Westland Petrel
Procellaria westlandica
Puffin du Westland
Pardela de Westland
CRITICALLY ENDANGEREDENDANGEREDVULNERABLE

NEAR THREATENEDLEAST CONCERN

NOT LISTED

Sometimes referred to as
Westland Black Petrel
Westland Shearwater

Photo © Tony Palliser

TAXONOMYCONSERVATION LISTINGS AND PLANS

Procellariiformes
Procellariidae
Procellaria
P. westlandica

International[3]
 Agreement on the Conservation of Albatrosses and Petrels – Annex 1[4]
 2010 IUCN Red List of Threatened Species – Vulnerable (since 2000)[5]
 Convention on Migratory Species – Appendix II

Described relatively recently (Falla
1946) [1] and originally considered asubspecies of the Black Petrel, P.
parkinsoni, the Westland Petrel P.
westlandica is the second largest of
the five Procellaria petrels [2].

Australia
 Environment Protection and Biodiversity Conservation Act 1999 (EPBC
ACT) [6]- Listed Migratory Species- Listed Marine Species
 Threat Abatement Plan 2006 for the incidental catch (or bycatch) of
seabirds during oceanic longline fishing operations [7]Order
FamilyGenus
SpeciesChileNational Plan of Action for reducing by-catch of seabirds in longline
fisheries (PAN-AM/CHILE) [8]

New Zealand New Zealand Wildlife Act 1953 [9] New Zealand Threat Classification System 2008 – Naturally Uncommon[10]

Action Plan for Seabird Conservation in New Zealand; Part A:[11]
Threatened Seabirds

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1Westlad Petrel Procellaria westlandica

BREEDING BIOLOGY
Procellaria westlandica is a colonial, burrow-nesting, annually breeding species. It breeds in winter with birds returning tocolonies from mid February to early April [2, 12, 13]. Pre-laying exodus is thought to be c. 15 days [14] . Most eggs are laid in
May (starting c. 12 May and peaking c. 23 May) and hatch mostly in the last half of July, with incubation taking 57 to 65 days
[2, 14]. Chicks fledge from November to January at about 120-140 days old [2, 14, 15] (Table 1). Minimum age of first return toland is three and the youngest recorded age of first breeding is five years [16].
Table 1. Breeding cycle of P. westlandica.
Jun

Jul

Aug

Sep

Oct

Nov

Dec

Jan

Feb

Mar

Apr

May

At colonies
Egg laying
Incubating
Chick provisioning

BREEDING STATESTable 2. Distribution of the global
P. westlandica population among
Parties to the Agreement.
New Zealand
Breeding pairs

100%

BREEDING SITES
Procellaria westlandica is a New
Zealand endemic (Table 2, Figure1), breeding at only one site overan area of 16 square kilometres inforested hills on the west coast ofSouth Island. The total population,
including juveniles and nonbreeders, was estimated at 20,000±5,000 individuals in 1982 (J.A.
Bartle in [13]).
In 2008, thebreeding population was estimatedto number 4,000 pairs [17] (Table 3).

Figure 1. Location of the single breeding sites and approximate range of P.
westlandica with the boundaries of selected Regional Fisheries Management
Organisations (RFMOs) also shown.
CCAMLR – Commission for the Conservation of Antarctic Marine Living Resources
CCSBT - Convention for the Conservation of Southern Bluefin Tuna
IATTC - Inter-American Tropical Tuna Commission
ICCAT - International Commission for the Conservation of Atlantic Tunas
IOTC - Indian Ocean Tuna Commission
WCPFC - Western and Central Pacific Fisheries Commission

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Westland Petrel Procellaria westlandica
Table 3. Monitoring methods and estimates of the population size (annual breeding pairs) for the single P. westlandica
breeding site. See Glossary and Notes section for explanation of monitoring method codes and accuracy levels.
Breeding site location

Jurisdiction

Years monitored

Punakaiki
45° 46’S 170° 43’E

New Zealand

1954-1956, 1972, 1974,
1976, 1982, 2003-2005,
2007, 2008

Monitoring
methodMonitoring
accuracy

Annual breedingpairs (last census)

