Procellaria westlandica 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Procellariiformes Procellariidae

Scientific Name: Procellaria westlandica Falla, 1946
Common Name(s):
English Westland Petrel, Westland Black Petrel
Taxonomic Source(s): Turbott, E.G. 1990. Checklist of the Birds of New Zealand. Ornithological Society of New Zealand, Wellington.
Identification information: 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.

Assessment Information [top]

Red List Category & Criteria: Endangered B2ab(iii) ver 3.1
Year Published: 2017
Date Assessed: 2017-10-01
Assessor(s): BirdLife International
Reviewer(s): Symes, A.
Contributor(s): Baker, B., Tennyson, A. & Wilson, K.
Facilitator/Compiler(s): Anderson, O., Black, A., Calvert, R., Martin, R, McClellan, R., Stattersfield, A., Sullivan, B., Taylor, J., Wheatley, H.
This species qualifies as Endangered because it is restricted to one very small area when breeding, and its habitat is declining in quality due to erosion and landslips.

Previously published Red List assessments:

Geographic Range [top]

Range Description:Procellaria westlandica breeds in the densely forested coastal foothills near Punakaiki, South Island, New Zealand (Best and Owen 1976). It migrates in summer to central Pacific and eastern New Zealand waters, the east coast of Australia and off South America (Marchant and Higgins 1990, Brinkley et al. 2000), and is regularly recorded off the coast of Chile extending into the South Atlantic to the east of Tierra del Fuego (Spear et al. 2005). A large number were recorded in the area of the Golfo de Penas (400 individuals) and Canal Messier (850 individuals), Aisen, Chile, and all in heavy primary moult (Fraser 2009), potentially representing 10% of the world population of this species (Fraser 2009).

Countries occurrence:
Chile; New Zealand
Argentina; Australia
Additional data:
Estimated area of occupancy (AOO) - km2:3Continuing decline in area of occupancy (AOO):Unknown
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:30600000
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:2-5Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:No
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:The most recent estimate of population size is 2,954-5,137 annual breeding pairs (Wood and Otley 2013), but given that not all individuals breed each year this is likely to be an underestimate for the number of mature individuals. Assuming that 25% of breeding age birds may skip breeding in any one year (as derived from long-term data sets on similar species) (B. Baker in litt. 2012), the population size is estimated at 7,877-13,698 mature individuals, rounded here to 7,900-13,700 mature individuals.

Following Tropical Storm Ita in 2014, there was considerable damage to the breeding area, with the loss or damage of up to 50% of the major colonies, which contain up to 75% of the breeding population (Waugh et al. 2015b). Fortunately, the storm occurred before the laying period and so adults may not have been killed in their nests, unless they were visiting prior to breeding (which some birds have been reported to do) (S. Waugh in litt. 2016), and some birds have moved between impacted colonies (S. Waugh in litt. 2016). Therefore, the level of destruction may not equate to any decline in population, and no population data subsequent to the storm are yet available, though surveys are currently underway (S. Waugh in litt. 2016).

Trend Justification:  Despite population modelling, based on earlier poor data, that suggested a decline in the population since 1985 (Freeman and Wilson 2002), recent analysis has estimated that the population slowly increased at a rate of 1.8% per year between 1970 and 2012 (Waugh et al. 2015a). However, earlier counts are considered unreliable (S. Waugh in litt. 2017) so the population trend is uncertain.
Current Population Trend:Unknown
Additional data:
Number of mature individuals:7900-13700Continuing decline of mature individuals:No
Extreme fluctuations:NoPopulation severely fragmented:No
No. of subpopulations:1Continuing decline in subpopulations:No
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:Yes
No. of individuals in largest subpopulation:100

Habitat and Ecology [top]

Habitat and Ecology:Behaviour The species is a colonial, winter breeder. Most eggs are laid in late May, and hatch mostly in mid to late July. Chicks fledge from November to December (ACAP 2012). In any given year, a large proportion of the population skip breeding, however, there is no discernible pattern to this behaviour although it maybe linked with El Niño events (Waugh et al. 2006). Skipped breeders have lower survival rates, possibly owing to differences in the 'fitness' of individuals. Juveniles return to the colony as young as three years, but the age of first breeding is 7.5 years (Waugh et al. 2015a). During incubation and chick-rearing, satellite-tracking data indicate foraging principally on the continental slope off the West Coast of South Island, but birds regularly visit Cook Strait, the Chatham Rise, and Fiordland, and frequently forage in the mid-Tasman sea (Freeman et al. 1997, 2001). Habitat Breeding They nest on densely forested hills at 20-250 m. Burrows are usually concentrated in areas where the ground is relatively open, and where take-off areas are close by. This is one of the few remaining petrels still nesting on mainland New Zealand, possibly due to more aggressively resisting attacks from land-based predators (Brooks 2011). Diet Fisheries waste is an important dietary component, perhaps forming more than half of solid food fed to chicks during the hoki fishing season (Freeman 1998). 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 acquire a large proportion of their food elsewhere (Freeman et al. 2001, Freeman and Wilson 2002).

