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Juan José Soler - One of the best experts on this subject based on the ideXlab platform.
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eggshell bacterial load is related to antimicrobial properties of Feathers lining barn swallow nests
Microbial Ecology, 2014Co-Authors: Juan Manuel Peraltasanchez, Juan José Soler, Antonio M Martinplatero, Rob Knight, Manuel Martinezbueno, Anders Pape MøllerAbstract:The use of Feathers to line bird’s nests has traditionally been interpreted as having a thermoregulatory function. Feather-degrading bacteria growing on Feathers lining nests may have antimicrobial properties, which may provide an additional benefit to lining nests with Feathers. We test the hypothesis that the production of antimicrobial substances by feather bacteria affects the microbiological environment of the nest, and therefore the bacterial density on eggshells and, indirectly, hatching success. These effects would be expected to differ between nests lined with pigmented and white Feathers, because bacteria grow differently on Feathers of different colors. We experimentally manipulated the composition of pigmented and unpigmented Feathers in nests of the barn swallow (Hirundo rustica) and studied the antimicrobial properties against the keratin-degrading bacterium Bacillus licheniformis of bacteria isolated from Feathers of each color. Analyzed Feathers were collected at the end of the incubation period, and antimicrobial activity was defined as the proportion of bacteria from the Feathers that produce antibacterial substances effective against B. licheniformis. Our experimental manipulation affected antimicrobial activity, which was higher in nests with only white Feathers at the beginning of incubation. Moreover, white Feathers showed higher antimicrobial activity than black ones. Interestingly, antimicrobial activity in Feathers of one of the colors correlated negatively with bacterial density on feather of the opposite color. Finally, antimicrobial activity of white Feathers was negatively related to eggshell bacterial load. These results suggest that antimicrobial properties of Feathers in general and of white Feathers in particular affect the bacterial environment in nests. This environment in turn affects the bacterial load on eggshells, which may affect hatching success.
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colour composition of nest lining Feathers affects hatching success of barn swallows hirundo rustica passeriformes hirundinidae
Biological Journal of The Linnean Society, 2011Co-Authors: Juan José Soler, Anders Pape Møller, Juan Manuel PeraltasanchezAbstract:Many bird species use Feathers as lining material, and its functionality has traditionally been linked to nest insulation. However, nest lining Feathers may also influence nest detection by predators, differentially affect reproductive investment of mates in a post-mating sexual selection process, and affect the bacterial community of the nest environment. Most of these functions of nest lining Feathers could affect hatching success, but the effect might vary depending on feather coloration (i.e. pigmented versus white Feathers). This would be the case if coloration is related to: (1) thermoregulatory properties; (2) attractiveness of Feathers in the nest for mates; (3) eggshell bacterial density. All of these hypothetical scenarios predict that Feathers of different colours would differentially affect the hatching success of birds, and that birds should preferentially choose the most beneficial feather colour for lining their nests. Results from two different experiments performed with a population of Danish barn swallow, Hirundo rustica, were in accordance with these predictions. First, H. rustica preferentially selected white experimentally offered Feathers for lining their nests. Second, the experimental manipulation of the feather colour composition of nests of H. rustica had a significant effect on hatching success. Experimental nests with more white Feathers added at the beginning of incubation had a lower probability of hatching failures, suggesting differential beneficial effects of lining nests with Feathers of this colour. We discuss the relative importance of hypothetical functional scenarios that predicted the detected associations, including those related to sexual selection or to the community of microorganisms associated with Feathers of different colours. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102, 67–74.
