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Wing-assisted incline running

December 15, 2023

Wing-assisted incline running (abbreviated as "WAIR") is a running behavior observed in living birds as well as a model proposed to explain the evolution of avian flight. WAIR allows birds to run up steep or vertical inclines by flapping their wings, scaling greater inclines than possible through running alone. The WAIR origin-of-flight hypothesis proposes that the nascent wings of theropod dinosaurs were used to propel the animal up slopes, such as cliffs or trees, in a similar manner to that employed by modern birds, and that powered flight eventually evolved from this usage.[1] During its proposal, it was suggested that WAIR might have plausibly been used by feathered theropods like Caudipteryx to develop aerial flight.[2]

WAIR in living birds edit

 
An adult chukar running on a horizontal plane

Wing-assisted incline running has been studied extensively in chicks of the chukar partridge (Alectoris chukar),[2][3][4] and has been observed in juveniles and adults of other species of Galliformes as well as the rock dove (Columba livia).[5] In chukar chicks, WAIR was experimentally demonstrated by comparing maximum inclines ascended by normal chicks to those with wing feathers trimmed or plucked entirely. On both smooth and rough surfaces, normal chicks were able to run up much steeper slopes than the other two groups, reaching maximum angles of 105° from the horizontal. Chicks used running alone at slopes up to 45°, then employed wing-flapping at greater slopes, and maximum slope successfully scaled increased with age.[2] When baby chukars hatch, they have not yet developed their flight feathers. As the babies develop, it takes approximately one week for feathers to appear, and about three weeks for the ability to fly. As the baby chukars grow and before flying for the first time, they use WAIR as a transition to adult flight.[4] WAIR has also been studied in the Australian brushturkey (Alectura lathami), although maximum slope decreased with age, such that hatchlings could scale greater slopes (up to 110°) than adults (up to 70°).[6] In rock doves, adults employ WAIR at angles greater than 65°.[5]

Explanation of using WAIR over normal flight edit

These galliformes might use WAIR instead of normal flight to reach tree branches because WAIR uses less energy than normal flight. Fewer muscles are used in the process of WAIR than normal flight, specifically pectoral and shoulder muscles which contribute to wing flapping.[5] This provides an additional explanation as to why birds continue to use WAIR: it is faster than normal flight take-off, and running requires less energy than does flying. Therefore; the hindlimbs, in conjunction with the wings, may produce quick bouts of energy which may allow the bird to catch prey.[7] This strategy also allows energy to be stored for use in a fight-or-flight situation such as to escape becoming eaten or caught.[5][6] WAIR imposes less aerodynamic and physical forces than normal avian flight on the bird, an advantageous trait which may increase fitness.[6] WAIR could have been used for balance purposes.[3] Many theories propose that the manifestation of WAIR in birds is for predatory escape purposes, in that they are able to run up extremely steep and past vertical slopes (such as the trunk of a tree) to escape from a ground-dwelling predator.[3][5] Another reason for the manifestation of WAIR may be for dispersal or to find food or resources, but this idea is mostly proposed as a survival strategy.[7] Whether it is to evade predation, catch prey, enhance reproductive success, or simply a variation imposed for dispersal, flight among avian creatures has evolved to be a highly successful trait.

Origin of flight hypothesis edit

The WAIR hypothesis for the origin of flight is a version of the "cursorial model" of the evolution of avian flight, in which birds' wings originated from forelimb modifications that provided downforce, enabling the proto-birds to run up extremely steep slopes such as the trunks of trees. The hypothesis was prompted by the observation of living young chukar chicks using WAIR, and proposes that dinosaur wings developed their aerodynamic functions as a result of the need to run quickly up very steep slopes such as tree trunks, possibly to escape from predators.[2] Originally, it was thought that birds need downforce to give their feet increased grip in this scenario.[2][3] However, a study found lift generated from wings to be the primary factor for successfully accelerating, indicating the onset of flight ability was constrained by neuromuscular control or power rather than by the shape of the wing itself, and that partially developed wings not yet capable of flight could indeed provide useful lift during WAIR.[4] Additionally, when both the power and work needed for WAIR were examined, it was identified that the need for pectoral muscles in flight increases with the angle being scaled. Thus, WAIR is a hypothesis providing a model for an evolutionary transition from terrestrial to aerial locomotion as birds skeletally adapted to meet the requirements to scale steeper and steeper inclines by flight.[5] This might have allowed smaller, potentially juvenile maniraptorans to scale the sides of trees to escape predators that were too big to climb. WAIR may have been present in oviraptorosaurs and therizinosauroids, but as the adults, especially of therizinosauroids, would probably break the trees trying to climb, their hatchlings or chicks would have made it up easily. Because of this way to escape predation, early maniraptorans might have evolved their long arms, true feathers and fused wishbones.[8]

