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Tuesday, 15 July 2014

Looking for light through a flock to keep flock stable. 'Role of projection in the control of bird flocks.' PNAS July 7, 2014

PNAS July 7, 2014

Role of projection in the control of bird flocks

Daniel J. G. Pearce, a, b
Adam M. Miller, a, c
George Rowlands, a
Matthew S. Turner, a,c,d

Author Affiliations:
Departments of 
a: Physics and b: Chemistry and c: Centre for Complexity Science,
 University of Warwick, Coventry CV4 7AL, United Kingdom; 

d: Laboratoire Physico-Chimie Théorique, Gulliver, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7083, Ecole Supérieure de Physique et de Chimie Industrielles, 75231 Paris Cedex 05, France

PubMed ID25002501

We propose a new model for long-range information exchange in bird flocks based on the projected view of each individual out through the flock. Visual input is coarse grained to a pattern of (dark) bird against (light) sky. We propose the simplest hybrid projection model that combines metric-free coalignment, and noise, with this projected view; here the birds fly toward the resolved vector sum of all the domain boundaries. This model leads to robustly coherent flocks that self-assemble to a state of marginal opacity. It therefore provides a mechanism for the control of density. Although it involves only two primary control parameters, it also gives rise to several distinct phenotypes. We compare our predictions with experimental data.

Swarming is a conspicuous behavioral trait observed in bird flocks, fish shoals, insect swarms, and mammal herds. It is thought to improve collective awareness and offer protection from predators. Many current models involve the hypothesis that information coordinating motion is exchanged among neighbors. We argue that such local interactions alone are insufficient to explain the organization of large flocks of birds and that the mechanism for the exchange of long-range information necessary to control their density remains unknown. We show that large flocks self-organize to the maximum density at which a typical individual still can see out of the flock in many directions. Such flocks are marginally opaque—an external observer also still can see a substantial fraction of sky through the flock. Although this seems intuitive, we show it need not be the case; flocks might easily be highly diffuse or entirely opaque. The emergence of marginal opacity strongly constrains how individuals interact with one another within large swarms. It also provides a mechanism for global interactions: an individual can respond to the projection of the flock that it sees. This provides for faster information transfer and hence rapid flock dynamics, another advantage over local models. From a behavioral perspective, it optimizes the information available to each bird while maintaining the protection of a dense, coherent flock.

Starling murmurations represent one of the most impressive examples of organization in the natural world, with flocks of up to 300,000 individuals or more able to coordinate themselves into a cohesive and highly coherent group. Although the primary source of sensory information to a bird is visual, it would be unrealistic to expect that individual to recognize and track the position and orientation of a significant proportion of the other members of a flock. Indeed, observations on real starling flocks show that a bird responds to this type of information only from its seven nearest neighbors and that these interactions are scale-free. Local interactions such as this are enough to create order within a flock but do not give any information on the state of the flock as a whole, nor do they explain how density might be regulated. Most models use attraction and repulsion interactions, use a fictitious potential field, or simply fix the available volume to control the density.
To make progress, we first ask a simple question: “What does a bird actually see when it is part of a large flock?” Its view out from within a large flock likely would present the vast majority of individuals merely as silhouettes, moving too fast and at too great a distance to be tracked easily or even discriminated from one another. Here the basic visual input to each individual is assumed to be based simply on visual contrast: a dynamic pattern of dark (bird) and light (sky) across the field of vision (although it might be possible to extend this to other swarming species and environmental backgrounds, respectively). This has the appealing feature that it also is the projection that appears on the retina of the bird, which we assume to be its primary sensory input.
A typical individual within a very dense flock would see other,
overlapping individuals (dark) almost everywhere it looked. Conversely, an isolated individual, detached from the flock, would see only sky (light). The projected view gives direct information on the global state of the flock. It is a lower-dimensional projection of the full 6N degrees of freedom of the flock and therefore is more computationally manageable, both for the birds themselves and for the construction of simple mathematical models of swarm behavior.
The information required to specify the projection mathematically is linear in the number of boundaries. Our simplifying assumption is that the individual registers only such a black-and-white projection (in addition to nearest-neighbor orientation). This information, then, is all that would be available to an agent, regardless of the behavioral model that might be chosen. Individuals in a flock that is sparse enough for them to typically see a complex projected pattern of dark and light have more information about the global state of the flock. Such sparse flocks also allow an individual to see out in a significant fraction of all directions, which would allow the approach of a predator, or at least the response of distant individuals to the approach of a predator, to be registered. Conversely, a dense, completely opaque flock would offer little information about either the global state of the flock or the approach of predators.
In the remainder of this article, we focus on proposing a model for how bird flocks organize and specifically on how the global density is regulated, which remains an open question. We develop what we believe to be the simplest possible model that takes the projected view described above as sensory input while retaining coalignment with (visible) nearest neighbors and allowing for some noise. We then compare the swarms generated by this model with data.

Figure 3
(A) A snapshot of a flock of starlings (image contributes to the data presented in B–D; see also Movies S7 and S8). (B) Typical time variation of the opacity Θ′ of starling flocks observed in dim light (black) and under brighter conditions (red). (C) Cross-correlation function of the horizontal acceleration a of the center of mass of a flock and its opacity C(δt) as a function of the delay δt. (D) Histogram of the opacity Θ′ of different Starling flocks from across the United Kingdom, corresponding to n = 118 uncorrelated measurements. The red line displays a Gaussian distribution fitted to this data with μ = 0.30, σ2 =
0.059. (E) The opacity Θ′ of images of starling flocks in the public domain (μ = 0.41, σ2 = 0.012). In both D and E, the null hypothesis that the opacities are drawn from a uniform distribution on [X,1] can be rejected at the 99.99% confidence level for all values of X. These flocks are all marginally opaque. See SI Appendix for details throughout.

We believe opacity may be related to evolutionary fitness in flocking animals. Dense swarms are thought to give an advantage against predation due to target degeneracy, in which the predator has difficulty distinguishing individual targets (22). Balancing this is the need for the individuals to be aware of the predator so as to execute evasion. In flocks with very high opacity, only a very small fraction of all individuals would be able to see out of the flock and monitor either the first or subsequent approaches of the predator. Individuals in the interior of such a flock could neither see the predator directly nor respond to the behavior of individuals near the edge that were able to see it. Information about the approaches of a predator instead would have to propagate inward, being passed from (the behavior of) neighbor to neighbor, i.e., very much slower than the speed of light, which instead would operate on a clear line of sight. The state of marginal opacity therefore would seem to balance the benefit of compactness (target degeneracy) with information [“many eyes”]. In particular, very little information would be gained by decreasing the opacity beyond a marginal state. Thus, projection-based models that give rise to marginally opaque states would seem to be both cognitively plausible and evolutionarily fit.