C

Mediumc. 4,000 (2008) [17]CONSERVATION LISTINGS AND PLANS FOR THE BREEDING SITESInternational
None
New Zealand
Punakaiki
 Paparoa National Park - National Parks Act 1980 [18]
 Specially Protected Area - Conservation Act 1987 [19]POPULATION TRENDS
The breeding range of P. westlandica is thought to have been more extensive in the past, with Holocene fossils of the species
found 10 km to the north of the current distribution [20]. Jackson (1958) [12] carried out the first survey in 1955 and estimatedbetween 3,000 adults and 3,000 pairs by counting returning birds and estimating the number of subcolonies. Best and Owen
(1976) [21] however, estimated the number of occupied burrows to be less than 1,000 from a count of 818 in 1974. Based ondata collected in 1982, Bartle (1993 in [13]) suggested that an average of 2,000 pairs bred in any one year. More recent
surveys estimated 4,291 breeding burrows in 2003-2005, out of a total of 14,162 burrows found, including in previously
unrecorded colonies [22]. Based on surveys carried out in 2007-2008 at 10 of the 26 sites visited in 2003-2005, the mean
number of occupied burrows was estimated at 2,436 (95% Confidence Interval 1,205-3,666). Data collection at the remaining
16 small sites will continue in 2011, and based on the 2003-2005 counts, another 1,300 occupied burrows may exist in theseareas [17]. This would confirm a global P. westlandica population of approximately 4,000 annual breeding pairs [17]. However,as the methodologies are not comparable between any of the past surveys, population trends are unknown.
Table 4. Summary of population trend data for P. westlandica at the single breeding site.
Location

Current monitoring

Trend years% averagechange per year

Trend

% of
population

Punakaiki

yes

-

-

Unknown-

The most recent average breeding success rate of 62% between 1995 and 2002 is similar to the range recorded in P.
parkinsoni, another New Zealand endemic [23, 24], and higher than those recorded for P. aequinoctialis on several subantarctic
islands [25, 26, 27]. Adult survival for breeding birds is also higher than for either of the congeners [23, 25].
Table 5. Demographic data for the single P. westlandica breeding site.
Location

Punakaiki

Mean breeding success
3.0%-5.7% (1970-1971) [14]27% (1983-1989) [13]39% (20-63%, 1976-1991) (DOC 1996 in [28])59% (1990-1994) (J.A. Bartle in [13])50% (38-63%, 1991-1996) [28]62% (± 4 SE, 1995-2002) [16]Juvenile survival

Adult survival (±SE)

No data

72.6% (±17.3%,1995-2003)1 [16]96.5% (±3.8%, 1995-2003)2 [16]

1 skipped-breeders
2 breeding birds

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3Westlad Petrel Procellaria westlandica

BREEDING SITES: THREATS
The majority of the nesting colonies (75% of known burrows) is within a Specially Protected Area, with access by permit only[22]. About 20% of known burrows are within the Dick Jackson Memorial Reserve, with the remaining 5% situated on private
land [11, 22].
Table 6. Summary of known threats causing population level changes at the breeding site of P. westlandica. Table basedon data submitted to the ACAP Breeding Sites Working Group in 2008.
Breedingsite
Punakaiki

Human
disturbanceNo

Human Natural
takedisaster
No a
No

Parasite or
PathogenNo

Habitat loss ordegradation
No b

Predation byalien species
No cContaminationNo

a Taking of large chicks is suspected to have occurred in the past [14].

b Cattle, goats and humans sometimes trample burrows, and grazing by cattle, goats and possums modifies the habitat andmay lead to increased likelihood of landslips at the colonies [11, 13]. Birds also occasionally strike power lines when leaving or
returning to the colony [11, 13]. Birds are known to be grounded when attracted to lights in near-by centres of habitation, thismay be of more relevance for chicks at fledging than for other groups, and if foggy conditions occur during the fledging or
breeding period, may be worse in some years than others. The level of mortality due to this threat is unknown. Efforts havebeen made with the local community to raise awareness of this issue and reduce exposed lighting.
c Predation by feral cats, stoats and possibly rats is known to occur, with dogs also occasionally attacking adults and chicks[11, 13].

Some stoat control efforts are in place during the breeding season [13].

