Migrants in double jeopardy: Ecology of Montagu's Harriers on breeding and wintering grounds

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Long-distance migratory birds are in decline, especially species breeding in agricultural landscapes. The intensification of agriculture has been shown to be the main cause of the dramatic decline of farmland birds in Europe. However, species that depend on agricultural landscapes also during their overwintering stay in Africa are in double jeopardy because rapid and dramatic land use changes degrade and destroy their wintering habitats. In this thesis, I describe the annual movements and habitat use of Montagu’s Harriers tracked with GPS-trackers. Harriers winter in the Sahel where they apparently lead an easy life compared to the breeding season: they spend less time in flight compared to other annual cycle phases. However, at the end of the winter, harriers work harder to sustain themselves and prepare for migration. Our fieldwork in Africa showed that their main food becomes scarce at the end of the winter. Individuals wintering under harsh conditions depart later for spring migration, with possible knock-on effects for reproduction. In addition, more direct effects of adverse wintering conditions may exist, since mortality at the end of the winter and during spring migration has increased in recent years. In the Dutch breeding areas, Montagu’s Harriers seem to be food-limited and have to work hard to raise their young in the intensified agricultural landscape. Fortunately, our results indicate that increasing high-quality foraging habitat by implementing agri-environment schemes such as Birdfields, might help harriers.
Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • University of Groningen
  • Both, Christiaan, Supervisor
  • Bretagnolle, Vincent, Supervisor, External person
  • Klaassen, Raymond, Co-supervisor
Award date11-Oct-2019
Place of Publication[Groningen]
Print ISBNs978-94-034-2025-7
Electronic ISBNs978-94-034-2024-0
Publication statusPublished - 2019

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