Monday, 14 July 2014

The Auk, July 2014 : Volume 131, Issue 3. Contents and Abstracts

The Auk

Published by: The American Ornithologists' Union

Table of Contents

July 2014 : Volume 131 Issue 3


Winter body condition in the Collared Flycatcher: Determinants and carryover effects on future breeding parameters 
Rita Hargitai, Gergely Hegyi, Márton Herényi, Miklós Laczi, Gergely Nagy, Balázs Rosivall, Eszter Szöllősi, and János Török
pg(s) 257–264
Factors that determine the condition of migratory birds at their wintering sites are poorly known. Age, sex, and morphological characteristics of birds may have an influence on their winter condition by affecting their foraging and competitive abilities. Winter body condition could have long-term consequences on the reproductive success of migratory birds during the subsequent breeding season. Using 3 yr of data from Collared Flycatchers (Ficedula albicollis), we examined the characteristics of winter-grown tail feathers, as indicators of winter body condition, in relation to sex, age, morphological traits, and future breeding variables. Tail feather mass was highly repeatable between years, but feather growth rate was not repeatable, which suggests that the latter trait mainly indicates environmental circumstances during molt, whereas feather mass may more strongly reflect genetic effects. Tail feathers of males and adults showed better quality than those of females and juveniles, possibly because of differences between age classes and sexes in individual quality and foraging skills or because of winter habitat segregation. Birds with longer wings produced better-quality tail feathers, which suggests that wing and tail feather characteristics are similarly affected, presumably by individual genetic quality. Smaller Collared Flycatchers grew their tail feathers faster during the winter molt, possibly because they had better foraging ability due to better flight maneuverability. Tail feather quality showed no relationship with laying date; however, females that had produced heavier tail feathers during winter laid larger clutches during the following breeding season, which suggests that tail feather mass potentially reflects intrinsic individual quality.

On the “real estate market”: Individual quality and the foraging ecology of male Cory's Shearwaters 
Antje Chiu Werner, Vitor H. Paiva, and Jaime A. Ramos
pg(s) 265–274
An extended reproductive period and high variability in food resource availability at sea make good quality nest sites particularly important for the survival of pelagic seabird chicks. Despite high philopatry during the early pre-laying period, males compete strongly for nests, making this period a unique opportunity to independently assess the influence of nest-site characteristics and individual quality on the foraging behavior of Cory's Shearwater (Calonectris diomedeaborealis) individuals. We found significant differences in the at-sea foraging behavior of males and females at temporal (trip duration) and spatial (foraging areas, trip distance, and trip sinuosity) scales, both of which are greater in females. Furthermore, we suggest that nests of higher quality are deeper and closer to the nest of a conspecific neighbor because both variables were associated with males foraging closer to the colony. Finally, we showed that during the early pre-laying period the influence exerted by nests on males' behavior at sea is independent from the individual's quality. Our study links nest-site features with the at-sea behavior of pelagic male seabirds during a period of nest competition and suggests that nest-site characteristics are important to explain foraging patterns of central-place foraging birds.
Carotenoid coloration predicts escape performance in the House Finch (Haemorhous mexicanus
Fernando Mateos-Gonzalez, Geoffrey Hill, and Wendy Hood
pg(s) 275–281
Carotenoid coloration has been repeatedly shown to serve as a sexually selected signal of individual quality. Across different species, individuals showing brighter carotenoid-based signals have been found to have superior foraging abilities, to recover faster from diseases and, in general, to enjoy a better body condition. Experiments with birds have also shown that carotenoid supplementation can enhance flight performance, allowing birds to take off faster from the ground. Healthy, agile individuals should be better prepared to avoid predators, so it could be expected that individuals displaying brighter carotenoid-based coloration would show a higher escape ability from predator attacks. To test this prediction, we measured the escape ability of male House Finches (Haemorhous mexicanus) from a human with a net in a large aviary and related the escape ability of each individual to its breast coloration. Males with redder feathers showed a higher individual ability to escape than duller individuals. The superior flight performance of redder birds would be an important asset in escape from predators, as well as when foraging or maintaining a territory. In the specific case of the House Finch, the higher escape ability of redder individuals could be the reason for their higher overwinter survival rate.


Type specimens in modern ornithology are necessary and irreplaceable 
A. Townsend Peterson
pg(s) 282–286
Recent years have seen a series of new species descriptions in which no type specimen or fragmentary type specimen material was provided as documentation. These descriptions have been controversial, but the Code of Zoological Nomenclature makes clear that such nondiagnostic types are not acceptable specimen documentation. A more appropriate approach is documentation of the discovery, but without formal naming of the species, until suitable specimen documentation can be assembled.


