University of Groningen
Migrants in double jeopardy
Schlaich, Almut
DOI:
10.33612/diss.97354411
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Publication date:
2019
Link to publication in University of Groningen/UMCG research database
Citation for published version (APA):
Schlaich, A. (2019). Migrants in double jeopardy: Ecology of Montagu's Harriers on breeding and wintering
grounds. Rijksuniversiteit Groningen. https://doi.org/10.33612/diss.97354411
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Stellingen behorende bij het proefschrift
Migrants in double jeopardy
Ecology of Montagu's Harriers on breeding and wintering grounds
Almut E. Schlaich
1. Wintering Montagu’s Harriers adjust their individual timing of intra-tropical movements in response to local environmental conditions.
Chapter 2 of this thesis
2. The late wintering period likely is a bottleneck during the annual cycle of Montagu’s Harriers with possible carry-over effects to spring migration (Klaassen et al. 2014 J. Anim. Ecol.) and to the breeding season.
Chapter 3 of this thesis
3. Migration is often considered the most demanding period by biologists studying migration, whereas repro-ductive biologists consider reproduction as the most demanding period for birds during their annual cycle (Drent & Daan 1980). For male Montagu’s Harriers the breeding season is nearly as demanding as migration
periods in terms of flight distance per day, but because it lasts much longer, it likely is overall far more demanding than migration.
Chapter 5 of this thesis
4. Space use strategies of male Montagu’s Harriers during the breeding season seem to be an intrinsic charac-ter of the individual bird.
Chapter 6 of this thesis
5. Birdfields are an effective agri-environment scheme (AES) for Montagu’s Harriers. Chapter 7 of this thesis.
But we have to keep in mind that Birdfields might not be the only solution and could form an ecological trap
for other farmland bird species, such as breeding Skylarks. Therefore, we should never stop evaluating and developing new measures.
6. One individual track makes an anecdote but you need to track many individuals in different years and places to see the whole picture.
Chapters 2-6 of this thesis
7. It is impossible to determine absolute home range size.
8. It would be optimistic to expect the number of migrants seeking a winter home in Africa to be maintained without diminution in face of continued ‘development’ in Eurasia.
After R.E. Moreau 1970, Bird Study
9. Tracks on the map directly show you the movements of individual birds but are much more valuable if you know the ecological conditions the species is facing in the field at that place and moment.
10. It might turn out to be difficult to maintain the effort for harrier nest protection in the long term. 11. It is demanding to investigate long-distance migrants during the breeding season as well as during winter in a single PhD project.
12. “All that is gold does not glitter, not all those who wander are lost...” J.R.R. Tolkien 1954, The Lord of the Rings
