Small Buttonquail (Andaulusian Hemipode, Common Buttonquail) Turnix sylvaticus
Once a rare breeding resident of southern Spain but now sadly presumed extinct in Europe. South of the Sahara it is much commoner but still extremely hard to see due to its tiny size and secretive nature. Buttonquails are something of an anomaly taxonomically-speaking having been variously treated over the years as being relatives of Quails (understandable) or Cranes (less ovious, but the more similar Flufftails are usually placed in the same order). In recent years most authorities have moved away from either treatments and they are now widely placed among (or at the begiinning of) the shorebirds (waders).
One of most exciting birding moments was in Malawi when I saw a buttonquail accompanied by 3 tiny chicks running across and along the dirt track in front of me. The photos are poor, taken through a dusty windscreen, but I consider myself very fortunate to get any photos of a buttonquail with chicks. For an idea of size if you're unfamiliar with buttonquails, the adult here is about the size of a sparrow...
Small Buttonquail with chicks, Dzalanyama (Malawi), 24th May 2011