Large-scale sampling of potential breeding sites in male ruffs
Migratory birds typically move twice a year between an area where they breed and an area where they spend the non-breeding season. This pattern may be the rule in species that are socially monogamous with both pair members providing care to the offspring. However, few studies have focused on the movements of polygamous species with uniparental care. Using satellite telemetry, we analyzed the movements of males of the ruff Calidris pugnax during the breeding season. Ruffs are waders with a polygynous mating system and female-only parental care and with a unique, genetically-determined polymorphism in appearance and mating behaviour. We show that within one breeding season, ruff males of all three morphs travelled thousands of kilometers and visited on average 11 potential breeding sites. Our study leads to the hypothesis that breeding site sampling may be a common feature of migratory species that are polygamous with uniparental care. Individuals of the non-caring sex may increase their reproductive success by sampling multiple potential breeding sites during a single breeding season. Such large-scale breeding range sampling would blur the distinction between migration and breeding.
(Kempenaers, Valcu, Piersma, Santema, and Vervoort 2025)