FORAGING ECOLOGY AND DIET
There have been two studies on the diet of P. westlandica. In contrast to an earlier study where squid comprised 89.5% of
items and fish 10.5% in samples collected in July 1969 [29], Freeman (1998) [30] found that the diet during chick rearing(August-October) was dominated by fish (92% of samples, 78.8 ±6.5% by weight of solids), followed by cephalopods (32%of samples, 18.7 ±6.2% by solid weight), with small amounts of Crustacea (4% of samples, 2.4 ±2.4% solid weight). Of the
12 fish families identified, Macrouridae and Myctophidae remains were the most common. Fisheries waste was the largest
source of fish (80%) during the winter Hoki Macruronus novaezelandiae fishing season (August to mid-September),decreasing thereafter to 31%, as birds switched to capturing or scavenging of more natural prey and a wider variety of
species. Histioteuthidae and Cranchiidae were the most common of the six cephalopod families identified.

MARINE DISTRIBUTION
During chick-rearing, satellitetracking data indicate foraging
principally on the continental slope
off the West Coast of South
Island, with one trip undertaken
through Cook Strait to the
Chatham Rise east of South
Island [31, 32] (Figure 2).

Figure 2. Satellite-tracking data of breeding adult P. westlandica (Number of tracks= 20). Map based on data contributed to the BirdLife Global Procellariiform
Tracking Database.

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Westland Petrel Procellaria westlandica
The non-breeding range of P. westlandica extends east to the Humboldt Current off Chile, from 20°S to 50°S, but mostly
south of 40°S, with densities highest over the continental slope [33]. Generalized additive model analyses estimated anaverage of 3,464 birds (95% CI 2,053-6,388) during spring/ summer in waters off Chile between 1980 and 1995 [33]. The
species is also sighted off south-eastern Australia all year round, but it is considered rare in that area [2, 34].
Procellaria westlandica overlap with four Regional Fisheries Management Organisations, but principally the WCPFC,CCSBT, and the planned South Pacific Regional Fisheries Management Organisation (SPRFMO) (Figure 1; Table 7).
Table 7. Summary of the known ACAP Range States, Regional Fisheries Management Organisations and Exclusive
Economic Zones of non-ACAP countries that overlap with the marine distribution of P. westlandica.

Breeding and feeding
range
Known ACAP Range States
Non-ACAP Exclusive Economic Zones
Regional Fisheries Management
Organisations 1

New Zealand
CCSBT
WCPFC
SPRFMO2Foraging range
only
Australia
Chile-

Few records - outsidecore foraging range
Peru
Argentina
-

IATTC

-

1 see Figure 1 and text for list of acronyms
2 not yet in force

MARINE THREATS
As opportunistic scavengers of fishery waste [35], P. westlandica are vulnerable tointeractions with fishing vessels and are infrequently observed killed on pelagic
long-lines and trawl vessels in New Zealand waters [36, 37]. The species is also
likely to overlap with longline fisheries off the coast of Chile. There is no record of
P. westlandica bycatch in the pelagic longline swordfish fleet in the area, which
operates from March to December [38], however, there have only been limited
observations in this fishery. Interactions with Patagonian toothfish Dissostichus
eleginoides vessels in the Humboldt Current System are also undocumented.

KEY GAPS IN SPECIES ASSESSMENT
Further burrow surveys in the breeding area planned for 2011 will allow moreaccurate population estimates for this species. The long-term monitoring of the
population should continue in order to track population trends as well as annual
variations in adult and juvenile survival which are at present unknown or data arelimited.
Satellite and/or data logger tracking, or observations at sea of birds of different
age classes and at different stages of the annual cycle is needed to determine full
foraging range, overlap with fisheries and general at-sea distribution. Further
study of interactions with fisheries in non-breeding foraging locations, particularly
off South America, is essential to assess the degree of threat posed to thespecies.