Previous success and current body condition determine breeding propensity in Lesser Scaup: evidence for the individual heterogeneity hypothesis 
Jeffrey M. Warren, Kyle A. Cutting, John Y. Takekawa, Susan E. De La Cruz, Tony D. Williams, and David N. Koons
pg(s) 287–297
The decision to breed influences an individual's current and future reproduction, and the proportion of individuals that breed is an important determinant of population dynamics. Age, experience, individual quality, and environmental conditions have all been demonstrated to influence breeding propensity. To elucidate which of these factors exerts the greatest influence on breeding propensity in a temperate waterfowl, we studied female Lesser Scaup (Aythya affinis) breeding in southwestern Montana. Females were captured during the breeding seasons of 2007–2009, and breeding status was determined on the basis of (1) presence of an egg in the oviduct or (2) blood plasma vitellogenin (VTG) levels. Presence on the study site in the previous year, a proxy for adult female success, was determined with stable isotope signatures of a primary feather collected at capture. Overall, 57% of females had evidence of breeding at the time of capture; this increased to 86% for females captured on or after peak nest initiation. Capture date and size-adjusted body condition positively influenced breeding propensity, with a declining body-condition threshold through the breeding season. We did not detect an influence of age on breeding propensity. Drought conditions negatively affected breeding propensity, reducing the proportion of breeding females to 0.85 (SE = 0.05) from 0.94 (SE = 0.03) during normal-water years. A female that was present in the previous breeding season was 5% more likely to breed than a female that was not present then. The positive correlation between age and experience makes it difficult to differentiate the roles of age, experience, and individual quality in reproductive success in vertebrates. Our results indicate that individual quality, as expressed by previous success and current body condition, may be among the most important determinants of breeding propensity in female Lesser Scaup, providing further support for the individual heterogeneity hypothesis.
Genetic and morphometric diversity in the Lark Sparrow (Chondestes grammacus) suggest discontinuous clinal variation across major breeding regions associated with previously characterized subspecies  
Jeremy D. Ross and Juan L. Bouzat
pg(s) 298–313
Quantifiable geographic variation in DNA or morphology is often used to gauge past and present levels of population interchange and has thus helped define taxonomic boundaries, resolve evolutionary histories, and develop effective conservation strategies to preserve evolutionary diversity. We examined rangewide patterns of genetic (mtDNA and microsatellites) and morphological diversity within the Lark Sparrow (Chondestes grammacus), focusing on diversity patterns across potentially independent Western, Central, and Eastern USA regional breeding zones. Phylogenetic analysis of mtDNA sequences did not support phylogeographic patterns associated with previously characterized subspecies, though the presence of regionally specific clades suggests incipient evolutionary diversification. Regional differentiation was evidenced by significant differences in morphological traits, significant levels of genetic differentiation, reduced estimates of migration among regions, and the characterization of 2 distinct populations through Bayesian clustering. Morphometric and genetic variation distinguished Western Lark Sparrow populations historically characterized as subspecies C. g. actitus from conspecifics across a secondary cline. By contrast, regional variation between Central and Eastern populations, encompassing subspecies C. g. strigatus and C. g. grammacus, was less pronounced and was consistent with a primary cline across the American Great Plains. Our results indicate that clinal variation among populations of long-distance migratory birds may reflect incipient evolutionary divergence, secondary contact zones, and local adaptation of populations to continuously variable environments.
Do nestling Tree Swallows (Tachycineta bicolor) respond to parental alarm calls? 
Emma McIntyre, Andrew G. Horn, and Marty L. Leonard
pg(s) 314–320
Nestling birds use a conspicuous begging display, which includes loud begging calls, to solicit food from their parents. Although these calls are important in communicating offspring need, predators can use begging calls to locate nests. Parents may, however, counteract nestling vulnerability by giving alarm calls to silence calling nestlings when predators are nearby. This defense has been observed in grass- and reed-nesting species, whose nestlings beg to vibrational cues of a parent's arrival, even in the absence of the parents. It is considered less likely to occur, however, in cavity-nesting species, because the rigid substrate of the nest does not provide vibrational cues, and nestlings instead wait for a parental food call before begging. Cavity-nesting Tree Swallows (Tachycineta bicolor) use food calls to solicit begging, which suggests that parental alarm calls are not required to silence them. Older nestling Tree Swallows, however, beg in the absence of their parents, which suggests that responding to parental alarm calls with silence might be adaptive after all, at least at older ages. The goal of our study was to determine whether nestling Tree Swallows alter their begging behavior in response to parental alarm calls and, if so, whether this response varies with age. We found that older nestlings (15 days posthatch) reduced calling and crouched in the nest in response to playback of parental alarm calls, unlike younger nestlings (5 and 10 days posthatch). Our results suggest that parent Tree Swallows might reduce predation risk caused by calling nestlings, especially older nestlings, by giving alarm calls when predators are near their nests. Counter to our prediction, nestlings of cavity-nesting species may indeed respond to alarm calls, particularly if they beg in the absence of parents.


A call for the preservation of images, recordings, and other data in association with avian genetic samples, and the introduction of a solution: OMBIRDS 
Ildiko Szabo, Grant Hurley, Stephanie Cavaghan, and Darren E. Irwin
pg(s) 321–326
Much current and historical research in ornithology employs catch-and-release methods, resulting in a variety of data and materials from birds for which whole-body specimens have not been collected. Often, a genetic specimen (e.g., blood or feathers) is collected along with “media specimens” such as images and/or sound recordings, providing a rich source of research material as well as an opportunity to use each type of specimen as a source of validation of the other. Despite the abundance of these datasets and their potential use in future research, the preservation of such data and associated materials is currently a task that each researcher must confront individually, which results in the loss of these research materials over time. To promote the long-term utility of information collected from the thousands of birds that are captured and released each year, we present a protocol and database template (OMBIRDS; the Online Museum of Bird Images, Recordings, and DNA Samples) for organizing and preserving images, recordings, and data associated with genetic samples. This protocol can be used by individual researchers and institutions to organize their own collections, and it also facilitates submission of records to international data repositories such as VertNet. By contributing OMBIRDS to the research community as a free database tool that can be downloaded and adapted by researchers and institutions, we hope to encourage the collection of media along with genetic samples and to facilitate the archiving of these materials for their use in future research.


