Chatham Albatross | Thalassarche eremita

Voice

At sea it is usually quiet. At the colony there is bill clacking, harsh croaking and a braying that runs into a series of calls rendered aka aka aka; on a rock packed with thousands of pairs the sound goes on all day.

Identification

About 90 cm long and 3.1 to 4.7 kg. Head and neck carry a dark slate-grey hood, with white behind the eye and a thick black line in front of the eye running towards the bill. The bill is bright orange-yellow along its whole length, with a dark spot at the tip — the most conspicuous bill of any mollymawk (an albatross of the genus Thalassarche) here. The upperparts are blackish brown, the tail dark grey, the underparts white. The underwing is white with a thin black edge and a small dark patch where the wing meets the body. The legs are light grey to flesh. Immature birds have a paler grey hood, a variable underwing pattern and a yellowish-black bill; in newly fledged birds the bill is dark grey.

Confusion species

Salvin's Albatross (Thalassarche salvini) is the nearest double: it has a much paler, silvery-grey hood and a bill that is grey to horn with only a yellow upper ridge and a black spot below — never the wholly bright orange-yellow bill. Shy Albatross (Thalassarche cauta) has a white crown with pale grey cheeks and a grey-green bill with a yellow tip. Buller's Albatross (Thalassarche bulleri) has a black bill with two yellow plates and a broad black leading edge on the underwing, where this species has only a thin rim. In immatures all these marks blunt: a young Chatham does have the darkest hood and the most yellow at the bill base, but with a dark-grey bill a single passing youngster at sea often cannot be lifted out of the cauta group with confidence — an honest limit to this identification. The great albatrosses of the genus Diomedea, such as Antipodean Albatross (Diomedea antipodensis), are twenty to thirty centimetres longer, pink-billed and without a dark hood.

Habitat

Open ocean over the Chatham Rise and, outside the breeding season, over the cold upwelling of the Humboldt Current. Breeding is on bare rock ledges of a surf-battered sea stack, where the mud-and-guano nests stand packed together with no shelter at all.

Range and movements

Breeds only on The Pyramid in the Chatham Islands, with about 5,300 pairs — the whole species on one rock of a few hectares. At sea it is commonest over the Chatham Rise and east of New Zealand; between April and July much of the population moves to the South American coast, as far north as six degrees south off Peru. In Australian waters it is a rare visitor, with only a handful of records on pelagic trips off the south-east coast.

• Breeding (summer)
• dark = core range, pale = thinly spread

Where and when to look

The surest place is a boat trip at the Chatham Islands; on New Zealand pelagics east of the South Island it sits among the far commoner Salvin's Albatrosses. So do not look for the hood alone but for hood plus bill: an evenly bright orange-yellow bill under a dark hood is Chatham, a grey bill with only a yellow ridge under a pale hood is Salvin's. For immatures, photographs of the bill and the underwing are indispensable.

Conservation

Vulnerable (VU). One colony on one unsheltered rock is the heart of the problem: a heavy storm can sweep away a large share of the nests in a single season, as happened in the 1980s when the vegetation was stripped from the summit and the birds were left on bare stone. Beyond that, birds are killed as bycatch in New Zealand longline and trawl fisheries, and above all in the artisanal longline fisheries off Peru and Chile, where they spend the non-breeding season.

Scientific name

Thalassarche eremita | Murphy, 1930

Robert Cushman Murphy described the bird in 1930 from a specimen taken on The Pyramid, as the subspecies Thalassarche cauta eremita; because he placed it in Thalassarche from the start, author and year carry no parentheses. eremita is Latin for 'hermit' and refers to the lonely rock on which the whole species lives. The type locality is Pyramid Rock off Pitt Island in the Chatham Islands. The genus Thalassarche was introduced by Reichenbach in 1853 and means, from the Greek thalassa and archē, something like 'ruler of the sea'.