Avian Biology

Role of carbon dioxide and ion transport in the formation of sub-embryonic fluid by the blastoderm of the Japanese quail

by Glenn Baggott

Development of extra-embryonic membranes and fluid compartments

by Glenn Baggott

Soulsbury, C.D., Alatalo, R.V., Lebigre, C. & Siitari, H. (2012) Restrictive mate choice criteria causes age-specific inbreeding in female black grouse Tetrao tetrix. Animal Behaviour.

by Carl Soulsbury

Online early

Inbreeding is generally rare in large, natural populations yet mate choice often appears to be random with respect to... more Inbreeding is generally rare in large, natural populations yet mate choice often appears to be random with respect to kinship. This suggests that the risks of inbreeding may be small because passive mechanisms of inbreeding avoidance, for example dispersal, are effective at lowering inbreeding risk. Previous theoretical and empirical studies have assumed that the risks of inbreeding are constant over an individual's life span, but in the lek-breeding black grouse, inbreeding increases with female age. To determine whether inbreeding avoidance mechanisms are also age dependent, we generated four null models of random mate choice ranging from complete randomness to more biologically realistic mate choice criteria and compared these to 8 years of data on inbreeding levels at four different female age classes. We additionally tested whether mate fidelity decreased inbreeding risk. Observed inbreeding in female age classes 1, 2 or ≥3 were not significantly different from random, but was approximately 3.5 times higher in female age class ≥4. Alternative models using mate choice criteria showed no significant differences between observed and expected levels for any age class. Our results are in line with previous studies on noncooperatively breeding passerine birds, which indicate that mating is random with respect to kinship and that increased inbreeding in older females can be explained by reduced male availability caused by restrictive mate choice criteria. We also found that individuals that switched mates significantly increased relatedness to partners suggesting that mate fidelity may have evolved as an important passive inbreeding avoidance mechanism.

Dominance and plumage traits: meta-analysis and meta-regression analysis

by Eduardo S A Santos

Santos ESA, Scheck D & Nakagawa S. 2011. Animal Behaviour, 82, 3-19.

The study of avian signalling systems is an important avenue for research on animal communication. More specifically,... more The study of avian signalling systems is an important avenue for research on animal communication. More specifically, the use of plumage traits to signal status or fighting ability has been extensively investigated for over 30 years. Yet, little is known about how strong and general the relationship between dominance and plumage traits is across different bird species. We conducted meta-analysis and meta-regression analysis to investigate the relationship between dominance and plumage characteristics, using published literature on avian species. Our analyses tested possible moderators of this relationship, such as plumage trait and plumage colour, plumage manipulation, study location, type of dominance interaction, the use of model birds, type of dominance assessment, and dominance context (breeding or non-breeding). Our results revealed a significant effect size for the association between dominance and plumage. Our analyses revealed that the relationship between dominance and plumage was significantly influenced by the dominance assessment method used in the source study (direct or indirect). Furthermore, our analyses provide evidence that the role of plumage signalling may be similarly important during the breeding and non-breeding seasons. We conclude that plumage signalling is a ubiquitous form of communicating status or fighting ability across bird species with different plumage types.

Calcified cartilage shape in archosaur long bones reflects overlying joint shape in stress‐bearing elements: Implications for nonavian dinosaur locomotion

by Matthew Bonnan

Veer dam as important winter migratory ground for Bar-headed Geese Anser indicus (Latham, 1790) Family: Anatidae, with special reference to observations of …

by Aditya Ponkshe

Annual variation in fat storage by a migrant warbler overwintering in the Indian tropics

by Madhusudan Katti

Role of testosterone in stimulating seasonal changes in a potential avian chemosignal

by Danielle Whittaker

Co-authored with Helena Soini, Nicole Gerlach, Amanda Posto, Milos Novotny, and Ellen Ketterson. Journal of Chemical Ecology.

Songbird preen oil contains volatile and semivolatile compounds that may contain information about species, sex,... more Songbird preen oil contains volatile and semivolatile compounds that may contain information about species, sex, individual identity, and season. We examined the relationship between testosterone (T) and the concentration of preen oil volatile and semivolatile compounds in wild and captive dark-eyed juncos (Junco hyemalis). In wild males and females, we observed an increase in volatile compound concentration early in the breeding season. This increase mirrored previously described seasonal elevation in T levels in wild males and females, suggesting a positive relationship between hormone levels and preen gland secretions and a possible role for those secretions in signaling receptivity. In females, the highest concentrations of most compounds were observed close to egg laying, a time when steroid hormones are high and also the only time that females respond to an injection of gonadotropin-releasing hormone with a short-term increase in T. In a study of captive juncos held on short days, we asked whether the seasonal increases observed in the wild could be induced with experimental elevation of T alone. We found that exogenous T stimulated the production of some volatile compounds in non-breeding individuals of both sexes. However, of the 15 compounds known to increase significantly during the breeding season, only four showed a significant increase in concentration in birds that received T implants. Our results suggest that testosterone levels likely interact with other seasonally-induced physiological changes to affect volatile compound concentrations in preen oil.

