Facts about North Island robin

North Island robin

There are three forms of the New Zealand robin, each found on one of the main islands; the North Island robin (Petroica longipes), South Island robin (Petroica australis australis), and Stewart Island robin (Petroica australis rakiura). The first two forms are not threatened, but the Stewart Island robin is 'nationally vulnerable' because of the impacts of introduced predators.

What does it look like?

North Island robins are dark slaty-grey with a pale greyish-white lower breast and belly. The upper dark feathers have pale shafts and so the birds appear faintly streaked. Exact colouration depends on age and sex. Males older than three years of age are almost black over the upper parts, while females and most males less than two years old are mainly pale to dark grey above.

Both sexes have a small patch of white feathers at the base of the beak which is kept covered much of the time, occasionally being flashed when interacting with robins and other small forest birds.

Where is it found?

The North Island robin is found in native and exotic forests, mainly in the central North Island from Taranaki through to the Bay of Plenty. In addition, populations occur on Little Barrier and Kapiti Islands.

Since 1991, populations have been established on several predator-free islands (Mokoia, Tiritiri Matangi, Tuhua, Matiu/Somes, Mana, Moturoa) and several mainland sites which are encircled by predator-proof fences (Karori Sanctuary, Bushy Park Reserve) or where mammalian predators (rats, stoats, possums) have been controlled to very low levels (Trounson Kauri Park, Pangareoa Mainland Island, Kakepuku Mountain, Hunua Ranges, Boundary Stream Mainland Island, Wenderholm Regional Park, Kotuku Peninsula and Windy Hill Catchment of Great Barrier Island, Mangaokewa Reserve, Barnett Reserve, Stephenson Covenant, Tawharanui Open Sanctuary, Ocean Beach Wildlife Preserve).

Male robins are renowned songsters of the forest. From August to December, males spend much time loudly singing from high perches in the canopy, especially in the early morning. Bachelor males also spend much time through the day giving full song in an attempt to attract a mate. Full song consists of a variety of simple notes strung together and sustained for up to 30 minutes with regular brief pauses.

What does it eat?

The robin's diet consists mainly of invertebrates, including species from the size of aphids to those as large as an adult tree weta, stick insect, or earthworm. Items too large to swallow whole are taken to the ground and flung from side to side against the ground or log until broken into pieces.

Although robins are unable to eat such large prey items all at once, the excess is not wasted. Uneaten portions are stored in crevices, holes or depressions on trunks and branches of trees near where the item was found, to be retrieved and eaten later in the day or the next day. In late summer-autumn, when conditions are dry and there is little invertebrate prey available, robins supplement their diet with small berries and fruit.

When does it breed and nest?

Although the oldest robin known lived to at least 16 years of age, most have a much shorter lifespan. Both sexes start breeding when one year old. The breeding season of the North Island robin starts in September and extends to February. At sites where food is readily available, pairs rear two, and occasionally three, broods in a season.

The nest, commonly built in a trunk or branch-trunk fork, consists of an outer layer of twigs, fibers and moss bound together with cobwebs. The inner layer consists of moss, fine grasses, and/or tree fern scales.

As well as building the nest on her own, the female incubates her clutch of 2-3, unusually 4, eggs on her own. However, during both of these phases of the nesting cycle, her mate brings her food about 3 times an hour through the day. Incubation lasts about 18 days, chick-rearing about 21 days. The male assists with chick-rearing, and once the chicks have left the nest, each parent looks after particular fledglings.

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