title: Windscapes shape seabird instantaneous energy costs but adult behavior buffers impact on offspring.
abstract: BACKGROUND
  Windscapes affect energy costs for flying animals, but animals can adjust their behavior to accommodate wind-induced energy costs. Theory predicts that flying animals should decrease air speed to compensate for increased tailwind speed and increase air speed to compensate for increased crosswind speed. In addition, animals are expected to vary their foraging effort in time and space to maximize energy efficiency across variable windscapes.
  
  
  RESULTS
  We examined the influence of wind on seabird (thick-billed murre Uria lomvia and black-legged kittiwake Rissa tridactyla) foraging behavior. Airspeed and mechanical flight costs (dynamic body acceleration and wing beat frequency) increased with headwind speed during commuting flights. As predicted, birds adjusted their airspeed to compensate for crosswinds and to reduce the effect of a headwind, but they could not completely compensate for the latter. As we were able to account for the effect of sampling frequency and wind speed, we accurately estimated commuting flight speed with no wind as 16.6 ms(?1) (murres) and 10.6 ms(?1) (kittiwakes). High winds decreased delivery rates of schooling fish (murres), energy (murres) and food (kittiwakes) but did not impact daily energy expenditure or chick growth rates. During high winds, murres switched from feeding their offspring with schooling fish, which required substantial above-water searching, to amphipods, which required less above-water searching.
  
  
  CONCLUSIONS
  Adults buffered the adverse effect of high winds on chick growth rates by switching to other food sources during windy days or increasing food delivery rates when weather improved.
authors.affiliation: Department of Biological Sciences, University of Manitoba, Winnipeg R3T 2N2, Manitoba, Canada.
authors.forename: Kyle Hamish
authors.initials: KH
authors.lastname: Elliott
authors.affiliation: The Buntings, Sandy SG19 2TT, Bedfordshire, UK.
authors.forename: Lorraine S
authors.initials: LS
authors.lastname: Chivers
authors.affiliation: Department of Biological Sciences, University of Manitoba, Winnipeg R3T 2N2, Manitoba, Canada.
authors.forename: Lauren
authors.initials: L
authors.lastname: Bessey
authors.affiliation: Environment Canada, National Wildlife Research Centre, Carleton University, Ottawa K1A 0H3, Ontario, Canada.
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Gaston
authors.affiliation: Institute for Seabird Research and Conservation, Anchorage, AK, USA.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Hatch
authors.affiliation: Université de Strasbourg, IPHC, 23 rue Becquerel, Strasbourg 67087, France ; CNRS, UMR7178, Strasbourg 67087, France.
authors.forename: Akiko
authors.initials: A
authors.lastname: Kato
authors.affiliation: Department of Biology, University of Victoria, Victoria, British Columbia, Canada.
authors.forename: Orla
authors.initials: O
authors.lastname: Osborne
authors.affiliation: Université de Strasbourg, IPHC, 23 rue Becquerel, Strasbourg 67087, France ; CNRS, UMR7178, Strasbourg 67087, France.
authors.forename: Yan
authors.initials: Y
authors.lastname: Ropert-Coudert
authors.affiliation: Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen, UK ; State Key Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, 1 West Beichen Road, Chaoyang, Beijing, CN-100101, PR China.
authors.forename: John R
authors.initials: JR
authors.lastname: Speakman
authors.affiliation: Department of Biological Sciences, University of Manitoba, Winnipeg R3T 2N2, Manitoba, Canada.
authors.forename: James F
authors.initials: JF
authors.lastname: Hare