Plastic doodads deter enemies.

BLACK-shouldered kite; NEST building -- Research; PLASTIC bags; WARNINGS; ANIMAL communication -- Research; SERGIO, Fabrizio

The article discusses research reported by ecologist Fabrizio Sergio and colleagues in the January 21, 2011 issue of "Science" on nest-building by black kite birds or Milvus migrons. The birds reportedly incorporate shredded white plastic bags in their nests to ward off prospective intruders. Rival birds are said to interpret the plastic remnants as a warning to stay away or face physical resistance.