2014-05-09T08:26:52.447612-05:
      DOI: 10.1111/jav.00454
  • Effect of photoperiod on incubation period in a wild passerine, Sylvia
    • Authors: Suzanne H. Austin; Michaela Hau, W. Douglas Robinson
      Abstract: Time required for avian embryos to develop is influenced by incubation temperature and the amount of time adults incubate eggs. Experiments on poultry indicate that photoacceleration, the light‐induced stimulation of embryonic development, decreases the length of the incubation period as embryos receive more light. We hypothesized that eggs of wild birds exposed to longer periods of light should also have shorter incubation periods. We tested whether photoacceleration would occur in a species of open‐cup nesting passerine, the blackcap Sylvia atricapilla. We artificially incubated blackcap eggs under four different photoperiods, four hours of light (4L) and 20 h of dark (20D), 12L:12D, 20L:4D, and a skeleton photoperiod (1 h light, 2 times per day) that framed a 20 h day. While incubation periods were accelerated with increasing photoperiod length, the differences among photoperiods of 4, 12 and 20L were weak. Embryos exposed to skeleton photoperiods developed as fast as those exposed to 20L and significantly faster than those exposed to 4L and 12L treatments. Skeleton photoperiods may most closely approximate natural patterns of light exposure that embryos experience during dawn and dusk incubation recesses typically associated with adult foraging. If our results from this species also occur in other wild birds, exposure to different day lengths may help explain some of the variation in the observed seasonal and latitudinal trends in avian incubation period.
      PubDate: 2014-05-09T08:26:10.566162-05:
      DOI: 10.1111/jav.00046
  • Extra‐pair paternity in relation to breeding synchrony in ground
           tits: an individual‐based approach
    • Authors: Chen Wang; Xin Lu
      Abstract: Previous studies thought that at the within‐population level, whether a female bird engages in extra‐pair (EP) mating depends on how synchronous she is in breeding time with all other females around her, presumably the synchronization might affect the female's opportunities to meet potential EP sires who socially pair with these other females. However, when females or males are choosy about EP partners and mate with one EP individual only, the probability of EP mating may be most influenced by breeding synchrony between the EP partners. In such a case, the ‘individual‐level’ synchrony should act to determine EP mating success. We test this idea in a socially monogamous passerine, the ground tit Parus humilis. Fifty‐five out of 172 sampled females produced 122 EP offspring, each mating with one EP sire in most cases (92%), usually her intermediately‐related kin. As expected, the broader‐scale synchrony did not predict the probability of EP paternity but the individual‐level did, for females having EP offspring bred more synchronously with their EP than with their nearest neighbors, and females without EP offspring were least synchronous with their nearest neighbors. We argue that this kind of individual‐based approaches will shine light on the synchrony‐EP mating relationship in birds.
      PubDate: 2014-05-09T08:25:41.177146-05:
      DOI: 10.1111/jav.00318
  • Foraging strategy of the little auk Alle alle throughout breeding season
           – switch from unimodal to bimodal pattern
    • Authors: Dariusz Jakubas; Katarzyna Wojczulanis-Jakubas, Lech Iliszko, Mirosław Darecki, Lech Stempniewicz
      Abstract: Energy and time allocation differs between incubation and chick‐rearing periods, which may lead to an adjustment in the foraging behaviour of parent birds. Here, we investigated the foraging behaviour of a small alcid, the little auk Alle alle during incubation and compared it with the chick‐rearing period in West Spitsbergen, using the miniature GPS (in Hornsund) and temperature loggers (in Magdalenefjorden). GPS‐tracking of 11 individuals revealed that during incubation little auks foraged 8–55 (median 46) km from the colony covering 19–239 (median 120) km during one foraging trip. Distance from the colony to foraging areas was similar during incubation and chick‐rearing period. During incubation 89% of foraging positions were located in the zone over shallower parts of the shelf (isobaths up to 200–300 m) with sea surface temperature below 2.5°C. Those environmental conditions are preferred by Arctic zooplankton community. Thus, little auks in the Hornsund area restrict their foraging (both during the incubation and chick‐rearing period) to the area under influence of cold, Arctic‐origin water masses where its most preferred prey, copepod Calanus glacialis is most abundant. The temperature logger data (from 4 individuals) indicate that in contrast to the chick‐rearing period, when parent birds alternated short and long trips, during the incubation they performed only long trips. Adopting such a flexible foraging strategy allows little auks to alter their foraging strategy to meet different energy and time demands during the two main stages of the breeding.
      PubDate: 2014-05-09T08:25:36.760143-05:
      DOI: 10.1111/jav.00303
  • Spring phenology and timing of breeding in short‐distance migrant
           birds: phenotypic responses and offspring recruitment patterns in common
    • Authors: Robert G. Clark; Hannu Pöysä, Pentti Runko, Antti Paasivaara
      Abstract: Understanding how organisms adjust breeding dates to exploit resources that affect fitness can provide insights into impacts of climate change on avian demography. For instance, mismatches have been reported in long‐distance migrant bird species when environmental cues experienced during spring migration are decoupled from conditions on breeding grounds. Short‐distance migrant bird species that store reproductive nutrients prior to breeding may avoid or buffer adverse phenological effects. Furthermore, reduced short‐term reproductive success could be offset by higher future recruitment of surviving offspring. We evaluated whether recruitment of locally‐hatched female offspring was related to hatching date alone or strength of mismatched breeding date for 405 individually‐marked adult female common goldeneyes Bucephala clangula (a short‐distance migrant) and their ducklings from a site in central Finland where ice‐out date has advanced by ˜ 2 weeks over 24 yr. Path analyses revealed that older, early‐nesting females with good body condition and larger broods recruited the most female offspring. Offspring recruitment decreased strongly among females that bred late relative to other females in the population each year; the extent of mismatched breeding date, i.e. hatching date scaled to annual ice‐out date, was less influential. Overall, most females advanced breeding dates when ice‐out occurred earlier in spring, but some females exhibited greater flexibility in response to ice‐out conditions than did others. In general, directional selection favoured early breeding over a wide range of ice‐out dates. Our results seem most consistent with a hypothesis that some short‐distance migrant species like goldeneyes have the capacity to track and respond appropriately to changing environmental conditions prior to onset of breeding.
