February 22, 1939

Don Merton is the conservationist who “[l]ed the team that saved the black robin from extinction ...” We learn about this in a National Geographic blog post.

We learn first that ships brought "cats, stoats, and rats" to New Zealand islands and these predators ravaged a population of black robins, which bird was described by Ed Yong as "an endearing ball of beaked fluff, found only in the Chatham Islands off the eastern coast of New Zealand. " And because of the predators mentioned, by "1980, there were just five of them left.

Now though the problem was not cats. The robins were living on rocky cliffs the predators could not scale. The problem was the wind was so strong the birds could not thrive with their nests exposed in that climate.  In Yong's words:

They lived in a rocky outcrop about the size of a few city blocks. The precipitous cliffs kept them safe from the cats, stoats and rats that sailors had brought to the islands. But the high winds were too much for these small birds, and most of the survivors had died. With a single breeding pair left—Old Blue and Old Yellow—their future looked bleak.

Donald Merton, (February 22,  1939 to April 10,  2011), himself a native of New Zealand, decided to save them. Five birds, with only ONE breeding pair, composed the entire population of black robins. 
They relocated the tiny population to larger islands and managed their reproduction over many years, transferring their eggs to foster parents for incubation. By 1989, there were 80 robins. By 1998, there were over 200.Once the world’s most endangered bird, the black robin became a flagship example of conservation success.

But now another problem surfaced. To maximize the population the scientists saved eggs that nature would have discarded: some eggs were laid by certain robins on the rim of the nest and were, without the conservation efforts, eliminated from the population.  Now the population of black robins had a much larger portion of a dangerous  gene (allele),  the one enforcing such behavior, laying an egg on the rim of the nest,  in the general population of black robins.

The team stopped repositioning the eggs [from the nest rim] in 1990, once robin numbers had bounced back to more promising levels. Natural selection started doing its thing and the proportion of rim-laying females has fallen from 50 percent to around 10 percent. ...

The goal of conservation isn’t just to save a species temporarily, but to create a wild population that can sustain itself without our help. The black robin shows just how difficult this goal can be, [since ] good intentions ...[can lead to] unintended consequences....

Yong meant his post to point up the difficulties of conservation. And so Yong titled his blog post: "In Saving A Species, You Might Accidentally Doom It". But he does not address the real mystery: how come people so often forget this obvious fact: -- good intentions can have bad consequences.