The South Island robin is a familiar bird to those who venture into the South Island back-country. It occurs in forest and scrub habitats, where it spends much time foraging on the ground, and can be recognised by its erect stance and relatively long legs. It is a territorial species, males in particular inhabiting the same patch of forest throughout their lives. Males are great songsters, particularly bachelors, singing loudly and often for many minutes at a time. Where robins are regularly exposed to people, such as along public walking tracks, they become quite confiding, often approaching to within a metre of a person sitting quietly. Juveniles will sometimes stand on a person’s boot.

Identification

The adult male South Island robin is dark grey-black over the head, neck, mantle and upper chest; the flight feathers and tail are brownish-black, and the lower chest and belly white to yellowish white with a sharp demarcation between black and white on chest. Adult females are light to dark grey over the upper body. They further differ from males in the  white chest-belly area being smaller and not having such a distinct demarcation between grey and white feathering. Juveniles are similar to females, but often with a smaller or no white patch on the underparts. Adults of both sexes are able to expose a small white spot of feathers above the base of the beak during intraspecific and interspecific interactions.         

Voice: South Island robins have four recognisable vocalisations. Fullsong is a series of phrases given loudly by males only, generally from a high perch. Robins can be heard giving fullsong year round, but particularly during the breeding season. It is used to indicate territorial occupancy and to attract a mate – bachelors spend much more time singing than paired males. Subsong is similar to fullsong but given at much less volume, is given by both sexes, and most frequently during the moult. The downscale is a series of very loud ‘chuck’ calls, descending in tone, and which start in rapid succession and finish slowly. The call lasts 3-4 seconds, is given by both sexes, and is most frequently heard during the non-breeding season (January-June). The fourth vocalisation type is the ‘chuck’, which is given as single notes (contact calls) or in rapid succession and loudly (as an alarm call) when a predator is nearby.      

Similar species:there are no species that are similar to the robin in the South Island or Stewart Island. Robins are much larger and lack the white wing-bars of tomtits.

Distribution

The South Island robin has a disjunct distribution through both the South and Stewart Islands. Its strongholds in the South Island are Marlborough, Nelson, West Coast as far south as about Harihari, and through Fiordland, with outliers at Jackson Bay and Dunedin. A comparison of the Ornithological Society of New Zealand’s atlas scheme results of 1969-79 and 1999-2004 suggest that the South Island robin’s distribution has changed little during the 20 year interval. Several populations, particularly on islands, have been established by translocations.

Habitat

Robins occur in mature forest, scrub, and exotic plantations, particularly those that are fairly mature with an open understorey. They seem to favour moist areas where there is an open understorey under a closed canopy on fertile soils. Habitats that tend to be shunned are those with widely scattered trees and where the ground is covered by grasses or sparse vegetation on stony, droughty soils.  

Population

South Island robin is patchily distributed through its range, and is absent from some seemingly suitable areas while common in others. Pairs have territories of 1-5 ha on the mainland, although populations on pest-free islands can occur at much greater densities (0.2-0.6 ha / pair). 

Threats and conservation

While forest clearance for farmland during the 19th and 20th centuries resulted in loss of habitat for the South Island robin, today the main threat to its conservation is predation by introduced mammalian predators, such as feral cats, stoats, possums and ship rats. Eggs, nestlings and adult females (which carry out all incubation and brooding of young) are frequently taken during the breeding season where predators are not controlled. As a result populations become male biased. Where pest control is carried out, populations increase rapidly, and the sex ratio returns to almost 1:1 within a few years – there are usually a few more males than females.    

Breeding

South Island robins start nesting in July, with the last clutches laid in December. The female builds the nest while her mate brings her food 2-3 times per hour. Only females incubate the 2-4 eggs; her mate calls her from the nest every 20 minutes or so to provide her with food. Both parents feed the nestlings. Nestlings leave the nest when about 3 weeks old, and continue to be fed by their parents for a further 5-6 weeks. If one fledgling is reared the male feeds it while the female builds a nest and incubates the next clutch. If there are two fledglings, each is usually fed by a different parent, and if three the male usually looks after two and the female one.         

Behaviour and ecology

Male robins are territorial year round, although their aggression towards intruders is subdued during the moult. Pairs remain in their territories most of the time, occasionally sneaking elsewhere to feed, drink or bathe. Males dominate their mates during the non-breeding season, such that pair members are occasionally found apart.

Robins use a variety of activities to flush hidden or camouflaged prey, such as foot trembling, wing-flicking and tail-flicking. Occasionally they capture relatively large prey, which are killed, dismembered, and some portions are often cached. These are usually retrieved later the same day or the following one. Other activities of South Island robins include anting, sunbathing and pellet casting.

Food

While robins spend much time foraging on the ground, they also scan from perches for prey. Much of their diet consists of invertebrates, and large prey items include earthworms, cicadas, stick insects, tree weta and slugs. Slugs are wiped on the ground from side to side, presumably to get rid of slim, before being eaten. Robins also eat small ripe fruit in summer and autumn, particularly during drought when few soil-dwelling invertebrates are available.   

Websites

BirdLife factsheet

Wikipedia

https://www.doc.govt.nz/nature/native-animals/birds/birds-a-z/nz-robin-toutouwai/

References

Flack, J.A.D. 1979. Biology and ecology of the South Island robin. In Hunt, D.M.; Gill, B.J. (eds). Ecology of Kowhai Bush, Kaikoura. Mauri Ora Special Publication 2: 22-26.

Higgins, P.J.; Peter, J.M. (eds). 2002. Handbook of Australian, New Zealand & Antarctic birds. Vol. 6, pardalotes to shrike-thrushes. Oxford University Press, Melbourne.

Miskelly, C.M.; Powlesland, R.G. 2013. Conservation translocations of New Zealand birds, 1863-2012. Notornis 60: 3-28.

Powlesland, R.G. 1981. The foraging behaviour of the South Island robin. Notornis 28: 89-102.

Powlesland, R.G. 1983. Seasonal and diurnal variation in vocal behaviour of the South Island robin. New Zealand Journal of Zoology 10: 225-232.

Robertson, C.J.R.; Hyvonen, P.; Fraser, M.J.; Pickard, C.R. 2007. Atlas of bird distribution in New Zealand, 1999-2004. Ornithological Society of New Zealand, Wellington.

Robertson, H.A; Baird, K.; Elliott, G.P.; Hitchmough, R.A.; McArthur, N.J.; Makan, T.; Miskelly, C.M.; O’Donnell, C.F.J.; Sagar, P.M.; Scofield, R.P.; Taylor, G.A.; Michel, P. 2021. Conservation status of birds in Aotearoa New Zealand birds, 2021. New Zealand Threat Classification Series 36. Wellington, Department of Conservation. 43p.

Recommended citation

Powlesland, R.G. 2013 [updated 2022]. South Island robin | kakaruai. In Miskelly, C.M. (ed.) New Zealand Birds Online. www.nzbirdsonline.org.nz