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number and colour composition of nest lining Feathers predict eggshell bacterial community in barn swallow nests an experimental study
Functional Ecology, 2010Co-Authors: Juan Manuel Peraltasanchez, Anders Pape Møller, Antonio M Martinplatero, Juan José SolerAbstract:Summary 1. The use of Feathers as nest lining material has traditionally been explained by the thermoregulatory properties of Feathers. Feather nest lining could additionally affect nest detectability by predators, or play a role in a sexually selected context. Furthermore, feather nest lining harbours microorganisms that may influence environmental conditions where eggs and nestlings develop. 2. Microorganisms growing on nest lining Feathers could affect the bacterial load of eggshells because they occupy space and/or produce antimicrobial substances against other bacteria, including egg pathogens. Feathers of different colours are known to differ in their bacterial community (i.e. feather degrading bacteria) and, thus, colour composition of nest lining feather could also affect the bacterial environment of avian nests. 3. Here we tested this hypothesis in the barn shallow (Hirundo rustica) by exploring the relationship between eggshell bacterial loads and number of Feathers, and the effect of experimentally modified colour composition of nest lining Feathers on eggshell bacterial load. 4. In agreement with the hypothesis we found that, before treatment, the number of nest lining Feathers (mainly that of unpigmented-white colour) predicted eggshell bacterial load, and that, at the end of the incubation period, eggshells of experimental nests with white Feathers had a lower bacterial density than those in experimental nests with black Feathers. 5. We failed to detect a relationship between bacterial load and hatching success. However, since evidence of that relationship exists for other species, these results would explain the previously detected experimental effect of colour composition of nest lining Feathers on hatching success of swallows. 6. Nest design in general, and the use of nest-lining white Feathers in particular, may therefore have important consequences for reproductive success of birds. The reduced eggshell bacterial loads of experimental white nests would explain preferences by barn swallows for Feathers of white colour.
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Symbiotic Bacteria Living in the Hoopoe's Uropygial Gland Prevent Feather Degradation
Journal of Experimental Biology, 2009Co-Authors: Magdalena Ruiz-rodríguez, Manuel Martín-vivaldi, Antonio M. Martín-platero, Juan José Soler, Eva Valdivia, Manuel Martínez-buenoAbstract:SUMMARY Among potential agents that might damage bird Feathers are certain microorganisms which secrete enzymes that digest keratin, as is the case of the ubiquitous bacterium Bacillus licheniformis , present in both the Feathers and skin of wild birds. It is therefore a good candidate for testing the effects of bird defences against feather-degrading microorganisms. One of these defences is the oil secreted by the uropygial gland, which birds use to protect their Feathers against parasites. In previous studies we have shown how Enterococcus faecalis strains isolated from nestling hoopoes exert antagonistic effects against B. licheniformis , mediated by the production of bacteriocins. Consequently we hypothesized that this enterococcus and the bacteriocins it engenders might act as a defence against feather-degrading microorganisms in hoopoes. We investigated this hypothesis in a series of laboratory experiments and evaluated the extent to which the keratinolytic effects caused by B. licheniformis were reduced by the E. faecalis MRR10-3 strain, isolated from hoopoes, and its bacteriocins. In different treatments, Feathers or pure keratin was incubated with B. licheniformis , B. licheniformis together with E. faecalis MRR10-3, and B. licheniformis together with the bacteriocins produced by E. faecalis MRR10-3. Our results were in accordance with the predicted effects on hoopoe Feathers. There was a significant decrease both in pure keratin loss and in feather degradation in the presence of the symbiotic bacterium or its bacteriocin. These results suggest that by preening their Feathers hoopoes benefit from their symbiotic relationship with bacteriocin-producing enterococci, which constitute a chemical defence against feather degradation.
Yves Cherel - One of the best experts on this subject based on the ideXlab platform.