Agreement on the Conservation of Albatrosses and Petrels – www.acap.aq

5Westlad Petrel Procellaria westlandica

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Falla, R.A. 1946. An undescribed form of the black petrel. Records of theCanterbury Museum 5: 111-113.
Marchant, S. and Higgins, P.J., eds. 1990. Handbook of Australian, New
Zealand, and Antarctic Birds. Vol. 1 Ratites to Ducks. Oxford University
Press: Melbourne. 1536 pp.
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http://www.acap.aq.
IUCN. 2010. 2010 IUCN Red List of Threatened Species. Version
2010.3. www.iucnredlist.org
Bonn Convention. Convention on the Conservation of Migratory Speciesof Wild Animals. http://www.cms.int/
Australian Government Environment Protection and Biodiversity
Conservation Act. 1999. http://www.deh.gov.au/epbc/
Department of Environment and Heritage. 2006. Threat Abatement Planfor the incidental catch (or bycatch) of seabirds during oceanic longline
fishing
operations
http://www.environment.gov.au/biodiversity/threatened/tapapproved.html
Subsecretaría de Pesca. 2006. Plan de Acción Nacional para reducir las
capturas incidentales de aves en las pesquerías de palangre (PANAM/CHILE). 26 pp. www.subpesca.cl/mostrararchivo.asp?id=5768
New Zealand Government. New Zealand Wildlife Act 1953, No 31.
http://www.legislation.govt.nz/act/public/1953/0031/latest/DLM276814.ht
ml?search=ts_act_wildlife_resel&sr=1
Miskelly, C.M., Dowding, J.E., Elliott, G.P., Hitchmough, R.A.,
Powlesland, R.G., Robertson, H.A., Sagar, P.M., Scofield, R.P., andTaylor, G.A. 2008. Conservation status of New Zealand birds, 2008.
Notornis 55: 117-135.
Taylor, G.A. 2000. Action plan for seabird conservation in New Zealand.
Part A: threatened seabirds. Threatened Species Occasional Publication
No. 16. Department of Conservation. Wellington.
Jackson, R. 1958. The Westland Petrel. Notornis 7: 230-233.
Lyall, J., Taylor, G.A., and Adams, L. 2004. Westland petrel (taiko)
recovery plan 2004-14. Department of Conservation, New Zealand.
Baker, A.J. and Coleman, J.D. 1977. The breeding cycle of the Westland
Black Petrel (Procellaria westlandica). Notornis 24: 211-231.
Brooke, M. 2004. Albatrosses and petrels across the world. Oxford:
Oxford University Press. 499 pp.
Waugh, S.M., Doherty, P.F., Freeman, A.N.D., Adams, L., Woods, G.C.,
Bartle, J.A., and Hedley, G.K. 2006. Demography of Westland Petrels(Procellaria westlandica), 1995-2003. Emu 106: 219-226.
Baker, B., Cunningham, R., Hedley, G., and King, S. 2008. Data
collection of demographic, distributional and trophic information on theWestland petrel to allow estimation of effects of fishing on population
viability. Unpublished report prepared for the Ministry of Fisheries
PRO2006-01H. Latitude 42 Environmental Consultants. Kettering,
Australia.
New Zealand Government. 1980. National Parks Act 1980.
http://www.legislation.govt.nz/act/public/1980/0066/latest/DLM36963.htm
l?search=ts_act_National+Parks+Act+1980_resel&sr=1
New Zealand Government. 1987. Conservation Act 1987.
http://www.legislation.govt.nz/act/public/1987/0065/latest/DLM103610.ht
ml?search=ts_act_Conservation+Act+1987_resel&sr=1
Worthy, T.H. and Holdaway, R.N. 1993. Quaternary Fossil Faunas from
Caves in the Punakaiki Area, West-Coast, South-Island, New-Zealand.
Journal of the Royal Society of New Zealand 23: 147-254.
Best, H.A. and Owen, K.L. 1976. Distribution of breeding sites of theWestland Petrel (Procellaria westlandica). Notornis 23: 233-242.
Wood, C. Undated. Westland Petrel (Procellaria westlandica) colony andburrow distribution survey 2003-2005. Unpublished Report. New ZealandDepartment of Conservation. Punakaiki field base.