Testing the effect of transient Plio‐Pleistocene barriers in monsoonal Australo‐Papua: did mangrove habitats maintain genetic connectivity in the Black Butcherbird?

by Anna Kearns

KEARNS, A. M., JOSEPH, L., OMLAND, K. E. and COOK, L. G. (2011), Testing the effect of transient Plio-Pleistocene barriers in monsoonal Australo-Papua: did mangrove habitats maintain genetic connectivity in the Black Butcherbird?. Molecular Ecology, 20: 5042–5059. doi: 10.1111/j.1365-294X.2011.05330.x

Changes in climate and sea level are hypothesized to have promoted the diversification of biota in monsoonal Australia... more Changes in climate and sea level are hypothesized to have promoted the diversification of biota in monsoonal Australia and New Guinea by causing repeated range disjunctions and restricting gene flow between isolated populations. Using a multilocus (one mtDNA locus, five nuclear introns) phylogeographic approach, we test whether populations of the mangrove and rainforest restricted Black Butcherbird (Cracticus quoyi) have diverged across several geographic barriers defined a priori for this region. Phylogeographic structure and estimates of divergence times revealed Plio-Pleistocene divergences and long-term restricted gene flow of populations on either side of four major geographic barriers between and within Australia and New Guinea. Overall, our data are consistent with the hypothesis that mesic-adapted species did not disperse across the open dry woodlands and grasslands that dominated the transient palaeo-landbridges during the Plio-Pleistocene despite the presence of mangrove forests that might have acted as dispersal corridors for mesic-adapted species. Our study offers one of the first multilocus perspectives on the impact of changes in climate and sea level on the population history of widespread species with disjunct ranges in Australia and New Guinea.

Evolution and connectivity in the world-wide migration system of the mallard: Inferences from mitochondrial DNA

by Robert Kraus

R. H. S. Kraus, A. Zeddeman, P. van Hooft, D. Sartakov, S. A. Soloviev, R. C. Ydenberg and H. H. T. Prins; BMC Genetics. 2011. 12:99

Background
Main waterfowl migration systems are well understood through ringing activities. However, in mallards... more Background
Main waterfowl migration systems are well understood through ringing activities. However, in mallards (Anas platyrhynchos) ringing studies suggest deviations from general migratory trends and traditions in waterfowl. Furthermore, surprisingly little is known about the population genetic structure of mallards, and studying it may yield insight into the spread of diseases such as Avian Influenza, and in management and conservation of wetlands. The study of evolution of genetic diversity and subsequent partitioning thereof during the last glaciation adds to ongoing discussions on the general evolution of waterfowl populations and flyway evolution. Hypothesised mallard flyways are tested explicitly by analysing mitochondrial mallard DNA from the whole northern hemisphere.

Results
Phylogenetic analyses confirm two mitochondrial mallard clades. Genetic differentiation within Eurasia and North-America is low, on a continental scale, but large differences occur between these two land masses (FST = 0.51). Half the genetic variance lies within sampling locations, and a negligible portion between currently recognised waterfowl flyways, within Eurasia and North-America. Analysis of molecualr variance (AMOVA) at continent scale, incorporating sampling localities as smallest units, also shows the absence of population structure on the flyway level. Finally, demographic modelling by coalescence simulation proposes a split between Eurasia and North-America 43,000 to 74,000 years ago and strong population growth (~100fold) since then and little migration (not statistically different from zero).

Conclusions
Based on this first complete assessment of the mallard's world-wide population genetic structure we confirm that no more than two mtDNA clades exist. Clade A is characteristic for Eurasia, and clade B for North-America although some representatives of clade A are also found in North-America. We explain this pattern by evaluating competing hypotheses and conclude that a complex mix of historical, recent and anthropogenic factors shaped the current mallard populations. We refute population classification based on flyways proposed by ornithologists and managers, because they seem to have little biological meaning. Our results have implications for wetland management and conservation, with special regard to the release of farmed mallards for hunting, as well as for the possible transmission of Avian Influenza by mallards due to migration.

