In 1980 the black robin population was at five individuals and only one breeding pair remained – Old Blue and Old Yellow. It looks as though the species faced certain extinction. In 1984 one of the five female robins laid an egg on the rim of her nest rather than in the centre. If left in its original position this egg would not have hatched, so conservation staff repositioned the egg. By 1989 over half the female population were laying rim eggs, all of which were moved. By 1990 the population had recovered enough for staff to stop moving the eggs but twenty years later 9% are still rim layers. Repositioning of these misplaced eggs by staff led to a rapid increase of this maladaptive trait. It was a close call; had this trait become more established it could have led to the entire species being dependent on human assistance for reproduction.