Peripheral androgen action helps modulate vocal production in a suboscine passerine 
Matthew J. Fuxjager, Jonathan B. Heston, and Barney A. Schlinger
pg(s) 327–334
Androgenic activation of intracellular androgen receptors (AR) influences avian vocal production, though this has largely been investigated at the level of the brain. We investigated the influence of predominantly peripheral AR on vocal output in wild Golden-collared Manakins (Manacus vitellinus). In this suboscine species, males court females by performing acrobatic displays and by producing relatively simple chee-poo vocalizations. To assess whether peripheral AR influences the acoustic structure of these vocal signals, we treated reproductively active adult males with the peripherally selective antiandrogen bicalutamide and then measured phonation performance. Inhibiting AR outside of the central nervous system increased the duration of the chee note and decreased the fundamental frequency of the poo note. This treatment caused no discernable change to chee-poo frequency modulation or entropy. Our results show that activation of peripheral AR mediates note-specific changes to temporal and pitch characteristics of the Golden-collared Manakin's main sexual call. Thus, our study provides one of the first demonstrations that androgenic action originating outside of the brain and likely on musculoskeletal targets can modulate avian vocal production.
A falconid from the Late Miocene of northwestern China yields further evidence of transition in Late Neogene steppe communities 
Zhiheng Li, Zhonghe Zhou, Tao Deng, Qiang Li, and Julia A. Clarke
pg(s) 335–350
Although the family Falconidae, which includes extant falcons and caracaras, has a long evolutionary history, most previously reported fossils referred to this family are isolated single elements. We report a new species, Falco hezhengensis sp. nov., represented by a nearly complete and articulated skeleton from the Late Miocene deposits of Linxia Basin in northwestern China. The new fossil shares an array of derived morphologies with the genus Falco, and analysis of the largest morphological dataset for Falconidae, sampling most genera, identifies the specimen as a new stem kestrel. The phylogeny shows a high degree of congruence with published molecular phylogenies and time trees supporting a Miocene radiation of Falconidae. The species provides a new calibration for the divergence of extant kestrels from other Falco. Remains of a small mammal, a jerboa (Dipodidae), are preserved in the abdominal region of the specimen. Integrated with data from other avian remains from the Linxia Basin, the new fossil provides further support for changes in the open steppe environment of Central Asia since the Late Miocene. Changes in falconid ecology and diet, shifts in small-mammal abundances, as well as the extinction of the Central Asian ostrich may be involved in community turnover in the Late Neogene.
Influence of climate on annual survival of Barn Swallows (Hirundo rustica) breeding in North America 
Belén García-Pérez, Keith A. Hobson, Gretchen Albrecht, Michael D. Cadman, and Antonio Salvadori
pg(s) 351–362
Population dynamics of migratory birds are influenced by both local weather and larger-scale patterns in climate that can operate at various stages of their annual cycle. We investigated correlations between (1) annual climatic indices and weather during the breeding season and (2) the annual survival of Barn Swallows (Hirundo rustica) breeding at 2 sites in North America. Mark–recapture data collected during a 10-yr period for each of the 2 colonies in eastern and western North America were analyzed to model annual survival probabilities. Annual survival rates of Barn Swallows breeding in Seattle, Washington, USA, were higher in years preceded by El Niño Southern Oscillation (ENSO) winters and higher in years with more positive North Atlantic Oscillation (NAO) values. ENSO was expected to primarily influence wintering conditions through rainfall amount, and NAO was expected to influence climate on the breeding grounds; thus, climatic conditions on both breeding and wintering grounds likely affected the survival of these Seattle-breeding birds. By contrast, annual survival of swallows breeding in southern Ontario, Canada, remained constant over time and were not affected by any of the climatic parameters studied, which suggests that NAO did not have a strong effect on climatic conditions there and/or that these birds winter in regions where ENSO is not strongly correlated with local weather conditions. Alternatively, there may be less geographic variation in wintering-ground locations for Barn Swallows breeding in Seattle, resulting in stronger ENSO effects on survival for the Seattle population. Our results demonstrate how correlations between climate patterns on wintering grounds and annual survival can provide information on migratory connectivity at continental scales and underline the importance of local weather conditions throughout the annual cycle on survivorship and population dynamics of aerial insectivorous birds.
Can wheatears weather the Atlantic? Modeling nonstop trans-Atlantic flights of a small migratory songbird 
Marc Bulte, James D. McLaren, Franz Bairlein, Willem Bouten, Heiko Schmaljohann, and Judy Shamoun-Baranes
pg(s) 363–370
Oceans represent extreme ecological barriers for land birds. Yet the Northern Wheatear (Oenanthe oenanthe leucorhoa), a 25-g songbird, negotiates the North Atlantic Ocean twice yearly between Canadian natal and sub-Saharan wintering grounds. Each autumn, these migrants appear to have 2 options: (1) a detour via Greenland, Iceland, and/or Europe to reduce the extent of open-ocean flights or (2) an astonishing nonstop flight of 4,000–5,000 km without resting opportunities between eastern Canada and northwestern Africa. We assessed the feasibility and reliability of nonstop trans-Atlantic migration of Northern Wheatears from Canada to Africa using an individual-based model incorporating flight costs and autumnal wind data from 1979 to 2011. Prevalent wind conditions were supportive of nonstop migration, especially at high altitudes and when winds at departure were favorable. For modeled individuals with high fuel loads, flying at altitudes of ∼3,000 m, successful nonstop trans-Atlantic flights reached Africa on 62% of departure days. On 24% of unsuccessful departure days, individuals could have first stopped in Europe before continuing to Africa. Durations of successful flights varied between 31 and 68 hr, with significantly shorter flights after mid-September. It remains unclear whether natural selection might favor nonstop ocean crossings by O. o. leucorhoa between North America and Africa, but we conclude that reliably supportive winds en route and potentially huge time savings render it a feasible migration strategy.


Searching for consensus in molt terminology 11 years after Howell et al.'s “first basic problem” 
Jared D. Wolfe, Erik I. Johnson, and Ryan S. Terrill
pg(s) 371–377
Howell et al. (2003) published an innovative augmentation to terminology proposed by Humphrey and Parkes (1959) that classified bird molt on the basis of perceived evolutionary relationships. Despite apparent universal applicability, Howell et al.'s (2003) proposed terminological changes were met with criticism that cited a failure to verify the evolutionary relationships of molt and an inability to recognize homologous molts even within closely related taxa. Eleven years after Howell et al. (2003), we revisit arguments against a terminological system of molt based on evolutionary relationships, suggest an analytical framework to satisfactorily respond to critics, clarify terminology, and consider how to study molt variation within an evolutionary framework.


