Beck's Petrel Pseudobulweria becki Scientific name definitions

In a family of poorly known birds, Beck’s Petrel was until recently, arguably, the greatest of enigmas. Initially collected during the Whitney South Seas Expedition in the late 1920s, and described by the great American ornithologist Robert Cushman Murphy in honour of the Californian collector and pioneer of attracting seabirds to ‘chum’, Rollo Howard Beck, who Murphy memorably feted as ‘the supreme seabird specialist’, this petrel was not definitely seen again until 2007. Like three other members of its genus, Beck’s Petrel is ranked as Critically Endangered on the IUCN Red List and, despite it now being encountered reasonably frequently in the waters around the Bismarck Archipelago and the Solomon Islands, its breeding grounds have yet to be pinpointed, although they seem most likely to lie in the montane forests of southern New Ireland, specifically in the Hans Meyer Range. Most recently, in 2016 and 2017, researchers used on-land and at-sea observations, local interviews and satellite telemetry to identify that the area of Silur Bay, in New Ireland, is a significant site for Beck’s Petrel and estimated that the local population there numbers in the low thousands. The evidence from one bird that was fitted with a satellite transmitter further argues that the breeding grounds lie nearby the mountains, but the quest to find at least one of the bird’s colonies remains unconquered, for now.

Compared to Tahiti Petrel (Pseudobulweria rostrata  ), identical in plumage but 25% smaller (which difference is apparent in the field, especially in side-by-side comparative views), except wings  and tail (15% smaller) (1 Shirihai, H. (2008). Rediscovery of Beck’s Petrel Pseudobulweria becki, and other observations of tubenoses from the Bismarck archipelago, Papua New Guinea. Bull. Brit. Orn. Club 128(1):3–16. Close ), with a proportionately more slender bill  , but this difference is not easily appreciated at sea (1 Shirihai, H. (2008). Rediscovery of Beck’s Petrel Pseudobulweria becki, and other observations of tubenoses from the Bismarck archipelago, Papua New Guinea. Bull. Brit. Orn. Club 128(1):3–16. Close ), and appears plumper bodied, has looser, languid and more elastic wingbeats, shorter, more swooping glides, sometimes with more erratic changes of direction, and arcing/banking actions often distinctly shorter and steeper, almost like mid-sized Pterodroma (1 Shirihai, H. (2008). Rediscovery of Beck’s Petrel Pseudobulweria becki, and other observations of tubenoses from the Bismarck archipelago, Papua New Guinea. Bull. Brit. Orn. Club 128(1):3–16. Close ). Juvenile as adult.

With experience, it should be possible to reliably identify the distinctly smaller and lighter built Beck’s from the larger Tahiti Petrel, but direct and close comparison with the latter, and preferably photographs will be needed for certain distinction. This depends on a correct evaluation of the overall size differences, and the shorter but relatively stubbier bill of Beck’s (1 Shirihai, H. (2008). Rediscovery of Beck’s Petrel Pseudobulweria becki, and other observations of tubenoses from the Bismarck archipelago, Papua New Guinea. Bull. Brit. Orn. Club 128(1):3–16. Close ). Beck’s shares many structural characters, flight modes and behaviour with Tahiti: both have an elongated body, long tapering tail, long neck but relatively small head, and bulbous bill; they fly on long, narrow wings that, when gliding into the wind, tend to be held rather stiff and seemingly straight, but which in head-on or back views can be seen to be held in a shallow arc (1 Shirihai, H. (2008). Rediscovery of Beck’s Petrel Pseudobulweria becki, and other observations of tubenoses from the Bismarck archipelago, Papua New Guinea. Bull. Brit. Orn. Club 128(1):3–16. Close ). Both have ‘relaxed’ wingbeats, but due to its shorter and narrower-winged appearance, in Beck’s the looser, languid and more elastic wingbeats appear more pronounced. Beck’s also appears plumper bodied than Tahiti. In some instances, Beck’s has clearly more rapid wingbeats and shorter, more swooping glides, sometimes with more erratic changes of direction, whilst when arcing/banking these actions are often distinctly shorter and steeper, almost like a mid-sized Pterodroma petrel (1 Shirihai, H. (2008). Rediscovery of Beck’s Petrel Pseudobulweria becki, and other observations of tubenoses from the Bismarck archipelago, Papua New Guinea. Bull. Brit. Orn. Club 128(1):3–16. Close ). In direct comparison, especially larger and heavier individuals of Tahiti Petrel are clearly stronger built, fly on longer and stiffer wings, with much gliding and long arcs, at greater speed, thereby affording an almost miniature albatross-like impression (1 Shirihai, H. (2008). Rediscovery of Beck’s Petrel Pseudobulweria becki, and other observations of tubenoses from the Bismarck archipelago, Papua New Guinea. Bull. Brit. Orn. Club 128(1):3–16. Close ). A few other medium-sized, white-bellied gadfly petrels might be confused with Beck’s (and Tahiti) Petrels, e.g., Phoenix Petrel Pterodroma alba, but these are readily distinguished, if seen well, by plumage characteristics and shape, e.g., Phoenix Petrel has a diagnostic whitish leading edge to the underwing (1 Shirihai, H. (2008). Rediscovery of Beck’s Petrel Pseudobulweria becki, and other observations of tubenoses from the Bismarck archipelago, Papua New Guinea. Bull. Brit. Orn. Club 128(1):3–16. Close ).