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Moulting patterns drive within-individual variations of stable isotopes and mercury in seabird body Feathers: implications for monitoring of the marine environment
Marine Biology, 2014Co-Authors: Alice Carravieri, Paco Bustamante, Carine Churlaud, Aymeric Fromant, Yves CherelAbstract:One major limitation in the use of body Feathers of seabirds as a monitoring tool of the trophic structure and contamination levels of marine ecosystems is the degree of heterogeneity in feather chemical composition within individuals. Here, we tested the hypothesis that moulting patterns drive body feather heterogeneity, with synchronous moult minimizing within-individual variations, in contrast to asynchronous feather growth. Chicks of white-chinned petrels Procellaria aequinoctialis (representative of bird chicks) and adults of king penguins Aptenodytes patagonicus (representative of adult penguins) that moult their body Feathers synchronously showed very low within-individual variations in their feather δ13C and δ15N values and Hg concentrations. By contrast, body Feathers of adults of Antarctic prions Pachyptila desolata (representative of adult seabirds with asynchronous feather growth during a protracted moult) presented much higher within-individual variances for the three parameters. These findings have three important implications for birds presenting a synchronous body moult. (i) They suggest that all body Feathers from the same individual have identical δ13C and δ15N values and Hg content. (ii) They predict negligible within-individual variations in the body feather values of other useful stable isotopes, such as δ2H and δ34S, as well as in the concentrations of other compounds that are deposited in the keratin structure. (iii) Analysis of one or any number of pooled body Feathers is equally representative of the individual. In conclusion, we recommend that long-term routine monitoring investigations focus on birds presenting synchronous rather than asynchronous moult of body Feathers both in marine and terrestrial environments. This means targeting chicks rather than adults and, for seabirds, penguins rather than adults of flying species.
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moulting patterns drive within individual variations of stable isotopes and mercury in seabird body Feathers implications for monitoring of the marine environment
Marine Biology, 2014Co-Authors: Alice Carravieri, Paco Bustamante, Carine Churlaud, Aymeric Fromant, Yves CherelAbstract:One major limitation in the use of body Feathers of seabirds as a monitoring tool of the trophic structure and contamination levels of marine ecosystems is the degree of heterogeneity in feather chemical composition within individuals. Here, we tested the hypothesis that moulting patterns drive body feather heterogeneity, with synchronous moult minimizing within-individual variations, in contrast to asynchronous feather growth. Chicks of white-chinned petrels Procellaria aequinoctialis (representative of bird chicks) and adults of king penguins Aptenodytes patagonicus (representative of adult penguins) that moult their body Feathers synchronously showed very low within-individual variations in their feather δ13C and δ15N values and mercury (Hg) concentrations. By contrast, body Feathers of adults of Antarctic prions Pachyptila desolata (representative of adult seabirds with asynchronous feather growth during a protracted moult) presented much higher within-individual variances for the three parameters. These findings have three important implications for birds presenting a synchronous body moult. (1) They suggest that all body Feathers from the same individual have identical δ13C and δ15N values and Hg content. (2) They predict negligible within-individual variations in the body feather values of other useful stable isotopes, such as δ2H and δ34S, as well as in the concentrations of other compounds that are deposited in the keratin structure. (3) Analysis of one or any number of pooled body Feathers is equally representative of the individual. In conclusion, we recommend that long-term routine monitoring investigations focus on birds presenting synchronous rather than asynchronous moult of body Feathers both in marine and terrestrial environments. This means targeting chicks rather than adults and, for seabirds, penguins rather than adults of flying species.
Anders Pape Møller - One of the best experts on this subject based on the ideXlab platform.
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The trade-off between rapid feather growth and impaired feather quality increases risk of predation
Journal of Ornithology, 2017Co-Authors: Anders Pape Møller, J. T. NielsenAbstract:Feathers are used for flight, and any damage to Feathers impairs efficient escape from predators. Because individuals can either rapidly produce Feathers of poor quality or slowly produce Feathers of high quality, prey experience a trade-off between speed of molt, quality of Feathers, and risk of predation. We analyzed Feathers produced by Woodpigeon Columba palumbus prey captured by Goshawks Accipiter gentilis and compared those to Feathers shed during molt in the same areas. Feathers that were produced rapidly as reflected by long daily growth increments suffered from a greater degree of feather wear than Feathers that were produced slowly. Prey had longer daily growth increments and a shorter period of molt than non-prey. Woodpigeons with worn Feathers were more likely to fall prey to Goshawks than those with little or no wear to the plumage. These effects were independent of age, year, and time during the breeding season. These findings are consistent with a trade-off between speed of molt and feather quality affecting predation risk.
