Albert de Jong
|Breeding large gulls in Poland: distribution, numbers, trends and hybridisation.
Neubauer, G., M. Zagalska-Neuhauer, R. Gwiazda, M. Faber, D. Bukaciriski, J. Betleja & R Chylarecki IN: Vogelwelt 2006-127: 11-22.
Fig. 4. Origin of foreign settlers in Polish colonies of large gulls and exchange of individuals between colonies within Poland. Numbers given at each arrow represent the number of individuals that moved between colonies and from abroad.