Systems:Terrestrial; Marine
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):30.2
Movement patterns:Full Migrant
Congregatory:Congregatory (and dispersive)

Threats [top]

Major Threat(s): Introduced mammals and the native Weka Gallirallus australis prey on eggs, chicks and adults, goats trample burrows, and contribute to the erosion of subcolonies (Best and Owen 1976, Marchant and Higgins 1990, A. J. D. Tennyson in litt. 1994, Taylor 2000, Waugh et al. 2006). There is a high risk of predation by incursions of pigs or dogs, due to the proximity of these two species to the petrel's nesting habitat. Vagrant dogs have killed petrels at their colonies in the past, and pigs have been liberated nearby by people seeking to establish a pig population for hunting (Waugh & Wilson in prep.). Human harvest may have occurred since 2010 (Wilson 2016). 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 farming (K.-J. Wilson in litt. 2008). The coastal plain between the colonies and the sea is rich in ilmenite and in the past, mining of ilminite seemed likely, but it now appears that mining will not proceed (K.-J. Wilson in litt. 2008, 2012). Birds are occasionally killed by flying into power pylons, wires or buildings, and are attracted to lights and noisy machinery at dawn and dusk (Taylor 2000). Punakaiki is a growing tourist destination, and lights from newly built hotels may pose a minor threat to the petrels (K.-J. Wilson in litt. 2012). It is a bycatch species of commercial fisheries in New Zealand and Australia (Heather and Robertson 1997), and it is exposed to several longline fisheries off the coast of Chile. Birds regularly follow commercial trawlers and may be killed when nets are hauled (Taylor 2000). Assessment of the likelihood of capture by New Zealand commercial fisheries indicates that trawl, bottom longline, and surface longline cause 88 (37 – 183 95% CI) fatalities of Westland petrels annually (Richard & Abraham 2015). The species is considered to be at high risk of adverse population effects from New Zealand commercial fisheries (Richard & Abraham 2015). The colonies are at risk of damage from tropical storms; Following Tropical Storm Ita in 2014, there was considerable damage to the breeding area, with the loss or damage of up to 50% of the major colonies, which contain up to 75% of the breeding population (Waugh et al. 2015b). There is an ongoing decline in habitat quality due to slips, windfall and continuing erosion of burrowed areas at the edges of these slips (Waugh & Wilson in prep.). Climate change may lead to further erosion at breeding colonies and reduce foraging returns for breeding petrels (Waugh & Wilson in prep.).

Conservation Actions [top]

Conservation Actions: Conservation Actions 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 restricts 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 (Waugh et al. 2006). Monitoring is being undertaken to check for the presence of pigs and dogs in the petrel habitat (S. Freeman, pers. comm. in February 2017, per Waugh & Wilson in prep.) Work is ongoing to raise awareness of the risks of lights and power line strikes among local residents so that downed petrels may be recovered and released (Waugh & Wilson in prep.).

Conservation Actions Proposed
Census all burrows every 10 years, and continue annual monitoring of study burrows, and band chicks and adults. Identify and minimise hazards to birds flying to and from the colony. Carry out predator control and monitoring of nests to identify predation events, and respond accordingly, and carry out sustained control of browsing mammals, particularly goats and possums. Exclude stock and dogs from colonies (Taylor 2000), eg. with fencing, bait stations or management of buffer land (Waugh & Wilson in prep.). Ensure that local people are aware of the risk posed by dogs (Wilson 2016). Minimise the impact of tourist infrastructure through planning control (K.-J. Wilson in litt. 2008).  Maintain vigilance in assessing seabird-fisheries interaction data in New Zealand and other areas to ensure that changes in fisheries operations, gear types and areas of activity do not lead to concomitant changes in bycatch (B. Baker in litt. 2012). Enforce standards around lighting and structures (Waugh & Wilson in prep.). Research impact of light pollution on the population (Wilson 2016). Monitor whether human harvest is taking place (Waugh & Wilson in prep.).

Citation: BirdLife International. 2017. Procellaria westlandica. The IUCN Red List of Threatened Species 2017: e.T22698155A119318610. . Downloaded on 25 September 2018.
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