CR
Beck's Petrel Pseudobulweria becki



Justification

Justification of Red List Category
This species has recently been rediscovered, with confirmed records of at least 30 and at most 160 birds from expeditions in 2007 and 2008 and with a minimum of 100 birds estimated in 2012 and a minimum count of 300 individuals recorded in 2016. It may have declined severely from depredation by introduced cats and rats on its breeding grounds (which are unknown but thought likely to be include New Ireland). However, the paucity of records is most likely because there have been relatively few searches at sea, plus petrels that are nocturnal at the nesting grounds are notoriously difficult to detect, and there are numerous possible breeding sites on isolated atolls and islands that require surveying. A very small number of mature individuals are currently known, all within a single subpopulation which is suspected to have declined, and it is consequently classified as Critically Endangered. It may however qualify for downlisting in the future if further surveys reveal it to be more numerous than is currently known.

Population justification

The population is assumed to be very small, with the species only definitely known from two specimens taken in 1928 and 1929 until its rediscovery in 2007. The largest single record since its rediscovery was a minimum count of 300 individuals in Silur Bay, April 2016 (J. Bird in litt. 2016). It is placed in the band 50-249 mature individuals here, equivalent to 75-374 individuals in total, rounded here to 70-400 individuals.

Trend justification
It may have declined severely from depredation by introduced cats and rats on its breeding grounds (which are unknown but probably include, or are restricted to, New Ireland). However, the rate of decline has not been estimated.

Distribution and population

Until 2007 Pseudobulweria becki was only known from two specimens: a female taken at sea east of New Ireland and north of Buka, Papua New Guinea, on 6 January 1928, and a male taken north-east of Rendova, Solomon Islands, on 18 May 1929 (Murphy and Pennoyer 1952). Three birds probably of this species were seen off New Ireland in the Bismarck Archipelago in 2003 (H. Shirihai in litt. 2007, Shirihai 2008) and in July and August 2007 an expedition recorded the species on seven days from at least four localities off New Ireland, with at least 30 recorded in a day and a maximum of 16 together, finally confirming the species's rediscovery (Shirihai 2008). Cape St George, at the southern end of the island, appeared the most favoured locality, where birds outnumbered Tahiti Petrel P. rostrata, recently fledged juveniles and moulting adults were seen close to land, and a freshly dead fledgling was found (Shirihai 2008). In 2008 at least 11 were seen off western Bougainville and eastern New Ireland in April (C. Collins in litt. 2008). Subsequently, Beck’s Petrels have been recorded annually in the Bismarck Sea between the Solomon Islands and New Ireland by a birdwatching cruise that stays beyond the 12 nautical mile limit to territorial waters. An expedition in July-August 2008 reported 160 birds between New Britain and New Ireland (Shirihai 2008a), though this is the summed count for multiple days and made no attempt to avoid double-counting individuals (J. Bird in litt. 2012). Following the upsurge in interest in this species following the 2007/2008 observations, targeted searches have focussed on identifying breeding sites. This led to the discovery of a regular aggregation of birds in Silur Bay of south-east New Ireland, with a minimum of 100 birds estimated in March 2012 (Bird 2012) and a minimum count of 300 individuals recorded in April 2016 (J. Bird in litt. 2016).

Away from southern New Ireland two were seen near Efate in the Vanuatu archipelago in February 2010 (P. Harrison in litt. 2010), while a possible record was seen and photographed from a boat crossing the Coral Sea east of Australia's Great Barrier Reef in 2006 (A. Wilson in litt. 2006); due to the difficulty of reliable identification in the field a number of records of P. rostrata from the Solomon Islands and Bismarck Archipelago (Coates and Swainson 1978, Coates 1985, Palliser 1987), may also refer to P. becki.

There is speculation that the species breeds in the montane forests of southern New Ireland on the upper slopes of Mt. Agil in the Hans Meyer Range (Bird 2012, Bird et al. 2014), or further south in Mt Gilaut (Shirihai 2008). However the islands of Western Province, Solomon Islands could support suitable habitat (Bird et al. 2014). The extent of its breeding range and at-sea distribution is still unknown. 


Ecology

Like P. rostrata elsewhere in the Pacific, it is likely to nest in burrows on the slopes of high mountains on larger islands, but may also breed on small islets. The recent records at sea off New Ireland suggest it may well breed in montane forest at the southern end of this island, around Mt Gilaut and the peaks further east and north, including the Hans Meyer range (Shirihai 2008). Off New Ireland it rarely followed boats for long periods but appeared more tolerant of them than P. rostrata, approaching boats more closely and for longer periods (Shirihai 2008), although this should not be assumed to be a general characteristic or means of distinguishing the two species. 

Threats

This species is potentially threatened by predation from introduced cats and rats on its unknown breeding grounds. Loss of forest habitat through mining, logging and oil palm concessions is a potential threat (Bird et al. 2014).

Conservation actions

Conservation Actions Underway

Searches for breeding locations have taken place in southern New Ireland including liaison and outreach to local communities. A two-year project is currently underway attempting to deploy satellite-transmitters to birds captured at sea, to narrow down search areas for the species’ breeding grounds.

Conservation Actions Proposed

Locating breeding sites for this species is imperative. Scrutinise and photograph all P. rostrata types seen within the region and refine knowledge of at-sea identification. Deploy satellite transmitters to birds captured at sea to identify where birds visit on land and refine search areas for breeding locations. A number of other methods could be employed to identify breeding sites: model the colony distribution of Tahiti Petrel to identify potentially suitable habitat in the Bismarck Archipelago and Solomon Islands; trap individuals at sea to ascertain their breeding status and therefore when breeding occurs; use trained dogs to search for nesting burrows; install automated audio recording devices at potentially suitable sites (Bird et al. 2014). Once breeding areas have been located, research is needed into the ecology and behaviour of the species (Bird et al. 2014). 


Identification

29 cm. Small, rather atypical gadfly petrel. Dark, glossy brown upperparts, head and throat. Dark underwings with variably distinct white underwing bar. White breast and belly. Probably solitary at sea, banking and towering more than shearwaters, on straight wings, slightly swept back at tips. Pale throat. Similar spp. Similar to P. rostrata but 25% smaller and with a proportionately more slender bill. In the field Beck's Petrel is apparently noticeably smaller than Tahiti Petrel. Voice Unknown. P. rostrata has a long, elaborate series of whistles at its breeding grounds. Hints Check all gadfly petrels seen from boat trips in northern Melanesia.

Acknowledgements

Text account compilers
Ashpole, J, Bird, J., Butchart, S., Dutson, G., Martin, R, Moreno, R., O'Brien, A., Stattersfield, A., Symes, A.

Contributors
Pym, T., Bird, J., Shirihai, H., Wilson, A., Collins, C.


Recommended citation
BirdLife International (2017) Species factsheet: Pseudobulweria becki. Downloaded from http://www.birdlife.org on 22/10/2017. Recommended citation for factsheets for more than one species: BirdLife International (2017) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 22/10/2017.