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Morphometric characterisation of wing feathers of the barn owl Tyto alba pratincola and the pigeon Columba livia.

Bachmann T, Klän S, Baumgartner W, Klaas M, Schröder W, Wagner H - Front. Zool. (2007)

Bottom Line: 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.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: RWTH Aachen University, Institute of Biology II, Aachen, Germany. bachmann@bio2.rwth-aachen.de.

ABSTRACT

Background: 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.

Results: 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.

Conclusion: 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.

No MeSH data available.


Feather position and measured feather parameters. (A) Position of the investigated feathers in the barn owl (left) and the pigeon (right); scale bar: 10 cm. (B) Investigated parameters on the flight feather (p5 of a barn owl). Measurements were taken every 10% of feather length. (C) Scanning electron microscopy pictures of two connected barbs at 60% of the inner vane of feather p10 of the barn owl (above) and the pigeon (below) from dorsal (left) and ventral (right) view (bs: barb shaft, hr: hook radiate, br: bow radiate, p: pennulum, h: hooklet); scale bar 200 μm. (D) Investigated barb parameters.
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Figure 1: Feather position and measured feather parameters. (A) Position of the investigated feathers in the barn owl (left) and the pigeon (right); scale bar: 10 cm. (B) Investigated parameters on the flight feather (p5 of a barn owl). Measurements were taken every 10% of feather length. (C) Scanning electron microscopy pictures of two connected barbs at 60% of the inner vane of feather p10 of the barn owl (above) and the pigeon (below) from dorsal (left) and ventral (right) view (bs: barb shaft, hr: hook radiate, br: bow radiate, p: pennulum, h: hooklet); scale bar 200 μm. (D) Investigated barb parameters.

Mentions: The wing feathers can be divided into remiges (or flight feathers) and coverts. Furthermore, both types of feathers can be subdivided into primaries and secondaries. This nomenclature is commonly used [20] and will be used here to describe the position of the feathers on the wing (Fig. 1A).


Morphometric characterisation of wing feathers of the barn owl Tyto alba pratincola and the pigeon Columba livia.

Bachmann T, Klän S, Baumgartner W, Klaas M, Schröder W, Wagner H - Front. Zool. (2007)

Feather position and measured feather parameters. (A) Position of the investigated feathers in the barn owl (left) and the pigeon (right); scale bar: 10 cm. (B) Investigated parameters on the flight feather (p5 of a barn owl). Measurements were taken every 10% of feather length. (C) Scanning electron microscopy pictures of two connected barbs at 60% of the inner vane of feather p10 of the barn owl (above) and the pigeon (below) from dorsal (left) and ventral (right) view (bs: barb shaft, hr: hook radiate, br: bow radiate, p: pennulum, h: hooklet); scale bar 200 μm. (D) Investigated barb parameters.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2211483&req=5

Figure 1: Feather position and measured feather parameters. (A) Position of the investigated feathers in the barn owl (left) and the pigeon (right); scale bar: 10 cm. (B) Investigated parameters on the flight feather (p5 of a barn owl). Measurements were taken every 10% of feather length. (C) Scanning electron microscopy pictures of two connected barbs at 60% of the inner vane of feather p10 of the barn owl (above) and the pigeon (below) from dorsal (left) and ventral (right) view (bs: barb shaft, hr: hook radiate, br: bow radiate, p: pennulum, h: hooklet); scale bar 200 μm. (D) Investigated barb parameters.
Mentions: The wing feathers can be divided into remiges (or flight feathers) and coverts. Furthermore, both types of feathers can be subdivided into primaries and secondaries. This nomenclature is commonly used [20] and will be used here to describe the position of the feathers on the wing (Fig. 1A).

Bottom Line: 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.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: RWTH Aachen University, Institute of Biology II, Aachen, Germany. bachmann@bio2.rwth-aachen.de.

ABSTRACT

Background: 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.

Results: 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.

Conclusion: 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.

No MeSH data available.