New Zealand Found 5 of These Birds Left on Earth — What One Old Female Did Was Impossible

#BlackRobin #WildlifeRecovery #ConservationSuccess In 1980, the entire black robin species came down to five birds, living on one small island in the Chatham group, eight hundred kilometres east of New Zealand. Of those five, only one female could still breed. She wore a blue leg band, so the team called her Old Blue, and every black robin alive today descends from her. There was no backup population anywhere on Earth. Wildlife officer Don Merton proposed a method never tried on a wild songbird this close to extinction. His team removed Old Blue's eggs so she would lay a second clutch, then carried those eggs by boat to nests of a different species, the Chatham Island tomtit, and let the tomtits do the incubating. If the transfer failed, the last fertile eggs of the species were gone. It worked, and Old Blue kept laying until she was about thirteen, three times longer than a black robin normally lives. Then the rescue began working against itself. As numbers climbed, many females started laying eggs on the rim of the nest, where they could never hatch. The trait was heritable, and by rescuing every rim-laid egg, the team had removed the only force that would normally erase it. At its peak, roughly half of all females carried it. The only fix was to stop intervening and let natural selection do the work. It was an uncomfortable decision, and it worked. Today around 250 black robins survive, all of them descended from a single female who outlived her own biology at the exact moment the species needed it. Chapters: 0:00 The Last Five 1:47 Why Island Birds Disappear 4:39 Seven Birds on a Sea Stack 5:17 The Move to Mangere 7:26 The Egg Gamble 11:38 When the Rescue Backfired 14:48 Still Not Safe Subscribe @PlanetRewild for more fascinating documentaries, wildlife recovery, hidden history, and unbelievable true stories. Sources: New Zealand Department of Conservation IUCN Red List BirdLife International Peer-reviewed black robin conservation research