Conservation Comment: Dispelling robin rumours

When is a robin not a black robin? When it lives in Bushy Park. The park's robins are North Island robins, like this one.

Why do so many people keep repeating that Bushy Park has resident black robins? I hear this more and more, (and even at the Bushy Park homestead last month).

Journalists writing about Bushy Park might read this nonsense in a publication and believe it to be true, so they copy it without checking. I read it myself, recently. Others also assume the material they read about is factual. They mention it to someone else, that person repeats it and so on, ad infinitum.

Fact check: All the robins at Bushy Park are North Island robins (Petroica longipes) one of three subspecies of New Zealand robin. Please tell people who say otherwise.

Seven females and 21 males were released into Bushy Park in 2001. In 2004, 11 females and seven males were translocated, just before the present predator-proof fence was erected in 2005. The release served to reinforce a tiny pre-existing population. Until the fence was complete and rats and other mammalian predators were eradicated, the robin population struggled to establish and maintain itself. Since 2005, however, the population has thrived.

The regional representative of Birds New Zealand, Peter Frost, says, "There is absolutely no possibility of black robins being seen at Bushy Park. People are either seeing old North Island robin males (dark grey), perhaps in dull light, which may make the birds seem darker, or they are seeing male tomtits but aren't noting the white wing bar or off-white underparts."

The North Island robin or toutouwai (status: declining) occurs in forest and scrub habitats from Taranaki to the Bay of Plenty, plus Little Barrier and Kapiti Islands. Several populations beyond these areas (like Tiritiri Matangi Island) have also been established by translocations.

Toutouwai can be recognised by its erect stance and relatively long legs. At 18 cm high, it spends much time foraging on the ground. It is a territorial species, males in particular inhabiting the same patch of mainland forest of 1-5 ha throughout their lives. Males are great songsters, singing loudly and often for many minutes at a time.

Where toutouwai are regularly exposed to people, such as along public walking tracks in Bushy Park, they often approach to within a metre of a person sitting quietly. Naive juveniles will sometimes stand on a person's boot.

Male toutouwai exhibit delayed plumage maturation whereby the plumage becomes darker at each of the first two to three annual moults. Males at independence are light grey or dark grey, like females.

Most males achieve adult colouration (generally dark grey-black) at their second moult (19-22 months) but some take another year before becoming blackish, and a few seem to remain dark grey throughout their lives. Males breed successfully whether they are light grey (less than 12 months old), dark grey or blackish.

Many contour feathers of North Island robins have pale shafts, which give the species its faintly streaked appearance. Both sexes have a pale grey-white patch over the lower chest-belly, and sometimes expose a small white spot of feathers above the base of the beak.

The only places the black robin (Petroica traversii) exists today are predator-free Mangere Island and South East Island in the Chathams.

According to DoC, in 2013 the population was about 250. Its status is threatened: nationally critical.

Both sexes are completely black at all ages, though juveniles have subtle pale streaking on the crown. Birds appear short and round through their habit of holding their large heads hunched close to their bodies. The sexes are indistinguishable to casual observation (weight and size ranges overlap).

The black robin is smaller than the North Island robin, measuring 10 to 15 cm. Its plumage is almost entirely brownish-black, with a black bill and brownish-black, yellow-soled feet.

All of today's black robins are descended from the last breeding female, Old Blue. She was one of the longest-lived robins known, reaching 14 years of age.

The story of bringing the black robin back from extinction is one of the most inspiring conservation stories in the world. There were only five black robins in the world in 1980, with just a single breeding pair left. The outlook was bleak.

The species was saved by Don Merton (1939-2011) and his NZ Wildlife Service team, and by Old Blue and Old Yellow (a male), and a foster species, the Chatham Island tit.
Could it be that all the publicity about saving the black robin has given rise to the notion that all robins in New Zealand sanctuaries are black robins? Do people not realise there are other robin species in NZ?

■http://nzbirdsonline.org.nz/species/north-island-robin
■http://www.nzbirdsonline.org.nz/species/black-robin
■www.doc.govt.nz/nature/native-animals/birds/birds-a-z/black-robin/

Margi Keys is a bird watcher, a member of Forest & Bird, Project Tongariro and the Green Party of Aotearoa/New Zealand. She is on the committee of the Whanganui Regional Museum Botanical Group and co-ordinates the Conservation Comment scribes.