page_title: Wing-assisted incline running
section_title: WAIR in living birds
hierarchical_section_title: Wing-assisted incline running / WAIR in living birds
caption_attribution_description: English: Chukar Partridge or Chukar (Alectoris chukar) - Hawaii
context_page_description: Wing-assisted incline running 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. During its proposal, it was suggested that WAIR might have plausibly been used by feathered theropods like Caudipteryx to develop aerial flight.
context_section_description: Wing-assisted incline running has been studied extensively in chicks of the chukar partridge (Alectoris chukar), and has been observed in juveniles and adults of other species of Galliformes as well as the rock dove (Columba livia). 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. 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. 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°). In rock doves, adults employ WAIR at angles greater than 65°.
caption: An adult chukar running on a horizontal plane
exif: {"Image Make": "Canon", "Image Model": "Canon EOS DIGITAL REBEL XTi", "Image Orientation": "Horizontal (normal)", "Image XResolution": "350", "Image YResolution": "350", "Image ResolutionUnit": "Pixels/Inch", "Image Software": "Adobe Photoshop Elements 10.0 Macintosh", "Image DateTime": "2012:03:24 12:25:11", "Image YCbCrPositioning": "Centered", "Image ExifOffset": "244", "Thumbnail Compression": "JPEG (old-style)", "Thumbnail XResolution": "72", "Thumbnail YResolution": "72", "Thumbnail ResolutionUnit": "Pixels/Inch", "Thumbnail JPEGInterchangeFormat": "1082", "Thumbnail JPEGInterchangeFormatLength": "12845", "EXIF ExposureTime": "1/500", "EXIF FNumber": "8", "EXIF ExposureProgram": "Program Normal", "EXIF ISOSpeedRatings": "200", "EXIF ExifVersion": "0220", "EXIF DateTimeOriginal": "2009:05:29 13:32:18", "EXIF DateTimeDigitized": "2009:05:29 13:32:18", "EXIF ComponentsConfiguration": "YCbCr", "EXIF ShutterSpeedValue": "293791/32768", "EXIF ApertureValue": "6", "EXIF ExposureBiasValue": "0", "EXIF MeteringMode": "Pattern", "EXIF Flash": "Flash did not fire, compulsory flash mode", "EXIF FocalLength": "400", "EXIF SubSecTime": "704", "EXIF FlashPixVersion": "0100", "EXIF ColorSpace": "sRGB", "EXIF ExifImageWidth": "2400", "EXIF ExifImageLength": "1800", "Interoperability InteroperabilityIndex": "R98", "Interoperability InteroperabilityVersion": "[48, 49, 48, 48]", "EXIF InteroperabilityOffset": "956", "EXIF FocalPlaneXResolution": "3888000/877", "EXIF FocalPlaneYResolution": "432000/97", "EXIF FocalPlaneResolutionUnit": "2", "EXIF CustomRendered": "Normal", "EXIF ExposureMode": "Auto Exposure", "EXIF WhiteBalance": "Auto", "EXIF SceneCaptureType": "Standard"}