      PubDate: 2014-05-06T10:35:23.850049-05:
      DOI: 10.1111/jav.00290
  • Costs of rearing and sex‐ratio variation in southern grey shrike
           Lanius meridionalis broods
    • Authors: Gregorio Moreno-Rueda; Francisco Campos, Francisco Gutiérrez-Corchero, M.-Ángeles Hernández
      Abstract: Several non‐mutually exclusive hypotheses predict adaptive variation in the offspring sex ratio. When conditions for breeding are adverse, parents are predicted to produce more offspring of the less costly sex to rear (‘the cost‐of‐reproduction hypothesis’). Moreover, they also should produce the more dispersing sex in order to diminish future competition (‘the local‐resource‐competition hypothesis’). Here, we analyse brood sex ratio according to rearing conditions in the southern shrike Lanius meridionalis, a species with moderately reversed sexual dimorphism. Our results suggest that females are more costly to rear than males in this species. Adult females proved heavier than males, and female nestling tended to be heavier than male nestlings. Moreover, the greater brood reduction, the more male‐biased was the brood, suggesting that brood reduction implied higher mortality in female nestlings. Consistent with these findings, the brood sex ratio was biased to the less costly sex (males) when breeding conditions were adverse (bad years or low‐quality male parents), supporting the cost‐of‐reproduction hypothesis. By contrast, these findings did not support the local‐resource‐competition hypothesis, which predicted female‐biased brood sex ratio under adverse conditions. As a whole, our results support the idea that birds adaptively modulate sex ratio in order to minimize reproduction costs.
      PubDate: 2014-04-28T09:54:59.249766-05:
      DOI: 10.1111/jav.00367
  • Maternal dietary carotenoids mitigate detrimental effects of maternal GnRH
           on offspring immune function in Japanese quail Coturnix japonica
    • Authors: Susana I. Peluc; Wendy L. Reed, Penelope Gibbs, Kevin J. McGraw
      Abstract: Maternal resources deposited in eggs can affect the development of several offspring phenotypic traits and result in trade‐offs among them. For example, maternal androgens in eggs may be beneficial to offspring growth and competitive ability, but detrimental to immunocompetence and oxidative stress. In contrast, maternal antioxidants in eggs may be beneficial if they mitigate oxidative stress and immunosuppressive effects of androgens. We investigated possible interactive effects of maternal steroids and carotenoids on aspects of offspring physiology and phenotype, by simultaneously manipulating levels of androgens (via gonadotropin‐releasing hormone, GnRH‐challenges) and carotenoids (via diet supplementation) in captive female Japanese quail Coturnix japonica during egg laying. Carotenoid supplementation of hens, which elevates yolk concentrations of carotenoid and vitamins A and E, enhanced egg hatching success, offspring survival to age 15 d, and size of the bursa of Fabricius in offspring. In contrast, repeated maternal GnRH challenges, which elevated yolk testosterone concentrations, enhanced offspring neonatal size, but negatively affected bursa size. However, interaction among the treatments suggests that the positive effect of maternal carotenoid supplementation on plasma bactericidal capacity was mediated by maternal GnRH challenges. Chicks originating from carotenoid‐supplemented hens were less immunosuppressed than those originating from carotenoid‐supplemented + GnRH‐challenged hens, which were less immunosuppressed than chicks from GnRH‐challenged females not supplemented with carotenoids. Females availability of carotenoid enriched diets allows them to enhance the development of offspring immune system via carotenoids and vitamins deposited in egg yolks and offset detrimental effects of androgens deposited by GnRH‐challenged females.
      PubDate: 2014-04-10T05:40:19.188353-05:
      DOI: 10.1111/jav.00360
  • Colony attendance and at‐sea distribution of thin‐billed
           prions during the early breeding season
    • Authors: Petra Quillfeldt; Richard A. Phillips, Melanie Marx, Juan F. Masello
      Abstract: Procellariiform seabirds have extreme life histories; they are very long‐lived, first breed when relatively old, lay single egg clutches, both incubation and chick‐rearing are prolonged and chicks exhibit slow growth. The early part of the breeding season is crucial, when pair bonds are re‐established and partners coordinate their breeding duties, but is a difficult period to study in burrow‐nesting species. Miniature geolocators (Global Location Sensors or GLS loggers) now offer a way to collect data on burrow attendance, as well as determine at‐sea movements. We studied the early breeding season in thin‐billed prions Pachyptila belcheri breeding at New Island, Falkland Islands. Males and females arrived back at the colony at similar times, with peak arrival in the last days of September. However, males spent more time on land during the pre‐laying period, presumably defending and maintaining the burrow and maximising mating opportunities. Males departed later than females, and carried out a significantly shorter pre‐laying exodus. Males took on the first long incubation shift, whereas females returned to sea soon after egg laying. During the pre‐laying exodus and incubation, males and females travelled at similar speeds (> 250 km d−1) and were widely distributed over large areas of the Patagonian Shelf. Inter‐annual differences in oceanographic conditions were stronger during the incubation than during the pre‐laying exodus and were matched by stronger differences in distribution. The study thus suggests that extended trips and flexible distribution enable thin‐billed prions to meet the high energy demands of egg production and incubation despite low productivity in waters around the colony during the early summer.
