Little shearwater

Puffinus assimilis Gould, 1838

New Zealand status: Native

Conservation status: Recovering

Other names: allied shearwater

Geographical variation: Four subspecies, three known from New Zealand: North Island little shearwater P.a. haurakiensis, breeding on islands from the Bay of Plenty to the Three Kings; Kermadec little shearwater P.a. kermadecensis from the Kermadec Islands; Norfolk Island little shearwater P.a. assimilis from Norfolk Island.

Little shearwater. Adult in flight. Hauraki Gulf, November 2009. Image © Phil Swanson by Phil Swanson

Little shearwater. Adult in flight. Hauraki Gulf, November 2009. Image © Phil Swanson by Phil Swanson

Little shearwaters are not well known because they are small, relatively shy and do not flock like other shearwaters. They also tend keep a little further offshore than similar seabirds. Little shearwaters are winter breeders, and so are present at their colonies at a time of year when fewer people are out on the water or doing field work. Their breeding behaviour and many other facets of their lives are not yet well known.

Identification

Little shearwaters are the smallest of the shearwaters, and are black above and white below. These colours are fairly clearly demarcated, especially on the head and neck. They have a much whiter face than similar birds, the boundary between black and white runs through the eye or above it. They are a clean white under the wings with a very narrow black margin. They also have small white tabs on the sides of their back just behind the wings. Their flight has the typical small shearwater pattern of a series of rapid shallow wing beats followed by a glide and they usually stay close to the surface of the water. The bill is fine and dark grey, but blackish on the top and tip; the legs and feet are blue with pinkish cream webs.

Voice: a loud harsh rapidly repeated call kakakakakakak-urrr; the last syllable sounds as if the bird is drawing breath while uttering it.

Similar species: the common small shearwater in northern New Zealand is the fluttering shearwater which is larger and often seen in flocks. They are brownish black rather than black although this is least apparent immediately after the moult. Fluttering shearwaters are extensively brownish under the wings, especially the trailing edge and near the body, the face and sides of their necks are brownish black becoming smudgy. Hutton’s shearwaters are very similar to fluttering shearwaters but even darker on the neck and under the wings. Subantarctic little shearwater mainly differs in having a darker face, with the demarcation line between black and white passing below the eye. The common diving petrel can also be mistaken for a little shearwater, especially from a moving boat in choppy water. The diving petrel is also black above and white below, but is smaller and much stouter, with short wings that beat rapidly and continuously in flight.

Distribution and habitat

Little shearwaters are pelagic in temperate to sub-tropical waters, usually on the outer edge of the continental shelf or just beyond. They are mainly seen around the Kermadec Islands and off the coast of northern half of the North Island, down to about Wellington on the west coast. In addition to the Kermadec Islands, the breeding islands are scattered off the north-eastern coast of the North Island south to the northern Bay of Plenty.

Population

There are estimated to be about 100,000 pairs of Kermadec little shearwaters breeding on Curtis Island, with hundreds to thousands of pairs on most of the other islands in the group. They were extirpated from Raoul Island by introduced rats and cats (since eradicted). There are probably only about 10,000 pairs of North Island little shearwaters with notable populations on the Alderman Islands (c.4000 pairs) and Red Mercury Island (c.1000 pairs). Other islands have hundreds of pairs at best.

The Norfolk Island little shearwater, which occasionally visits New Zealand, has a population of about 5000 pairs breeding in the Norfolk and Lord Howe Island groups.

Threats and conservation        

Not surprisingly for such a small petrel, little shearwaters suffer badly from exotic predators. They can coexist with Pacific rats (kiore) but breeding success and colony size is significantly reduced. They are not able to coexist with Norway or ship rats, feral cats or stoats. Little shearwaters are likely to have benefitted from the eradication of Pacific rats from many of their breeding islands off the north-east North Island (Hen and Chickens, Mokohinau, Mercury and Alderman Islands), and therefore have a conservation ranking of Recovering.

The Kermadec Islands are active volcanoes and eruptions, especially on Curtis Island where the vast bulk of the population of the endemic subspecies breeds, could be disastrous.