Information taken from Shirihai (1 Shirihai, H. (2008). Rediscovery of Beck’s Petrel Pseudobulweria becki, and other observations of tubenoses from the Bismarck archipelago, Papua New Guinea. Bull. Brit. Orn. Club 128(1):3–16. Close ).

Juvenile

Underwing-coverts initially mainly dark, without or with only a limited pale wash to the edges of the coverts on the central underwing, whereas adults develop broader and whiter feather centres which, due to wear and bleaching, form a large central belt across the underwing (subject to much individual variation).

Adult

Uniform dark sooty-brown hood reaching to the breast and sharply demarcated from the white underparts, as well as, often, a variable paler brown transition on the lower breast. The upperparts, including wings, back and tail, are very dark brown to almost blackish brown, whilst the uppertail-coverts are variably paler. The vent, basal and central undertail-coverts are mostly white, but the outer coverts and their tips are always washed brown. Variable brown smudges on the body-sides and, especially, upper flanks, often merge broadly with the brown breast. The underwings vary from uniform blackish brown to having a pale central area. The paler uppertail-coverts are most obvious in worn plumage and appear most pronounced in adults/immatures (much less so in fresh juveniles). In August 2007, two main molt types were evident: evenly fresh-feathered juveniles, and adults in different stages of feather wear and post-nuptial moult of body, tail and flight feathers. Extremely worn adults show some exposed white basal feathers on the upperwing and a pale central throat/breast area, as well as often-obvious molt limits and gaps in the wings.

Virtually nothing known; adults in active primary molt, with the outer five/six primaries old, and molt ongoing among the inner five/four primaries, have been observed at sea in late January (2 Flood, R. L., A. C. Wilson, and K. Zufelt (2017). Observations of five little-known tubenoses from Melanesia in January 2017. Bulletin of the British Ornithologists’ Club 137(3):226–236. Close ).

Bill

Black (3 Murphy, R. C. (1928). Birds collected during the Whitney South Sea Expedition. IV. American Museum Novitates 322:1–5. Close ).

Iris

Brown (3 Murphy, R. C. (1928). Birds collected during the Whitney South Sea Expedition. IV. American Museum Novitates 322:1–5. Close ).

Legs and Feet

Tarsi of fresh juvenile mostly bluish pink with dark brownish-black outer side, feet and webs mainly dark brownish black with pinkish lower base and basal corner to inner web (forming oval patch) (4 Brooke, M. (2004). Albatrosses and Petrels Across the World. Oxford University Press, Oxford, UK. Close ).

Linear Measurements

Overall length 29–34 cm (4 Brooke, M. (2004). Albatrosses and Petrels Across the World. Oxford University Press, Oxford, UK. Close , 5 Howell, S. N. G., and K. Zufelt (2019). Oceanic Birds of the World. Princeton University Press, Princeton, NJ, USA. Close ).