      PubDate: 2014-04-10T05:38:32.818254-05:
      DOI: 10.1111/jav.00307
  • Inland flights of young red‐eyed vireos Vireo olivaceus in relation
           to survival and habitat in a coastal stopover landscape
    • Authors: Bradley K. Woodworth; Charles M. Francis, Philip D. Taylor
      Abstract: Inland dispersal of migrating land birds away from the coast, often opposite to the direction of migration, occurs frequently. Many of these movements may involve migrants seeking improved stopover conditions farther inland, but direct study of inland flights and of the ecological factors influencing their occurrence is limited. We used an automated telemetry array and ground‐tracking to assess flight behaviours, survival, and habitat use of young red‐eyed vireos Vireo olivaceus during fall migration at a coastal island and an inland stopover site in southwest Nova Scotia. We recorded inland flights for 41% (11/27) of individuals that departed the island. At least 25% of 16 individuals tagged at the inland site also relocated within the landscape prior to continuing migration, but due to the higher proportion of ambiguous flights at the inland site (44%) compared to the island (15%), we could not be sure if actual proportions of relocations differed between sites. Mortality on the island (at least 10 of 39 individuals) was significantly higher than at the inland site (0 of 16 individuals). At mainland sites near the coast where we found 6 of 11 individuals after they relocated away from the island, mortality remained high (2/6). Lack of deciduous canopy cover may have contributed to the high mortality on the island, but coastal mainland sites had a relatively high amount of deciduous canopy cover, similar to at the inland site where there was no mortality. Although coastal stopover sites may be important for migrating songbirds, especially before or after making a large water crossing, our results show that mortality can be much higher, and habitat poorer, at the coast compared to farther inland. Therefore, relocating inland may be an adaptive strategy for individuals that initially settle at the coast and that need to rest and refuel before they continue migration.
      PubDate: 2014-04-09T07:11:26.454179-05:
      DOI: 10.1111/jav.00276
  • Age‐dependent dispersal and habitat choice in black‐tailed
           godwits Limosa limosa limosa across a mosaic of traditional and modern
           grassland habitats
    • Authors: Rosemarie Kentie; Christiaan Both, Jos C. E. W. Hooijmeijer, Theunis Piersma
      Abstract: Whether to disperse, and where to, are two of the most prominent decisions in an individual's life, with major consequences for reproductive success. We studied natal and breeding dispersal in the monogamous black‐tailed godwit Limosa limosa limosa in the Netherlands, where they breed in agricultural grasslands. The majority of these grasslands recently changed from wet herb‐rich meadows into well‐drained grassland monocultures, on which godwits have a lower reproductive success. Here we examine habitat selection with a multistate mark–recapture analysis. Habitat transition probabilities between meadows and monocultures were estimated on the basis of 1810 marked chicks and 531 adults during seven years in a 8500 ha study area. Young and adult godwits may differ in habitat selection because: 1) adults may have gained experience from previous nest success where to settle, 2) younger individuals may find it harder to compete for the best territories. Both young and adults moved at a higher rate from the predominant monocultures to meadows than the other way around, thus actively selecting the habitat with better quality. However, dispersal distance of adults was not affected by previous nest success. The average dispersal distance from place of birth of godwits breeding for the first time was ten times larger than that of adult godwits. That godwits breeding in their second calendar year arrived and laid at similar dates and were equally able to select territories in areas with high breeding densities, suggests that young birds were not competitively inferior to adults. Although on monocultures reproduction is insufficient to maintain constant populations, birds sometimes moved from meadows to monocultures. This explains why even after 30 years of land‐use intensification, godwits still breed in low‐quality habitat. The adjustment to changing habitat conditions at the population level appears to be a slow process.
      PubDate: 2014-04-09T07:11:24.102258-05:
      DOI: 10.1111/jav.00273
  • Regional and seasonal flight speeds of soaring migrants and the role of
           weather conditions at hourly and daily scales
    • Abstract: Given that soaring birds travel faster with supportive winds or in good thermal soaring conditions, we expect weather conditions en route of migration to explain commonly observed regional and seasonal patterns in the performance of soaring migrants. We used GPS‐loggers to track 13 honey buzzards and four Montagu's harriers for two to six migrations each. We determined how tailwinds, crosswinds, boundary layer height (a proxy for thermal convection) and precipitation affected hourly speeds, daily distances and daily mean speeds with linear regression models. Honey buzzards mostly travel by soaring while Montagu's harriers supplement soaring with flapping. Therefore, we expect that performance of harriers will be less affected by weather than for buzzards. Weather conditions explained between 30 and 50% of variation in migration performance of both species. Tailwind had the largest effect on hourly speeds, daily mean speeds and daily travel distances. Honey buzzards travelled significantly faster and farther, and Montagu's harriers non‐significantly faster, under better convective conditions. Honey buzzards travelled at slower speeds and shorter distances in crosswinds, whereas harriers maintained high speeds in crosswinds. Weather conditions varied between regions and seasons, and this variation accounted for nearly all regional and seasonal variation in flight performance. Hourly performance was higher than predicted at times when we suspect birds had switched to intermittent or continuous flapping flight, for example during sea‐crossings. The daily travel distance of Montagu's harriers was determined to a significant extent by their daily travel time, which differed between regions, possibly also due to weather conditions. We conclude with the implications of our work for studies on migration phenology and we suggest an important role for high‐resolution telemetry in understanding migratory behavior across entire migratory journeys.