No evidence of food limitation during the breeding season of a freshwater marsh-nesting tern 
David A. Shealer
pg(s) 378–387
Food availability is considered an important limiting factor in the breeding performance of marine birds, which exhibit restraint in reproductive life-history characteristics (e.g., delayed maturation, small clutch size, slow growth). Less well understood, however, is the extent to which taxonomic analogue species that breed in freshwater habitats are similarly regulated by food availability. Marsh-nesting Forster's Terns (Sterna forsteri) were studied from 2004 to 2008 at Horicon Marsh, a freshwater colony site in Wisconsin, USA, where reproductive success has been chronically poor. The adequacy of the food base to support a breeding colony of terns was evaluated (1) indirectly, through measures of breeding performance correlated with food availability during the egg-laying and incubation stages; and (2) directly, through a supplemental feeding experiment, conducted in 2004 and 2006, to determine whether nestling growth was limited by food availability. Clutch size, egg size, and adult body condition did not differ significantly among years, despite considerable annual fluctuation in environmental conditions and the rapid and extensive colonization of the wetland complex during the study period by a potential food competitor, American White Pelican (Pelecanus erythrorhynchos). Growth rates of chicks were ∼10% higher, on average, in 2006 than in 2004, but no difference was found in mean daily growth rates between food-supplemented and control chicks, nor did chick growth differ according to hatching order in the brood or hatching date. These results suggest that food availability is not a limiting factor during the breeding season for Forster's Terns at Horicon Marsh, the only actively managed breeding site remaining for this species in Wisconsin.
Offspring sex ratio varies according to nest location within a colony of Great Cormorants 
Piotr Minias, Katarzyna Wojczulanis-Jakubas, and Krzysztof Kaczmarek
pg(s) 388–395
Offspring sex ratio in birds is adjusted according to the relative fitness payoff of producing sons and daughters, which is known to depend on parental quality. Therefore, spatial patterns in offspring sex ratio should be consistent with the distribution of pair quality within avian colonies. In many colonial birds, central parts of colonies provide greater safety against predators and thus are occupied by high-quality pairs, who relegate conspecifics of poorer quality to the peripheral zones of colonies. For this reason, we expected that offspring sex ratio was likely to follow similar central–periphery gradients. This hypothesis was tested in a colony of tree-nesting Great Cormorants (Phalacorcorax carbo sinensis) in central Poland, where 204 nestlings from 53 broods were molecularly sexed. We found a clear central–periphery pattern in offspring sex ratio within the studied colony. There was a considerable bias toward male offspring in the broods of centrally nesting pairs, while edge pairs invested more in female progeny. We also found that broods with a higher proportion of male offspring were associated with higher nesting densities. A nonrandom distribution of offspring sex ratio within the studied colony of Great Cormorants indicates that special care should be taken by researchers to randomize sampling of broods when studying sex allocation in colonial species.
Compensatory growth in nestling Zebra Finches impacts body composition but not adaptive immune function 
Tess L. Killpack, Dan Nan Tie, and William H. Karasov
pg(s) 396–406
Compensatory strategies have evolved in birds to minimize the effects of poor rearing conditions on future survival and fitness. Undernourished nestlings may accelerate growth and/or development relative to age, termed compensatory growth, to achieve normal asymptotic size at the same time as well-fed chicks. While compensatory growth allows birds to fledge at a suitable size and time, it may have persistent detrimental effects on the development of complex body systems. Our study examined compensatory growth following short-term food restriction of caged groups of Zebra Finches (Taeniopygia guttata; adult breeding pair and their brood) during the nestling period, and tested for postrestriction effects on tissue maturity (indexed by body tissue water content) and adaptive immune function. Food restriction reduced nestling body mass, tarsus, and culmen growth. Rapid compensatory growth in body mass, but not in tarsus and culmen lengths, was observed upon return to ad libitum feeding of the food-restricted group. Nestlings that were raised in food-restricted treatment cages showed no significant difference in adaptive antibody response to a model antigen compared with those raised in control cages with ad libitum feeding. Reductions in tissue maturity were observed in nestlings that experienced food restriction, indicating a decoupling of chronological age and physiological age. These data provide evidence of capacity for rapid, compensatory body mass growth in nestling Zebra Finches, and suggest that the energetic costs of body growth and development are relatively larger than the costs of development of the humoral immune system.
Resource configuration and abundance affect space use of a cooperatively breeding resident bird 
Richard A. Stanton, Jr., Dylan C. Kesler, and Frank R. Thompson, III
pg(s) 407–420
Movement and space use of birds is driven by activities associated with acquiring and maintaining access to critical resources. Thus, the spatial configuration of resources within home ranges should influence bird movements, and resource values should be relative to their locations. We radio-tracked 22 Brown-headed Nuthatches (Sitta pusilla) and related their space use and home range sizes to available resources while taking nest site locations into account. We developed utilization distributions (UDs) from nuthatch locations, and treated the area of each 95% isopleth as home range size and the height of the UD as relative probability of use. We fit models relating home range size to mean resource measures within home ranges, and used lognormal regression to relate intensity of use to resource metrics at random points by ranking linear mixed models. Nuthatch home ranges typically had two centers of activity. Areas of high use were associated with the density of recently killed snags (likely a foraging resource), recent prescribed fire, pine dominance, low tree stocking rates, and grassy herbaceous cover. Home ranges were generally large (median: 7.1 ha; range: 0.3–47.6 ha), and smaller home range sizes were associated with pine dominance and higher nest snag density. Predicted home range sizes decreased by 77% and 69%, respectively, when percent pine and nest snag density were maximized. Our results illustrate that movement decisions within home ranges are driven by both the availability and spatial distribution of resources, while ongoing savannah-woodland management is providing resources that are used by Brown-headed Nuthatches.
Vocal distinctiveness of the Red Crossbill (Loxia curvirostra) on the island of Newfoundland, Canada 
Douglas P. Hynes and Edward H. Miller
pg(s) 421–433
Ten vocal types of Red Crossbill (Loxia curvirostra) are recognized in North America. Little is known about this species' vocalizations on the island of Newfoundland, where the subspecies L. c. percna (Bent 1912) was described on the basis of study skins collected in a single year from one area; subsequently a distinctive vocal type was proposed on the basis of one sound recording. We made field recordings (∼1000 min) of Red Crossbill vocalizations in Newfoundland to describe vocalizations and compare them with vocal types recognized elsewhere in North America. One class of call (“flight call”; class I call hereafter) was distinctive, and discriminant analysis distinguished 98% of Newfoundland class I calls from mainland North American and European samples. Class I calls of 5 (out of 83) Newfoundland birds resembled recognized vocal types from mainland North America. Other call classes (“excitement/alarm” and “chitter”) of Newfoundland birds also differed from mainland North American samples. We conclude that several vocal types of Red Crossbill, one of which may represent L. c. percna, occur in Newfoundland. Samples from other areas are needed to determine whether the distinctive vocal type in insular Newfoundland (a) represents L. c. percna and (b) is restricted to Newfoundland or also occurs in other areas such as Cape Breton Island.
Resource partitioning in three congeneric sympatrically breeding seabirds: Foraging areas and prey utilization 
G. S. Robertson, M. Bolton, W. J. Grecian, L. J. Wilson, W. Davies, and P. Monaghan
pg(s) 434–446
Morphologically similar sympatric species reduce competition by partitioning resources, for example by occupying different dietary niches or foraging in different areas. In this study, we examine the foraging behavior of Arctic (Sterna paradisaea), Common (Sterna hirundo), and Roseate terns (Sterna dougallii) breeding on Coquet Island, northeast England, using colony-based observations and coincident at-sea visual tracking of foraging birds to quantify interspecific overlap in prey selection and foraging areas. Although visual tracking methods have been used in previous studies, our study is the first example of this method being used to quantify multi-species overlap in foraging areas and the first time Roseate Tern foraging locations have been conclusively identified using a visual tracking method. Percentage overlap in foraging areas varied among species with Arctic and Common terns sharing a higher percentage of their foraging range with each other (63%) than either species did with Roseate Terns (Common = 41% and Arctic = 0%). Arctic and Common terns utilized similar foraging areas and partitioned resources by diet while Roseate Terns differed from other species in both diet and foraging area. Arctic and Common terns varied provisioning rate, prey length, and foraging areas with increasing brood age, while Roseate Terns fed similar prey and foraged consistently inshore. Although there were some similarities in areas utilized by these species, there were sufficient differences in behavior to minimize interspecific competition. Our study further demonstrates the successful use of a visual tracking method to show how morphologically similar sympatric seabird species partition resources by diet, foraging area, and response to increasing brood age.

Bird research this week on PubMed: July 2014 Week 2

PubMed listing for 'bird' OR 'songbird' excluding references to influenza and flu - July 2014 Week 2

1. J Environ Manage. 2014 Jul 8;144C:322-335. doi: 10.1016/j.jenvman.2014.05.036. [Epub ahead of print]

Metrics to assess ecological condition, change, and impacts in sandy beach ecosystems.

