Townsends Shearwater (Puffinus auricularis)

Townsends Shearwater

[order] PROCELLARIIFORMES | [family] Procellariidae | [latin] Puffinus auricularis | [authority] Townsend, 1890 | [UK] Townsends Shearwater | [FR] Puffin de auricularis | [DE] Townsend-Sturmtaucher | [ES] Pardela de Townsend | [NL] Townsends Pijlstormvogel

Subspecies

Genus Species subspecies Region Range
Puffinus auricularis PO ec, islands off w Mexico

Genus

Until recently the shearwaters were devided in two genera Calonectris and Puffinus, but based on dna-analysis Penhallurick and Wink (2004) have proposed a splitting of the shearwaters into three genera: Calonectris for the large shearwaters of the Northern Atlantic, the Mediterranean and the waters around Japan, Ardenna for a group of large Southern Hemisphere breeders and Puffinus for the smaller shearwaters such as the Manx’ group, Audubon’s and Little Shearwaters. This new taxonomy is now widely accepted, but not by all and is stil subject of discussion.

Physical charateristics

Medium-sized shearwater. Generally black above and white below. Sharp transition at side of head from black (with some freckling) to white. White underparts except for black half-collar, blackish undertail-coverts and thighs. Prominent white flank patch extending to side of rump. Underwing black around leading and trailing borders sharply demarcated from central white areas. Black-vented Shearwater P. opisthomelas is larger, distinctly brownish and has less clear separation of dark and light areas.


wingspan min.: 76 cm wingspan max.: 89 cm
size min.: 31 cm size max.: 35 cm
incubation min.: 0 days incubation max.: 0 days
fledging min.: 0 days fledging max.: 0 days
broods: 1   eggs min.: 1  
      eggs max.: 1  

Range

Pacific Ocean : Eastcentral, islands off West Mexico. Puffinus auricularis breeds around Cerro Evermann on Socorro in the Revillagigedo Islands, Mexico.

Habitat

On Socorro, it breeds in rocky burrows within dense bushy areas at the forest edge. Breeding is concentrated above 700 m2, but observations in 1981 suggested that the major breeding sites were at 500-650 m. Birds have been seen roosting in the naval base at Cape Rule4. On Clarion, it nested in burrows on grassy and bracken-covered slopes. In the non-breeding season marine and pelagic prefering warm sub-tropical water.

Reproduction

Breeds in burrows, clutch size is 1 egg. Breeding start in march/april, young flegde in october/november. Breeding occurs in latitueds from 500-700 meter above sealevel.

Feeding habits

Little Known, mainly fish and squid.

Conservation

This species has been extirpated from two islands, and breeding is now restricted to an extremely small area on one island. It qualifies as Critically Endangered because habitat is being degraded by sheep grazing, whilst feral cats are reducing numbers.
Cats were introduced to Socorro in the early 1970s, and more than 92% of cat scats above 500 m contain shearwater remains. Reports that rats have recently colonised Socorro are not confirmed. Sheep are destroying nesting habitat across some parts of its colonies, through overgrazing and soil compaction. Pigs were introduced to Clarion soon after 1979, and by 1988 numerous shearwater remains littered burrows destroyed by severe pig rooting. Sheep (introduced in c.1990) and rabbits have also destroyed habitat and nesting sites on Clarion. In 1952, a volcanic eruption obliterated the San Benedicto population. Potential developments on Socorro including enlargements to the airstrip and the possibility of a new federal prison could destroy breeding habitat, increase light pollution and increase the risk of accidental introduction of other invasive species8. Having a distribution on relatively low-lying islands, this species is potentially susceptible to climate change through sea-level rise and shifts in suitable climatic conditions.
Townsends Shearwater status Critically Endangered

Migration

Little known; thought to disperse to adjacent seas; recorded S to waters just N of Galapagos Is.

Distribution map

Townsends Shearwater distribution range map

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