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Sep 11 2011

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Broad-billed Prion (Pachyptila vittata)


Broad-billed Prion

[order] PROCELLARIIFORMES | [family] Procellariidae | [latin] Pachyptila vittata | [authority] Forster, 1777 | [UK] Broad-billed Prion | [FR] Prion de Forster | [DE] Grosser Enten-Sturmvogel | [ES] Pato petrel Piquiancho | [NL] Breedbekprion

Subspecies

Genus Species subspecies Region Range
Pachyptila vittata SO New Zealand, Tristan da Cunha Island

Genus

Prions are a race of abundant small petrels from the Antarctic and subantarctic region with very similar plumages: a white body, bluish grey upperparts with a dark M on the back and upper sides of the wings when seen from above. Although there is considerable difference in measurements, the main difference between the species lies in the shape of the bills. These vary from small ‘pointed’ via ‘fulmarish’ to extreme broad. Characteristic are the lamellae along the sides of the palate in all species. These form a sieving structure to filter small food particles from the water. The development of these lamellae and grooves vary depending on the species. Bills of all Prions are bluish, except in the Broad-billed which has a blackish bill. Identification of the Prions at sea is very difficult. Therefore much of the pelagic distribution is unknown.
The taxonomy of the Prions is difficult and possibly not yet fully understood. It is mainly based on size and structure of the bill. But since there is a lot of intraspecific variability and intergradation between the recognized species and subspecies, the discussion on this topic is not closed yet. The list below shows the seven species that are accepted generally, including the recent separation of the MacGillivrayi’s Prion.

Physical charateristics

It has blue-grey upperparts, white underparts, a black crown, a dark eye stripe, and a black-tipped tail. Its bill is also black. The head pattern is more distinct and the tail band is less extensive than that of the similar Fairy Prion. It has a broad flat bill with comb-like fringes. This is a large prion measuring 25 to 30 cm long, with a wingspan of 57 to 66 cm.


wingspan min.: 57 cm wingspan max.: 66 cm
size min.: 25 cm size max.: 30 cm
incubation min.: 48 days incubation max.: 52 days
fledging min.: 48 days fledging max.: 52 days
broods: 1   eggs min.: 1  
      eggs max.: 1  

Range

Southern Ocean : New Zealand, Tristan da Cunha Island. This species breeds on Gough Island and Tristan da Cunha (St Helena to UK) in the south Atlantic, and on the Chatham Islands, New Zealand and south of New Zealand’s south island. Adults are thought to remain in waters adjacent to colonies; however young birds occur north of the colonies to Australia and South Africa

Habitat

Highly pelagic, breeds on rocky slopes or large lava fields. Also rocky soil and caves.

Reproduction

Breeding begins on the coastal slopes of the breeding islands in July or August. The parents incubate the egg for 50 days, and then spend another 50 days raising the chick. Colonies disperse from December onwards.

Feeding habits

They utilize a technique called hydroplaning, which is where the bird flies with its bill in the water and it skims water in, and then filters the food. They also surface-seize. This prion doesn’t follow fishing boats regularly.

Video Broad-billed Prion

copyright: Youtube


Conservation

This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Breeds islands off New Zealand and Tristan da Cunha group. Ranges to Southern Africa (Namibia and South Africa) and Australia.
Broad-billed Prion status Least Concern

Migration

Adults thought to remain in waters adjacent to colonies, which they visit intermittently in winter. Young birds more dispersive, occurring N to Australia, South Africa and S America, reaching 10 degrees South in tropical Indian Ocean and 15 degrees South off Peru.

Distribution map

Broad-billed Prion distribution range map

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