Winter distribution and migratory strategies of Eurasian Spoonbills (Platalea leucorodia) from the Pannonian breeding population: are they long-distance migrants?

Abstract

In this paper, the wintering characteristics of the Eurasian Spoonbills (Platalea leucorodia) breeding in the Carpathian Basin (Pannonian population) were analysed. The data of 305 wintering Spoonbills marked with colour-rings in Hungary was used. A significant part, 80% of the Spoonbills, wintered in Africa, while 20% spent the winter in Europe and only two birds in the Asian part of western Turkey. The most important wintering sites were in the central part of North Africa (in Algeria, Libya, but mainly Tunisia) and Italy. The tidal area in the Gulf of Gabes in Tunisia was the most important area where a significant proportion, 65% of all wintering Spoonbills, spent the winter. This study provided new evidence of Spoonbills occurring in Saharan wetlands (Chott Tindla in Algeria) in winter. 2% of the resighted Spoonbills were reported from the wetlands of the Sahel in Sudan, Nigeria, Niger, Mali, Mauritania, and Senegal. European winterers were mainly found in Italy and, to a lesser extent, in the Balkans and the Carpathian Basin. The mean distance between the natal colonies and the wintering areas was 1,535 km. Spoonbills migrated in a south-southwestern direction (mean: 213°) to reach their wintering sites. In the Hungarian population, most specimens (94%) were short-distance migrants (wintered north of 22°N), 2% were long-distance migrants, and 4% were residents. However, the proportions of the residents and short-distance migrants are supposed to be overestimated and the proportion of the long-distance migrants is likely to be underestimated due to the lack of observation effort in sub-Saharan Africa. However, based on the winter census data and the proportion of ringed individuals of Hungarian origin in the wintering flocks, I estimated that the lack of observation effort would only slightly modify the result. There were two shifts in migratory strategies on an individual level: a resident Spoonbill became a short-distance migrant, and a short-distance migrant became a long-distance migrant by a following winter. While most of the East Atlantic Spoonbills are long-distance migrants, the results of this study indicate that most birds in the Pannonian population are likely to be rather short-distance migrants. The results of the GPS tracking also confirm that most Pannonian Spoonbills are short-distance migrants and support the main conclusion of this paper.