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Losing the last feather: feather loss as an antipredator adaptation in birds
2015Co-Authors: Anders Pape Møller, Jan Tøttrup A Nielsen, Johannes ErritzøecAbstract:Birds often lose Feathers during predation attempts, and this ability has evolved as a means of escape. Because predators are more likely to grab Feathers on the rump and the back than on the ventral side of an escaping bird, we predicted that the former Feathers would have evolved to be relatively loosely attached as an antipredator strategy in species that frequently die from predation. We estimated the force required to remove Feathers from the rump, back, and breast by pulling Feathers with a spring balance from a range of European bird species in an attempt to investigate ecological factors associated with ease of feather loss during predation attempts. The force required to loosen a feather from the rump was less than that required to loosen a feather from back, which in turn was less than that required to loosen a feather from the breast. The relative force needed to loosen rump Feathers compared with Feathers from the back and the breast was smaller for prey species preferred by the most common predator of small passerine birds, the sparrowhawk Accipiter nisus. Likewise, the relative force was also smaller in species with a high frequency of complete tail loss among free-living birds, which we used as an index of the frequency of failed predation attempts. The relative force required to remove Feathers from the rump was smaller in species with a high frequency of fear screams, another measure of the relative importance of predation as a cause of death. Feather loss required particularly little force among solitarily breeding bird species that suffer the highest degree of predation. Antipredator defense in terms of force required to remove Feathers from the rump was larger in species with a strong antiparasite defense in terms of T-cell–mediated immune response. These findings are consistent with the hypothesis that different defenses are antagonistic and that the
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eggshell bacterial load is related to antimicrobial properties of Feathers lining barn swallow nests
Microbial Ecology, 2014Co-Authors: Juan Manuel Peraltasanchez, Juan José Soler, Antonio M Martinplatero, Rob Knight, Manuel Martinezbueno, Anders Pape MøllerAbstract:The use of Feathers to line bird’s nests has traditionally been interpreted as having a thermoregulatory function. Feather-degrading bacteria growing on Feathers lining nests may have antimicrobial properties, which may provide an additional benefit to lining nests with Feathers. We test the hypothesis that the production of antimicrobial substances by feather bacteria affects the microbiological environment of the nest, and therefore the bacterial density on eggshells and, indirectly, hatching success. These effects would be expected to differ between nests lined with pigmented and white Feathers, because bacteria grow differently on Feathers of different colors. We experimentally manipulated the composition of pigmented and unpigmented Feathers in nests of the barn swallow (Hirundo rustica) and studied the antimicrobial properties against the keratin-degrading bacterium Bacillus licheniformis of bacteria isolated from Feathers of each color. Analyzed Feathers were collected at the end of the incubation period, and antimicrobial activity was defined as the proportion of bacteria from the Feathers that produce antibacterial substances effective against B. licheniformis. Our experimental manipulation affected antimicrobial activity, which was higher in nests with only white Feathers at the beginning of incubation. Moreover, white Feathers showed higher antimicrobial activity than black ones. Interestingly, antimicrobial activity in Feathers of one of the colors correlated negatively with bacterial density on feather of the opposite color. Finally, antimicrobial activity of white Feathers was negatively related to eggshell bacterial load. These results suggest that antimicrobial properties of Feathers in general and of white Feathers in particular affect the bacterial environment in nests. This environment in turn affects the bacterial load on eggshells, which may affect hatching success.
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colour composition of nest lining Feathers affects hatching success of barn swallows hirundo rustica passeriformes hirundinidae
Biological Journal of The Linnean Society, 2011Co-Authors: Juan José Soler, Anders Pape Møller, Juan Manuel PeraltasanchezAbstract:Many bird species use Feathers as lining material, and its functionality has traditionally been linked to nest insulation. However, nest lining Feathers may also influence nest detection by predators, differentially affect reproductive investment of mates in a post-mating sexual selection process, and affect the bacterial community of the nest environment. Most of these functions of nest lining Feathers could affect hatching success, but the effect might vary depending on feather coloration (i.e. pigmented versus white Feathers). This would be the case if coloration is related to: (1) thermoregulatory properties; (2) attractiveness of Feathers in the nest for mates; (3) eggshell bacterial density. All of these hypothetical scenarios predict that Feathers of different colours would differentially affect the hatching success of birds, and that birds should preferentially choose the most beneficial feather colour for lining their nests. Results from two different experiments performed with a population of Danish barn swallow, Hirundo rustica, were in accordance with these predictions. First, H. rustica preferentially selected white experimentally offered Feathers for lining their nests. Second, the experimental manipulation of the feather colour composition of nests of H. rustica had a significant effect on hatching success. Experimental nests with more white Feathers added at the beginning of incubation had a lower probability of hatching failures, suggesting differential beneficial effects of lining nests with Feathers of this colour. We discuss the relative importance of hypothetical functional scenarios that predicted the detected associations, including those related to sexual selection or to the community of microorganisms associated with Feathers of different colours. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102, 67–74.
