La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	Reactions of Common Terns Sterna hirundo and Black-headed Gulls Chroicocephalus ridibundus to motor boat disturbances during their breeding season
Auteurs :	Milan Vogrin, Auteur
Type de document :	Article
Dans :	Acrocephalus (34(156) 2013)
Article en page(s) :	43-48
Résumé :	The Common Tern Sterna hirundo and Black-headed Gull Chroicocephalus ridibundus are regular breeders on the islets and electricity transmission pedestals on Ptujsko jezero reservoir (Lake Ptuj) on the Drava River. Here, sports and recreation activities with various types of vessels also take place between May and September. The Decree on navigation on the lake prohibits vessels approaching the birds' nest-sites at a lesser distance than 100 m. In 2009 and 2010, tests were made with motor boats whether the prescribed distance is appropriate from the aspect of disturbance of birds during their breeding season. It was established that colonial Common Terns are flushed by motor boats at a mean distance of 73 m and Black-headed Gulls at 67 m. After being flushed, Common Terns returned to their nests in 5 min, Black-headed Gulls in 11 min on average. Both Common Tern and Black-headed Gull are more timid during the incubation period than at the time of rearing their chicks. The 100 m long protection zone around the islets is enough to protect breeding terns and gulls from being disturbed by motor boats.

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