  • Effects of experimental tail shortening on the phenotypic condition of
           barn swallows Hirundo rustica: implications for tail‐length
    • Abstract: Some studies have suggested that tail streamers in the barn swallow Hirundo rustica may have been elongated 10–12 mm by sexual selection, but according to other studies, the length of these feathers is at the aerodynamic optimum or very close to it. To shed light on this issue, outermost tail feathers were experimentally shortened in male and female barn swallows by 1, 11 or 21 mm. Changes in four physiological parameters commonly used to estimate phenotypic condition in birds (weight, erythrocyte sedimentation rate, blood leukocyte concentration and heterophil/lymphocyte ratio) were checked one month later. Health improved (blood leukocyte concentration decreased) in the group of birds with tails shortened by 11 mm (both males and females), but body condition deteriorated (weight decreased) compared to the other two experimental groups. There was no significant effect of tail‐length manipulation on the other two physiological parameters. These contradictory results suggest trade‐offs between components of phenotypic condition. Possible negative relationships between condition‐related traits imply that using one or very few physiological parameters to estimate phenotypic condition might not be appropriate. The most plausible explanation for the turning point in phenotypic condition when streamers were shortened by 11 mm is that these feathers are 7–15 mm longer than the aerodynamic optimum in both sexes. Therefore, our results are consistent with the hypothesis that tail streamers have been elongated 10–12 mm by sexual selection. This conclusion disagrees with a previous study on the effect of experimental tail shortening on haematocrit, but the complexity of interpreting changes in haematocrit might account for this discrepancy.
  • Snake predation on North American bird nests: culprits, patterns and
           future directions
    • Abstract: Predation is the leading cause of nest failure for most birds. Thus, for ornithologists interested in the causes and consequences of variation in nest success, knowing the identity and understanding the behavior of dominant nest predators is likely to be important. Video documentation of nests has shown that snakes are frequent predators. Here we reviewed 53 North American studies that used nest cameras and used these data to identify broad patterns in snake predation. Snakes accounted for 26% (range: 0–90%) of recorded predation events, with values exceeding 35% in a third of studies. Snakes were more frequent nest predators at lower latitudes and less frequent in forested habitat relative to other nest predators. Although 12 species of snakes have been identified as nest predators, ratsnakes Elaphe obsoleta, corn snakes E. guttata and fox snakes E. vulpina were the most frequent, accounting for > 70% of all recorded nest predation events by snakes and have been documented preying on nests in 30–65% of studies conducted within their geographic ranges. Endotherm‐specialist snakes (Elaphe and Pituophis genera) were more likely to depredate nests in forests and the canopy relative to other snakes, due to their affinity for edge habitat. Predation by only ratsnakes and corn snakes was predominantly nocturnal and only ratsnakes were more likely to prey on nests during the nestling stage. Snakes were not identified to species in over 30% of predation events, underlining the need for more complete reporting of results. A review of research to date suggests the best approach to investigating factors that bring snakes and nests into contact involves combining nesting studies with radio tracking of locally important snake nest predators.
  • Density‐dependent effects on nesting success of
           temperate‐breeding Canada geese
    • Abstract: Density‐dependent effects on reproduction can arise through variation in habitat quality or increased competition and interference among neighbours. Negative effects have been found in avian populations and these have been mainly attributed to food limitations. In this study, we investigated whether density‐dependent effects could result from either heterogeneity in habitat suitability, interference among neighbours, or predation. To test these hypotheses, we collected data over eight years in a growing population of temperate‐nesting Canada geese Branta canadensis maxima. We compared different parameters of nesting success of geese between two sites characterized by different nest densities and looked at the effects of nest proximity on these parameters within each site. At the landscape level, we found density‐dependent effects due to variation in habitat quality associated with predation probabilities and flooding events. At a finer scale, nesting success declined with proximity to neighbours, probably due to increased aggressive interactions among pairs. However, complete clutch predation showed both positive and negative density‐dependence, due to differences in predator community at each site. We concluded that density‐dependent effects reduced nesting success of Canada geese through both heterogeneity in habitat safety and agonistic interference between neighbours but that density‐dependent effects could also be positive in some instances.
  • Foraging movements of Leach's storm‐petrels Oceanodroma leucorhoa
           during incubation
    • Abstract: Knowledge of foraging movements during the breeding season is key to understanding energetic stresses faced by seabirds. Using archival light loggers (geolocators), a Bayesian state–space model, and stable isotope analysis, we compared foraging movements of Leach's storm‐petrels Oceanodroma leucorhoa during their incubation periods in 2012 and 2013. Data were collected from two colonies, Bon Portage Island and Country Island, which are 380 km apart along the coast of Nova Scotia, Canada. Based on allometry for procellariiform mass, predicted foraging ranges for Leach's storm‐petrels are 200 km; however, observed maximum distances from the colony were 3 to 5 times that. Storm‐petrels from Country Island travelled 1015 ± 238 km southeast to the Laurentian fan and south of the Grand Banks whereas storm‐petrels from Bon Portage Island travelled 613 ± 167 km southeast, beyond the continental slope, east of Georges Bank. The average distance travelled in a return trip was 2287 ± 603 km and 1303 ± 351 km for Country Island and Bon Portage Island, respectively. There were no differences between years in cumulative distances travelled within islands, but foraging trips did not last as long in 2013 (4.7 ± 1.5 d) as they did in 2012 (6.2 ± 2.1 d). Stable isotope analyses indicated that, during the incubation period, prey items from Country Island were from higher trophic levels and possibly had higher energy content than those from Bon Portage Island, perhaps explaining the more distant and longer foraging trips for Country Island birds.