Response edit

One possible problem with the WAIR origin of flight hypothesis was noticed by Philip Senter. He argued that early birds, including Archaeopteryx, lacked the shoulder mechanism by which modern birds' wings produce swift, powerful upstrokes. Since the downforce on which WAIR depends is generated by upstrokes, Senter argued that early birds were incapable of WAIR or flapping flight.[9]

Evidence has been proposed against the WAIR hypothesis, stating that it is too simplistic and does not take additional information into effect. There have been additional mechanisms suggested, such as climbing claws, that would have provided an advantage for the birds, but are absent in fossil records or extant birds.[10] Other arguments against WAIR include a lack of fossil evidence and no additional intermediate or transition stages available for study which would provide supplementary evidence for WAIR.[3][7]

See also edit

References edit

  1. ^ Bicudo, J. Eduardo (May 26, 2010). Ecological and Environmental Physiology of Birds. Oxford University Press. p. 15. ISBN 978-0199228454.
  2. ^ a b c d e Dial, K.P. (2003). "Wing-Assisted Incline Running and the Evolution of Flight" (PDF). Science. 299 (5605): 402–404. Bibcode:2003Sci...299..402D. doi:10.1126/science.1078237. PMID 12532020. S2CID 40712093.
  3. ^ a b c d e Bundle, M.W & Dial, K.P. (2003). "Mechanics of wing-assisted incline running (WAIR)" (PDF). The Journal of Experimental Biology. 206 (Pt 24): 4553–4564. doi:10.1242/jeb.00673. PMID 14610039. S2CID 6323207.
  4. ^ a b c Tobalske, B. W. & Dial, K. P. (2007). "Aerodynamics of wing-assisted incline running in birds". The Journal of Experimental Biology. 210 (Pt 10): 1742–1751. doi:10.1242/jeb.001701. PMID 17488937. S2CID 18502446.
  5. ^ a b c d e f Jackson, B. E., Tobalske, B. W. and Dial, K. P. (2011). "The broad range of contractile behaviour of the avian pectoralis: functional and evolutionary implications" (Automatic PDF download). The Journal of Experimental Biology. 214 (Pt 14): 2354–2361. doi:10.1242/jeb.052829. PMID 21697427. S2CID 7496862.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  6. ^ a b c Dial, K. P.; Jackson, B. E. (2010). "When hatchlings outperform adults: locomotor development in Australian brush turkeys (Alectura lathami, Galliformes)". Proceedings of the Royal Society B: Biological Sciences. 278 (1712): 1610–1616. doi:10.1098/rspb.2010.1984. PMC 3081770. PMID 21047855.
  7. ^ a b c Dial, K. P.; Randall, R. J.; Dial, T. R. (2006). "What Use Is Half a Wing in the Ecology and Evolution of Birds?". BioScience. 56 (5): 437–445. doi:10.1641/0006-3568(2006)056[0437:WUIHAW]2.0.CO;2.
  8. ^ Holtz, T.R. Jr. (2007). "Oviraptorosaurs and Therizinosauroids (Egg-thief and sloth dinosaurs)". In Holtz, Thomas R. Jr. (ed.). Dinosaurs: The Most Complete, Up-to-date Encyclopedia for Dinosaur Lovers of All Ages. Random House Books for Young Readers. p. 149. ISBN 978-0-375-92419-4.
  9. ^ Senter, P. (2006). "Scapular orientation in theropods and basal birds, and the origin of flapping flight" (Automatic PDF download). Acta Palaeontologica Polonica. 51 (2): 305–313.
  10. ^ Nudds, Robert L.; Dyke, Gareth J. (2009). "Forelimb posture in dinosaurs and the evolution of the avian flapping flight- stroke". Evolution. 63 (4): 994–1002. doi:10.1111/j.1558-5646.2009.00613.x. PMID 19154383. S2CID 29012467.

