I would like to acknowledge the participation of Mrs. J.J. Platteel (Loosdrecht), Mrs. E. Koning (Hilversum), Mr. J.A. Oosterlaken (Laren), Mr. M. Rotermundt (Huizen), Mr. M. Matthyssen (Kortenhoef), Mr. P. Calis (Laren), Mr. F.C. Jager (Hilversum), Mrs. J. Baas (Huizen), Mr. G. Bieshaar (Laren), Mrs. I.G. Jeltes (Bussum), Mrs. A. de Vries (Hilversum), Mr. R. van Oorschot (Nederhorst den Berg), Mr. J. van Dijk (Weesp), Mr. C. Rotermundt (Hilversum), Mrs. M. van der Hoek (Naarden) and Mrs. W.J. Bindt (Bussum)who joined me in counting House Sparrows in 1997 and 1998. Together we formed "sample 1".
In 1998 24 new participants formed an independent new sample ("sample 2"). The following persons returned a completed counting form: Mr. M. Slotemaker (Utrecht), Mrs. F. ter Avest (Eemnes), Mrs. W.J.M. Beerlage (Hilversum), Mr. and Mrs Petri Abelmann (Bussum), Mrs Slotemaker & van den Berg (Bussum), Mrs. Melk (Zaandam), Mrs. C.A. Baar (Bussum), Mrs. M. van der Weyden (Muiden), T. Loyer (Nederhorst den Berg), Mr. A.H. Bierens (Ankeveen), Mr. G. Brasser (Huizen), Mrs. C. Smit (Huizen), Mr. J. Jongerden (Huizen), Mrs. J. van Gelderen (Eemnes), Mrs. J. Speelman (Bussum), Mrs. Y. Volkersz (Weesp), Mrs. M. Beugelaar (Bussum), Mr. B. van Voorst (Nigtevecht), Mr. H.P.L. Warmerdam (Weesp), Mrs. J. van Putten (Hilversum), Mrs. Z. Boerma (Soest), Mrs. I. de Graaf (Bussum), Mr. P.H. de Nooij (Hilversum) and Mrs. C. Klaverblaas (Bussum).
It is obvious that without the loyalty and dedication of all participants this study would not have been possible.
I also gratefully acknowledge the support given by Dick Jonkers, coordinator of the Garden Bird Survey who provided me with the data gathered by the participants to that survey in 1997. It gave me the opportunity to analyse the possible influence of the presence of Magpies on the population density of House Sparrows.
Finally, I would like to express my sincere gratitude to my friend Kenneth W. Perry (Coleraine, Northern Ireland) who took the trouble to mend my English. It meant a substantial improvement of the readibility of the texts.
Created on ... August 13, 2000