Differential Development of Breeding Plumage in Adult and Second-Year Male Ruffs Philomachus pugnax

[摘要] Westudiedthedevelopmentofbreedingplumagein641RuffPhilomachuspugnaxmalesduringspringin2004–2006insouthernBelaruswithspecialemphasisonthegrowthrateofruffandtuftfeathers,whicharethemostcolourfulandspectacularpartsofthemaleplumage.Duringnorthwardmigration,maleRuffsarrivingintheendofMarchorearlyAprilshowedamixtureofwinterandstripedfeathers.Thefirstadultswithfullydevelopedbreedingplumagewererecordedinthelast10daysofAprilandtheproportionofindividualswithbreedingplumagegraduallyincreasedthroughspring.However,individualswithatleasttracesofwinterorstripedplumagewerecaughtduringthewholestudyperiod.Birdsdidnotshedthewholewinterplumageatonce,whichistypicalforRuffmalesinwesternEurope.Immature(secondyear)birdswerelessadvancedindevelopingbreedingplumagethanadults.Only20%ofall55trappedsecond-yearmaleswereinfullbreedingplumage.Duringthemainmigrationperiodtherewerenoannualdifferencesinthegrowthrateofbreedingplumagefeathers.Rufflengthsincreased1.6mm/dayinadultsand1.5mm/dayinsecond-yearmales,whereasthetuftgrew1.1mm/dayinadultsand1.0mm/dayinimmatures.Althoughgrowingratesofruffandtuftfeathersweresimilarinimmaturesandadults,immaturemalesstartedtomoultintobreedingplumagelaterthanadults,resultinginlessdevelopedbreedingplumagewhentheydepartedtothebreedinggrounds.Assecond-yearmaleshadlowerbodymassandslowerbodymassincreasethanadults,itwasproposedthatenergeticconstraintsduringmigrationarethemainreasonofdelayedmoultintobreedingplumageinimmaturebirds.

[学科分类] 动物科学

[关键词] Spring Migration