External links edit

  • Video: Development of wing-assisted incline running in Chukars from University of Montana Flight Lab
  • Video: Phylogeny of wing-assisted incline running from University of Montana Flight Lab

December 15, 2023
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Wing assisted incline running abbreviated as WAIR is a running behavior observed in living birds as well as a model proposed to explain the evolution of avian flight WAIR allows birds to run up steep or vertical inclines by flapping their wings scaling greater inclines than possible through running alone The WAIR origin of flight hypothesis proposes that the nascent wings of theropod dinosaurs were used to propel the animal up slopes such as cliffs or trees in a similar manner to that employed by modern birds and that powered flight eventually evolved from this usage 1 During its proposal it was suggested that WAIR might have plausibly been used by feathered theropods like Caudipteryx to develop aerial flight 2 Contents 1 WAIR in living birds 1 1 Explanation of using WAIR over normal flight 2 Origin of flight hypothesis 2 1 Response 3 See also 4 References 5 External linksWAIR in living birds edit nbsp An adult chukar running on a horizontal planeWing assisted incline running has been studied extensively in chicks of the chukar partridge Alectoris chukar 2 3 4 and has been observed in juveniles and adults of other species of Galliformes as well as the rock dove Columba livia 5 In chukar chicks WAIR was experimentally demonstrated by comparing maximum inclines ascended by normal chicks to those with wing feathers trimmed or plucked entirely On both smooth and rough surfaces normal chicks were able to run up much steeper slopes than the other two groups reaching maximum angles of 105 from the horizontal Chicks used running alone at slopes up to 45 then employed wing flapping at greater slopes and maximum slope successfully scaled increased with age 2 When baby chukars hatch they have not yet developed their flight feathers As the babies develop it takes approximately one week for feathers to appear and about three weeks for the ability to fly As the baby chukars grow and before flying for the first time they use WAIR as a transition to adult flight 4 WAIR has also been studied in the Australian brushturkey Alectura lathami although maximum slope decreased with age such that hatchlings could scale greater slopes up to 110 than adults up to 70 6 In rock doves adults employ WAIR at angles greater than 65 5 Explanation of using WAIR over normal flight edit These galliformes might use WAIR instead of normal flight to reach tree branches because WAIR uses less energy than normal flight Fewer muscles are used in the process of WAIR than normal flight specifically pectoral and shoulder muscles which contribute to wing flapping 5 This provides an additional explanation as to why birds continue to use WAIR it is faster than normal flight take off and running requires less energy than does flying Therefore the hindlimbs in conjunction with the wings may produce quick bouts of energy which may allow the bird to catch prey 7 This strategy also allows energy to be stored for use in a fight or flight situation such as to escape becoming eaten or caught 5 6 WAIR imposes less aerodynamic and physical forces than normal avian flight on the bird an advantageous trait which may increase fitness 6 WAIR could have been used for balance purposes 3 Many theories propose that the manifestation of WAIR in birds is for predatory escape purposes in that they are able to run up extremely steep and past vertical slopes such as the trunk of a tree to escape from a ground dwelling predator 3 5 Another reason for the manifestation of WAIR may be for dispersal or to find food or resources but this idea is mostly proposed as a survival strategy 7 Whether it is to evade predation catch prey enhance reproductive success or simply a variation imposed for dispersal flight among avian creatures has evolved to be a highly successful trait Origin of flight hypothesis editThe WAIR hypothesis for the origin of flight is a version of the cursorial model of the evolution of avian flight in which birds wings originated from forelimb modifications that provided downforce enabling the proto birds to run up extremely steep slopes such as the trunks of trees The hypothesis was prompted by the observation of living young chukar chicks using WAIR and proposes that dinosaur wings developed their aerodynamic functions as a result of the need to run quickly up very steep slopes such as tree trunks possibly to escape from predators 2 Originally it was thought that birds need downforce to give their feet increased grip in this scenario 2 3 However a study found lift