VU
Black Petrel Procellaria parkinsoni



Justification

Justification of Red List Category
This species qualifies as Vulnerable because it breeds on just two very small islands where introduced predators are a potential threat, and could drive the taxon towards extinction in a very short time. The population is assumed to be stable, but if a decline is detected, the species should be uplisted to Endangered.

Population justification

There are c.880 pairs in the 35-ha study site of Great Barrier Island and 620 pairs in Little Barried Island (Bell et al. 2016a, b). A recent assessment of the whole population derived from band recoveries from fisheries bycatch estimated 2,750 breeding pairs (equivalent to 5,500 mature individuals) and 11,000 individuals (Richard and Abraham 2015).

Trend justification

The trend obtained from census grid data for Great Barrier Island estimated a population growth rate between -2.3% and 2.5% per year, depending on juvenile annual survival. Assuming a juvenile annual survival rate of 88%, the population growth rate was estimated to be -1.1% per year (Bell et al. 2014). Nevertheless, there is considerable uncertainty in the model and further research is needed to clarify the population trend.

Distribution and population

Procellaria parkinsoni breeds on Great and Little Barrier Islands, New Zealand, where the populations number c.880 pairs (in the 35-ha study site) and 620 pairs respectively (Bell et al. 2016a, b). It once bred in the mountains of the North and South Islands, but had disappeared from the mainland by the 1960s. It migrates to the eastern Pacific Ocean between the Galápagos Islands, southern Mexico and northern Peru (Heather and Robertson 1997). On Little Barrier, it was abundant in the late 1800s but the population was decimated, mainly by feral cats, until predators were eradicated in 1980. The trend obtained from census grid data for Great Barrier Island estimated a population growth rate between -2.3% and 2.5% per year, depending on juvenile annual survival. Assuming a juvenile annual survival rate of 88%, the population growth rate was estimated to be -1.1% per year (Bell et al. 2014). Nevertheless, there is considerable uncertainty in the model and further research is needed to clarify the population trend.

Ecology

Behaviour It is a colonial burrow-nesting, annually-breeding species (ACAP 2009). Most eggs are laid in mid-November/late December, hatch in late January/February and chicks fledge in May/June at about three months old. Chick provisioning can continue until June (Bell et al. 2009). The youngest recorded bird returning to a colony was two years of age, and the age of first breeding has been recorded at four years of age (Bell et al. 2016a). Feeding behaviour is characterised by surface feeding and shallow diving in groups of up to 300 individuals that are frequently seen to associate with fishing vessels and cetaceans. Black Petrels have been recorded diving up to 34 m, but over 85% of all dives were less than 5 m and over 90% were during the day (Bell 2016). Preliminary geolocator data suggest that it preferentially forages on the continental shelf or at seamounts (ACAP 2009), with most foraging trips taking at least 15 days (Bell et al. 2009). Further data suggest foraging areas are highly variable, although birds travel mainly west and east of northern New Zealand (Bell et al. 2009). Habitat Breeding It nests in virgin podocarp and mixed broadleaf forest above 500 m. On the mainland, it reportedly bred up to 1,200 m, mostly in tall forest, but also in alpine tussock grasslands (Marchant and Higgins 1990). Diet Its diet is dominated by squid and supplemented by tunicates, crustaceans and cyclostomes (Bell et al. 2009). 

Threats

The main threat faced by the Black Petrel is bycatch from commercial and subsistence fisheries. It was assessed as the species at greatest risk from mortality due to bycatch by New Zealand commercial fisheries in both 2011 and 2013, with 65 observed captures of black petrel in bottom longline fisheries in New Zealand in 2002-2003 (Baird and Bell 2013). Black petrels are caught in small-scale demersal long lining fisheries for hake and in surface longlining for tuna in Ecuador (Mangel 2012). Given this species is restricted to just two islands out of its much larger historical range, it is possible that the majority of the population may consist of non-breeding ‘floaters’ which potentially obscures the observation of a decline at breeding sites, raising concerns that the level of observed bycatch may be severely impacting the species.

El Niño fluctuations are known to impact this species through fluctuations in prey abundance, especially in the east Pacific off Ecuador and Peru where it is a near-obligate associate of small crustaceans (Pitman and Ballance 1992).

Introduced cats decimated the Little Barrier population, killing up to 100% of fledglings in some years (Imber 1987) as well as taking adults, but have since been eradicated from the island. They remain a threat on Great Barrier where annual predation rates are between zero and 1.5% with ongoing efforts to control the threat (Bell et al. 2007). Pigs, although currently excluded from breeding colonies, have been recorded within the breeding area and are suspected to have had minor impacts on the species through damage to burrows and increased erosion. Black and Polynesian Rats likely result in some loss of reproductive success; this is likely to have increased on Little Barrier Island where the population has dramatically increased since the eradication of cats (Rayner et al. 2007).

Conservation actions

Conservation Actions Underway
CMS Appendix II and ACAP Annex 1. Cats were eradicated on Little Barrier Island by 1980. Between 1986 and 1990, 249 fledglings were transferred from Great Barrier to Little Barrier in an attempt to boost population size. Follow-up monitoring indicates mixed results (Imber et al. 2003). The population on Little Barrier has been studied since 2014/15 (Bell et al. 2016b). A long-term population study was initiated on Great Barrier in 1996 to study populations annually to determine trends and assess breeding success (Taylor 2000, Bell et al. 2007). Tracking research has been completed on both Little Barrier and Great Barrier (E. Bell in litt. 2012). Feral cat trapping was undertaken on Great Barrier Island in 2011/2012 and is scheduled to continue in future breeding seasons, along with a rodent control programme (per E. Bell in litt. 2012). Rattus exulans was eradicated from Little Barrier in 2004 (E. Bell in litt. 2012).

Conservation Actions Proposed
Complete an accurate census of Little Barrier Island. Monitor Great Barrier study populations annually to determine trends, and assess breeding success. Monitor the effectiveness of increased mitigation application in the main fisheries threat in New Zealand from bottom longlining through an electronic monitoring project (Black Petrel Working Group 2016). Continue and expand predator control at Great Barrier if monitoring indicates that any predators are causing a population decline (Taylor 2000). 

Identification

46 cm. Large, black petrel, becoming more brown as plumage ages. Undersides of primaries may appear silvery. Yellow-white bill on adults, blue-white on juveniles, has black tip. Black legs, feet. Similar spp. Smallest Procellaria species. Smaller, especially bill, than Westland Petrel P. westlandica and has less laboured flight. Large, all-dark Flesh-footed Shearwater P. carneipes have pink feet and distinctive flight. Voice Varied calls at colony after dark.

Acknowledgements

Text account compilers
Small, C., Stuart, A., Black, A., Symes, A., Taylor, J., Bird, J., Calvert, R., Fjagesund, T., Anderson, O., Hermes, C., Martin, R., Moreno, R.

Contributors
Debski, I., Weeber, B., Bell, E., Taylor, G.A.


Recommended citation
BirdLife International (2019) Species factsheet: Procellaria parkinsoni. Downloaded from http://www.birdlife.org on 19/10/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 19/10/2019.