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number and colour composition of nest lining Feathers predict eggshell bacterial community in barn swallow nests an experimental study
Functional Ecology, 2010Co-Authors: Juan Manuel Peraltasanchez, Anders Pape Møller, Antonio M Martinplatero, Juan José SolerAbstract:Summary 1. The use of Feathers as nest lining material has traditionally been explained by the thermoregulatory properties of Feathers. Feather nest lining could additionally affect nest detectability by predators, or play a role in a sexually selected context. Furthermore, feather nest lining harbours microorganisms that may influence environmental conditions where eggs and nestlings develop. 2. Microorganisms growing on nest lining Feathers could affect the bacterial load of eggshells because they occupy space and/or produce antimicrobial substances against other bacteria, including egg pathogens. Feathers of different colours are known to differ in their bacterial community (i.e. feather degrading bacteria) and, thus, colour composition of nest lining feather could also affect the bacterial environment of avian nests. 3. Here we tested this hypothesis in the barn shallow (Hirundo rustica) by exploring the relationship between eggshell bacterial loads and number of Feathers, and the effect of experimentally modified colour composition of nest lining Feathers on eggshell bacterial load. 4. In agreement with the hypothesis we found that, before treatment, the number of nest lining Feathers (mainly that of unpigmented-white colour) predicted eggshell bacterial load, and that, at the end of the incubation period, eggshells of experimental nests with white Feathers had a lower bacterial density than those in experimental nests with black Feathers. 5. We failed to detect a relationship between bacterial load and hatching success. However, since evidence of that relationship exists for other species, these results would explain the previously detected experimental effect of colour composition of nest lining Feathers on hatching success of swallows. 6. Nest design in general, and the use of nest-lining white Feathers in particular, may therefore have important consequences for reproductive success of birds. The reduced eggshell bacterial loads of experimental white nests would explain preferences by barn swallows for Feathers of white colour.
Juan Manuel Peraltasanchez - One of the best experts on this subject based on the ideXlab platform.
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eggshell bacterial load is related to antimicrobial properties of Feathers lining barn swallow nests
Microbial Ecology, 2014Co-Authors: Juan Manuel Peraltasanchez, Juan José Soler, Antonio M Martinplatero, Rob Knight, Manuel Martinezbueno, Anders Pape MøllerAbstract:The use of Feathers to line bird’s nests has traditionally been interpreted as having a thermoregulatory function. Feather-degrading bacteria growing on Feathers lining nests may have antimicrobial properties, which may provide an additional benefit to lining nests with Feathers. We test the hypothesis that the production of antimicrobial substances by feather bacteria affects the microbiological environment of the nest, and therefore the bacterial density on eggshells and, indirectly, hatching success. These effects would be expected to differ between nests lined with pigmented and white Feathers, because bacteria grow differently on Feathers of different colors. We experimentally manipulated the composition of pigmented and unpigmented Feathers in nests of the barn swallow (Hirundo rustica) and studied the antimicrobial properties against the keratin-degrading bacterium Bacillus licheniformis of bacteria isolated from Feathers of each color. Analyzed Feathers were collected at the end of the incubation period, and antimicrobial activity was defined as the proportion of bacteria from the Feathers that produce antibacterial substances effective against B. licheniformis. Our experimental manipulation affected antimicrobial activity, which was higher in nests with only white Feathers at the beginning of incubation. Moreover, white Feathers showed higher antimicrobial activity than black ones. Interestingly, antimicrobial activity in Feathers of one of the colors correlated negatively with bacterial density on feather of the opposite color. Finally, antimicrobial activity of white Feathers was negatively related to eggshell bacterial load. These results suggest that antimicrobial properties of Feathers in general and of white Feathers in particular affect the bacterial environment in nests. This environment in turn affects the bacterial load on eggshells, which may affect hatching success.