Linear measurements (in mm, for three specimens presented individually, from Shirihai (1 Shirihai, H. (2008). Rediscovery of Beck’s Petrel Pseudobulweria becki, and other observations of tubenoses from the Bismarck archipelago, Papua New Guinea. Bull. Brit. Orn. Club 128(1):3–16. Close ), alternative measurements of the male and female holotype were presented by Murphy and Pennoyer 6 Murphy, R. C., and J. M. Pennoyer (1952). Larger petrels of the genus Pterodroma. American Museum Novitates 1580:1–43. Close ):

AMNH = American Museum of Natural History, New York; NHMUK = Natural History Museum, Tring.

Mass

No data.

Wingspan

84–89 cm (5 Howell, S. N. G., and K. Zufelt (2019). Oceanic Birds of the World. Princeton University Press, Princeton, NJ, USA. Close ).

Small replica (weight probably only half) of Tahiti Petrel (Pseudobulweria rostrata), and found close to latter’s range, indicating complete independence and predicting distinctive breeding vocalizations. Previously considered conspecific with both P. rostrata and Mascarene Petrel (P. aterrima) (7 Jouanin, C., and J.-L. Mougin (1979) Order Procellariformes. Pages 48-121 in Check-list of birds of the world, Volume 1, wecond edition (E. Mayr and G. W. Cottrell, editors). Museum of Comparative Zoology, Cambridge, Massachusetts, USA. Close ), but the available molecular data support recognizing all three at species level (8 Bretagnolle, V., Attié, C. and Pasquet, E. (1998). Cytochrome-b evidence for validity and phylogenetic relationships of Pseudobulweria and Bulweria (Procellariidae). Auk 115(1):188–195. Close ,9 Gangloff, B., H. Shirihai, D. Watling, C. Cruaud, A. Couloux, A. Tillier, E. Pasquet, and V. Bretagnolle (2012). The complete phylogeny of Pseudobulweria, the most endangered seabird genus: systematics, species status and conservation implications. Conservation Genetics 13(1):39–52. Close ).

None.

Monotypic.

Seas around Bismarck Archipelago and Solomon Islands, and also recorded in Vanuatu (10 BirdLife International (2013). IUCN Red List for birds. URL: http://www.birdlife.org (download Aug 2013). Close ); breeding grounds still not confirmed, but likely to be in montane forests of southern New Ireland (11 Shirihai, H. (2008). Rediscovery of Beck’s Petrel Pseudobulweria becki, and other observations of tubenoses from the Bismarck archipelago, Papua New Guinea. Bulletin of the British Ornithologists’ Club 128(1):3–16. Close ,12 Bird, J.P. (2012). Targeted searches to identify nesting grounds of Beck’s Petrel Pseudobulweria becki. Notornis 59(3–4):189–193. Close ).

Marine and highly pelagic; breeding areas unknown, but see Conservation and Management.

Movements not known (especially as breeding grounds remain to be discovered), as is overall at-sea range, but see Conservation and Management. In 2017 a single P. becki was captured at sea, fitted with a satellite transmitter and tracked for eight months; it maintained a core distribution off the southeast coast of New Ireland and north of Bougainville for 122 days, during which time it was located over land at night seven times, predominantly over southern New Ireland, where the signal was lost for extended periods suggesting it could have been in an underground burrow (13 Rayner, M. J., K. A. Baird, J. Bird, S. Cranwell, A. F. Raine, B. Maul, J. Kuri, J. Zhang, and C. P. Gaskin (2019). Land and sea-based observations and first satellite tracking results support a New Ireland breeding site for the Critically Endangered Beck’s Petrel Pseudobulweria beckii [sic]. Bird Conservation International. Close ). In August the bird migrated 1,400 km to the seas north of West Papua before the signal was eventually lost (13 Rayner, M. J., K. A. Baird, J. Bird, S. Cranwell, A. F. Raine, B. Maul, J. Kuri, J. Zhang, and C. P. Gaskin (2019). Land and sea-based observations and first satellite tracking results support a New Ireland breeding site for the Critically Endangered Beck’s Petrel Pseudobulweria beckii [sic]. Bird Conservation International. Close ).