Achieving luster: prenuptial molt pattern predicts iridescent structural coloration in Blue-black Grassquits

by Rafael Maia

2010; Journal of Ornithology152:243-252

Colors in feathers are produced by pigment deposition or by nanostructures within barbs or barbules. In the absence of... more Colors in feathers are produced by pigment deposition or by nanostructures within barbs or barbules. In the absence of pigments or nanostructures, light is scattered incoherently, producing white coloration. Honest advertisement models predict that ornamental colors evolve if they reliably signal individual properties such as viability, health, or nutritional state. In this study, we tested if (1) iridescent structural and (2) unpigmented plumage coloration signal male quality in the Blue-black Grassquit (Volatinia jacarina). During three reproductive seasons, we captured males and measured morphological variables and nuptial plumage coverage, and collected feathers for spectrometry. We found that saturation of the iridescent coloration was positively related to relative molting speed, indicating that males investing more in prenuptial molt also produced more saturated, UV-shifted plumage. Body condition was not related to brightness or saturation of the iridescent plumage, and no male morphological attributes were associated with the white underwing patch coloration or size. Our results suggest that patterns of molt, and possibly feather growth, may affect the organization of optical nanostructures responsible for iridescent coloration, and that the ontogeny of iridescent plumage ornaments must be taken into account in hypotheses concerning honest advertisement of such signals. Thus, coloration in this species may reliably reflect energy allocation to molting, constituting an honest indicator of male quality, life history decisions, or endocrine state. To our knowledge, this is the first report of natural variation in molting pattern being associated with sexually-selected structural color plumage.

Social environment affects testosterone level in captive male blue–black grassquits

by Rafael Maia

2010; Hormones and Behavior 59:51-55

The challenge hypothesis proposes that testosterone (T) elevation above what is needed for breeding is associated with... more The challenge hypothesis proposes that testosterone (T) elevation above what is needed for breeding is associated with social factors, and males possibly modulate their hormonal response to variations in population density and sex ratio. We investigated the role of social environment in altering testosterone levels and aggression in a tropical, seasonally breeding grassquit (Volatinia jacarina). We exposed males to three social conditions during 1 year: all-males treatment (six males), mixed treatment (three males–three females), and paired treatment (one male–one female). We quantified aggressiveness among males and T plasma concentration for each individual in each treatment monthly. We found that more aggressive interactions occurred in the all-males treatment than in the mixed treatment. The data also revealed that, coincident with these behavioral changes, the patterns of T variation through time in each treatment were markedly different. The all-males treatment exhibited an early increase in T concentration, which was sustained for a lengthy period with two distinctive peaks, and subsequently declined sharply. The mixed treatment presented an intermediate pattern, with more gradual increase and decrease in T levels. At the other extreme, the paired treatment presented a later rise in T concentration. We conclude that the more competitive environment, with higher density of males, caused the early and higher elevation in T level, thus the presence of competitors may influence the decision of how much a male should invest in reproduction. We suggest that the male's perception of his social environment ultimately mediates hormonal production and alters his reproductive strategy.

Nanostructural self-assembly of iridescent feather barbules through depletion attraction of melanosomes during keratinization

by Rafael Maia

In Press; Journal of the Royal Society Interface

Avian plumage colours are model traits in understanding the evolution of sexually selected ornamental traits.... more Avian plumage colours are model traits in understanding the evolution of sexually selected ornamental traits. Paradoxically, iridescent structural colours, probably the most dazzling of these traits, remain the most poorly understood. Though some data suggest that expression of bright iridescent plumage colours produced by highly ordered arrays of melanosomes and keratin is condition-dependent, almost nothing is known of their ontogeny and thus of any developmental mechanisms that may be susceptible to perturbation. Here, we use light and electron microscopy to compare the ontogeny of iridescent male and non-iridescent female feathers in blue-black grassquits. Feather barbules of males contain a single layer of melanosomes bounded by a thin layer of keratin-producing blue iridescent colour, while those of females contain disorganized melanosomes and no outer layer. We found that nanostructural organization of male barbules occurs late in development, following death of the barbule cell, and is thus unlikely to be under direct cellular control, contrary to previous suggestions. Rather, organization appears to be caused by entropically driven self-assembly through depletion attraction forces that pin melanosomes to the edge of barbule cells and to one another. These forces are probably stronger in developing barbules of males than of females because their melanosomes are (i) larger, (ii) more densely packed, and (iii) more homogeneously distributed owing to the more consistent shape of barbules during keratinization. These data provide the first proposed developmental pathway for iridescent plumage colours, and suggest that any condition dependence of iridescent barbules is likely driven by factors other than direct metabolic cost.