  • The role of territory settlement, individual quality, and nesting
           initiation on productivity of Bell's vireos Vireo bellii bellii
    • Abstract: Variation in habitat quality among territories within a heterogeneous patch should influence reproductive success of territory owners. Further, territory settlement order following an ideal despotic distribution (IDD) should predict the fitness of occupants if territory selection is adaptive. We recorded settlement order and monitored nests in territories occupied by individually marked Bell's vireos Vireo bellii bellii across a range of shrubland habitats in central Missouri, USA. We used an information theoretic approach to evaluate multiple hypotheses regarding the relationship between territory settlement order and seasonal territory productivity (productivity), which we define as the number of young fledged from all nest attempts in a territory. Territory settlement order and arrival date were not analogous and later arriving males displaced early settlers in 13 of 49 territories. Settlement order and lay date together were the best predictors of a territory's productivity; productivity decreased 2.08 young from earliest to latest settlement rank and lay date. Males that defended the same territory in successive years occupied territories with earlier settlement dates, but we found little evidence that age or prior ownership influenced productivity. Territory selection by male Bell's vireos was adaptive because males preferred to settle in territories that had high seasonal offspring production, but even though settlement rank was linked to territory quality, high productivity was only realized on high quality territory when also linked to early nest initiation date. While settlement rank was related to territory quality, obtaining a high quality territory had to be combined with early nest initiation to maximize productivity. We found support for the IDD hypothesis because the highest quality territories, (i.e. most productive), were settled earlier. Research that identifies high quality habitat by linking individual fitness with habitat characteristics may elucidate the importance of habitat quality, individual experience and temporal factors to productivity of Bell's vireos.
  • Temporal and environmental influences on the vocal behaviour of a
           nocturnal bird
    • Abstract: Temporal and environmental variation in vocal activity can provide information on avian behaviour and call function not available to short‐term experimental studies. Inter‐sexual differences in this variation can provide insight into selection effects. Yet factors influencing vocal behaviour have not been assessed in many birds, even those monitored by acoustic methods. This applies to the New Zealand kiwi (Apterygidae), for which call censuses are used extensively in conservation monitoring, yet which have poorly understood acoustic ecology. We investigated little spotted kiwi Apteryx owenii vocal behaviour over 3 yr, measuring influences on vocal activity in both sexes from time of night, season, weather conditions and lunar cycle. We tested hypotheses that call rate variation reflects call function, foraging efficiency, historic predation risk and variability in sound transmission, and that there are inter‐sexual differences in call function. Significant seasonal variation showed that vocalisations were important in kiwi reproduction, and inter‐sexual synchronisation of call rates indicated that contact, pair‐bonding or resource defence were key functions. All weather variables significantly affected call rates, with elevated calling during increased humidity and ground moisture indicating a relation between vocal activity and foraging conditions. A significant decrease in calling activity on cloudy nights, combined with no moonlight effect, suggests an impact of light pollution in this species. These influences on vocal activity provide insight into kiwi call function, have direct consequences for conservation monitoring of kiwi, and have wider implications in understanding vocal behaviour in a range of nocturnal birds.
  • Temporal patterns of avian body size reflect linear size responses to
           broadscale environmental change over the last 50 years
    • Abstract: Alongside well researched shifts in species' distributions and phenology, reduction in the body size of organisms has been suggested as a third universal response to contemporary climate change. Despite mounting evidence for declining body size, several recent reviews highlight studies reporting increases in body size or no change over time. This variability in response may derive from the geographic scale of contributing studies, masking species‐level responses to broad‐scale environmental change and instead reflecting local influences on single populations. Using museum specimens, we examine temporal patterns of body size of 24 Australian passerine species, sampling multiple populations across the geographic ranges of each species between 1960 and 2007. Generalised additive models indictated that the majority (67%) of species showed important inter‐annual body size variation, and there was striking cross‐species similarity in temporal size patterns. Most displayed near‐linear or linear, unidirectional size trends, suggesting a pervasive and directional change in environmental conditions, consistent with climate change. For species showing linear size responses, the absolute rate of size change ranged between 0.016 and 0.114% of body size (wing length) per year, consistent with studies on other continents. Overall, 38% (9/24) of species showed temporal declines in body size and 21% (5/24) showed increases, consistent with the variability and direction of size responses thus far documented among populations; declining body size is a pervasive response to climate change but it is not universal.