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colour composition of nest lining Feathers affects hatching success of barn swallows hirundo rustica passeriformes hirundinidae
Biological Journal of The Linnean Society, 2011Co-Authors: Juan José Soler, Anders Pape Møller, Juan Manuel PeraltasanchezAbstract:Many bird species use Feathers as lining material, and its functionality has traditionally been linked to nest insulation. However, nest lining Feathers may also influence nest detection by predators, differentially affect reproductive investment of mates in a post-mating sexual selection process, and affect the bacterial community of the nest environment. Most of these functions of nest lining Feathers could affect hatching success, but the effect might vary depending on feather coloration (i.e. pigmented versus white Feathers). This would be the case if coloration is related to: (1) thermoregulatory properties; (2) attractiveness of Feathers in the nest for mates; (3) eggshell bacterial density. All of these hypothetical scenarios predict that Feathers of different colours would differentially affect the hatching success of birds, and that birds should preferentially choose the most beneficial feather colour for lining their nests. Results from two different experiments performed with a population of Danish barn swallow, Hirundo rustica, were in accordance with these predictions. First, H. rustica preferentially selected white experimentally offered Feathers for lining their nests. Second, the experimental manipulation of the feather colour composition of nests of H. rustica had a significant effect on hatching success. Experimental nests with more white Feathers added at the beginning of incubation had a lower probability of hatching failures, suggesting differential beneficial effects of lining nests with Feathers of this colour. We discuss the relative importance of hypothetical functional scenarios that predicted the detected associations, including those related to sexual selection or to the community of microorganisms associated with Feathers of different colours. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102, 67–74.
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number and colour composition of nest lining Feathers predict eggshell bacterial community in barn swallow nests an experimental study
Functional Ecology, 2010Co-Authors: Juan Manuel Peraltasanchez, Anders Pape Møller, Antonio M Martinplatero, Juan José SolerAbstract:Summary 1. The use of Feathers as nest lining material has traditionally been explained by the thermoregulatory properties of Feathers. Feather nest lining could additionally affect nest detectability by predators, or play a role in a sexually selected context. Furthermore, feather nest lining harbours microorganisms that may influence environmental conditions where eggs and nestlings develop. 2. Microorganisms growing on nest lining Feathers could affect the bacterial load of eggshells because they occupy space and/or produce antimicrobial substances against other bacteria, including egg pathogens. Feathers of different colours are known to differ in their bacterial community (i.e. feather degrading bacteria) and, thus, colour composition of nest lining feather could also affect the bacterial environment of avian nests. 3. Here we tested this hypothesis in the barn shallow (Hirundo rustica) by exploring the relationship between eggshell bacterial loads and number of Feathers, and the effect of experimentally modified colour composition of nest lining Feathers on eggshell bacterial load. 4. In agreement with the hypothesis we found that, before treatment, the number of nest lining Feathers (mainly that of unpigmented-white colour) predicted eggshell bacterial load, and that, at the end of the incubation period, eggshells of experimental nests with white Feathers had a lower bacterial density than those in experimental nests with black Feathers. 5. We failed to detect a relationship between bacterial load and hatching success. However, since evidence of that relationship exists for other species, these results would explain the previously detected experimental effect of colour composition of nest lining Feathers on hatching success of swallows. 6. Nest design in general, and the use of nest-lining white Feathers in particular, may therefore have important consequences for reproductive success of birds. The reduced eggshell bacterial loads of experimental white nests would explain preferences by barn swallows for Feathers of white colour.
Richard O. Prum - One of the best experts on this subject based on the ideXlab platform.
