A research team from the Doñana Biological Station (CSIC), the University of Granada, and the University of Illinois (Urbana-Champaign, USA) has studied the nocturnal activity of mites living permanently on bird flight feathers. They have found that feather mites are nocturnal beings: they move, feed, and lay eggs at night while the bird sleeps. It has been estimated that they clean ca. 80,000?m2 of “dirt” (fungi, bacteria, and other particles) in just European passerines