  • Nutritional stress affects corticosterone deposition in feathers of
           Caspian tern chicks
    • Abstract: Stressful environmental conditions affect the adrenocortical function of developing animals, which can have consequences for their fitness. Discovery of the avian stress hormone corticosterone (CORT) in feathers has the potential to broaden the application of endocrine research in ecological and evolutionary studies of wild birds by providing a long‐term measure of CORT secretion. Mechanisms of CORT deposition in feathers are not well known and few studies have related feather CORT to circulating plasma CORT during feather growth. Our objective was to experimentally test the validity of using feather CORT as a measure of CORT secretion in developing birds experiencing nutritional stress. Caspian tern Hydroprogne caspia chicks were fed ad libitum or restricted (35% less than ad libitum) diets for four weeks. We measured CORT in feathers from these chicks to examine the relationship between feather CORT concentrations and nutritional limitation, circulating plasma CORT, and feather development. We found that feather CORT was higher in controls fed ad libitum than in restricted individuals, despite higher levels of plasma CORT in restricted chicks compared to controls. Feather mass and growth rates were strongly and positively related to feather CORT concentrations in both treatments. This is the first experimental study to show that feather CORT concentrations can be lower in response to nutritional stress, even when plasma CORT concentrations are elevated. Our results indicate that CORT deposition in feathers may be confounded when feather mass and growth rates are compromised by nutritional stress. We conclude that feather CORT can be used for assessing nutritional stress in growing birds, but the direction of response depends on how strongly stress affects feather development.
  • Variation in adrenocortical stress physiology and condition metrics within
           a heterogeneous urban environment in the song sparrow Melospiza melodia
    • Abstract: In urban habitats, organisms face unique fitness challenges including disturbance from human activity and noise. One physiological mechanism that may be plastically or evolutionarily modified to ameliorate deleterious effects of anthropogenic disturbance is the adrenocortical stress response. Individuals in urban environments may display smaller stress responses, which may prevent pathologies associated with consistent elevation of stress hormones, and may also show differences in baseline corticosterone (CORT, the primary avian stress hormone), due to altered energetic demands or chronic stress. We examined whether stress physiology and condition metrics in male song sparrows Melospiza melodia vary as a function of discrete differences in anthropogenic disturbance level (activity centers and refuges) or with continuous variation in an urbanization score and noise environment. Males breeding in activity centers displayed lower maximal (acute) CORT levels than activity refuge males, and acute CORT also tended to negatively correlate with urbanization score. Baseline CORT did not differ between habitat types, and activity center males also showed no evidence of changes in body mass, hematocrit, or antioxidant capacity. Further, activity center males had higher quality feathers (indicative of higher condition at molt) than activity refuge males. We found no indication that the noise environment altered stress physiology or condition in song sparrows. Overall, results suggest that song sparrows are an urban adapter species, which are not detrimentally affected by unique selective pressures encountered in the urban environment.
  • Seasonal patterns of vocal mimicry in northern mockingbirds Mimus
    • Abstract: Many aspects of birdsong vary seasonally, but we know almost nothing about seasonal variation in vocal mimicry, a conspicuous feature of the songs of 15–20% of bird species. I sampled spontaneous song from nine, free‐living, male northern mockingbirds Mimus polyglottos four times during the calendar year – three times during the breeding season, and once during the non‐breeding season. Results showed that mockingbirds did not mimic summer migrants significantly more during any sampling period. Results also showed significant differences across sampling periods in the frequency, but not diversity, of mimicry. Frequency of mimicry was highest in late spring (61.3%) and lowest during the non‐breeding season (48.3%), suggesting mimicry might play a role in reproductive stimulation of multiple‐brooded females. Because mockingbirds mimicked summer migrants throughout the year, regardless of whether migrants were present, mimicry is unlikely to facilitate interspecies communication. Seasonal patterns also suggest that females might be attracted to a high frequency of mimicry, but not to a high diversity of mimicry. I argue that observational studies of seasonal variation in additional mimics could provide key insights into the functional role of vocal mimicry.
  • Comparative reproductive biology of sympatric species: nest and chick
           survival of American avocets and black‐necked stilts
    • Abstract: Identifying differences in reproductive success rates of closely related and sympatrically breeding species can be useful for understanding limitations to population growth. We simultaneously examined the reproductive ecology of American avocets Recurvirostra americana and black‐necked stilts Himantopus mexicanus using 1274 monitored nests and 240 radio‐marked chicks in San Francisco Bay, California. Although there were 1.8 times more avocet nests than stilt nests, stilts nonetheless fledged 3.3 times more chicks. Greater production by stilts than avocets was the result of greater chick survival from hatching to fledging (avocet: 6%; stilt: 40%), and not because of differences in clutch size (avocet: 3.84; stilt: 3.77), nest survival (avocet: 44%; stilt: 35%), or egg hatching success (avocet: 90%; stilt: 92%). We reviewed the literature and confirmed that nest survival and hatching success are generally similar when avocets and stilts breed sympatrically. In addition to species, chick survival was strongly influenced by age, site, and year. In particular, daily survival rates increased rapidly with chick age, with 70% of mortalities occurring ≤ 1 week after hatch. California gulls Larus californicus caused 55% of avocet, but only 15% of stilt, chick deaths. Differential use of micro‐habitats likely reduced stilt chick's vulnerability to gull predation, particularly during the first week after hatch, because stilts nested in vegetation 2.7 times more often than avocets and vegetation height was 65% taller at stilt nests compared with avocet nests. Our results demonstrate that two co‐occurring and closely related species with similar life history strategies can differ markedly in reproductive success, and simultaneous studies of such species can identify differences that limit productivity.