What makes a feather shine? A nanostructural basis for glossy black colours in feathers

by Rafael Maia

2010; Proceedings of the Royal Society of London B: Biological Sciences 278:1973-1980

Colours in feathers are produced by pigments or by nanostructurally organized tissues that interact with light. One of... more Colours in feathers are produced by pigments or by nanostructurally organized tissues that interact with light. One of the simplest nanostructures is a single layer of keratin overlying a linearly organized layer of melanosomes that create iridescent colours of feather barbules through thin-film interference. Recently, it has been hypothesized that glossy (i.e. high specular reflectance) black feathers may be evolutionarily intermediate between matte black and iridescent feathers, and thus have a smooth keratin layer that pro- duces gloss, but not the layered organization of melanosomes needed for iridescence. However, the morphological bases of glossiness remain unknown. Here, we use a theoretical approach to generate pre- dictions about morphological differences between matte and glossy feathers that we then empirically test. Thin-film models predicted that glossy spectra would result from a keratin layer 110–180 nm thick and a melanin layer greater than 115 nm thick. Transmission electron microscopy data show that nanostructure of glossy barbules falls well within that range, but that of matte barbules does not. Further, glossy bar- bules had a thinner and more regular keratin cortex, as well as a more continuous underlying melanin layer, than matte barbules. Thus, their quasi-ordered nanostructures are morphologically intermediate between matte black and iridescent feathers, and perceived gloss may be a form of weakly chromatic iridescence.

Proximate bases of silver color in anhinga (Anhinga anhinga) feathers

by Rafael Maia

2011; Journal of Morphology In Press

Colors of living organisms are produced by selective light absorption from pigments and/or by light scattering from... more Colors of living organisms are produced by selective light absorption from pigments and/or by light scattering from highly ordered nanostructures (i.e., structural color). While the physical bases of metallic colors of arthropods and fish are fairly well-known, those of birds are not. Here we examine structurally based silver color and its production in feathers of the waterbird species Anhinga. This achromatic color is distinguished from grey by high specular reflectance, from white by low diffuse reflectance, and from both by high gloss. Light and electron microscopy revealed three modifications of feathers likely leading to silver color. First, proximal barbules were highly elongated and contained glossy black color at their base and white color at their pennulum. Second, this glossy black portion contained a single outer layer of keratin weakly bounded by melanosomes. Finally, the white portion contained a disordered amorphous matrix of keratin and air. Optical analyzes suggest that these structures produce, respectively, glossy black color through thin-film interference and white color through incoherent light scattering. Silver color likely results from the combined reflectance of these adjacent structures. This represents a distinct mechanism for attaining silver colors that may have been partially derived through selection for display, thermoregulation or decreased hydrophobicity.

Social class influences degree of variance-sensitivity in wild Siberian jays.

by Irja Ida Ratikainen

Ratikainen, I. I., Wright, J. and Kazem, A. J. N. (2010) Behavioral Ecology. 21 (5) 1067-1072. doi:10.1093/beheco/arq106

Sanderlings using African–Eurasian flyways: a review of current knowledge

by Jeroen Reneerkens

Wader Study Group Bulletin 116(1): 2–20

Despite the worldwide occurrence of Sanderlings Calidris alba on popular beaches, strikingly little is known about... more Despite the worldwide occurrence of Sanderlings Calidris alba on popular beaches, strikingly little is known about their biology compared to other common waders. Here we review the limited available knowledge of Sanderlings that use African–Eurasian flyways. The basis for this review was a workshop on Sanderlings, held during the International Wader Study Group conference in Jastrzębia Góra, Poland in 2008. We focus on biogeography, trends, numbers, diet, migration patterns and reproduction. Gaps in our knowledge are identified and we discuss the evidence for a Siberian origin of Sanderlings wintering in NW Europe, and plead for more
non-estuarine surveys and collaboration between colour-ring projects both in space and time to get a better understanding of population dynamics and migration phenology.

Avian Influenza Surveillance with FTA Cards: Field Methods, Biosafety, and Transportation Issues Solved

by Robert Kraus

This is a VIDEO article! Check out the link!

R. H. S. Kraus, P. van Hooft, J. Waldenström, N. Latorre-Margalef, R. C. Ydenberg and H. H. T. Prins “Avian Influenza surveillance with FTA® cards: Field methods, biosafety, and transportation issues solved” Journal of Visualized Experiments. 2011. 54:e2832.