Schlacher TA1, Schoeman DS2, Jones AR3, Dugan JE4, Hubbard DM5, Defeo O6, Peterson CH7, Weston MA8, Maslo B9, Olds AD10, Scapini F11, Nel R12, Harris LR13, Lucrezi S14, Lastra M15, Huijbers CM16, Connolly RM17.Author information:
1School of Science and Engineering, The University of the Sunshine Coast, Q-4558 Maroochydore, Australia. Electronic address:
2School of Science and Engineering, The University of the Sunshine Coast, Q-4558 Maroochydore, Australia. Electronic address:
3Division of Invertebrates, The Australian Museum, Sydney, NSW 2010, Australia. Electronic address:
4Marine Science Institute, University of California, Santa Barbara, CA 93106-6150, USA. Electronic address:
5Marine Science Institute, University of California, Santa Barbara, CA 93106-6150, USA. Electronic address:
6UNDECIMAR, Facultad de Ciencias, Igua 4225, PO Box 10773, 11400 Montevideo, Uruguay. Electronic address:
7Institute of Marine Sciences, University of North Carolina, Chapel Hill, Morehead City, NC 28557, USA. Electronic address:
8Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Burwood, VIC 3125, Australia. Electronic address:
9Department of Ecology, Evolution and Natural Resources, Rutgers, The State University of New Jersey, 14 College Farm Road, New Brunswick, NJ 08901, USA. Electronic address:
10School of Science and Engineering, The University of the Sunshine Coast, Q-4558 Maroochydore, Australia. Electronic address:
11Department of Biology, University of Florence, via Romana 17, 50125 Firenze, Italy. Electronic address:
12Department of Zoology, Nelson Mandela Metropolitan University, Port Elizabeth, 6031, South Africa. Electronic address:
13Department of Zoology, Nelson Mandela Metropolitan University, Port Elizabeth, 6031, South Africa. Electronic address:
14TREES-Tourism Research in Economic Environs and Society, North-West University, Potchefstroom, South Africa. Electronic address:
15Department of Ecology and Animal Biology, Faculty of Marine Science, University of Vigo, 36310 Vigo, Spain. Electronic address:
16Australian Rivers Institute, Coast and Estuaries, and School of Environment, Gold Coast Campus, Griffith University, Queensland, 4222, Australia. Electronic address:
17Australian Rivers Institute, Coast and Estuaries, and School of Environment, Gold Coast Campus, Griffith University, Queensland, 4222, Australia. Electronic address:


Complexity is increasingly the hallmark in environmental management practices of sandy shorelines. This arises primarily from meeting growing public demands (e.g., real estate, recreation) whilst reconciling economic demands with expectations of coastal users who have modern conservation ethics. Ideally, shoreline management is underpinned by empirical data, but selecting ecologically-meaningful metrics to accurately measure the condition of systems, and the ecological effects of human activities, is a complex task. Here we construct a framework for metric selection, considering six categories of issues that authorities commonly address: erosion; habitat loss; recreation; fishing; pollution (litter and chemical contaminants); and wildlife conservation. Possible metrics were scored in terms of their ability to reflect environmental change, and against criteria that are widely used for judging the performance of ecological indicators (i.e., sensitivity, practicability, costs, and public appeal). From this analysis, four types of broadly applicable metrics that also performed very well against the indicator criteria emerged: 1.) traits of bird populations and assemblages (e.g., abundance, diversity, distributions, habitat use); 2.) breeding/reproductive performance sensu lato (especially relevant for birds and turtles nesting on beaches and in dunes, but equally applicable to invertebrates and plants); 3.) population parameters and distributions of vertebrates associated primarily with dunes and the supralittoral beach zone (traditionally focused on birds and turtles, but expandable to mammals); 4.) compound measurements of the abundance/cover/biomass of biota (plants, invertebrates, vertebrates) at both the population and assemblage level. Local constraints (i.e., the absence of birds in highly degraded urban settings or lack of dunes on bluff-backed beaches) and particular issues may require alternatives. Metrics - if selected and applied correctly - provide empirical evidence of environmental condition and change, but often do not reflect deeper environmental values per se. Yet, values remain poorly articulated for many beach systems; this calls for a comprehensive identification of environmental values and the development of targeted programs to conserve these values on sandy shorelines globally.
Copyright © 2014 Elsevier Ltd. All rights reserved.
PMID: 25014753 [PubMed - as supplied by publisher]
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2. Int J Parasitol. 2014 Jul 8. pii: S0020-7519(14)00146-5. doi: 10.1016/j.ijpara.2014.04.011. [Epub ahead of print]

Distribution, diversity and drivers of blood-borne parasite co-infections in Alaskan bird populations.

Oakgrove KS1, Harrigan RJ2, Loiseau C3, Guers S4, Seppi B5, Sehgal RN3.Author information:
1Department of Biology, San Francisco State University, 1600 Holloway Avenue, San Francisco, California, 94132, USA. Electronic address:
2Center for Tropical Research, Institute of the Environment and Sustainability, University of California, Los Angeles, California, 90095, USA.
3Department of Biology, San Francisco State University, 1600 Holloway Avenue, San Francisco, California, 94132, USA.
4Alaska Songbird Institute, PO Box 82035, Fairbanks, Alaska, 99708, USA.
5Bureau of Land Management, Anchorage Field Office, 4700 BLM Road, Anchorage, Alaska, 99507, USA.


Avian species are commonly infected by multiple parasites, however few studies have investigated the environmental determinants of the prevalence of co-infection over a large scale. Here we believe that we report the first, detailed ecological study of the prevalence, diversity and co-infections of four avian blood-borne parasite genera: Plasmodium spp., Haemoproteus spp., Leucocytozoon spp. and Trypanosoma spp. We collected blood samples from 47 resident and migratory bird species across a latitudinal gradient in Alaska. From the patterns observed at collection sites, random forest models were used to provide evidence of associations between bioclimatic conditions and the prevalence of parasite co-infection distribution. Molecular screening revealed a higher prevalence of haematozoa (53%) in Alaska than previously reported. Leucocytozoons had the highest diversity, prevalence and prevalence of co-infection. Leucocytozoon prevalence (35%) positively correlated with Trypanosoma prevalence (11%), negatively correlated with Haemoproteus prevalence (14%) and had no correlation with Plasmodium prevalence (7%). We found temperature, precipitation and tree cover to be the primary environmental drivers that show a relationship with the prevalence of co-infection. The results provide insight into the impacts of bioclimatic drivers on parasite ecology and intra-host interactions, and have implications for the study of infectious diseases in rapidly changing environments.
Copyright © 2014. Published by Elsevier Ltd.
PMID: 25014331 [PubMed - as supplied by publisher]
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3. J Ethnobiol Ethnomed. 2014 Jul 10;10(1):55. [Epub ahead of print]

Ethnotaxonomy of birds by the inhabitants of Pedra Branca Village, Santa Teresinha municipality, Bahia state, Brazil.

