ENDANGERED: Black Robin (Petroica traversi)

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4 min readFeb 21, 2023

Day #15

The Black Robin is a 15 cm bird from the passerine family. It looks like a cute ball of down with a beak and is only found on the Chatham Islands off the east coast of New Zealand. The living environment is lowland, bushy forests.

The Black Robin feeds on insects. It looks for food on the ground or in low branches.
The breeding season lasts from early October to late December. The nest is located in a hollow or other hole in a tree or in a broken trunk. The female lays 1–3 cream-colored eggs with purple spots. Incubation lasts about 18 days. Both birds of the pair participate in feeding. The young leave the nest at the age of 23 days, but are still fed by their parents until they are 65 days old.

https://commons.wikimedia.org/w/index.php?curid=11763306

In 1980, their number was only 5 individuals: three males and two females.
They lived on rocks several hundred square meters in size. Steep cliffs protected them from cats, stoats and rats brought to the islands by sailors. The harsh winds, however, proved too dangerous for these small birds, and most died out. With only one pair left — Old Blue and Old Yellow — their future did not look bright.

Don Merton and a team of conservationists launched a heroic effort to save them. They moved the pair to a larger island and oversaw their breeding for many years, transferring their eggs to foster parents for the incubation period.
In 1989, there were already 80 Black Robins.
In 1998, there were over 200.

By Peter de Lange — https://www.inaturalist.org/photos/2305008, CC0

The Black Robin, once the world’s most endangered bird, has become a flagship example of conservation success.
Thanks to the implemented protection program, it was possible to rebuild the population to 260 animals in 2011.

However, during this process, an anomaly was discovered that could make these birds unable to reproduce without human help. It was an anomaly written in the bird’s genes.
It turned out that some females lay eggs on the edge of the nest, not in the middle. The eggs laid on the rim never developed and hatched. So the team of researchers repositioned the eggs from the edge and placed them inside. Thanks to this, the population grew, but it could not develop without human intervention.

Therefore, the entire process was traced from the beginning of the protection of these birds.
Old Blue, the last fertile female from 1980, laid eggs normally. In 1984 there were five females and one laid one egg on the edge. In 1989, there were 35 females, of which 18 (more than half) laid their eggs on the edge.
Edge-laying seemed to have a strong genetic basis. In fact, it was most likely caused by a dominant allele — a version of the gene that gives edge splicing, even when a bird inherits only one copy from either parent.
The team stopped repositioning the eggs in 1990, when Black Robins numbers had reached a more promising level.
Natural selection took its toll, and the percentage of edge-laying females dropped from 50 percent to about 10 percent. However, these alleles still exist, hiding in the bodies of males, waiting to pass on to the next generation.

By Peter de Lange — https://www.inaturalist.org/photos/2235630, CC0

The goal of conservationists is not just to save the species temporarily, but to create a wild population that can survive without our help. The Black Robin shows how difficult it can be. The team saved the bird, but their actions threatened to prevent it from reproducing on its own.

According to the IUCN, the species is still classified as vulnerable to extinction.

The Black Robin is considered a national symbol of New Zealand’s conservation efforts, and it has been celebrated in art, literature, and music.

Sources:
https://pl.wikipedia.org/wiki/Skalinek_czarny
https://www.listyznawszysadu.pl/pl/article_print.php?id=558188

photo:
By frances schmechel — originally posted to Flickr as DSCF3430 black robin by NG, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=11763306

By Peter de Lange — https://www.inaturalist.org/photos/2305008, CC0, https://commons.wikimedia.org/w/index.php?curid=123791822

By Peter de Lange — https://www.inaturalist.org/photos/2235630, CC0, https://commons.wikimedia.org/w/index.php?curid=123791782

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