Pterodroma magentae 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Procellariiformes Procellariidae

Scientific Name: Pterodroma magentae (Giglioli & Salvadori, 1869)
Common Name(s):
English Magenta Petrel, Chatham Island Taiko
Spanish Fardela taiko, Petrel taiko
Taxonomic Source(s): Turbott, E.G. 1990. Checklist of the Birds of New Zealand. Ornithological Society of New Zealand, Wellington.
Identification information: 38 cm. Medium-sized, dark brownish-grey and white petrel. Mostly uniform brownish-grey head, neck, upper breast, upperparts, upperwing, tail. White lower breast, belly, undertail. Brown underwing, paler under primaries. Black bill. Pink legs. Feet pink proximally, black distally. Similar spp. Phoenix Petrel P. alba is smaller, more brown. Atlantic Petrel P. incerta is bulkier with brown undertail. Voice Calls or-wik, si, si, si and orr.

Assessment Information [top]

Red List Category & Criteria: Critically Endangered A2ce ver 3.1
Year Published: 2016
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Bell, M., Lawrence, H., Miskelly, C., Ogle, M. & Taylor, G.A.
Facilitator/Compiler(s): Ashpole, J, Benstead, P., Bird, J., Calvert, R., Lascelles, B., McClellan, R., Moreno, R., Pilgrim, J., Symes, A., Taylor, J.
This species qualifies as Critically Endangered as it has undergone an extremely rapid historical decline over three generations. The on-going declines appear to have ceased and the population is slowly recovering thanks to intensive conservation work, which may lead to the downlisting of this species in the future.

Previously published Red List assessments:

Geographic Range [top]

Range Description:Pterodroma magentae was rediscovered in 1978 in the south-west corner of Chatham Island, New Zealand, 111 years after it was first collected at sea (Crockett 1994). Its prevalence in Moriori middens suggests it was once common and has undergone a massive historical decline (Imber et al. 2005). In 1994, only four breeding pairs were known, although it was suspected that others remained undetected, and that the population was still declining at this time. In 2004, surveys indicated a population of 120 individuals, including 15 breeding pairs (Hilhorst 2000, Brooke 2004, G. Taylor in litt. 2005). Just 16 chicks were known to have fledged from 1987-1988 to 2000 (Taylor 2000), but in 2002, a total of seven chicks were fledged (M. Ogle in litt. 2002). By 2006, there were 35 active burrows, an estimated 25 breeding pairs, and 11 known chicks, taking the total number of chicks fledged since 1987 to 63 (Stephenson 2006b). A total of 17 pairs are believed to have laid in the 2009/2010 breeding season (C. Miskelly in litt. 2008, 2010). Between 2007 and 2011, a total of 59 chicks were successfully moved from the Tuku Nature Reserve in the south of Chatham Island to the nearby Sweetwater Conservation Covenant, where they all successfully fledged (Miskelly et al. 2009, G.Taylor pers. comm. 2016). Inshore waters (1-2 km offshore from the colony) around Otawae Point are thought to be important for non-breeders visiting the colony and during courtship at night (Imber et al. 2005). Its range at sea is known to extend across the entire South Pacific Ocean from the Tasman Sea to South America, based on recent tracking results using geolocators from 2008 to 2012 (G. Taylor in litt. 2016). During the breeding season, birds feed mainly south and south-east of the Chatham Islands; they then disperse widely during the non-breeding season, ranging from Tasman Sea to the west coast of South America (G. Taylor in litt. 2012).  

Countries occurrence:
New Zealand
Additional data:
Estimated area of occupancy (AOO) - km2:2Continuing decline in area of occupancy (AOO):No
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:1850000
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:1Continuing 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:In 2012, the total population was estimated to number around 150-200 individuals, including 80-100 mature individuals (G. Taylor in litt. 2012).

Trend Justification:  Although intensive conservation management (predator control in particular), appears to have allowed the population to increase slowly since the late 1990s, the species has undergone a severe decline over the last century, in excess of 80% over the last 60 years (three generations). The species is very long-lived with two birds first captured as adults in Oct 1982 still breeding in 2015 (at least 37 years old) (G. Taylor, D. Boyle pers. comm. 2016)

Current Population Trend:Increasing
Additional data:
Number of mature individuals:80-100Continuing decline of mature individuals:No
Extreme fluctuations:NoPopulation severely fragmented:No
No. of subpopulations:1Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:Yes
No. of individuals in largest subpopulation:100

Habitat and Ecology [top]

Habitat and Ecology:It breeds in a fragmented colony under dense forest (Heather and Robertson 1996), 4-6 km inland. Burrows are up to 5 m long and breeding takes place from September to May (Taylor et al. 2012). Males occupy burrows for 1-3 years before pair formation and breeding; non-breeding females rarely visit the colony (Imber et al. 2005). Its diet is not well known, but includes squid (Imber et al. 1995) and fish (G. Taylor in litt. 2012). Recent ringing returns show that males return to the colony aged 3-10 years, females at 4-9 years, and first breeding is attempted at around five years of age (Department of Conservation 1999, Imber et al. 2005, G. Taylor in litt. 2012). The pairs form a life-long bond, one egg is laid per year, incubated by both parents, and fledging chicks climb trees from which they launch themselves to fly out to sea (C. Miskelly in litt. 2008, 2010).

