A songbird compensates for wing molt during escape flights by reducing the molt gap and increasing angle of attack

Barbara M. Tomotani, Florian T. Muijres

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

During molt, birds replace their feathers to retain feather quality and maintain flight performance. However, wing gaps inherent of this process can also reduce flight capacities, which could be detrimental when foraging or escaping predators. Still, many bird species will not cease their normal activities when molting. In this study, we investigated whether and how birds adjust their escape flight behavior to compensate for the reduction in performance when flying with wing gaps. Using stereoscopic high-speed videography, we filmed 146 upward-directed escape flights of 19 and 22 pied flycatchers (Ficedula hypoleuca) with and without simulated molt gaps, respectively. We then reconstructed the three-dimensional body and wing movements throughout each maneuver. By comparing flights with and without gaps, we determined how wing molt gaps affected wing morphology and escape flight performance, and how the birds adjusted their flight kinematics in order to negate possible negative aerodynamic effects. Our manipulations resulted in a lower second moment of area of the wings, but flight speed and net aerodynamic force production did not differ between the two groups. We found that in manipulated birds, the size of the gap was reduced as the flight feathers adjacent to the gap had moved towards each other. Moreover, the experimental decrease in second moment of area was associated with an increase in angle of attack, whereas changes in wingbeat-induced speeds were associated with variations in aerodynamic force production. This suggests that the control of escape flight in molting birds might be modular, allowing relatively simple flight control, thus reducing the burden on the neuro-muscular flight control system.
LanguageEnglish
Article numberjeb195396
Number of pages11
JournalThe Journal of experimental biology
Volume222
Issue number10
DOIs
Publication statusPublished - 28 May 2019

Fingerprint

Songbirds
songbird
songbirds
molt
Birds
molting
flight
Feathers
Molting
bird
feather
birds
aerodynamics
feathers
Biomechanical Phenomena
wing morphology
videography
flight behavior
escape behavior
control system

Cite this

@article{b2a7dbe7cd1146e3b47813084cfd7fa3,
title = "A songbird compensates for wing molt during escape flights by reducing the molt gap and increasing angle of attack",
abstract = "During molt, birds replace their feathers to retain feather quality and maintain flight performance. However, wing gaps inherent of this process can also reduce flight capacities, which could be detrimental when foraging or escaping predators. Still, many bird species will not cease their normal activities when molting. In this study, we investigated whether and how birds adjust their escape flight behavior to compensate for the reduction in performance when flying with wing gaps. Using stereoscopic high-speed videography, we filmed 146 upward-directed escape flights of 19 and 22 pied flycatchers (Ficedula hypoleuca) with and without simulated molt gaps, respectively. We then reconstructed the three-dimensional body and wing movements throughout each maneuver. By comparing flights with and without gaps, we determined how wing molt gaps affected wing morphology and escape flight performance, and how the birds adjusted their flight kinematics in order to negate possible negative aerodynamic effects. Our manipulations resulted in a lower second moment of area of the wings, but flight speed and net aerodynamic force production did not differ between the two groups. We found that in manipulated birds, the size of the gap was reduced as the flight feathers adjacent to the gap had moved towards each other. Moreover, the experimental decrease in second moment of area was associated with an increase in angle of attack, whereas changes in wingbeat-induced speeds were associated with variations in aerodynamic force production. This suggests that the control of escape flight in molting birds might be modular, allowing relatively simple flight control, thus reducing the burden on the neuro-muscular flight control system.",
author = "Tomotani, {Barbara M.} and Muijres, {Florian T.}",
year = "2019",
month = "5",
day = "28",
doi = "10.1242/jeb.195396",
language = "English",
volume = "222",
journal = "Journal of Experimental Biology",
issn = "0022-0949",
publisher = "Company of Biologists",
number = "10",

}

A songbird compensates for wing molt during escape flights by reducing the molt gap and increasing angle of attack. / Tomotani, Barbara M.; Muijres, Florian T.

In: The Journal of experimental biology, Vol. 222, No. 10, jeb195396, 28.05.2019.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - A songbird compensates for wing molt during escape flights by reducing the molt gap and increasing angle of attack

AU - Tomotani, Barbara M.

AU - Muijres, Florian T.

PY - 2019/5/28

Y1 - 2019/5/28

N2 - During molt, birds replace their feathers to retain feather quality and maintain flight performance. However, wing gaps inherent of this process can also reduce flight capacities, which could be detrimental when foraging or escaping predators. Still, many bird species will not cease their normal activities when molting. In this study, we investigated whether and how birds adjust their escape flight behavior to compensate for the reduction in performance when flying with wing gaps. Using stereoscopic high-speed videography, we filmed 146 upward-directed escape flights of 19 and 22 pied flycatchers (Ficedula hypoleuca) with and without simulated molt gaps, respectively. We then reconstructed the three-dimensional body and wing movements throughout each maneuver. By comparing flights with and without gaps, we determined how wing molt gaps affected wing morphology and escape flight performance, and how the birds adjusted their flight kinematics in order to negate possible negative aerodynamic effects. Our manipulations resulted in a lower second moment of area of the wings, but flight speed and net aerodynamic force production did not differ between the two groups. We found that in manipulated birds, the size of the gap was reduced as the flight feathers adjacent to the gap had moved towards each other. Moreover, the experimental decrease in second moment of area was associated with an increase in angle of attack, whereas changes in wingbeat-induced speeds were associated with variations in aerodynamic force production. This suggests that the control of escape flight in molting birds might be modular, allowing relatively simple flight control, thus reducing the burden on the neuro-muscular flight control system.

AB - During molt, birds replace their feathers to retain feather quality and maintain flight performance. However, wing gaps inherent of this process can also reduce flight capacities, which could be detrimental when foraging or escaping predators. Still, many bird species will not cease their normal activities when molting. In this study, we investigated whether and how birds adjust their escape flight behavior to compensate for the reduction in performance when flying with wing gaps. Using stereoscopic high-speed videography, we filmed 146 upward-directed escape flights of 19 and 22 pied flycatchers (Ficedula hypoleuca) with and without simulated molt gaps, respectively. We then reconstructed the three-dimensional body and wing movements throughout each maneuver. By comparing flights with and without gaps, we determined how wing molt gaps affected wing morphology and escape flight performance, and how the birds adjusted their flight kinematics in order to negate possible negative aerodynamic effects. Our manipulations resulted in a lower second moment of area of the wings, but flight speed and net aerodynamic force production did not differ between the two groups. We found that in manipulated birds, the size of the gap was reduced as the flight feathers adjacent to the gap had moved towards each other. Moreover, the experimental decrease in second moment of area was associated with an increase in angle of attack, whereas changes in wingbeat-induced speeds were associated with variations in aerodynamic force production. This suggests that the control of escape flight in molting birds might be modular, allowing relatively simple flight control, thus reducing the burden on the neuro-muscular flight control system.

U2 - 10.1242/jeb.195396

DO - 10.1242/jeb.195396

M3 - Article

VL - 222

JO - Journal of Experimental Biology

T2 - Journal of Experimental Biology

JF - Journal of Experimental Biology

SN - 0022-0949

IS - 10

M1 - jeb195396

ER -