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.

Factors affecting the spatial distribution and breeding habitat of an insular cliff-nesting raptor community.

The specific spatial distribution and habitat association-strongly influenced by environmental factors or competitive interactions-are major issues in ecology and conservation. We located and georeferenced nesting sites of five cliff-nesting raptors (Egyptian vulture Neophron percnopterus [a locally extinct species], common buzzard Buteo buteo, osprey Pandion haliaetus, common kestrel Falco tinnunculus, Barbary falcon Falco peregrinus pelegrinoides), and common raven Corvus corax on one of the most biodiverse hotspot within the Canary Islands (Teno, Tenerife). We used generalized linear models to evaluate the factors affecting abundance, richness, and intra- and interspecific interactions. Raptor abundance increased with slope, shrub-covered area, and habitat diversity, and decreased with altitude, and forested and grassed areas. Richness increased with slope and decreased with altitude. Threatened species (osprey, Barbary falcon, and raven) occupied cliffs farther away from houses and roads, and more rugged areas than the non-threatened species. The models suggested that the probability of cliff occupation by buzzards, falcons, and ravens depended only on inter-specific interactions. Buzzard occupation increased with the distance to the nearest raven and kestrel nests, whereas falcons and ravens seek proximity to each other. Teno holds between 75% and 100% of the insular breeding populations of the most endangered species (osprey and raven), indicating the high conservation value of this area. Our study suggests that the preservation of rugged terrains and areas of low human pressure are key factors for raptor conservation and provide basic knowledge on the community structure and habitat associations to develop appropriated management actions for these fragile island populations.