Systems:Terrestrial; Marine
Continuing decline in area, extent and/or quality of habitat:No
Generation Length (years):19.5
Movement patterns:Full Migrant
Congregatory:Congregatory (and dispersive)

Threats [top]

Major Threat(s): Introduced species (particularly three rat species, pigs, cats, Weka, possums, hedgehogs and stray dogs [Johnston et al. 2003, Imber et al. 2005, Carboneras et al. 2014]) take eggs, chicks and adults, or compete for, destroy or cause the desertion of burrows. Flooding of burrows may also lower breeding success in some seasons (Taylor 2000). Loss of bush forest is attributed to grazing by cattle, sheep and brush-tailed possums (Trichosurus vulpecula) (Carboneras et al. 2014). Loss of forest habitat from accidental fire represents a threat (Aikman et al. 2001). Historically, the pastoralisation of Chatham Island probably caused  destruction of some colonies. Prior to 1900, local Moriori and Maori caught thousands of chicks for food (Crockett 1994, Stephenson 2006). Molecular analysis has found that, while the sex-ratio is approximately even in petrel chicks and breeding adults caught on the ground, 95% of non-breeding adults are male. This suggests that low population levels may be causing unpaired male birds difficulty in attracting a mate, as their calls are too spread out to attract the infrequent females which pass by (Lawrence et al. 2008). There are no at-sea threats that are known to be seriously and imminently impacting this species (G. Taylor in litt. 2012). Some closely related species (e.g. grey-faced petrels Pterodroma gouldi) have been caught on long-lines, thus there may be unrecorded impacts on this species. Longer term climate change impacts on oceans, such as acidification, may also become a threat. Its highly dispersed non-breeding movements lower risks to the species of localised threats such as oil spills (G. Taylor in litt. 2012). A proposed seabed mining operation on the Chatham Bank represented a potential threat to the species (Anderson 2014), however the application was rejected in February 2015 (Morton 2015).

Conservation Actions [top]

Conservation Actions: Conservation Actions UnderwayTen years of intensive searching led to its rediscovery in 1978, but no burrows were found (Crockett 1994). In 1987, radio-transmitters attached to the tail-feathers of birds finally led to the discovery of three burrows (Imber et al. 1994b), and trapping for predators was immediately commenced (Imber et al. 1994a). On-going searches located only three more burrows, but in 1999, at least 17 new burrows were discovered (Taylor 2000). Breeding areas have been protected by the Tuku Nature Reserve (Stephenson 2006a). Predator control was intensified in 1996 (Imber et al. 2005). All burrows are monitored annually for breeding attempts (Imber et al. 1994a, Taylor et al. 2012) and sometimes infra-red cameras are deployed at each nest to monitor activity and identify predators (Johnston et al. 2003). Since 2007, burrows have been monitored using automated PIT-tag readers, and most birds caught since 2001 have been fitted with PIT-tags (Taylor et al. 2012). Egg- and chick-rearing trials have been undertaken on the closely-related Grey-faced Petrel P. macroptera, and its diet analysed, to develop methods for captive rearing of P. magentae (Taylor 2000). 
The Chatham Island Taiko Trust was established in 1998 to provide legal status to the continuing work (Department of Conservation 2007), and has since provided substantial funding to much of the conservation work focussed on this species (M. Bell in litt. 2012). In 2006, a 3-ha safe colony with predator-proof fence, wooden burrows, and playback sound system was established at the Sweetwater Secure Breeding Site, and chicks have been transferred here prior to fledging to form a new colony (Taylor 2000, Stephenson 2006b). Eight chicks were successfully moved and fledged here in April-May 2007, as were a further 13 in 2008 and 13 in 2009 (C. Miskelly in litt. 2008, 2010). Over five summers, 58 chicks were transferred from Tuku Nature Reserve to Sweetwater (Chapman 2014). A chick that fledged in 2007 returned to Sweetwater in 2010, this was followed by another chick in 2011 and 12 chicks in 2012. The first two cohorts of chick transfers had a survival rate of approximately 60% (considerably higher than the 20-30% natural recruitment rate [Chapman 2014]). Birds bred at Sweetwater in 2013, with two eggs laid (Chapman 2014). The 1,200-hectare South Chatham Covenant, adjacent to the Tuku Nature Reserve and containing one known cluster of burrows, is now fenced, and is currently being surveyed to determine its actual area: as at Sweetwater ownership will remain with the existing landowners but the Covenant will ensure protection in perpetuity  (C. Miskelly in litt. 2008, 2010). The 2011 target is to establish a self-sustaining population of at least 250 individuals. Birds have been fitted with geolocators since 2008/2009 (G. Taylor in litt. 2012). A recent conservation action has been to catch birds through the use of spotlights and trained petrel dogs to locate additional burrows and attempting to introduce known females to burrow clusters that contain unpaired males (G. Taylor in litt. 2012). This action has resulted in 6 successful new pairings (G.Taylor pers.comm 2016). Passive Integrated Transponder (PIT) readers are used at Sweetwater to monitor breeding burrows (Chapman 2014).
Conservation Actions ProposedContinue ground and dog searches and telemetry to locate further burrows, as well as night surveys for prospecting birds and to collect data on survival. Continue to use study holes at all active nest burrows to enable active intervention if chicks are undernourished or abandoned. Continue sustained predator and herbivore control. Continue to study the species's ecology, including its at-sea distribution. Consider maintenance of genetic diversity when planning future conservation actions (Lawrence et al. 2008b). Continue to translocate chicks to Sweetwater Conservation Covenant to build up secure population (M. Bell in litt. 2012).

Citation: BirdLife International. 2016. Pterodroma magentae. The IUCN Red List of Threatened Species 2016: e.T22698049A93658301. . Downloaded on 18 August 2018.
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