Snares crested penguin
Eudyptes robustus Oliver, 1953
Other names: Snares penguin, Snares Island penguin
Geographical variation: Nil known, though birds on Western Chain islets breed 6 weeks later than the main population
The Snares crested penguin is one of eight similar-looking species of crested penguins, all of which have occurred in New Zealand, and four of which breed here. The Snares crested penguin has the most restricted breeding distribution of all the crested penguin species, being endemic to the 300 ha Snares Islands group. Moulting birds may occur on any of the subantarctic islands and north to Cook Strait. It is sometimes considered conspecific with the Fiordland crested penguin. However, despite 20-30 of the latter visiting the Snares Islands each breeding season, the two species have never been found interbreeding.
One of the mysteries of the Snares crested penguin is why birds in the tiny population on the Western Chain islets, 3 km south-west of the main islands, breed 6 weeks later than the birds on North East and Broughton Islands. Are these birds reproductively isolated, and therefore a cryptic species? Another mystery (likely to be solved soon) is where do Snares crested penguins go during May-August, when absent from their breeding islands?
The Snares crested penguin is a medium-sized crested penguin, about three times larger than the familiar little penguin. It has a black back, face and throat, sharply demarcated from white underparts. The robust orange bill has prominent pink skin around the base. Thin yellow eyebrow stripes start near the nostrils and spread into crests behind the red-brown eyes. From the front, the two crests spread out as a ‘V’. Immature birds have smaller bills and crests.
Voice: a very loud, pulsing bray.
Similar species: Fiordland crested penguin has a smaller bill, lacking bare skin at the base. It typically has broader stripes above the eye, and the pale bases to the cheek feather often show as whitish stripes on the cheek. Immature Fiordland crested penguins usually have whitish cheeks. Erect-crested penguins have crests starting nearer the corner of the mouth and rising obliquely over the eyes. From the front, the crests of erect-crested penguins appear more parallel than the splayed crests of other crested penguins. From the side, erect-crested penguins have a relatively large chin and a domed crown. The three rockhopper penguin species are smaller than Snares crested penguin, with redder eyes and more flared crests incorporating more black feathers.
Distribution and habitat
Snares crested penguins are seabirds that only come to land to breed and moult. During the breeding season, adults forage around and north of the Snares Islands and up to 200 km to the east. Distribution during the winter months is unknown, but the number of birds found on the Chatham Islands suggests a predominantly eastward distribution after leaving the Snares Islands. On the Snares Islands, penguins land at 12 sites on the east coasts of the two main islands, and walk up to 900 metres inland to about 150 separate colonies. Most colonies are under Olearia forest or among Hebe shrubland, but a few are on exposed rocky sites. The birds on the Western Chain nest at lower density among boulders and mollymawk nests.
Vagrant birds, mainly moulting during January-March, have been recorded from Chatham, Solander, Antipodes, Auckland, Campbell and Macquarie Islands, and from scattered sites around the South Island and Stewart Island (especially Otago, Banks and Kaikoura Peninsulas). There are single records from Wellington and Hawke Bay, and Snares crested penguins have also been recorded from Tasmania, South Australia and the Falkland Islands.
Snares crested penguins are endemic to the Snares Islands. About 30,000 pairs breed on North East and Broughton Islands, and a few hundred pairs on Toru and Rima Islets in the Western Chain. Colonies on the two main islands range in size from 3-1300 pairs (average 200 pairs). Snares crested penguins are unusual among crested penguins in that their population is apparently stable, while six of the seven other crested penguin species have declined over the last 30-100 years.
Threats and conservation
No threats are known, and the breeding islands are all free of introduced predators. However, the main prey species (arrow squid, red bait, and red cod) are all commercially harvested, and so there is potential for interactions with fisheries. In 2008-09, 23.2 tons of arrow squid were caught in the vicinity of the Snares Islands.
Natural predators include New Zealand sea lion, New Zealand fur seal and leopard seal (the latter vagrant at the Snares Island, but they consume many penguins when present). Subantarctic skuas and red-billed gulls take many eggs and young chicks, but have little effect on productivity as few pairs are capable of raising both chicks. Northern giant petrels take some fledglings when they first go to sea.
