As well as the studies on primates by Setchell, another study demonstrates the effect of red among birds. In an experiment, scientists put red plastic rings on the legs of male zebra finches and this increased the birds’ success with female zebra finches. Zebra finches already have bright red beaks, so this study suggests that, as with Olympic athletes, an extra flash of red is significant. In fact, researchers from the University of Glasgow say that the birds’ brightly coloured beaks are an indicator of health. Jonathan Blount, a biologist, says that females of many species choose to mate with the flashiest males. Now, Blount and his colleagues think they have found proof that bright red or orange beaks attract females because they mean that the males are healthier. Nothing in nature is simple, however, because in species such as the blue footed booby, a completely different colour seems to give the male birds the same advantage with females.