Westland black petrel
The Westland petrel (Procellaria westlandica ), (Māori: tāiko ), also known as the Westland black petrel, is a moderately large seabird in the petrel family Procellariidae, that is endemic to New Zealand. Described by Robert Falla in 1946, it is a stocky bird weighing approximately 1,100 grams (39 oz). It is a dark blackish-brown colour with black legs and feet. It has a pale yellow bill with a dark tip.
This species spends the majority of its life at sea but returns to land to breed. When at sea, it ranges across areas of the Pacific and Tasman seas around the subtropical convergence and migrates east to South American waters during the non-breeding season. They are nocturnal and feed on fish, squid and crustaceans. This species is also known to be an opportunistic feeder, scavenging fish waste discarded by hoki fishers.
The only known breeding colonies of the Westland petrel are in forest-covered coastal foothills on the West Coast of the South Island of New Zealand, between Barrytown and Punakaiki. The birds nest in burrows excavated into hillsides and slopes, and exhibit natal philopatry, that is they return to their natal colony to breed. The loss of a breeding colony can therefore have severe consequences for the population. The total area of all breeding colonies combined is only about 0.16 km2 (0.062 sq mi). In 2014, the breeding colony areas suffered extensive damage from landslips and tree fall during a severe storm. Other significant potential threats to the breeding colonies are predation by feral pigs and vagrant dogs from nearby settlements.
As of 2021, the International Union for Conservation of Nature classified this species as endangered, and the New Zealand Department of Conservation classified this species as "At Risk: Naturally Uncommon" under the New Zealand Threat Classification System.
Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal",...
A piscivore is a carnivorous animal that eats primarily fish. Piscivorous is equivalent to the Greek-derived word ichthyophagous. Fish were the die...
Scavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While sc...
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
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CongregatoryCongregatory animals tend to gather in large numbers in specific areas as breeding colonies, for feeding, or for resting.
Oviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
Precocial species are those in which the young are relatively mature and mobile from the moment of birth or hatching. Precocial species are normall...
A burrow is a hole or tunnel excavated into the ground by an animal to create a space suitable for habitation, temporary refuge, or as a byproduct ...
Soaring birds can maintain flight without wing flapping, using rising air currents. Many gliding birds are able to "lock" their extended wings by m...
Seabirds (also known as marine birds) are birds that are adapted to life within the marine environment. While seabirds vary greatly in lifestyle, b...
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MigratingAnimal migration is the relatively long-distance movement of individual animals, usually on a seasonal basis. It is the most common form of migrati...
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starts withThe adult Westland petrel is a stocky looking bird, weighing around 1,100 grams (39 oz). It is entirely dark blackish-brown, with black legs and feet. Some individuals may have a few white feathers. The bill is pale yellow with a dark tip. Falla measured the female and male birds for his original description and pointed out that the male of the species measured slightly larger than the female. However the female specimen weighted slightly more than the male.
Falla described the eggs of this species as follows:
Moulting occurs in the Westland petrel in their non-breeding season between October and February, during migration to South America. The immature birds moult prior to older individuals.
The Westland petrel is endemic to New Zealand. It spends the majority of its life at sea, only returning to land to breed, and breeds only in a small region of the West Coast of the South Island. The breeding range covers an 8 kilometre wide strip between Barrytown and Punakaiki on the West Coast, specifically between the Punakaiki River and Waiwhero (Lawson) Creek. This area comprises forest-covered coastal foothills within the Paparoa National Park, on other conservation land, or on land belonging to Forest And Bird. There is also a breeding colony located on private land, where guided tours of the colony are available.
However, the total area of all breeding colonies combined is only about 0.16 km2 (0.062 sq mi).
During the breeding season adults may be seen in waters around New Zealand from Cape Egmont to Fiordland in the west, through the Cook Strait, and from East Cape to Banks Peninsula in the east. They also range across areas of the Pacific Ocean and Tasman Sea around the subtropical convergence. In the non-breeding season, Westland petrels migrate east to South American waters and feed in the Humboldt Current. They are often found off the coast of Chile. Individuals usually remain solitary during this time, rejoining the colony when the next breeding cycle begins.
Petrels are nocturnal and hunt at night, preying primarily on fish, some squid, and less commonly on crustaceans. Westland petrels are known to opportunistically scavenge fish from waste discarded by hoki fisheries during their breeding season as it overlaps with the fishing season, switching back to natural foraging at other times. They capture their prey by surface seizing, surface diving, and, less frequently, pursuit plunging. They have been recorded diving up to 8 metres (26 ft). Their strong vision allows them to spot prey, and recent studies have shown that smell is also important to petrel foraging, specific odors seeming to attract the birds to certain areas.
Power lines have caused the deaths of adult petrels from collision during flight. They are dangerous because they attract the birds and cause disorientation, largely in young petrels. This leads to petrels being grounded, which is a significant issue due to the way that Westland petrels must take flight. When the time comes to leave their breeding sites high in the foothills, Westland petrels climb up the tall trees and throw themselves off to fly. With early grounding, oftentimes the birds will perish from starvation, dehydration, predation, or collision with manmade structures.
Commercial fishing produces competition for food, and sometimes petrels are accidentally captured in fishing nets. This is a prominent risk for Westland petrels due to their tendency to forage from commercial fishery waste, so they are known to interact closely with these vessels.
As of 2021, this species is regarded as being endangered under the International Union for Conservation of Nature Red List of Threatened Species. The Department of Conservation assessed its conservation status in 2021 as "At Risk: Naturally Uncommon" under the New Zealand Threat Classification System.