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barb geometry of asymmetrical Feathers reveals a transitional morphology in the evolution of avian flight
Proceedings of The Royal Society B: Biological Sciences, 2015Co-Authors: Teresa J. Feo, Daniel J Field, Richard O. PrumAbstract:The geometry of feather barbs (barb length and barb angle) determines feather vane asymmetry and vane rigidity, which are both critical to a feather's aerodynamic performance. Here, we describe the relationship between barb geometry and aerodynamic function across the evolutionary history of asymmetrical flight Feathers, from Mesozoic taxa outside of modern avian diversity (Microraptor, Archaeopteryx, Sapeornis, Confuciusornis and the enantiornithine Eopengornis) to an extensive sample of modern birds. Contrary to previous assumptions, we find that barb angle is not related to vane-width asymmetry; instead barb angle varies with vane function, whereas barb length variation determines vane asymmetry. We demonstrate that barb geometry significantly differs among functionally distinct portions of flight feather vanes, and that cutting-edge leading vanes occupy a distinct region of morphospace characterized by small barb angles. This cutting-edge vane morphology is ubiquitous across a phylogenetically and functionally diverse sample of modern birds and Mesozoic stem birds, revealing a fundamental aerodynamic adaptation that has persisted from the Late Jurassic. However, in Mesozoic taxa stemward of Ornithurae and Enantiornithes, trailing vane barb geometry is distinctly different from that of modern birds. In both modern birds and enantiornithines, trailing vanes have larger barb angles than in comparatively stemward taxa like Archaeopteryx, which exhibit small trailing vane barb angles. This discovery reveals a previously unrecognized evolutionary transition in flight feather morphology, which has important implications for the flight capacity of early feathered theropods such as Archaeopteryx and Microraptor. Our findings suggest that the fully modern avian flight feather, and possibly a modern capacity for powered flight, evolved crownward of Confuciusornis, long after the origin of asymmetrical flight Feathers, and much later than previously recognized.
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Structural resonance and mode of flutter of hummingbird tail Feathers
Journal of Experimental Biology, 2013Co-Authors: Christopher J. Clark, Damian O. Elias, Madeline B. Girard, Richard O. PrumAbstract:Feathers can produce sound by fluttering in airflow. This flutter is hypothesized to be aeroelastic, arising from the coupling of aerodynamic forces to one or more of the feather's intrinsic structural resonance frequencies. We investigated how mode of flutter varied among a sample of hummingbird tail Feathers tested in a wind tunnel. Feather vibration was measured directly at ~100 points across the surface of the feather with a scanning laser Doppler vibrometer (SLDV), as a function of airspeed, U air. Most Feathers exhibited multiple discrete modes of flutter, which we classified into types including tip, trailing vane and torsional modes. Vibratory behavior within a given mode was usually stable, but changes in independent variables such as airspeed or orientation sometimes caused Feathers to abruptly ‘jump’ from one mode to another. We measured structural resonance frequencies and mode shapes directly by measuring the free response of 64 Feathers stimulated with a shaker and recorded with the SLDV. As predicted by the aeroelastic flutter hypothesis, the mode shape (spatial distribution) of flutter corresponded to a bending or torsional structural resonance frequency of the feather. However, the match between structural resonance mode and flutter mode was better for tip or torsional mode shapes, and poorer for trailing vane modes. Often, the 3rd bending structural harmonic matched the expressed mode of flutter, rather than the fundamental. We conclude that flutter occurs when airflow excites one or more structural resonance frequencies of a feather, most akin to a vibrating violin string. * f : frequency L : characteristic length (e.g. aerodynamic chord) PSD : power spectral density, mass specific R1–5 : tail Feathers (rectrices): R1, innermost; R5, outermost SLDV : scanning laser Doppler vibrometer t : feather vane thickness U air : airspeed U * : critical airspeed at which aerodynamic energy exceeds damping, and the feather enters limit-cycle flutter α : angle of attack: angle of the feather relative to airflow, corresponding to rotation about the feather's longitudinal ( Y )-axis. β : sweep angle: angle of the feather relative to airflow, corresponding to rotation about the Z -axis, perpendicular to the plane of the feather vane
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Structural resonance and mode of flutter of hummingbird tail Feathers.