The following summary is for birds on the two main islands. Breeding on the Western Chain islets occurs 6 weeks later. Adults return to colonies in September and lay mid September – mid October. The second egg is significantly larger than the first. Both adults share incubation and care of the young. About 60% of pairs hatch both eggs (late October – early November), but in almost all cases, only one chick survives more than 9 days. Chicks are guarded for c.3 weeks, then form crèches for about 6 weeks before departing the island in late January.
Behaviour and ecology
Snares crested penguins are colonial breeders, and typically forage in small flocks when close to the breeding islands. Adults moult at breeding colonies in March and April. Non-breeders (mainly young birds) moult predominantly on coastal rocks above landing sites or on the margins of colonies, in January-March. Each bird stays ashore for the 3-4 weeks required to complete moult. They first breed when c. 6 years old.
Chicks are reared predominantly on small crustaceans (especially Nyctiphanes krill), with fish making up 30% of the diet (principally Hector’s lanternfish Lampanyctodes hectoris and long-snouted pipefish Leptonotus morae), and squid 10% (mainly arrow squid Nototodarus sloanii). Adults feed primarily on pelagic fish (mainly juvenile redbait Emmelichthys nitidus and red cod Pseudophycis bacchus) and squid species (mainly arrow squid, warty squid Morotheutis ingens and violet squid Histiotheuthis atlantica). Other fish and squid species and pelagic octopi are taken in smaller quantities. Food is obtained by pursuit diving at depths up to 120 metres (typically 15-80 metres).
Demongin, L.; Poisbleau, M.; Strange, G.; Strange, I. 2010. Second and third records of Snares penguins (Eudyptes robustus) in the Falkland Islands. Wilson Journal of Ornithology 122: 190-93.
Lamey, T.C. 1990. Snares crested penguin in the Falkland Islands. Notornis 37: 78.
Marchant, S.; Higgins, P.J. (eds) 1990. Handbook of Australian, New Zealand and Antarctic birds. Vol. 1, ratites to ducks. Melbourne, Oxford University Press.
Mattern, T. (in press). Snares penguin (Eudyptes robustus). In Garcia Borboroglu, P.; Boersma, P.D. Penguins: natural history and conservation. Washington University Press.
Mattern, T.; Houston, D.M.; Lalas, C.; Setiawan, A.N.; Davis, L.S. 2009. Diet composition, continuity in prey availability and marine habitat – keystones to population stability in the Snares penguin (Eudyptes robustus). Emu 109: 204-13.
Miskelly, C.M.; Bell, M. 2004. An unusual influx of Snares crested penguins (Eudyptes robustus) on the Chatham Islands, with a review of other crested penguin records from the islands. Notornis 51: 235-237.
Miskelly, C.M.; Sagar, P.M.; Tennyson, A.J.D.; Scofield, R.P. 2001. Birds of the Snares Islands, New Zealand. Notornis 48: 1-40.
Warham, J. 1974. The breeding biology and behaviour of the Snares crested penguin. Journal of the Royal Society of New Zealand 4: 63-108.
Miskelly, C.M. 2013. Snares crested penguin. In Miskelly, C.M. (ed.) New Zealand Birds Online. www.nzbirdsonline.org.nz
Snares crested penguin
- Social structure
- Breeding season
- Nest type
- lined scrape
- Nest description
- Shallow muddy scrape or low platform of twigs, Olearia leaves, bones or stones.
- Nest height (mean)
- 0 m
- Nest height (min)
- 0 m
- Nest height (max)
- 0 m
- Maximum number of successful broods
- Clutch size (mean)
- Mean egg dimensions (length)
- 69.6 mm
- Mean egg dimensions (width)
- 53.55 mm
- Egg colour
- Chalky white, with pale blue tinge when fresh rapidly soiled with mud
- Egg laying dates
- Interval between eggs in a clutch
- 4.4 days days
- Incubation behaviour
- Incubation length (mean)
- 33 days
- Incubation length (min)
- 31 days
- Incubation length (max)
- 37 days
- Nestling type
- Nestling period (mean)
- Approximately 21 days
- Age at fledging (mean)
- Approximately 75 days
- Age at independence (mean)
- Approximately 75 days
- Age at first breeding (min)
- 6 years
- Maximum longevity
- 22 years
- Maximum dispersal
- 3000 km