Dataset Information

The dusk chorus from an owl perspective: eagle owls vocalize when their white throat badge contrasts most.

ABSTRACT: BACKGROUND: An impressive number of studies have investigated bird vocal displays, and many of them have tried to explain the widespread phenomenon of the so-called dawn and dusk chorus, the sunrise and sunset peaks in bird song output. As many as twelve non-exclusive hypotheses have been proposed to explain why twilight peaks in vocal display might be advantageous; but, even after more than two decades of study, the basis underlying the dusk and dawn chorus is still unclear. Moreover, to date, the majority of studies on this topic have focused on songbirds. METHODOLOGY/PRINCIPAL FINDINGS: We investigate here a novel hypothesis on why nocturnal birds with patches of white feathers call at twilight. We propose that white plumage patches and the timing of visual signaling have co-evolved to maximize the effectiveness of social communication such as the dusk chorus. This hypothesis centers on the recent discovery that eagle owls can adopt specific forms of visual signaling and is supported by the observation that adult eagle owls possess a white throat badge that is only visible during vocal displays. By monitoring the calling of eagle owls at dusk, a peak time for bird call output, we found that white throat badges contrasted most with the surrounding background during the owls' twilight chorusing. CONCLUSIONS/SIGNIFICANCE: Crepuscular and nocturnal species appear to have evolved white patches that, shown in association with vocal displays, allow them to communicate in dark surroundings. The evolution of a white badge that operates jointly with call displays at dawn and dusk may be relevant to the eagle owls' social dynamics. Our explanation for the dusk chorus may possibly represent an overlooked but common pattern of signaling among crepuscular and nocturnal birds that combine patches of white feathers with twilight displays. Furthermore, our findings could be relevant to songbirds that breed in dark forest habitats and have contrasting white badges, as well as birds living in open habitats and showing contrasting bars.

SUBMITTER: Penteriani V

PROVIDER: S-EPMC2662407 | biostudies-literature | 2009

REPOSITORIES: biostudies-literature

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The dusk chorus from an owl perspective: eagle owls vocalize when their white throat badge contrasts most.

Penteriani Vincenzo V Delgado Maria del Mar Mdel M

PloS one 20090408 4

<h4>Background</h4>An impressive number of studies have investigated bird vocal displays, and many of them have tried to explain the widespread phenomenon of the so-called dawn and dusk chorus, the sunrise and sunset peaks in bird song output. As many as twelve non-exclusive hypotheses have been proposed to explain why twilight peaks in vocal display might be advantageous; but, even after more than two decades of study, the basis underlying the dusk and dawn chorus is still unclear. Moreover, to ...[more]

PMID: 19352433

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Project description:BACKGROUND:Capillary electrophoresis of plasma proteins has shown great potential as a complementary diagnostic tool for avian species. However, reference intervals for plasma proteins are sparse or lacking for several free-living avian species. The current study reports electrophoretic patterns and concentrations of plasma proteins determined for 70 free-living white-tailed eagle (Haliaeetus albicilla) nestlings from two locations in Norway (Steigen and Smøla) in order to establish reference values for this subpopulation using capillary electrophoresis. The nestlings were between 44 and 87 days of age, and the plasma protein concentrations were investigated for age, sex, year (2015 and 2016) and location differences. To our knowledge, this is the first report of reference intervals of plasma proteins analysed by capillary electrophoresis in free-living white-tailed eagle nestlings. RESULTS:The plasma protein concentrations (% of total protein, mean ± SE) were determined for prealbumin (13.7%, 4.34 ± 0.15 g/L), albumin (46.7%, 14.81 ± 0.24 g/L), α1-globulin (2.4%, 0.74 ± 0.03 g/L), α2-globulin (11.7%, 3.72 ± 0.06 g/L), β-globulin (15.9%, 5.06 ± 0.08 g/L) and γ-globulin (9.6%, 3.05 ± 0.09 g/L). Significant differences were found between the two locations for prealbumin, α2- and γ-globulins. No significant differences were found between the two sampling years or sexes, and no effect of age was found for any of the plasma proteins. However, prealbumin levels were several folds higher than previously reported from adults of closely related birds of prey species. There were no other studies on capillary electrophoresis of nestling plasma available for comparison. CONCLUSION:Significant differences were found between sampling locations for prealbumin, α2- and γ-globulins, which may indicate differences in inflammatory or infectious status between nestlings at the two locations. Sampling year, sex or age had no significant effect on the plasma protein concentrations. These results provide novel data on plasma protein concentrations by capillary electrophoresis and may be useful for evaluation of health status in free-living white-tailed eagle nestlings.

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Dataset Information

The dusk chorus from an owl perspective: eagle owls vocalize when their white throat badge contrasts most.

Publications

The dusk chorus from an owl perspective: eagle owls vocalize when their white throat badge contrasts most.

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