The breeding burrows are fragile, typically dug into very friable soil, and would be easily crushed by people walking in the breeding colonies.

Breeding         

Little shearwaters nest in burrows in soil, usually under scrub or forest. They are winter breeders but at least a few birds visit the colonies through most of the year. In the Kermadec Islands eggs are laid in mid to late June and July and the young fly between mid-October and early December. The North Island subspecies has a slightly later season with eggs laid in July and early August and the young leaving between mid-November and December.

Behaviour and ecology

At sea, little shearwaters are usually seen alone. They fly close to the water and take prey near the surface by dropping on it from flight, seizing it from the surface or chasing it in shallow dives.

Food

Small fish, squid and crustaceans have all been recorded but their relative importance is unknown.

References

Heather, B.D.; Robertson, H.A. 1996. The field guide to the birds of New Zealand. Viking, Auckland.

Marchant, S.; Higgins, P.J. (eds.), 1990. Handbook of Australian, New Zealand and Antarctic birds. Vol 1, ratites to ducks. Oxford University Press, Melbourne.

Taylor, G. A. 2000. Action plan for seabird conservation in New Zealand. Part A: Threatened seabirds. Threatened species occasional publication no. 16, Biodiversity Recovery Unit, Department of Conservation, Wellington.

Veitch, C.R.; Miskelly, C.M.; Harper, G.A.; Taylor, G.A.; Tennyson, A.J.D. 2004. Birds of the Kermadec Islands, south-west Pacific. Notornis 51: 61-90.

Recommended citation

Southey, I. 2013. Little shearwater. In Miskelly, C.M. (ed.) New Zealand Birds Online. www.nzbirdsonline.org.nz

Little shearwater

Breeding season
  • Jul
  • Aug
  • Sep
  • Oct
  • Nov
  • Dec
  • Jan
  • Feb
  • Mar
  • Apr
  • May
  • Jun
Egg laying dates
  • Jul
  • Aug
  • Sep
  • Oct
  • Nov
  • Dec
  • Jan
  • Feb
  • Mar
  • Apr
  • May
  • Jun

North Island little shearwater

Breeding season
  • Jul
  • Aug
  • Sep
  • Oct
  • Nov
  • Dec
  • Jan
  • Feb
  • Mar
  • Apr
  • May
  • Jun
Egg laying dates
  • Jul
  • Aug
  • Sep
  • Oct
  • Nov
  • Dec
  • Jan
  • Feb
  • Mar
  • Apr
  • May
  • Jun

Norfolk Island little shearwater

Breeding season
  • Jul
  • Aug
  • Sep
  • Oct
  • Nov
  • Dec
  • Jan
  • Feb
  • Mar
  • Apr
  • May
  • Jun
Egg laying dates
  • Jul
  • Aug
  • Sep
  • Oct
  • Nov
  • Dec
  • Jan
  • Feb
  • Mar
  • Apr
  • May
  • Jun

Kermadec little shearwater

Social structure
monogamous
Breeding season
  • Jul
  • Aug
  • Sep
  • Oct
  • Nov
  • Dec
  • Jan
  • Feb
  • Mar
  • Apr
  • May
  • Jun
Nest type
burrow
Nest description
Nest a burrow in soil.
Nest height (mean)
0.00 m
Maximum number of successful broods
1
Clutch size (mean)
1
Mean egg dimensions (length)
54.00 mm
Mean egg dimensions (width)
36.00 mm
Egg colour
White
Egg laying dates
  • Jul
  • Aug
  • Sep
  • Oct
  • Nov
  • Dec
  • Jan
  • Feb
  • Mar
  • Apr
  • May
  • Jun
Interval between eggs in a clutch
Not applicable
Incubation behaviour
shared
Incubation length (mean)
52-58 days
Incubation length (min)
52days
Incubation length (max)
58days
Nestling type
altricial
Age at fledging (mean)
70-75 days
Age at independence (mean)
70-75 days
Age at first breeding (typical)
Unknown
Maximum longevity
Unknown
Maximum dispersal
1,500 km