Justification This species has been downlisted to Endangered as, despite very rapid declines over the past three generations, the population stabilised and began to increase since 2000; a trend boosted by two recent translocations.

Family/Sub-family Procellariidae

Species name author (Salvin, 1893)

Taxonomic source(s) Brooke (2004), Sibley and Monroe (1990, 1993), Turbott (1990)

Identification 30 cm. Small, grey-and-white gadfly petrel with unique underwing pattern. Dark grey crown, sides of face and neck. Black mark behind eye. Grey upperparts. Grey tail with dark tip. Grey upperwing with dark, moderately distinct "M". Pale grey half-collar at sides of breast. Rest of underparts white. White underwing with dark tip, broad, black bar extending from axillaries (where broadest) to carpal joint, then less prominently towards tip. Similar spp. Black underwing bar of Black-winged Petrel P. nigripennis does not reach body and axillaries. Larger Mottled Petrel P. inexpectata has bold bar, but has dark centre to belly. Voice Flight call whis-whis-whis, oi, purring call given on ground.

Population estimate

Population trend

Range estimate (breeding/resident)

Country endemic?

500

decreasing

28 km²

Yes

Range & population Pterodroma axillaris is restricted to South East Island (= Rangatira) in the Chatham Islands, New Zealand, although subfossils indicate that it was once more widespread, being present on Chatham, Pitt and Mangere Islands^2,5. The earliest estimate of 50 birds was later revised to 200-400². A mark-recapture census in 2004 estimated the global population stands at 1,000-1,100 individuals comprising the 250 breeding pairs, a floater population of adults unable to breed each year owing to loss of partners or nesting sites and juveniles aged 0-5^3,11. The increase reflects an improvement in knowledge and since 2000, a marked response to successful management with over 100 chicks now fledging annually and many recruiting back to the island. Significant declines occurred during the 20th century and continued into the 1990s; an annual decline of 1% per annum has been crudely estimated and cautious interpretation suggests a gross decline of 40-50% or more may have occurred over the past three generations¹¹. Trends appear to have stabilised since 2000, prompted by successful conservation measures. Between 2002-2006, 200 chicks were moved to a newly created predator-free site, and successful breeding occurred in 2006⁶, 2007 and 2008¹⁰. A second translocation is underway with 47 chicks moved to the 7.5 hectare Sweetwater Conservation Covenant on the main Chatham Island in 2008¹⁰. It may migrate to the north Pacific Ocean like the closely-related P. nigripennis, and has been recorded at sea to the south of the islands^1,7.

Ecology: It nests in burrows in very friable densely burrowed soils in lowland temperate forest and scrub, on flat to moderate sloping ground². Its diet is not well known but includes squid and small fish. Some young have returned to the island at two years old¹, and breeding has been recorded at age three, though most individuals do not breed until age five¹¹. Much of the life cycle is spent at sea; birds return to land only to breed. Visits to the colony are after dark.

Threats On South East Island, intense competition for burrows with the abundant Broad-billed Prion Pachyptila vittata (including lethal attacks on chicks and eggs, and occasionally adults) is the primary threat⁸. Such competition may be the cause of the observed low breeding success and high rate of pair bond disruption. On the other islands in the group, exploitation by humans for food and introduced predators were the probable causes of extirpation³. Predator-proof fencing has facilitated translocations to two Conservation Covenants on Pitt Island and Chatham Island; alien invasive mammals will remain a constant potential threat to these sites and ongoing management will be required.

Conservation measures underway South East Island has been managed as a reserve since 1954, and cattle, sheep and goats were removed in 1961^2,3. Intensive research, ongoing since 1991, helped to identify the impact of Pachyptila vittata. As a consequence, artificial nest-sites have been provided and burrows have been blocked to prevent occupation by P. vittata during the absence of Pterodroma axillaris. P. vittata found occupying P. axillaris burrows are culled³. Since 2001, neoprene burrow flaps installed at burrow entrances have greatly reduced prion impacts during the period February to April⁹. These measures have greatly improved breeding success^3,4, from 10-30% in early 1990s to 70-80% in the past 10 years. Intensive burrow searches have now located over 160 active breeding sites of the estimated 250 pairs using the island. All newly located burrows are converted to artificial nest sites and are safe-guarded from prion interference. In 2002 a second population was created in a predator free enclosure on the 40 ha Ellen Elizabeth Preece Conservation Covenant (EEPCC). Over four years 200 chicks were transferred to this site, and by 2006 four birds had returned with a pair successfully rearing a single chick for the first time^3,6. In 2006-2007, four pairs nested and four chicks were reared. This included one pair of unbanded birds that have been lured presumably to the site by the sound attraction system. In 2008 seven chicks fledged from the EEPCC and 47 chicks were translocated to Sweetwater Conservation Covenant on Chatham Island¹⁰.

Conservation measures proposed Monitor breeding burrows annually and band all chicks. Continue to protect nesting birds. Continue translocating birds to the Sweetwater Conservation Covenant on Chatham Island until a self-maintaining population is established. Use tiny geolocation tags to investigate the species's at-sea distribution and identify potential threats.

References 1. Heather and Robertson (1997). 2. Marchant and Higgins (1990). 3. Taylor (2000). 4. G. A. Taylor in litt. (1999). 5. A. J. D. Tennyson per G. A. Taylor in litt. (1999). 6. Anon (2006). 7. R. Hitchmough in litt. (2005). 8. Was et al. (2000). 9. Sullivan and Wilson (2001). 10. C. Miskelly in litt. (2008). 11. G. Taylor in litt. (2009).

Further web sources of information

Alliance for Zero Extinction (AZE) species/site profile. This species has been identified as an AZE trigger due to its IUCN Red List status and limited range.

New Zealand Govt - Dept of Conservation - Recovery Plan

Text account compilers Phil Benstead (BirdLife International), Jeremy Bird (BirdLife International), Ben Lascelles (BirdLife International), Rachel McClellan (BirdLife International), Graeme A. Taylor (Department of Conservation), Helen Temple (BirdLife International)

Contributors Rod Hitchmough (Department of Conservation), Graeme A. Taylor (Department of Conservation), A. J. D. Tennyson, Kerry-Jayne Wilson (Lincoln University)

IUCN Red List evaluators Jeremy Bird (BirdLife International), Stuart Butchart (BirdLife International)

Recommended citation BirdLife International (2009) Species factsheet: Pterodroma axillaris. 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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