  • Laying‐sequence variation in yolk carotenoids and egg
           characteristics in the red‐winged blackbird Agelaius phoeniceus
    • Abstract: In many bird species with asynchronous hatching, smaller, later‐hatched nestlings are out‐competed for food by their larger, earlier‐hatched siblings and therefore suffer increased mortality via starvation. It is thought that female birds can either maintain or reduce the survival disadvantage of later‐hatched nestlings by differentially allocating maternal resources across the eggs of a clutch. Carotenoid pigments are an example of resources that female birds allocate differentially when producing a clutch, but laying sequence patterns for these pigments remain poorly studied in North American songbirds. We examined intraclutch variation in yolk carotenoids and egg metrics in 27 full clutches of red‐winged blackbird Agelaius phoeniceus eggs collected from eight wetlands in central Alberta, Canada. We predicted that carotenoids would decrease across the laying sequence, as in this species, later‐hatched, marginal nestlings suffer greater mortality than earlier‐hatched, core nestlings. We found nine carotenoid pigments in red‐winged blackbird egg yolks, including two that have never been described from avian yolks: α‐doradexanthin and adonirubin. As predicted, concentrations and amounts of most carotenoids decreased across the laying sequence, suggesting that female red‐winged blackbirds depleted their carotenoid resources as they laid more eggs. However, egg mass and yolk mass both increased across the laying sequence, suggesting that female red‐winged blackbirds may use other maternal resources to compensate for the size and survival disadvantage experienced by later‐hatched, marginal nestlings.
  • Body‐mass‐dependent trade‐off between immune response
           and uropygial gland size in house sparrows Passer domesticus
    • Abstract: Parasites greatly impact host fitness. The immune system is fundamental to combat endoparasites, and survival increases with greater investment in immunity. Some ectoparasites, by contrast, are reportedly combated by the use of the uropygial gland, an organ exclusive to birds, which secretes an oily substance (preen oil) that is spread on plumage. However, both mounting an immune response against a parasite and producing uropygial gland secretion depend on the same resources, a situation which may induce trade‐offs between the two antiparasitic functions. In this study, I experimentally test whether immune response is traded off against uropygial gland size in the house sparrow Passer domesticus. In the experiment, a group of sparrows were injected with an antigen (lipopolysaccharide, LPS), which stimulates the immune system, while the other group received a sham injection. The uropygial gland of LPS‐treated birds decreased significantly more than that of the control birds after treatment. Nevertheless, the effect of the treatment was limited to house sparrows with low body mass, suggesting that heavy house sparrows were able to produce an immune response while maintaining a relatively large uropygial gland. Given that uropygial gland size is strongly related to production of preen oil, these results suggest that preen oil production declines in birds in poor body condition when resources are preferentially diverted to other demanding functions, such as the immune system. Considering that the uropygial gland is involved in several fitness‐related processes in birds, the trade‐off between immune response and uropygial gland size may have important consequences for bird life histories.
  • Equal reproductive success of phenotypes in the Larus
           glaucescens–occidentalis complex
    • Abstract: Glaucous‐winged gulls Larus glaucescens and western gulls L. occidentalis hybridize extensively where their ranges overlap along the coasts of Washington and Oregon, producing a continuum of phenotypic intergrades between the two parental species. This zone often is considered an example of geographically bounded hybrid superiority, but studies of relative success among parental types and hybrids have not provided consistent support for this model. We tested the predictions of the dynamic‐equilibrium and geographically bounded hybrid superiority hypotheses by studying mate choice and reproductive success among gulls on Protection Island, Washington, the largest breeding colony of glaucous‐winged/western gulls within the hybrid zone. The dynamic‐equilibrium hypothesis posits that hybridization due to dispersal balances selection against less fit hybrids and assortative mating is adaptive. Geographically bounded hybrid superiority posits that hybrids are better fit than parental types within an ecotone between the environments to which the parental species are adapted, and a preference for hybrid mates is adaptive. Additionally, we investigated whether hatching success and nest site choice are correlated for Protection Island gulls. We assigned a hybrid index to each sample bird by examining plumage melanism and bare part coloration in the field. Sheltered nests contained larger clutches and exhibited increased hatching success, but choice of nest habitat was not associated with hybrid index. Western gull‐like pairs produced smaller third eggs; however, hybrid index was not correlated with clutch size or hatching success. Protection Island gulls did exhibit assortative mating. In short, we did not find strong support for either geographically bounded hybrid superiority or the dynamic‐equilibrium hypothesis.
  • Why water birds forage at night: a test using black‐tailed godwits
           Limosa limosa during migratory periods
    • Abstract: Many migratory water birds are known to feed both during day and night outside the breeding season, but the underlying factors and mechanisms determining this foraging pattern are poorly understood. We addressed this topic by comparing both diurnal and nocturnal foraging activity (FA) and metabolizable energy intake rate (MEIR) in migrating black‐tailed godwits Limosa limosa staging in two different habitats, rice fields and coastal salt pans. Black‐tailed godwits staging in rice fields during pre‐breeding migration fed on rice seeds, and only foraged during the daylight period (FA: 81.89 ± 3.03%; MEIR: 1.15 ± 0.03 kJ · min−1). Daily energy consumption (DEC) of godwits relying on seeds was enough to meet the theoretical daily energy expenditure (DEE). In contrast, black‐tailed godwits staging in salt pans during post‐breeding migration fed on chironomid larvae, and they foraged during both daylight (FA: 67.36 ± 4.30%; MEIR: 0.27 ± 0.01 kJ · min−1) and darkness (FA: 69.89 ± 6.89%; MEIR: 0.26 ± 0.00 kJ · min−1). Nocturnal energy intake contributed 31.7% to DEC, the latter being insufficient to fully meet DEE. Our findings give empirical support to the view that diurnal foraging is the norm in many migratory water birds outside the breeding season, and nocturnal foraging occurs when the daily energy requirements are not met during the daylight period, supporting the supplementary food hypothesis.
