Archived 2010-2011 topics: Collared Petrel (Pterodroma brevipes): uplist to Vulnerable?

Collared Petrel Pterodroma brevipes is currently listed as Near Threatened under criterion C2a(i), but with a caveat that clarification of its status outside Fiji might lead to uplisting to Vulnerable. Its population is recognised as being small (<10,000 mature individuals) and restricted to relatively few breeding locations. Population trends are uncertain, but all known breeding locations hold invasive alien species, so given the susceptibility of burrow-nesting Pterodroma petrels elsewhere to invasive mammalian predators a population decline is a near-certainty.

The species remains poorly known: recent breeding has been confirmed in Fiji on Gau. However, this constituted a single nest from several hundred ‘potential’ burrows searched. A recent survey to Mt Washington (Nabukelevu), Kadavu recorded a small number of calling birds (less than 5) but, this did occur outside the breeding period (S. Cranwell and J. Bird in litt.). Historically the birds have been known to local people who harvested chicks, this no longer occurs and nor is the birds’ presence known locally. Agricultural encroachment has also increased into forested areas, particularly in the South around Nabukulevu. The species is unlikely to survive on Viti Levu (if it ever occurred) owing to the presence of a suite of mammalian predators (mongoose Herpestes auropunctatus, pigs, cats, dogs) and is unlikely to survive on Cobia in the Ringgold Islands (severe habitat degradation from goats and presence of rats). There are no recent records from former sites Ovalau (surveys in 2004 failed to record the species) or Vanuabalavu. In Vanuatu, specimens have been collected on Aneityum, Tanna, Efate and at sea near Mere Lava (Bregulla, 1992). Several of these records are historic and the species may no longer be present at all sites. However, a visit to Tanna in July 2008 proved that Collared Petrels still breed in the mountains of southwest Tanna (S. Totterman, pers. obs.), and the newly described taxon P. b. magnificens, presumed to breed on Vanua Lava and possibly Gaua in the Banks Islands was found to be relatively abundant with 180 sighted at sea during a 2009 expedition (Bretagnolle and Shirihai 2010). Vanua Lava is the most populated island in the with feral pigs, cats Felis catus and introduced rats Rattus spp. likely to pose a serious threat. On Mt. Suretamatai, no evidence was found of any alien mammals, but pigs occur only a few km from the volcano. Local communities are reported to have heavily exploited petrels and especially shearwaters on the Banks for many generations until the 19th century, but in recent years they have apparently only been infrequently harvested at most (Totterman 2009). Harvesting of Collared Petrels is especially well known from Fiji (Watling 1986) and apparently still occurs on Tanna (www.positiveearth.org/vanbirds/), but it remains to be seen if this practice still affects P. b. magnificens on the Banks. Confusion remains over the species’s status in the Cook Islands; Moorea, Tahiti and the Austral Islands, French Polynesia; Samoa and Tau in American Samoa.

We invite here comments on the latest knowledge of Collared Petrel’s status throughout its Pacific range, and on the suggestion that it warrants uplisting to Vulnerable. On the current availability of records, the global population of Collared Petrel appears to support <10,000 mature individuals. This population is almost certainly in decline owing to widespread threats from invasive species and given that several local extinctions have been observed in recent decades. No known colony supports >1,000 mature individuals (although confirmation from the Banks Islands would be helpful), so it appears to meet the critera for listing as Vulnerable under C2a(i) i.e. <10,000 mature individuals with a continuing decline and no known population supporting >1,000 individuals.

Bregulla, H. (1992). Birds of Vanuatu. Oswestry: Anthony Nelson.

Bretagnolle, V. and Shirihai, H. (2010) A new taxon of Collared Petrel Pterodroma brevipes from the Banks Islands, Vanuatu. Bull. B.O.C. 130: 286-301.

Totterman, S. (2009) Vanuatu Petrel (Pterodroma occulta) discovered breeding on Vanua Lava, Banks Islands, Vanuatu. Notornis 56: 57–62.

Watling, D. (1986) Notes on the Collared Petrel Pterodroma (leucoptera) brevipes. Bull. Brit. Orn. Cl. 106: 63–70.

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One Response to Archived 2010-2011 topics: Collared Petrel (Pterodroma brevipes): uplist to Vulnerable?

  1. Guy Dutson says:

    I have no additional data to add but based on my experience in the region, I would support the suggestion that the total population is <10,000 individuals; the max sub-population size is <1000 individuals and that the species is undergoing a significant ongoing decline.

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