generated from wings to be the primary factor for successfully accelerating indicating the onset of flight ability was constrained by neuromuscular control or power rather than by the shape of the wing itself and that partially developed wings not yet capable of flight could indeed provide useful lift during WAIR 4 Additionally when both the power and work needed for WAIR were examined it was identified that the need for pectoral muscles in flight increases with the angle being scaled Thus WAIR is a hypothesis providing a model for an evolutionary transition from terrestrial to aerial locomotion as birds skeletally adapted to meet the requirements to scale steeper and steeper inclines by flight 5 This might have allowed smaller potentially juvenile maniraptorans to scale the sides of trees to escape predators that were too big to climb WAIR may have been present in oviraptorosaurs and therizinosauroids but as the adults especially of therizinosauroids would probably break the trees trying to climb their hatchlings or chicks would have made it up easily Because of this way to escape predation early maniraptorans might have evolved their long arms true feathers and fused wishbones 8 Response edit One possible problem with the WAIR origin of flight hypothesis was noticed by Philip Senter He argued that early birds including Archaeopteryx lacked the shoulder mechanism by which modern birds wings produce swift powerful upstrokes Since the downforce on which WAIR depends is generated by upstrokes Senter argued that early birds were incapable of WAIR or flapping flight 9 Evidence has been proposed against the WAIR hypothesis stating that it is too simplistic and does not take additional information into effect There have been additional mechanisms suggested such as climbing claws that would have provided an advantage for the birds but are absent in fossil records or extant birds 10 Other arguments against WAIR include a lack of fossil evidence and no additional intermediate or transition stages available for study which would provide supplementary evidence for WAIR 3 7 See also editFlying and gliding animals Outline of birdsReferences edit Bicudo J Eduardo May 26 2010 Ecological and Environmental Physiology of Birds Oxford University Press p 15 ISBN 978 0199228454 a b c d e Dial K P 2003 Wing Assisted Incline Running and the Evolution of Flight PDF Science 299 5605 402 404 Bibcode 2003Sci 299 402D doi 10 1126 science 1078237 PMID 12532020 S2CID 40712093 a b c d e Bundle M W amp Dial K P 2003 Mechanics of wing assisted incline running WAIR PDF The Journal of Experimental Biology 206 Pt 24 4553 4564 doi 10 1242 jeb 00673 PMID 14610039 S2CID 6323207 a b c Tobalske B W amp Dial K P 2007 Aerodynamics of wing assisted incline running in birds The Journal of Experimental Biology 210 Pt 10 1742 1751 doi 10 1242 jeb 001701 PMID 17488937 S2CID 18502446 a b c d e f Jackson B E Tobalske B W and Dial K P 2011 The broad range of contractile behaviour of the avian pectoralis functional and evolutionary implications Automatic PDF download The Journal of Experimental Biology 214 Pt 14 2354 2361 doi 10 1242 jeb 052829 PMID 21697427 S2CID 7496862 a href Template Cite journal html title Template Cite journal cite journal a CS1 maint multiple names authors list link a b c Dial K P Jackson B E 2010 When hatchlings outperform adults locomotor development in Australian brush turkeys Alectura lathami Galliformes Proceedings of the Royal Society B Biological Sciences 278 1712 1610 1616 doi 10 1098 rspb 2010 1984 PMC 3081770 PMID 21047855 a b c Dial K P Randall R J Dial T R 2006 What Use Is Half a Wing in the Ecology and Evolution of Birds BioScience 56 5 437 445 doi 10 1641 0006 3568 2006 056 0437 WUIHAW 2 0 CO 2 Holtz T R Jr 2007 Oviraptorosaurs and Therizinosauroids Egg thief and sloth dinosaurs In Holtz Thomas R Jr ed Dinosaurs The Most Complete Up to date Encyclopedia for Dinosaur Lovers of All Ages Random House Books for Young Readers p 149 ISBN 978 0 375 92419 4 Senter P 2006 Scapular orientation in theropods and basal birds and the origin of flapping flight Automatic PDF download Acta Palaeontologica Polonica 51 2 305 313 Nudds Robert L Dyke Gareth J 2009 Forelimb posture in dinosaurs and the evolution of the avian flapping flight stroke Evolution 63 4 994 1002 doi 10 1111 j 1558 5646 2009 00613 x PMID 19154383 S2CID 29012467 External links editVideo Development of wing assisted incline running in Chukars from University of Montana Flight Lab Video Phylogeny of wing assisted incline running from University of Montana Flight Lab Retrieved from https en wikipedia org w index php title Wing assisted incline running amp oldid 1175115377, wikipedia, wiki, book, books, library,

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