Justification This species qualifies as Vulnerable because it is restricted to one very small area when breeding, rendering the population highly vulnerable to stochastic events and other potential threats.

Family/Sub-family Procellariidae

Species name author Falla, 1946

Taxonomic source(s) Brooke (2004), Christidis and Boles (1994), SACC (2005 + updates), Sibley and Monroe (1990, 1993), Stotz et al. (1996), Turbott (1990)

Identification 50 cm. Large, black petrel. Undersides of primaries may appear silvery. Yellowish bill, whiter in juveniles, has black tip. Black legs, feet. Similar spp. Larger than southern hemisphere shearwaters. Black Petrel P. parkinsoni becomes browner as ages, is smaller, especially bill. Differs from White-chinned Petrel P. aequinoctialis in black-tipped bill, absence of white chin (sometimes almost absent in P. aequinoctialis). Voice Staccato, wheezy, moaning notes at colony.

Population estimate

Population trend

Range estimate (breeding/resident)

Country endemic?

20,000

stable

10,100,000 km²

Yes

Range & population Procellaria westlandica breeds in the densely forested coastal foothills at Punakaiki, South Island, New Zealand¹. In 1958, the population was estimated at 3,000-6,000 birds, in 1972, 6,000-10,000 birds, and in 1982, 1,000-5,000 pairs⁴. In 1974, however, only 818 occupied burrows were located¹. Recent estimates put the total population at less than 20,000 birds, and c.2,000 pairs^{3, 5, 12}. Population modeling suggests a decline in population number since 1985⁹. However, none of the population estimates are of high quality. It migrates in summer to central Pacific and eastern New Zealand waters, east coast of Australia and off South America^4,7. Regularly recorded off the coast of Chile and extends into the South Atlantic to the east of Tierra del Fuego¹⁰.

Ecology: Westland petrels are winter breeders, nesting in colonies on densely forested hills between 20-250 m. Burrows are usually concentrated in areas where the ground is relatively open, and where take-off areas are close by. Juveniles return to the colony as young as three years, but the age of first breeding is six to seven years ¹¹. In any given year, a large proportion of the population skip breeding, however, there is no discernable pattern to this behaviour although it maybe linked with El Niño events ¹¹. Skipped breeders have lower survival rates, possibly due to differences in the 'fitness' of individuals, although this could be biased by emigration. Fisheries waste is an important dietary component, perhaps forming more than half of solid food eaten during the hoki fishing season². Subsequent satellite tracking studies have suggested that dietary analysis over-estimates the amount of food scavenged from trawlers and that the species continues to forage over wider areas than those occupied by the hoki fishery. Even individuals known to forage at fishing fleets take a large proportion of their food elsewhere ^{8, 9}.

Threats Introduced mammals and the native Weka Gallirallus australis prey on eggs, chicks and adults, goats trample burrows, and contribute to the erosion of subcolonies^1,4,5,6,11. Mining and agriculture may have destroyed some available habitat but this has probably had little impact on the population as the birds breed on land too steep and difficult of access to be of interest to mining or farming¹⁴. The coastal plain between the colonies and the sea is rich in ilmenite and, for 20 years, mining of ilminite has seemed likely and the processing plant was placed on their major flightpath. Currently it appears mining will not proceed¹⁴. Birds are occasionally killed by flying into power pylons, and are attracted to lights and noisy machinery at dawn and dusk⁵. Punakaiki is a growing tourist destination and lights from newly built hotels may pose a threat to the petrels. It is a bycatch species of tuna longliners in New Zealand and Australia³. Exposed to several longline fisheries off the coast of Chile. Birds regularly follow commercial trawlers and may be killed when nets are hauled⁵.

Conservation measures underway CMS Appendix II and ACAP Annex 1. The breeding site is within the Paparoa National Park. A proposal to designate the colonies as the Westland Petrel Special Area was approved in 1999, and will restrict public access. A long-term study has been in place since 1969, covering social organisation, behaviour, breeding biology and aspects of population dynamics. A demographic study was undertaken between 1995 and 2003 ¹¹. Predator and herbivore control has been carried out in the main breeding colonies since 1990⁵. A survey of all breeding colonies and a new estimate for the breeding population is planned in 2009-2010. Research on species vocalisations, foraging behaviour and at sea movements is currently in progress¹³.

Conservation measures proposed Census all burrows every 10 years. Continue annual monitoring of study burrows, and band chicks and adults. Identify and minimise hazards to birds flying to and from the colony. Continue sustained predator control and monitoring of nests to identify predation events, and respond accordingly. Continue sustained control of browsing mammals, particularly goats and possums. Fence colony boundaries to exclude stock⁵. Minimise impact of tourist infrastructure through planning control¹⁴.

References 1. Best and Owen (1976). 2. Freeman (1998). 3. Heather and Robertson (1997). 4. Marchant and Higgins (1990). 5. Taylor (2000). 6. A. J. D. Tennyson in litt. (1994). 7. Brinkley et al. (2000). 8. Freeman et al. (2001).9. Freeman and Wilson (2002). 10. Spear et al. (2005). 11. Waugh et al. (2006). 12. Adams (1998). 13. G. Taylor in litt. (2008). 14. K.-J. Wilson in litt. (2008).

Text account compilers Phil Benstead (BirdLife International), Andy Black (BirdLife International Global Seabird Programme), Rachel McClellan (BirdLife International), Alison Stattersfield (BirdLife International), Ben Sullivan (BirdLife International Global Seabird Programme)

Contributors A. J. D. Tennyson, Kerry-Jayne Wilson (Lincoln University)

IUCN Red List evaluators Jeremy Bird (BirdLife International), Stuart Butchart (BirdLife International), Ben Sullivan (BirdLife International Global Seabird Programme)

Recommended citation BirdLife International (2009) Species factsheet: Procellaria westlandica. Downloaded from http://www.birdlife.org on 9/2/2010

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

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