University of Groningen
Earth, worms & birds
Onrust, Jeroen
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Publication date:
2017
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Onrust, J. (2017). Earth, worms & birds. Rijksuniversiteit Groningen.
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The research presented in this thesis was carried out at the Conservation Ecology Group, Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, The Netherlands
This work is part of the research programme of RUG/Campus Fryslân, which is financed by the Province of Fryslân.
Printing of this thesis was supported by the University of Groningen (RUG). COLOFON
Layout: Dick Visser Photographs: Jeroen Onrust
Printed by: GVO drukkers & vormgevers B.V., Ede ISBN: 978-94-034-0301-4
ISBN: 978-94-034-0300-7 (electronic version) © 2017 Jeroen Onrust (jeroen.onrust@gmail.com)
Earth, worms & birds
Proefschrift
ter verkrijging van de graad van doctor aan de
Rijksuniversiteit Groningen
op gezag van de
rector magnificus prof. dr. E. Sterken
en volgens besluit van het College voor Promoties.
De openbare verdediging zal plaatsvinden op
vrijdag 15 december 2017 om 16:15 uur
door
Jeroen Onrust
geboren op 18 februari 1989
te Emmen
Promotores
Prof. T. Piersma
Prof. H. Olff
Beoordelingscommissie
Prof. M.P. Berg
Prof. J.W. van Groenigen
Prof. P. Tittonell
Contents
Chapter 1 General Introduction 7
Chapter 2 Determining earthworm availability for visually hunting predators; a novel 23 method versus standard sampling
Box A How many earthworms does a meadow bird need? 32
Chapter 3 The detection of earthworm prey by Ruffs Philomachus pugnax 37
Chapter 4 The hungry worm feeds the bird 51
Box B Correction factors for earthworms preserved in ethanol 64
Chapter 5 How dairy farmers unwittingly manage the tritrophic interactions between 67 grassland fertilizers and earthworm ecotypes and their predators
Chapter 6 Intensive agricultural use of grasslands restricts earthworm activity and 79 their availability for meadow birds through drought
Chapter 7 Synthesis: Ecological consequences of conventional dairy farming 97
Bibliography 113
Addresses of co-authors 129
Nederlandse samenvatting: Boeren, wormen & vogels 131