The Journal of experimental biology, 2013Co-Authors: Christopher J. Clark, Damian O. Elias, Madeline B. Girard, Richard O. PrumAbstract:Feathers can produce sound by fluttering in airflow. This flutter is hypothesized to be aeroelastic, arising from the coupling of aerodynamic forces to one or more of the feather's intrinsic structural resonance frequencies. We investigated how mode of flutter varied among a sample of hummingbird tail Feathers tested in a wind tunnel. Feather vibration was measured directly at ~100 points across the surface of the feather with a scanning laser Doppler vibrometer (SLDV), as a function of airspeed, Uair. Most Feathers exhibited multiple discrete modes of flutter, which we classified into types including tip, trailing vane and torsional modes. Vibratory behavior within a given mode was usually stable, but changes in independent variables such as airspeed or orientation sometimes caused Feathers to abruptly 'jump' from one mode to another. We measured structural resonance frequencies and mode shapes directly by measuring the free response of 64 Feathers stimulated with a shaker and recorded with the SLDV. As predicted by the aeroelastic flutter hypothesis, the mode shape (spatial distribution) of flutter corresponded to a bending or torsional structural resonance frequency of the feather. However, the match between structural resonance mode and flutter mode was better for tip or torsional mode shapes, and poorer for trailing vane modes. Often, the 3rd bending structural harmonic matched the expressed mode of flutter, rather than the fundamental. We conclude that flutter occurs when airflow excites one or more structural resonance frequencies of a feather, most akin to a vibrating violin string.
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The colour of fossil Feathers
Biology letters, 2008Co-Authors: Jakob Vinther, Richard O. Prum, Derek E. G. Briggs, Vinodkumar SaranathanAbstract:Feathers are complex integumentary appendages of birds and some other theropod dinosaurs. They are frequently coloured and function in camouflage and display. Previous investigations have concluded that fossil Feathers are preserved as carbonized traces composed of feather-degrading bacteria. Here, an investigation of a colour-banded feather from the Lower Cretaceous Crato Formation of Brazil revealed that the dark bands are preserved as elongate, oblate carbonaceous bodies 1–2 μm long, whereas the light bands retain only relief traces on the rock matrix. Energy dispersive X-ray analysis showed that the dark bands preserve a substantial amount of carbon, whereas the light bands show no carbon residue. Comparison of these oblate fossil bodies with the structure of black Feathers from a living bird indicates that they are the eumelanin-containing melanosomes. We conclude that most fossil Feathers are preserved as melanosomes, and that the distribution of these structures in fossil Feathers can preserve the colour pattern in the original feather. The discovery of preserved melanosomes opens up the possibility of interpreting the colour of extinct birds and other dinosaurs.
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Evolution of the morphological innovations of Feathers
Journal of experimental zoology. Part B Molecular and developmental evolution, 2005Co-Authors: Richard O. PrumAbstract:Feathers are complex assemblages of multiple morphological innovations. Recent research on the development and evolution of Feathers has produced new insights into the origin and diversification of the morphological innovations in Feathers. In this article, I review and discuss the contribution of three different factors to the evolution of morphological innovations in Feathers: feather tubularity, hierarchical morphological modularity, and the co-option molecular signaling modules. The developing feather germ is a tube of epidermis with a central dermal pulp. The tubular organization of the feather germ and follicle produces multiple axes over which morphological differentiation can be organized. Feather complexity is organized into a hierarchy of morphological modules. These morphological modules evolved through the innovative differentiation along multiple different morphological axes created by the tubular feather germ. Concurrently, many of the morphological innovations of Feathers evolved through the evolutionary co-option of plesiomorphic molecular signaling modules. Gene co-option also reveals a role for contingency in the evolution of hierarchical morphological innovations. J. Exp. Zool. (Mol. Dev. Evol.) 304B:570-579, 2005. r 2005 Wiley-Liss, Inc.
