Use of marine debris as nest material by ospreys

The use of anthropogenic debris as nest-building materials may affect nest function. We study ospreys (Pandion haliaetus) on an island with scarce vegetation and high availability of beached marine debris. We describe the anthropogenic debris in osprey nests, evaluate the factors affecting its prevalence and abundance, and test its potential effects on breeding parameters. We also quantify plastic entanglements among adults and nestlings. Of the 36 studied nests, 92 % included non-natural items, with plastic being the most frequent material (88.9 %). Nests that were bigger and closer to the coast had more anthropogenic items. The abundance of anthropogenic items in nests did not correlate with osprey breeding parameters. We recorded two live entangled adult females, which represent 3.9 % of the adult population. Monitoring the abundance of anthropogenic debris and its effects on wildlife is necessary to guarantee long-term viability of coastal wildlife.