JOURNAL OF AVIAN BIOLOGY www.avianbiology.org Journal of Avian Biology 1 –––––––––––––––––––––––––––––––––––––––– © 2018 Te Authors. Journal of Avian Biology © 2018 Nordic Society Oikos Subject Editor: Paulo Catry Editor-in-Chief: Tomas Alerstam Accepted 17 July 2018 2018: e01709 doi: 10.1111/jav.01709 Events in the life cycle of migrant birds are generally time-constrained. Moult, together with breeding and migration, is the most energetically demanding annual cycle stages, but it is the only stage that can be scheduled at diferent times of the year. However, it is still not fully understood what factors determine this scheduling. We compare the timing of primary feather moult in relation to breeding and migration between two populations of Eurasian golden plover Pluvialis apricaria, the continental population breeding in Scandinavia and in N Russia that migrates to the Netherlands and southern Europe, and the Icelandic population that migrates mainly to Ireland and western UK. Moult was studied at the breeding grounds (N Sweden, N Russia, Iceland) and at stopover and wintering sites (S Sweden, the Netherlands). In both populations, primary moult overlapped with incubation and chick rearing, and females started on average 9 d later than males. Icelandic plovers overlapped moult with incubation to a larger extent and stayed in the breeding grounds until primary moult was completed. In contrast, continental birds only moulted the frst 5–7 primaries at the breeding grounds and completed moult in stopover and wintering areas, such as S Sweden and the Netherlands. Tis overlap, although rare in birds, can be understood from an annual cycle perspective. Icelandic plovers presumably need to initiate moult early in the season to be able to complete it at the breeding grounds. Te latter is not possible for con- tinental plovers as their breeding season is much shorter due to a harsher climate. Additionally, for this population, moulting all the primaries at the stopover/wintering site is also not possible as too little time would remain to prepare for cold-spell move- ments. We conclude that environmental conditions and migration strategy afect the annual scheduling of primary feather moult in the Eurasian golden plover. Keywords: primary moult, moult-breeding overlap, life cycle Conditions at the breeding grounds and migration strategy shape different moult patterns of two populations of Eurasian golden plover Pluvialis apricaria Paula Machín, Magdalena Remisiewicz, Juan Fernández-Elipe, Joop Jukema and Raymond H. G. Klaassen P. Machín (http://orcid.org/0000-0002-6774-3904) (machinpaula@gmail.com) and R. H. G. Klaassen, Conservation Ecology Group, Groningen Inst. for Evolutionary Life Sciences (GELIFES), Groningen Univ., Groningen, the Netherlands. RHGK also at: Dutch Montagu’s Harrier foundation, Scheemda, the Netherlands. – M. Remisiewicz, Bird Migration Research Station, Faculty of Biology, Univ. of Gdańsk, Gdańsk, Poland, and Animal Demography Unit, Dept of Biological Sciences, Univ. of Cape Town, Rondebosch, South Africa. – J. Fernández-Elipe, Candeleda, Ávila, Spain. – J. Jukema, AC Oosterbierum, the Netherland. Article