Morphometric characterisation of wing feathers of the barn owl Tyto alba pratincola and the pigeon Columba livia
Thomas Bachmann,Stephan Klän,Werner Baumgartner,Michael Klaas,Wolfgang Schröder,Hermann Wagner +5 more
TLDR
The quantitative description of the feathers and the specific structures of owl feathers can be used as a model for the construction of a biomimetic airplane wing or, in general, as a source for noise-reducing applications on any surfaces subjected to flow fields.Abstract:
Owls are known for their silent flight. Even though there is some information available on the mechanisms that lead to a reduction of noise emission, neither the morphological basis, nor the biological mechanisms of the owl's silent flight are known. Therefore, we have initiated a systematic analysis of wing morphology in both a specialist, the barn owl, and a generalist, the pigeon. This report presents a comparison between the feathers of the barn owl and the pigeon and emphasise the specific characteristics of the owl's feathers on macroscopic and microscopic level. An understanding of the features and mechanisms underlying this silent flight might eventually be employed for aerodynamic purposes and lead to a new wing design in modern aircrafts. A variety of different feathers (six remiges and six coverts), taken from several specimen in either species, were investigated. Quantitative analysis of digital images and scanning electron microscopy were used for a morphometric characterisation. Although both species have comparable body weights, barn owl feathers were in general larger than pigeon feathers. For both species, the depth and the area of the outer vanes of the remiges were typically smaller than those of the inner vanes. This difference was more pronounced in the barn owl than in the pigeon. Owl feathers also had lesser radiates, longer pennula, and were more translucent than pigeon feathers. The two species achieved smooth edges and regular surfaces of the vanes by different construction principles: while the angles of attachment to the rachis and the length of the barbs was nearly constant for the barn owl, these parameters varied in the pigeon. We also present a quantitative description of several characteristic features of barn owl feathers, e.g., the serrations at the leading edge of the wing, the fringes at the edges of each feather, and the velvet-like dorsal surface. The quantitative description of the feathers and the specific structures of owl feathers can be used as a model for the construction of a biomimetic airplane wing or, in general, as a source for noise-reducing applications on any surfaces subjected to flow fields.read more
Citations
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Silent Owl Flight: Bird Flyover Noise Measurements
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References
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Journal ArticleDOI
Acoustic location of prey by barn owls (Tyto alba).
TL;DR: A theory is presented to explain how a barn owl might locate the position of a sound source by moving its head until the intensity of all frequencies comprising a complex sound is brought to a maximum in both ears.
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Avian wingtip shape reconsidered: wingtip shape indices and morphological adaptations to migration
TL;DR: Two novel measures of avian wingtip shape, pointedness C2 and convexity C3, are derived, based on measurements of primary feather lengths, which confirm that migrants have wingtips that are relatively more pointed and more convex; they also have wings of relatively larger aspect ratio.
Journal ArticleDOI
How swifts control their glide performance with morphing wings
David Lentink,Ulrike K. Müller,Eize Stamhuis,R. de Kat,W. van Gestel,Leo Veldhuis,Per Henningsson,Anders Hedenström,John J. Videler,John J. Videler,J.L. van Leeuwen +10 more
TL;DR: In this article, the authors describe the aerodynamic and structural performance of actual swift wings, as measured in a wind tunnel, and on this basis build a semi-empirical glide model.
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Coding of auditory space.
TL;DR: Owls can localize sounds by using either the isomorphic map of auditory space in the midbrain or forebrain neural networks in which space is not mapped.
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How the Owl Tracks Its Prey
TL;DR: Author Masakazu Konishi describes clever and elegant experimentation to discover owls' binaural hearing, while including beautiful infrared photography of owl flight.