title: Respiratory mechanics of eleven avian species resident at high and low altitude.
abstract: The metabolic cost of breathing at rest has never been successfully measured in birds, but has been hypothesized to be higher than in mammals of a similar size because of the rocking motion of the avian sternum being encumbered by the pectoral flight muscles. To measure the cost and work of breathing, and to investigate whether species resident at high altitude exhibit morphological or mechanical changes that alter the work of breathing, we studied 11 species of waterfowl: five from high altitudes (>3000 m) in Perú, and six from low altitudes in Oregon, USA. Birds were anesthetized and mechanically ventilated in sternal recumbency with known tidal volumes and breathing frequencies. The work done by the ventilator was measured, and these values were applied to the combinations of tidal volumes and breathing frequencies used by the birds to breathe at rest. We found the respiratory system of high-altitude species to be of a similar size, but consistently more compliant than that of low-altitude sister taxa, although this did not translate to a significantly reduced work of breathing. The metabolic cost of breathing was estimated to be between 1 and 3% of basal metabolic rate, as low or lower than estimates for other groups of tetrapods.
authors.affiliation: Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, BC, Canada V6T 1Z4 york@zoology.ubc.ca.
authors.forename: Julia M
authors.identifier: 0000-0003-4947-0591
authors.initials: JM
authors.lastname: York
authors.affiliation: Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, BC, Canada V6T 1Z4.
authors.forename: Beverly A
authors.initials: BA
authors.lastname: Chua
authors.affiliation: Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON, Canada L8S 3K1.
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Ivy
authors.affiliation: Department of Biology and Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Coral Gables, FL 33146, USA.|Division of Ornithology, Centro de Ornitología y Biodiversidad - CORBIDI, Lima 33, Peru.|Institute of Arctic Biology and University of Alaska Museum, University of Alaska Fairbanks, Fairbanks, AK 99775, USA.
authors.forename: Luis
authors.initials: L
authors.lastname: Alza
authors.affiliation: Institute of Arctic Biology and University of Alaska Museum, University of Alaska Fairbanks, Fairbanks, AK 99775, USA.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Cheek
authors.affiliation: Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON, Canada L8S 3K1.
authors.forename: Graham R
authors.initials: GR
authors.lastname: Scott
authors.affiliation: Department of Biology and Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Coral Gables, FL 33146, USA.|Institute of Arctic Biology and University of Alaska Museum, University of Alaska Fairbanks, Fairbanks, AK 99775, USA.
authors.forename: Kevin G
authors.initials: KG
authors.lastname: McCracken
authors.affiliation: Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania 7001, Australia.
authors.forename: Peter B
authors.initials: PB
authors.lastname: Frappell
authors.affiliation: Department of Biology, McMaster University, 1280 Main Street West, Hamilton, ON, Canada L8S 3K1.|Department of Biology and Department of Marine Biology and Ecology, Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Coral Gables, FL 33146, USA.
authors.forename: Neal J
authors.initials: NJ
authors.lastname: Dawson
authors.affiliation: Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, BC, Canada V6T 1Z4.
authors.forename: Sabine L
authors.initials: SL
authors.lastname: Laguë
authors.affiliation: Department of Zoology, University of British Columbia, 6270 University Boulevard, Vancouver, BC, Canada V6T 1Z4.
authors.forename: William K
authors.initials: WK
authors.lastname: Milsom
mesh_terms: D000064:Acclimatization; D000531:Altitude; D000818:Animals; D001717:Birds / Q000033:anatomy & histology / Q000502:physiology*; D004734:Energy Metabolism; D010100:Oxygen / Q000378:metabolism; D012119:Respiration; D015656:Respiratory Mechanics; D013990:Tidal Volume
chemical_list: D010100:Oxygen
keywords: Avian respiratory system; Compliance; Hypoxia; Pulmonary mechanics; Waterfowl; Work of breathing