Galvagne Loss AT, Costa Neto EM, Machado CG, Flores FM.



Studies on popular names of birds help to understand the relationship between human beings and birds and it also contributes to the field of ornithology.


This study aims to register the ethnotaxonomy of birds in the village of Pedra Branca, Santa Teresinha municipality, Bahia State, Brazil, by cataloguing and identifying their popular names, besides understanding the ethnoclassification system of local bird species. The ethno-ornithological data were obtained by means of semi-structured open interviews, and projective tests.


We interviewed 48 residents and, in order to identify species, we chose five informants with a more detailed knowledge on local avifauna. We registered 139 common names, distributed into 108 ethnospecies and 33 synonyms, referring to 117 species. Nomenclatural criteria more frequently used were vocalization and coloring patterns. Following Berlin's principles of ethnobiological classification, three hierarchical levels were registered: life form, generic and specific, with three types of correspondence between Linnaean and folk classification systems. The bird life form ("passaro" in Portuguese) was associated only to wild species.


The ethno-ornithological research in Pedra Branca Village has contributed with new information on popular nomenclature of birds and their etymology, showing that folk knowledge on birds is conveyed within the community.
PMID: 25012812 [PubMed - as supplied by publisher]
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4. J Integr Neurosci. 2014 Apr;13(2):229-52. doi: 10.1142/S0219635214400093.

Quantum effects in the understanding of consciousness.

Hameroff SR1, Craddock TJ, Tuszynski JA.Author information:
1Center for Consciousness Studies, The University of Arizona, Tucson, Arizona 85721, USA.


This paper presents a historical perspective on the development and application of quantum physics methodology beyond physics, especially in biology and in the area of consciousness studies. Quantum physics provides a conceptual framework for the structural aspects of biological systems and processes via quantum chemistry. In recent years individual biological phenomena such as photosynthesis and bird navigation have been experimentally and theoretically analyzed using quantum methods building conceptual foundations for quantum biology. Since consciousness is attributed to human (and possibly animal) mind, quantum underpinnings of cognitive processes are a logical extension. Several proposals, especially the Orch OR hypothesis, have been put forth in an effort to introduce a scientific basis to the theory of consciousness. At the center of these approaches are microtubules as the substrate on which conscious processes in terms of quantum coherence and entanglement can be built. Additionally, Quantum Metabolism, quantum processes in ion channels and quantum effects in sensory stimulation are discussed in this connection. We discuss the challenges and merits related to quantum consciousness approaches as well as their potential extensions.
PMID: 25012711 [PubMed - in process]
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5. Ecotoxicology. 2014 Jul 11. [Epub ahead of print]

Breeding near a landfill may influence blood metals (Cd, Pb, Hg, Fe, Zn) and metalloids (Se, As) in white stork (Ciconia ciconia) nestlings.

de la Casa-Resino I1, Hernández-Moreno D, Castellano A, Pérez-López M, Soler F.Author information:
1Toxicology Unit, Animal Health Department, Faculty of Veterinary Medicine, University of Extremadura, Avda. de la Universidad s/n, 10003, Cáceres, Spain,


Cadmium, lead, mercury, selenium, iron, zinc and arsenic levels were measured in blood samples from 59 free-ranging white stork nestlings from colonies located in three different environmental conditions in Western Spain. The reference colony was situated in "Llanos de Cáceres y Sierra de Fuentes", an Area of Special Interest for Bird Protection. A second colony was located close to (4.9 km) an urban landfill and a third one was close to both an intensive agricultural area and an urban landfill (1.5 km). Blood samples were diluted and elemental analysis was performed using inductively coupled plasma mass spectrometer. In all cases, the essential metals zinc and iron were found at the highest mean concentrations followed by lead > selenium > mercury > arsenic > cadmium. Regarding toxic metals, the highest concentrations were found for lead (ranging from 23.27 to 146.4 µg/L) although in all cases the concentrations were lower than those considered to cause subclinical effects. The metals levels detected in the chick's blood were not related to the previously reported levels in the soil next to the colonies, which may indicate that landfills are the main source of metals in white stork nestlings. The present data showed that metal levels in white stork chicks may be influenced by the use of landfills as feeding areas by the parents. However, more studies on the metal content in the feed of white stork and the influence of the distance to the landfill are necessary to establish the causality of these findings.
PMID: 25011922 [PubMed - as supplied by publisher]
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6. Parasit Vectors. 2014 Jul 10;7(1):318. [Epub ahead of print]

Spotted fever Rickettsia species in Hyalomma and Ixodes ticks infesting migratory birds in the European Mediterranean area.

Wallménius K, Barboutis C, Fransson T, Jaenson TG, Lindgren PE, Nyström F, Olsen B, Salaneck E, Nilsson K.



A few billion birds migrate annually between their breeding grounds in Europe and their wintering grounds in Africa. Many bird species are tick-infested, and as a result of their innate migratory behavior, they contribute significantly to the geographic distribution of pathogens, including spotted fever rickettsiae. The aim of the present study was to characterize, in samples from two consecutive years, the potential role of migrant birds captured in Europe as disseminators of Rickettsia-infected ticks.


Ticks were collected from a total of 14,789 birds during their seasonal migration northwards in spring 2009 and 2010 at bird observatories on two Mediterranean islands: Capri and Antikythira. All ticks were subjected to RNA extraction followed by cDNA synthesis and individually assayed with a real-time PCR targeting the citrate synthase (gltA) gene. For species identification of Rickettsia, multiple genes were sequenced.


Three hundred and ninety-eight (2.7%) of all captured birds were tick-infested; some birds carried more than one tick. A total number of 734 ticks were analysed of which 353 +/- 1 (48%) were Rickettsia-positive; 96% were infected with Rickettsia aeschlimannii and 4% with Rickettsia africae or unidentified Rickettsia species. The predominant tick taxon, Hyalomma marginatum sensu lato constituted 90% (n = 658) of the ticks collected. The remaining ticks were Ixodes frontalis, Amblyomma sp., Haemaphysalis sp., Rhipicephalus sp. and unidentified ixodids. Most ticks were nymphs (66%) followed by larvae (27%) and adult female ticks (0.5%). The majority (65%) of ticks was engorged and nearly all ticks contained visible blood.


Migratory birds appear to have a great impact on the dissemination of Rickettsia-infected ticks, some of which may originate from distant locations. The potential ecological, medical and veterinary implications of such Rickettsia infections need further examination.
PMID: 25011617 [PubMed - as supplied by publisher]
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7. J R Soc Interface. 2014 Sep 6;11(98). pii: 20140541. doi: 10.1098/rsif.2014.0541.

Three-dimensional flow and lift characteristics of a hovering ruby-throated hummingbird.

