waders and their estuarine food supplies - Vlaams Instituut voor de ...

Long-term, broadly-based research can. of course,
only be done when many people work together, and
this is certainly also true for this research project. I
hope I have already personally expressed my gratitude
to all of them. Here. 1 only mention the people being
essential to the prosperity of the undertaking.
first of all. I thank all my superiors in the foi mer
'Rijksdienst voor de Usselmeerpolders'. later "Regionale
Directie Flevoland van Rijkswaterstaat', still
later 'Regionale Directie IJsselmeergebied van Rijkswaterstaat'
and now a department within RI/.A. for
their support, tolerance and patience. In its original set
up. the research programme dealt with the ecological
effect of the land reclamation works along the mainland
coast of ihe Wadden Sea. I still highly appreciate
the encouragement of Kees Berger and J.H. van Kampen
to extend the research programme to answer also
more fundamental questions. I am deeply convinced
this has been a wise decision.
One of the aims was to measure the seasonal variation
in food supply throughout the years. Hence, it was
decided to measure the fcxxl density each month and
the burying depth of the bivalves and worms even each
fortnight. Such a series of measurements can only be
built up if the field work continues during severe winter
conditions and foul weather. It was thanks to the
dedication of all members of the team tiiat these data
could be collected with only a few missing data during
a long series of years. Most of the samples of the macozoobenthos
were taken by Jan Bronkema. Justinus
v an Dijk. Sytse van de Meer and the late Lou Terpsira.
The same team, together with Harm Hoekstra. built the
towers, plotted the hundreds of study sites, measured
the altitude of these sites and collected the mud samples.
The burying depths of tens of thousands of bivalves
and worms were determined for many years by
Tonny van Dellen and Bert Toxopeus and later also by
Justinus van Dijk and Lou Terpstra. The macrofauna
INTRODUCTION
Acknowledgements
2i
samples were sorted out in Ihe laboratory by Tonny
van Dellen and Bert Toxopeus. In total, they must have
determined the lengths and weights of hundreds of
thousands of prey, whereas they also anal*, sed many
hundreds of pellets, droppings and gizzard contents.
The ash fraction and the energy density were determined
by J.L. Straat. who also did much of the first
calculations. Willem Hui/mgh kepi up the administration
of all these data.
Jan Wanink became involved in the research project
as conscientious objector. I highly appreciated that
he spent so much time in checking the huge data bases.
and 1 am glad we have promised each other now to finisfa
oil ihe several joint papers still in progress.
I am especially grateful lo Piel Zegeis who worked
day and night during several years to catch and count
birds, it was mainly due to his perseverance that the
bird work could be based on marked indiv iduals.
Many Students were involved in the project: Joke
Bloksma. Anne-Marie Blomert. Henrich Bruggemann.
Jenny Cremer. Meinte Ifngelmoer. Bruno Ens.
Peter Esselink. Roelof Hupkes, Doll" Logemann. Rick
Looijen. Bertrin Roukema. Piet Spaak. Bauke de
Vries. Marja de Vries and Renske de Vries. all from
the University of Groningen. Besides. Nienke
Bloksma from the Van Hall Institute, Renee Slooff
from the University of Leiden. Tjarda de Koe and Jan
Komdeur from the University of Wageningen. Kees
Hulsman from the University of Brisbane, and Carol
Cumming from the University of Edinburgh. 1 have
many cherished memories of the hours we spent together
in the hide or discussed the first results.
I am extremely grateful to Rudi Drent. He was not
only the supervisor of this project, but also my guide
during nearly a quarter century of research. During all
this lime, he made me leel at home at his institute, the
Zoological Laboratory of the University of Groningen.
I admire his sharp mind, but possibly still more his ca-