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Bell, E.A., Sim, J.L., and Scofield, R.P. 2007. Demographic parametersof the black petrels (Procellaria parkinsoni). DOC Research andDevelopment Series 273. Department of Conservation. Wellington.
Imber, M.J. 1987. Breeding ecology and the conservation of the black
petrel (Procellaria parksoni). Notornis 34: 19-39.
Barbraud, C., Marteau, C., Ridoux, V., Delord, K., and Weimerskirch, H.
2008. Demographic response of a population of white-chinned petrels
Procellaria aequinoctialis to climate and longline fishery bycatch. Journalof Applied Ecology 45: 1460-1467.
Berrow, S.D., Croxall, J.P., and Grant, S.D. 2000. Status of whitechinned petrels Procellaria aequinoctialis Linnaeus 1758, at Bird Island,South Georgia. Antarctic Science 12: 399-405.
Jouventin, P., Bried, J., and Micol, T. 2003. Insular bird populations canbe saved from rats: a long-term experimental study of white-chinned
petrels Procellaria aequinoctialis on Ile de la Possession (Crozet
archipelago). Polar Biology 26: 371-378.
Freeman, A.N.D. and Wilson, K.-J. 2002. Westland petrels and hoki
fishery waste: opportunistic use of a readily available resource? Notornis
49: 139-144.
Imber, M.J. 1976. Comparison of prey of the black Procellaria petrels of
New Zealand. New Zealand Journal of Marine and Freshwater Research
10: 119-130.
Freeman, A.N.D. 1998. Diet of Westland Petrels Procellaria westlandica:
The importance of fisheries waste during chick-rearing. Emu 98: 36-43.
Freeman, A.N.D., Nicholls, D.G., Wilson, K.-J., and Bartle, J.A. 1997.
Radio- and satellite-tracking Westland Petrels Procellaria westlandica.
Marine Ornithology 25: 31-36.
Freeman, A.N.D., Wilson, K.-J., and Nicholls, D.G. 2001. Westland
Petrels and the Hoki fishery: determining co-occurrence using satellite
telemetry. Emu 101: 47-56.
Spear, L.B., Ainley, D.G., and Webb, S.W. 2005. Distribution,
abundance, habitat use and behaviour of three Procellaria petrels off
South America. Notornis 52: 88-105.
Baker, G.B., Gales, R., Hamilton, S., and Wilkinson, V. 2002.
Albatrosses and petrels in Australia: a review of their conservation andmanagement. Emu 102: 71-97.
Freeman, A.N.D. 1997. The influence of Hoki fishing vessels on
Westland Petrel (Procellaria westlandica) distribution at sea. Notornis 44:
159-164.
Waugh, S.M., MacKenzie, D.I., and Fletcher, D. 2008. Seabird bycatchin New Zealand trawl and longline fisheries 1998-2004. Papers andProceedings of the Royal Society of Tasmania 142: 45-66.
Conservation Services Programme. 2008. Summary of autopsy reports
for seabirds killed and returned from observed New Zealand fisheries: 1
October 1996 - 30 September 2005, with specific reference to 2002/03,
2003/04, 2004/05. DOC Research and Development Series 291.
Department of Conservation. Wellington. 110 pp.
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Report 2007. Royal Society for the Protection of Birds, The Lodge,
Sandy, Bedfordshire, UK.

COMPILED BY
Wiesława Misiak
ACAP Secretariat

CONTRIBUTORS
Susan Waugh
BirdLife Global Seabird ProgrammeMark Tasker
Vice Chair, ACAP Advisory Commitee
ACAP Bycatch Working Group
Contact: Barry Baker
barry.baker@latitude42.com.au
ACAP Breeding Sites Working Group
Contact: Richard Phillips
raphil@bas.ac.uk
ACAP Status and Trends Working Group
Contact: Rosemary Gales
Rosemary.Gales@dpiw.tas.gov.au
ACAP Taxonomy Working Group
Contact: Michael Double
Mike.Double@aad.gov.au
BirdLife International,
Global Seabird Programme
Contact: Cleo Small
Cleo.Small@rspb.org.uk
Maps: Frances Taylor
Tracking Data Contributors:
David Nicholls (Chisholm Institute),
Amanda Freeman, K-J. Wilson (Lincoln
University).

RECOMMENDED CITATION
Agreement on the Conservation ofAlbatrosses and Petrels. 2011. ACAP
Species assessment: Westland Petrel
Procellaria westlandica. Downloaded fromhttp://www.acap.aq on 9 February 2011.

