Behavioural and energetic consequences of competition among three overwintering swan(Cygnus spp.)species  

作　　者：Kevin A.Wood Julia L.Newth Geoff M.Hilton Eileen C.Rees 

机构地区：[1]Wildfowl&Wetlands Trust,Slimbridge,Gloucestershire GL27BT,United Kingdom [2]Centre for Ecology and Conservation/Environment and Sustainabil-ity Institute,College of Life and Environmental Sciences,University of Exeter,Exeter TR109EZ,United Kingdom [3]Department of Zoology,University of Cambridge,Downing Street,Cambridge CB23EJ,United Kingdom

出　　处：《Avian Research》2021年第4期707-721,共15页鸟类学研究（英文版）

基　　金：funded by the Peter Scott Trust for Education and Research in Conservation;Peter Smith Charitable Trust for Nature;Olive Herbert Charitable Trust;D’Oyly Carte Charitable Trust;N.Smith Charitable Settlement;Robert Kiln Charitable Trust;the estate of the late Professor Geoffrey Matthews OBE;supported WWT’s“Hope for Swans”Appeal。

摘　　要：Background:Winter numbers of the northwest European population of Bewick's Swans(Cygnus columbianus bewickii)declined recently by c.40%.During the same period,numbers of two sympatric and ecologically-similar congeners,the Mute Swan(Cygnus olor)and Whooper Swan(Cygnus cygnus)showed increases or stability.It has been suggested that these opposing population trends could have a causal relationship,as Mute and Whooper Swans are larger and competitively dominant to Bewick's Swans in foraging situations.If so,effects of competition of Mute and Whooper Swans on Bewick's Swans should be detectable as measurable impacts on behaviour and energetics.Methods:Here,we studied the diurnal behaviour and energetics of 1083 focal adults and first-winter juveniles("cygnets")of the three swan species on their winter grounds in eastern England.We analysed video recordings to derive time-activity budgets and these,together with estimates of energy gain and expenditure,were analysed to determine whether individual Bewick's Swans altered the time spent on key behaviours when sharing feeding habitat with other swan species,and any consequences for their energy expenditure and net energy gain.Results:All three swan species spent a small proportion of their total time(0.011)on aggressive interactions,and these were predominantly intraspecific(≥0.714).Mixed-effects models indicated that sharing feeding habitat with higher densities of Mute and Whooper Swans increased the likelihood of engaging in aggression for cygnet Bewick's Swans,but not for adults.Higher levels of interspecific competition decreased the time spent by Bewick's Swan cygnets on foraging,whilst adults showed the opposite pattern.When among low densities of conspecifics(<c.200 individuals/km^(2)),individual Bewick's Swans spent more time on vigilance in the presence of higher densities of Mute and Whooper Swans,whilst individuals within higher density Bewick's Swan flocks showed the opposite pattern.Crucially,we found no evidence that greater numbers of interspecific comp

关 键 词：Avian behaviour Energy expenditure ETHOLOGY Interference competition Interspecific interactions Time activity budgets Video observations 

分 类 号：Q958[生物学—动物学]