Campbell black-browed mollymawk | Toroa
Thalassarche impavida Mathews, 1912
Other names: Campbell Island mollymawk, Campbell black-browed albatross, Campbell Island albatross, black browed mollymawk, blackbrowed mollymawk, black browed albatross, blackbrowed albatross, Campbell mollymawk, Campbell albatross
Geographical variation: Nil
The Campbell black-browed mollymawk is one of 12 species of albatross that breed in New Zealand, and one of seven endemic species. It is one of the smaller albatrosses, and characterised amongst this group by having an all-yellow-orange bill, and all white body. There is a black triangle around the eyes which contrasts strongly with the otherwise white head and gives the appearance that the bird is frowning. The upper wings are dark, and the underwings are white with broad black edges. The eyes are honey-coloured, which is the main distinguishing feature from the more widespread black-browed mollymawk, which has dark eyes.
Campbell black-browed mollymawk are found throughout the continental shelf area of southern New Zealand waters, and feed on small fish, squid and crustaceans, mainly in water depths less than 200 m. It is commonly found south of Cook Strait, but occurs as far south as 60° South, and around East Cape in the autumn to winter.
The Campbell black-browed mollymawk is a large white-bodied bird with dark upperwings and tail. The eye has a distinctive ‘black-brow’ from which the species takes part of its name. The rest of the name refers to its sole breeding location (Campbell Island) and is necessary to distinguish the local birds from the circumpolar black-browed mollymawk. The two differ mainly in their eye colour – pale yellow in the Campbell black-browed mollymawk, and black in the black-browed mollymawk. The underwing is white with broad black margins. The bill is a vibrant orange-yellow, the tip may be darker than the sides, and can be reddish. In juvenile birds the eye is dark, there may be a dusky hood or collar, and the bill is greyish-black, lightening progressively to orange along the sides and finally the tip over a period of 2-3 years.
Voice: a range of croaks, wails, throbbing groans, and grunts.
Similar species: the black-browed mollymawk (=albatross) retains a dark iris into adulthood and has a whiter underwing (i.e the black margins are broader in the Campbell Island birds). The Indian Ocean yellow-nosed mollymawk is another small albatross with a white head, but has a much slimmer, more elongated body shape and a proportionally much longer bill which (in adults) is black with a yellow strip along the top. It also has a much whiter underwing. Juvenile grey-headed mollymawks may be indistinguishable from juveniles of the two black-browed mollymawk species, as while the latter are generally paler on the head, all three can pass through a dark-headed stage with an olive-brown bill.
Distribution and habitat
Campbell black-browed mollymawks nest only at Campbell Island and offshore Isle de Jeanette Marie, where they breed on coastal cliffs alongside grey-headed mollymawks, often in mixed colonies. They occur throughout New Zealand seas, mainly south of Cook Strait in summer, and East Cape in autumn. Campbell black-browed mollymawks range widely in Australasian seas, even reaching the Ross Sea during the breeding season (September-May). Vagrants have been recorded north to Vanuatu, New Caledonia and other Pacific islands, but they are very rare in the Indian Ocean, and not known from the South Atlantic. Campbell black-browed mollymawks often follow ships and may spend a day or more keeping close to vessels in their zone, and scavenge actively for fish waste or offal released from vessels. Their feeding habitat is mainly in waters deeper than 200 m.
The numbers of Campbell black-browed mollymawks nesting at Campbell Island have been monitored sporadically since the 1940s, and showed a major decrease in numbers during the 1970s and 1990s. The most recent population estimate was around 21,000 breeding pairs.
Threats and conservation
The Campbell black-browed mollymawk has a secure breeding site with no introduced predators, (although Norway rats and feral cats were formerly present, and may have had some impact). Current threats are likely to result from changes in food availability within the foraging range of the birds, affecting how far they need to fly when feeding chicks. Occasional incidental mortality is noted for the species in longline fishing events, but this is a rare event.
Campbell black-browed mollymawks form long-term monogamous pair-bonds, with shared incubation and chick care. They breed annually, laying the single large (103 x 66 mm) creamy white egg on a pedestal earth nest in September or October, and incubating it for 65-72 days until it hatches in January or February. The chick is fed by regurgitation, and fledges in April-May when 120-125 days old. They typically breed when 10-12 years old, and may live for more than 30 years.
Behaviour and ecology
Campbell black-browed mollymawks are solitary at sea, although may raft in small groups. Birds foraged during breeding by both short and long range flights of > 1000 km. The main feeding area, is on the Campbell Plateau, but birds often fly as far as the Polar Front, 1000-1500 km south of Campbell Island. Campbell black-browed mollymawks often forage behind fishing boats, competing aggressively for offal and discards.
Diet at Campbell consisted mainly of fish, in particular southern blue whiting, also squid and crustaceans.
Cherel, Y.; Klages, N.T. 1998. A review of the food of albatrosses. Pp 113-136 in Robertson, G.; Gales, R. (eds) Albatross: biology and conservation. Surrey Beatty & Sons Pty Ltd, Chipping Norton.
Cherel, Y.; Waugh, S.; Hanchet, S. 1999. Albatross predation of juvenile southern blue whiting (Micromesistius australis) on the Campbell Plateau. New Zealand Journal of Marine and Freshwater Research 33: 437-441.
Marchant, S.; Higgins, P.J. (eds) 1990. Handbook of Australian, New Zealand and Antarctic birds. Vol.1, ratites to ducks. Oxford University Press, Melbourne.
Moore, P.J. 2004. Abundance and population trends of mollymawks on Campbell Island. Science for Conservation 242. Department of Conservation, Wellington. 62p.
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.
Waugh, S.M.; Sagar, P.M.; Cossee, R.O. 1999. New Zealand black-browed albatross Diomedea melanophrys impavida and grey-headed albatross D. chrysostoma banded at Campbell Island: recoveries from the South Pacific region. Emu 99: 29-35.
Waugh, S.M.; Weimerskirch, H.; Cherel, Y.; Shankar, U.; Prince, P.A.; Sagar, P.M. 1999. Exploitation of the marine environment by two sympatric albatrosses in the Pacific Southern Ocean. Marine Ecology - Progress Series 177: 243-254.
Waugh, S.M.; Weimerskirch, H.; Moore, P.J.; Sagar, P.M. 1999. Population dynamics of black-browed and grey-headed albatrosses Diomedea melanophrys and D. chrysostoma at Campbell Island, New Zealand, 1942-96. Ibis 141: 216-225.
Waugh, S.M. 2013 [updated 2022]. Campbell black-browed mollymawk | toroa. In Miskelly, C.M. (ed.) New Zealand Birds Online. www.nzbirdsonline.org.nz
Campbell black-browed mollymawk | Toroa
- Social structure
- Breeding season
- Nest type
- Nest description
- Pedestal nest built on over several years from mud and grasses.
- Nest height (mean)
- 0 m
- Maximum number of successful broods
- Clutch size (mean)
- Mean egg dimensions (length)
- 102.6 mm
- Mean egg dimensions (width)
- 66.1 mm
- Egg colour
- Creamy white occasionally with red-brown spots at the rounded end
- Egg laying dates
- Interval between eggs in a clutch
- Not applicable days
- Incubation behaviour
- Incubation length (mean)
- 65-72 days
- Incubation length (min)
- 65 days
- Incubation length (max)
- 72 days
- Nestling type
- Age at fledging (mean)
- 120-125 days
- Age at independence (mean)
- 120-125 days
- Age at first breeding (typical)
- 10-12 years
- Maximum longevity
- > 30 years
- Maximum dispersal
- Highly philopatric