Song J1, Luo H2, Hedrick TL3.Author information:
1Department of Mechanical Engineering, Vanderbilt University, Nashville, TN 37235, USA.
2Department of Mechanical Engineering, Vanderbilt University, Nashville, TN 37235, USA
3Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.


A three-dimensional computational fluid dynamics simulation is performed for a ruby-throated hummingbird (Archilochus colubris) in hovering flight. Realistic wing kinematics are adopted in the numerical model by reconstructing the wing motion from high-speed imaging data of the bird. Lift history and the three-dimensional flow pattern around the wing in full stroke cycles are captured in the simulation. Significant asymmetry is observed for lift production within a stroke cycle. In particular, the downstroke generates about 2.5 times as much vertical force as the upstroke, a result that confirms the estimate based on the measurement of the circulation in a previous experimental study. Associated with lift production is the similar power imbalance between the two half strokes. Further analysis shows that in addition to the angle of attack, wing velocity and surface area, drag-based force and wing-wake interaction also contribute significantly to the lift asymmetry. Though the wing-wake interaction could be beneficial for lift enhancement, the isolated stroke simulation shows that this benefit is buried by other opposing effects, e.g. presence of downwash. The leading-edge vortex is stable during the downstroke but may shed during the upstroke. Finally, the full-body simulation result shows that the effects of wing-wing interaction and wing-body interaction are small.
© 2014 The Author(s) Published by the Royal Society. All rights reserved.
PMID: 25008082 [PubMed - in process]
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8. J Agric Food Chem. 2014 Jul 9. [Epub ahead of print]

In vivo and in vitro addition of HIDROX®6% in poultry and its products.

King AJ, Griffin JK, Roslan F.


HIDROX®6%, a freeze dried powder from organic olive (Olea europaea) juice extract, contains 8.82% polyphenols and a minimum of 2.5% hydroxytyrosol (3,4-dihydroxyphenyl ethanol), an effective free radical scavenger and the major antioxidant in the by-product. A study was conducted primarily (1) to determine the effectiveness of hydroxytyrosol in HIDROX®6%, administered in vivo, to retard lipid oxidation in postmortem tissue and further processed products and to (2) compare the in vitro antioxidative capacity of hydroxytyrosol in HIDROX®6% and myricetin, another free radical scavenger. Secondarily, it was important to assess the capacity of HIDROX®6% to enhance the growth of poultry. HIDROX®6% was administered ad libitum in water at 6 mg and 12 mg of HIDROX®6% per bird per d for six wk in a factorial design of 3 diets (control plus two treatment levels) x 2 blocks x 2 replications. Results (P < 0.05) indicated that HIDROX®6% did not retard lipid oxidation in Fresh, Heated or NaCl (1.0% w/w)/Heated/Stored meat as assessed by absorpbency values for thiobarbituric acid reactive substances at 532 nm and 2,2- diphenylpicrylhydrazyl at 517 nm. HIDROX®6% and hydroxytyrosol are highly water soluble and may have been unavailable as an antioxidant in the tissue of broilers that did not consume water for four to six hours prior to processing. When added to processed thigh meat, 6% and 12% of HIDROX®6%, though not as effective as myricetin, reduced oxidation. Further assessment revealed that hydroxytyrosol in HIDROX®6% (0.025% to 0.05%), added at 1/38th the concentration of myricetin, was almost 50% as effective. Results (P < 0.05) showed no enhancement across treatments for feed consumption, BW or feed conversion; overall means for these measurements were 5.49 kg per bird, 3.32 kg per bird and 1.65 g feed per g live BW, respectively. Diagnostic examinations of two birds per pen over six weeks revealed no adverse effects due to consumption of HIDROX® 6%, a generally recognized as safe substance. Key words: olive extract, HIDROX®6%, hydroxytyrosol, antioxidant.
PMID: 25007306 [PubMed - as supplied by publisher]
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9. Oecologia. 2014 Jul 9. [Epub ahead of print]

Generalist birds govern the seed dispersal of a parasitic plant with strong recruitment constraints.

Mellado A1, Zamora R.Author information:
1Department of Ecology, Terrestrial Ecology Research Group, University of Granada, Av. Fuentenueva s/n, 18071, Granada, Spain,


Mistletoes constitute instructive study cases with which to address the role of generalist consumers in the study of plant-animal interactions. Their ranges of safe sites for recruitment are among the most restricted of any plant; therefore, frugivores specializing in mistletoe have been considered almost indispensable for the seed dispersal of these parasitic plants. However, the absence of such specialists in numerous regions inhabited by many mistletoe species raises the question of whether unspecialized vectors may successfully disperse mistletoe seeds to narrowly defined safe sites. Using the European mistletoe Viscum album subsp. austriacum as a study case, we recorded a broad range of 11 bird species that disperse mistletoe seeds. For these species, we studied the mistletoe-visitation rate and feeding behavior to estimate the quantity component of dispersal effectiveness, and the post-foraging microhabitat use, seed handling, and recruitment probabilities of different microhabitats as a measure of the quality component of effectiveness. Both endozoochory and ectozoochory are valid dispersal mechanisms, as the seeds do not need to be ingested to germinate, increasing seed-dispersal versatility. Thrushes were the most effective dispersers, although they were rather inefficient, whereas small birds (both frugivores and non-frugivores) offered low-quantity but high-quality services for depositing seeds directly upon safe sites. As birds behave similarly on parasitized and non-parasitized hosts, and vectors have broad home ranges, reinfection within patches and the colonization of new patches are ensured by an ample assemblage of generalist birds. Thus, a parasitic plant requiring precision in seed dispersal can rely on unspecialized dispersers.
PMID: 25004870 [PubMed - as supplied by publisher]
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10. J Environ Biol. 2014 Jul;35(4):703-8.

Avifaunal occurrence and distribution of wetland birds in Sakhya Sagar and Madhav Lakes in Madhav National Park, Shivpuri, India.

Arya M, Rao RJ, Mishra AK.


The present study on wetland birds was carried out at Madhav National Park, Shivpuri, M.P., India. This Park comprises of two lakes namely Sakhya Sagar and Madhav Lakes, which support fascinating wildlife. These lakes are winter resorts for variety of migratory birds for shelter, breeding, nesting and provide a suitable habitat for several resident and local migratory wetland bird species. This paper assesses the occurrence of 73 wetland birds (18 families and 8 orders) with their distribution in different locations and habitats. The present study provides a comprehensive checklist of wetland birds of Sakhya Sagar and Madhav Lakes by covering 15 locations and 10 habitats utilized by migratory, resident migratory and resident wetland bird species during different seasons of year and at various sighting frequencies.
PMID: 25004756 [PubMed - in process]
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