La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	Population development of the Common Tern Sterna hirundo in Bavaria
Auteurs :	Heribert Zintl, Auteur
Type de document :	Article
Dans :	Vogelwelt (Die) (119(3-5) 1998)
Article en page(s) :	123-132
Résumé :	During the 19th century the Common Tern population in Bavaria consisted of an estimated 1000 pairs. Due to river regulation it decreased to a minimum of 37 pairs in 1980. From 1984 onwards the population started to increase again (Fig. 4) and reached 143 breeding pairs in 1997. At this time almost the entire breeding population was concentrated in four colonies, two each with about 50 and 20 pairs, resp. The average rate of reproduction during the period of decrease and stagnation (0.75 fledglings per pair) did not differ from that during the phase of population increase. Therefore the increase must have been caused either by immigration from elsewhere or by improved post-fledgling survival. The last colony on an island in a natural river bed disappeared in 1982. Nowadays all breeding sites are situated on floating platforms, artificial islands etc. Biotic and abiotic factors and threats limiting the population are discussed and proposals are made for management measures. Every breeding site should be constantly checked and guarded by a team.

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