The Black Robin (Petroica traversi) is a small passerine bird endemic to the Chatham Islands of New Zealand. It is famous for being one of the world's most dramatic conservation success stories, having recovered from a population low of just five individuals in 1980.
Taxonomy and Etymology
The Black Robin belongs to the Australasian robin family Petroicidae. Its scientific name, Petroica traversi, commemorates Henry H. Travers, who collected specimens from the Chatham Islands. It is closely related to the New Zealand robin (Petroica australis) and the Chatham Island robin (Petroica chathamensis).
Description
The Black Robin is a small, plump bird, typically measuring about 15 cm (6 inches) in length and weighing around 22–25 grams (0.78–0.88 oz). As its name suggests, adults are entirely black, with glossy black plumage covering their entire body, including their beak, legs, and eyes. Juveniles have a duller, sooty-black plumage with some brownish tones. They have relatively long legs and a short tail. Their song is a series of simple, high-pitched whistles.
Habitat and Distribution
Historically, the Black Robin was found on several of the Chatham Islands. However, due to habitat loss and the introduction of mammalian predators, its range became severely restricted. Today, its population is confined primarily to two predator-free islands within the Chatham archipelago: Rangatira (South East Island) and Mangere Island. These islands provide dense forest and scrubland habitat, which is crucial for their survival.
Diet
Black Robins are insectivorous. They forage mainly on the ground, hopping amongst the leaf litter and peering for invertebrates such as insects (beetles, wētā, caterpillars), spiders, and worms. They also occasionally catch insects in flight.
Breeding and Behavior
Black Robins are monogamous and typically form long-term pair bonds. Breeding season usually runs from September to February. The female builds a cup-shaped nest, often in tree cavities or dense vegetation, using moss, twigs, and spiderwebs. She lays 1-3 eggs, which are incubated for about 18 days. Both parents participate in feeding the chicks, which fledge after approximately 23 days. They are known for their tameness and often approach humans.
Conservation Status and History
The Black Robin's conservation story is unparalleled. By 1972, the species was critically endangered, with only 18 individuals remaining on Little Mangere Island. After a severe storm reduced their numbers further, the population plummeted to just five individuals on Mangere Island in 1980, comprising only one breeding pair ("Old Blue" and "Yellow-Yellow"), two other males, and one non-breeding female.
A desperate recovery program, led by ornithologist Don Merton and his team, implemented innovative cross-fostering techniques. Black Robin eggs were transferred to the nests of Chatham Island warblers (Gerygone albofrontata), which acted as surrogate parents, allowing the Black Robins to lay second clutches. This strategy, combined with intensive predator control, habitat restoration, and translocations to new predator-free islands (Mangere Island and Rangatira), slowly began to rebuild the population.
The success of the program largely relied on the genetic contribution of the sole breeding female, "Old Blue," who lived for an impressive 14 years and was a prolific breeder. All living Black Robins today are descendants of "Old Blue" and "Yellow-Yellow."
Currently, the Black Robin is classified as "Conservation Dependent" or "Vulnerable" by the IUCN, reflecting the ongoing need for management and monitoring, despite its remarkable recovery. The population has grown to several hundreds of individuals, demonstrating the potential for successful species recovery even from the brink of extinction.