Westland Petrel

The Westland petrel, known to the Māori as tāiko, is a robust seabird of the petrel family Procellariidae, endemic to New Zealand. It is a dark blackish-brown bird, one of the largest burrowing petrels, with a pale yellow bill tipped in dark hues. Weighing in at approximately 1,100 grams, it boasts black legs and feet, and may occasionally display a smattering of white feathers.

Identification Tips

Adult Westland petrels are stocky and predominantly dark blackish-brown. Their legs and feet are black, and they have a distinctive pale yellow bill with a dark tip. Males are slightly larger than females, though females may weigh marginally more. During the non-breeding season, they undergo a molt which occurs while they migrate to South American waters.

Habitat

The Westland petrel is a pelagic bird that spends the majority of its life at sea. It is found in the Pacific and Tasman seas around the subtropical convergence and migrates east to the nutrient-rich Humboldt Current off South America during the non-breeding season.

Distribution

This species is endemic to New Zealand, breeding exclusively on the South Island's West Coast in a narrow strip of forest-covered coastal foothills. The total area of all breeding colonies combined is a mere 16 hectares.

Behaviour

Westland petrels exhibit natal philopatry, returning to their birth colony to breed. They nest in burrows on steep slopes and are winter breeders. The birds are solitary at sea but become social and vocal in their colonies during courtship and mating.

Song & Calls

The colonies are particularly vocal approximately three weeks before nesting, which is part of their courtship and mating rituals.

Breeding

The Westland petrel breeds in burrows, with colonies situated from 50 to 200 meters above sea level. They lay a single egg annually between May and June, with both parents sharing incubation duties. Chicks are cared for by the parents for about two weeks post-hatching and are then left alone, fed only at night until fledging.

Diet and Feeding

These petrels forage both day and night, feeding mainly on fish, squid, and crustaceans. They are opportunistic feeders, known to scavenge fish waste from hoki fisheries during the breeding season. They employ surface seizing and diving techniques to capture prey, diving to depths of up to 8 meters.

Conservation status

The Westland petrel is classified as Endangered by the IUCN and "At Risk: Naturally Uncommon" by the New Zealand Department of Conservation. Conservation efforts include local patrols during fledging season and initiatives to reduce artificial light pollution that disorients the birds.

Similar Species

The Westland petrel can be confused with the black petrel, Procellaria parkinsoni, but can be distinguished by its larger size and the specific pale yellow coloration of its bill.

Threats

The species faces several threats including predation by feral pigs and dogs, storm damage to breeding colonies, artificial lighting disorienting birds, mining activities, parasites, diseases, and collisions with power lines. Conservation measures are in place to mitigate these threats.

Relationship with Humans

The return of the Westland petrel to its breeding sites is celebrated annually in Punakaiki with the Tāiko Festival. Ecotourism opportunities are available for observing these birds at a breeding colony on private land. Historically, the chicks have been harvested for food, a practice known as muttonbirding.