Avian Influenza Viruses (AIVs) infect many mammals, including humans. These AIVs are diverse in their natural hosts,... more Avian Influenza Viruses (AIVs) infect many mammals, including humans. These AIVs are diverse in their natural hosts, harboring almost all possible viral subtypes. Human pandemics of flu originally stem from AIVs. Many fatal human cases during the H5N1 outbreaks in recent years were reported. Lately, a new AIV related strain swept through the human population, causing the 'swine flu epidemic4. Although human trading and transportation activity seems to be responsible for the spread of highly pathogenic strains, dispersal can also partly be attributed to wild birds. However, the actual reservoir of all AIV strains is wild birds.

In reaction to this and in face of severe commercial losses in the poultry industry, large surveillance programs have been implemented globally to collect information on the ecology of AIVs, and to install early warning systems to detect certain highly pathogenic strains. Traditional virological methods require viruses to be intact and cultivated before analysis. This necessitates strict cold chains with deep freezers and heavy biosafety procedures to be in place during transport. Long-term surveillance is therefore usually restricted to a few field stations close to well equipped laboratories. Remote areas cannot be sampled unless logistically cumbersome procedures are implemented. These problems have been recognised and the use of alternative storage and transport strategies investigated (alcohols or guanidine). Recently, Kraus et al. introduced a method to collect, store and transport AIV samples, based on a special filter paper. FTA cards preserve RNA on a dry storage basis and render pathogens inactive upon contact. This study showed that FTA cards can be used to detect AIV RNA in reverse-transcription PCR and that the resulting cDNA could be sequenced and virus genes and determined.

In the study of Kraus et al. a laboratory isolate of AIV was used, and samples were handled individually. In the extension presented here, faecal samples from wild birds from the duck trap at the Ottenby Bird Observatory (SE Sweden) were tested directly to illustrate the usefulness of the methods under field conditions. Catching of ducks and sample collection by cloacal swabs is demonstrated. The current protocol includes up-scaling of the work flow from single tube handling to a 96-well design. Although less sensitive than the traditional methods, the method of FTA cards provides an excellent supplement to large surveillance schemes. It allows collection and analysis of samples from anywhere in the world, without the need to maintaining a cool chain or safety regulations with respect to shipping of hazardous reagents, such as alcohol or guanidine.

Nest predation in relation to nest placement in the greater ani (Crotophaga major)

by Pablo Lau

In vitro and in ovo effects of four brominated flame retardants on toxicity and hepatic mRNA expression in chicken embryos

by Cristina Cassone

accepted by Toxicological Letters (August 2011)

Some currently used brominated flame retardants (BFRs), such as hexachlorocyclopentadienyl-dibromocyclooctane... more Some currently used brominated flame retardants (BFRs), such as hexachlorocyclopentadienyl-dibromocyclooctane (HCDBCO), bis(2-ethylhexyl)tetrabromophthalate (BEHTBP), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE) and decabromodiphenylethane (DBDPE), are persistent organic contaminants detected in various environmental matrices, including wild birds. Data on potential toxicological and molecular responses to exposure of these BFRs are lacking for avian species. A combined in vitro/in ovo approach was used to determine the concentration-dependent effects of these BFRs on overt toxicity and hepatic messenger RNA (mRNA) expression levels of 11 transcripts in (1) primary cultures of chicken embryonic hepatocytes (CEH; all four BFRs) and (2) chicken embryos (HCDBCO and BTBPE only). Neither hepatocyte viability nor embryonic pipping success were affected by the BFRs at any of the administered doses (CEH: 0.001-30 µM, egg injection: 0.1-10 µg/g nominal concentration). Variability in mRNA response was observed among the four BFRs. In CEH, 10µM HCDBCO induced cytochrome P450 2H1 (CYP2H1) and CYP3A37, while CYP1A4/5 were down-regulated at all tested concentrations. In contrast, only transthyretin was down-regulated by HCDBCO in embryonic liver. There was concordance between the BTBPE-induced transcriptional responses in vitro and in ovo for CYP1A4/5 (up-regulated) and type III iodothyronine 5’-deiodinase (DIO3; down-regulated). DBDPE induced CYP1A4/5 29- and 59-fold at 0.2µM in CEH and increased DIO1. None of the gene targets were responsive to BEHTBP exposure in CEH. To our knowledge, this is the first study to assess toxicological and molecular biological effects of these BFRs in an avian species using a multi-tiered in vitro/in ovo screening approach.