The breeding season starts in October. The birds perform a pre-laying exodus of 9-16 days at least. The egg-laying usually starts around early December.
The Mottled Petrel is monogamous with long term pair-bonds. They usually return to the same nesting-site every year. This species nests in rock crevices or caves, or in burrows excavated below tree roots or tussocks, between 10 and 130 metres above the sea-level. The nest is usually in contact with rock used as roof or walls for the tunnel or the nesting chamber. The birds are strictly nocturnal at nest-sites and they form dense colonies.

The female lays a single white egg. Both adults share the incubation that lasts 48-53 days with stints of 12-14 days, often longer by female with one day more. The birds have well-developed brood patches.
At hatching, the chick has grey down and bright blue eyes. It is brooded for 1-2 days and fledges between 90 and 105 days after hatching. There are few data on chick growth and feeding rates.

The Mottled Petrel is threatened by introduced predators on breeding islands, also by forest clearance and by harvesting for human consumption. Extreme weather events such as El Niño, may kill large numbers of birds.
The global population was recently estimated to number 1,500,000 individuals, but this species was formerly much more numerous and widespread.  
The Mottled Petrel is currently classified as Near Threatened.

Fr: Pétrel maculé
Ang: Mottled Petrel
All: Regensturmvogel
Esp: Petrel Moteado
Ita: Petrello maculato
Nd: Regenstormvogel
Sd: gråbukig petrell


Alan & Ann Tate
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Text by Nicole Bouglouan


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Mottled Petrel
Pterodroma inexpectata

Procellariiformes Order – Procellariidae Family

The Mottled Petrel is highly pelagic and comes to land only for breeding. It nests in burrows or rock crevices where a single white egg is laid. It feeds primarily on fish and squid, and some crustaceans.
This species is a long-distance migrant. It breeds in New Zealand on several nearby islands, and migrates as far as the Bering Sea and surrounding islands.
The Mottled Petrel is heavily threatened by introduced predators on the breeding islands, and the species is currently classified as Near Threatened.

Length: 32-36 cm
Wingspan: 74-92 cm
Weight: 247-441 g

The Mottled Petrel has white and grey plumage, with a dark M-shaped pattern on the upperparts across back, rump and wings.
On the underparts, the underwing shows distinctive pattern, a prominent black band from the bend of the wing and extending towards the body side. Lower breast and belly show a blurred grey patch.
The wings are long and pointed, whereas the tapering tail is long and narrow.

On the head, the face is white mottled with grey. There is a dark patch behind the eye.
The black bill is fairly short with hooked tip. The eyes are dark brown. Legs and webbed feet are pink with black tips to the webs.

Male and female are similar, but the female has slightly shorter tail.
The juvenile resembles adult, but it has pale scaling on the upperparts and more whitish on outer rectrices.

The Mottled Petrel breeds in southern New Zealand on the Snares, Codfish Island and Big South Cape Island. Small colonies can be found on islands around Stewart Island and in Fiordland. They remain throughout New Zealand subantarctic waters during the breeding season, and forage in the vicinity of the Polar Front during the chick-feeding period.
After breeding, the Mottled Petrel migrates to North Pacific Ocean and Bering Sea, with concentrations off Aleutian Islands and Gulf of Alaska.  

The Mottled Petrel is highly pelagic and comes to land only for nesting. It spends most of its life at sea.
The breeding colonies are established on offshore islands and rock stacks. It nests in natural cavities such as rock crevices or caves, but more often in burrows.

The Mottled Petrel is generally silent at sea, but it may become more vocal at night at the colonies, and especially during the courtship displays. The main call is a rapid “ti-ti-ti…” or “kek-kek-kek” although “oooi” and “gorr” calls are also given. A growling “gor-wik” call is given from the ground, often in response to other bird’s calls.

The Mottled Petrel feeds primarily on fish and squid, but crustaceans are also part of its diet, especially krill.
The prey is often taken from near the surface of the water, while the bird is flying before plunging just below the surface. However, it may also land on the water to catch prey at or near the surface. Hovering is also reported.

It may sometimes forage with Soft-plumaged Petrel and Sooty Shearwater. It is usually alone or in small groups at sea. They do not follow ships.  

The Mottled Petrel is monogamous with long term pair-bonds. It nests in colonies which become busy and noisy at start of the breeding season when the birds clean out the burrows and perform courtship displays.
The display flights occur at night accompanied by calls. Pairs, less often trios, twist and turn rapidly while calling loudly. Chases are reported too. Mutual billing and allopreening of each other’s necks are observed prior to copulation.

The Mottled Petrel is a long-distance migrant that breeds in New Zealand and nearby islands, and migrate northwards to the Bering Sea, Gulf of Alaska and Aleutian Islands to spend the non-breeding season.
There are few records off extreme South America and some recent records SE of Cape Horn and the Falkland Islands. This species is unfrequently recorded in Australian waters.

As other members of genus Pterodroma (gadfly petrels), the Mottled Petrel performs swift, weaving, elegant flight. High soaring arcs and glides alternate with rapid wingbeats.