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GLOSSARY AND NOTES(i)
Years.
The “split-year” system is used. Any count (whether breeding pairs or fledglings) made in the austral summer (e.g. of
1993/94) is reported as the second half of this split year (i.e. 1994).
The only species which present potential problems in this respect are Diomedea albatrosses, which lay in DecemberJanuary, but whose fledglings do not depart until the following October-December. In order to keep records of each
breeding season together, breeding counts from e.g. December 1993-January 1994 and productivity counts (ofchicks/fledglings) of October-December 1994 are reported as 1994.
If a range of years is presented, it should be assumed that the monitoring was continuous during that time. If the years ofmonitoring are discontinuous, the actual years in which monitoring occurred are indicated.

(ii)

Methods Rating Matrix (based on NZ rating system)METHODA
Counts of nesting adults (Errors here are detection errors (the probability of not detecting a bird despite its being
present during a survey), the “nest-failure error” (the probability of not counting a nesting bird because the nest had failed
prior to the survey, or had not laid at the time of the survey) and sampling error).
B
Counts of chicks (Errors here are detection error, sampling and nest-failure error. The latter is probably harder toestimate later in the breeding season than during the incubation period, due to the tendency for egg- and chick-failures toshow high interannual variability compared with breeding frequency within a species).
C
Counts of nest sites (Errors here are detection error, sampling error and “occupancy error” (probability of counting
a site or burrow as active despite it’s not being used for nesting by birds during the season).
D
Aerial-photo (Errors here are detection errors, nest-failure error, occupancy error and sampling error (error
associated with counting sites from photographs), and “visual obstruction bias” - the obstruction of nest sites from view,always underestimating numbers).
E
Ship- or ground- based photo (Errors here are detection error, nest-failure error, occupancy error, sampling errorand “visual obstruction bias” (the obstruction of nest sites from view from low-angle photos, always underestimating
numbers)F
Unknown
G
Count of eggs in subsample population
H
Count of chicks in subsample population and extrapolation (chicks x breeding success - no count of eggs)

RELIABILITY
1
Census with errors estimated2
Distance-sampling of representative portions of colonies/sites with errors estimated3
Survey of quadrats or transects of representative portions of colonies/sites with errors estimated4
Survey of quadrats or transects without representative sampling but with errors estimated5
Survey of quadrats or transects without representative sampling nor errors estimated6
Unknown(iii) Population Survey Accuracy
High
Within 10% of stated figure;Medium Within 50% of stated figure;Low
Within 100% of stated figure (eg coarsely assessed via area of occupancy and assumed density)
Unknown(iv) Population Trend
Trend analyses were run in TRIM software using the linear trend model with stepwise selection of change points (missing
values removed) with serial correlation taken into account but not overdispersion.

(v) Productivity (Breeding Success)Defined as proportion of eggs that survive to chicks at/near time of fledging unless indicated otherwise

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(vi) Juvenile Survival
defined as:
1 Survival to first return/resight;
2 Survival to x age (x specified), or
3 Survival to recruitment into breeding population
4 Other
5 Unknown(vii) Threats
A combination of scope (proportion of population) and severity (intensity) provide a level or magnitude of threat. Both scopeand severity assess not only current threat impacts but also the anticipated threat impacts over the next decade or so,
assuming the continuation of current conditions and trends.

Scope(% population affected)

Very High(71-100%)

SeverityHigh(likely % reduction ofaffected population
within ten years)(31-70%)Medium(11-30%)Low(1-10%)

Very High

High

MediumLow(71-100%)(31-70%)(11-30%)(1-10%)

Very High

High

Medium

Low

High

High

MediumLow

MediumMediumMedium

Low

Low

Low

Low

Low

(viii)Maps
The tracking maps shown were created from platform terminal transmitter (PTT) and global-positioning system (GPS)loggers. The tracks were sampled at hourly intervals and then used to produce kernel density distributions, which have been
simplified in the maps to show the 50%, 75% and 95% utilisation distributions (i.e. where the birds spend x% of their time).
The full range (i.e. 100% utilisation distribution) is also shown. Note that the smoothing parameter used to create the kernel
grids was 1 degree, so the full range will show the area within 1 degree of a track. In some cases the PTTs were dutycycled: if the off cycle was more than 24 hours it was not assumed that the bird flew in a straight line between successive on
cycles, resulting in isolated ‘blobs’ on the distribution maps. It is important to realise that these maps can only show wheretracked birds were, and blank areas on the maps do not necessarily indicate an absence of the particular species.

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