  • Diverse avian malaria and other haemosporidian parasites in Andean house
           wrens: evidence for regional co‐diversification by
    • Abstract: Recent research has revealed well over 1000 mtDNA lineages of avian haemosporidian parasites, but the extent to which this diversity is caused by host–parasite coevolutionary history or environmental heterogeneity is unclear. We surveyed haemosporidian and host mtDNA in a geographically structured, ecological generalist species, the house wren Troglodytes aedon, across the complex landscape of the Peruvian Andes. We detected deep genetic structure within the house wren across its range, represented by seven clades that were between 3.4–5.7% divergent. From muscle and liver tissue of 140 sampled house wrens we found 23 divergent evolutionary lineages of haemosporidian mtDNA, of which ten were novel and apparently specific to the house wren based on searches of haemosporidian databases. Combined and genus‐specific haemosporidian abundance differed significantly across environments and elevation, with Leucocytozoon parasites strongly associated with montane habitats. We observed spatial stratification of haemosporidians along the west slope of the Andes where five lineages were restricted to non‐overlapping elevational bands. Individual haemosporidian lineages varied widely with respect to host specificity, prevalence, and geographic distribution, with the most host‐generalist lineages also being the most prevalent and widely distributed. Despite the deep divergences within the house wren, we found no evidence for host‐specific co‐diversification with haemosporidians. Instead, host‐specific haemosporidian lineages in the genus Haemoproteus were polyphyletic with respect to the New World parasite fauna and appeared to have diversified by periodic host‐switches involving distantly related avian species within the same region. These host‐specific lineages appeared to have diversified contemporaneously with Andean house wrens. Taken together, these findings suggest a model of diffuse co‐diversification in which host and parasite clades have diversified over the same time period and in the same geographic area, but with parasites having limited or ephemeral host specificity.
  • Lower survival probability of house sparrows severely infected by the
           gapeworm parasite
    • Abstract: The effect of parasites in natural populations has received increasing attention in recent years. Studies have shown that parasites may play an important part in population ecology due to their potential effects on host fitness. The main purpose of the present study was to investigate the effect of a nematode parasite (gapeworm, Syngamus trachea) on survival probability of house sparrows Passer domesticus from six natural populations located on 4 islands in the Helgeland archipelago in northern Norway. Infection status was obtained from feces samples collected from 603 house sparrows in the summer and autumn of 2007–2011. We also collected data on a visible symptom of severe infection (gasping for air) in 1391 house sparrows in the summer and autumn 2004–2011. We took advantage of recent advances in disease modeling in a multi‐event capture–mark–recapture framework to account for imperfect observations (state uncertainty). Each dataset was separately analyzed, in both analyses we investigated the relationships of year, island, individual body condition, age class and population density with survival probabilities. The relationship between infection (determined by feces egg counts) on annual survival of house sparrows was not statistically significant. However, the probability of annual survival was found to be significantly lower for adult house sparrows exhibiting a symptom of severe gapeworm infection, gasping for air. The present study demonstrates that severe infection by a parasite can have a negative relationship with survival probability of short‐lived avian hosts in wild populations.
  • The mucous covering of fecal sacs prevents birds from infection with
           enteric bacteria
    • Abstract: Nestlings of many bird species produce fecal sacs, excrements encapsulated within a mucous covering. Although it facilitates parents' removal of feces from nests, which would improve hygienic conditions for developing nestlings, no functional (i.e. adaptive) explanation of fecal sac production has been previously investigated. We propose that the mucous covering would isolate enteric pathogenic bacteria, thereby preventing contamination of nestlings and parents. This antimicrobial hypothesis therefore predicts that density of bacteria would be drastically reduced from the inside to the outside of nestlings' droppings, and that the fecal sac covering would inhibit other bacterial grow. We tested these predictions by means of culturing bacteria obtained from different parts of the sac and inhibition tests. In accordance with the hypothesis, bacterial loads of the outside of fecal sacs were significantly lower than those estimated from the inside of the covering. In addition, we did not find evidence of antimicrobial activity of the covering, which suggests that the hypothesized bacterial isolation function is accomplished by a physical rather than a chemical protection. Bacterial density of the liquid that permeates out after 23 min does not differ with that estimated for the inside of the sac, suggesting short‐term effects of fecal sacs as bacterial barrier. These findings highlight the major role of bacterial infections as a selective pressure for explaining the evolution of traits that, as the covering of fecal sacs, facilitate nest sanitation in this group of animals.
  • Song‐based species discrimination in a rapid Neotropical radiation
           of grassland seedeaters
    • Abstract: Acoustic signals among newly diverged taxa have the potential to convey species identity, information that is key to reducing hybridization. Capuchino seedeaters constitute a remarkable example of recently radiated endemic species from the grasslands of South America. They are sexually dimorphic and show striking differences in male plumage coloration and song. Contrasting with this divergence in phenotype most species show extremely low neutral genetic differentiation and lack of reciprocal monophyly, which is interpreted to be a product of recent common ancestry and hybridization. Here we use field‐based playback experiments to test for the first time if males of two species, Sporophila hypoxantha and S. palustris, discriminate between conspecific and heterospecific song. Using various measures of behavior we find that both species react more strongly to their own songs. The response to playback from another southern capuchino cannot be differentiated from that of a control song from a more distantly related Sporophila species. Additionally, we did not find evidence for reinforcement as the response of S. hypoxantha did not differ between individuals that co‐occur with S. palustris and those that do not. Our finding suggests that song, a culturally inherited trait, may help maintain reproductive isolation between species in the rapid and explosive capuchino radiation.
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