All recorded observations involve surface-seizing (1 Shirihai, H. (2008). Rediscovery of Beck’s Petrel Pseudobulweria becki, and other observations of tubenoses from the Bismarck archipelago, Papua New Guinea. Bull. Brit. Orn. Club 128(1):3–16. Close ). Diet basically unknown. Has been recorded in association with other feeding seabirds, and also with surfacing pilot whales (Globicephala sp.); at least in Bismarcks in August. Seems more tolerant of boats and is more attracted to ‘chum’ than Tahiti Petrel Pseudobulweria rostrata (4 Brooke, M. (2004). Albatrosses and Petrels Across the World. Oxford University Press, Oxford, UK. Close ). No further information available.

Voice unknown.

Virtually unknown and the species’ breeding grounds have yet to be found. Season speculated to be February/March–July/August (2 Flood, R. L., A. C. Wilson, and K. Zufelt (2017). Observations of five little-known tubenoses from Melanesia in January 2017. Bulletin of the British Ornithologists’ Club 137(3):226–236. Close ), but the closely related Tahiti Petrel Pseudobulweria rostrata is known to nest year-round (14 Thibault, J.-C., and A. Cibois (2017). Birds of Eastern Polynesia. A Biogeographic Atlas. Lynx Edicions, Barcelona, Spain. Close ). Only specific information concerns a recently fledged young seen at sea in August (1 Shirihai, H. (2008). Rediscovery of Beck’s Petrel Pseudobulweria becki, and other observations of tubenoses from the Bismarck archipelago, Papua New Guinea. Bull. Brit. Orn. Club 128(1):3–16. Close ).

CRITICALLY ENDANGERED. Population thought to be declining and recently estimated by BirdLife International at just 50–249 mature individuals; breeding grounds thought to be in area of Solomon Islands, specifically perhaps in southern New Ireland, e.g., Mt Gilaut and the Hans Meyer Range (1 Shirihai, H. (2008). Rediscovery of Beck’s Petrel Pseudobulweria becki, and other observations of tubenoses from the Bismarck archipelago, Papua New Guinea. Bull. Brit. Orn. Club 128(1):3–16. Close ), especially given concentration of records at sea in this region (15 Bird, J.P., Carlile, N. and Miller, M.G.R. (2014). A review of records and research actions for the Critically Endangered Beck’s Petrel Pseudobulweria becki. Bird Conservation International 24(3):287–298. Close ) and satellite-tracking data from one individual (13 Rayner, M. J., K. A. Baird, J. Bird, S. Cranwell, A. F. Raine, B. Maul, J. Kuri, J. Zhang, and C. P. Gaskin (2019). Land and sea-based observations and first satellite tracking results support a New Ireland breeding site for the Critically Endangered Beck’s Petrel Pseudobulweria beckii [sic]. Bird Conservation International. Close ), but as yet undiscovered due to lack of dedicated surveys, the inability of those surveys to reach the most likely areas of suitable habitat, and the need to census areas at different seasons given lack of knowledge of the breeding periods of nocturnal colonial seabirds in this region (15 Bird, J.P., Carlile, N. and Miller, M.G.R. (2014). A review of records and research actions for the Critically Endangered Beck’s Petrel Pseudobulweria becki. Bird Conservation International 24(3):287–298. Close ). Until recently known solely from specimens, taken at sea in January 1928 (east of New Ireland) and May 1929 (east of Rendova, in the Solomon Islands), with a probable sight record in 2003, and confirmed sightings in July–August 2007 on seven days and at four localities off New Ireland, with at least 30 on a single day and a maximum of 16 together (1 Shirihai, H. (2008). Rediscovery of Beck’s Petrel Pseudobulweria becki, and other observations of tubenoses from the Bismarck archipelago, Papua New Guinea. Bull. Brit. Orn. Club 128(1):3–16. Close ). Subsequently, in April 2008 at least 11 were seen off western Bougainville and eastern New Ireland, and in July–August a minimum of 160 birds was seen between New Britain and New Ireland (1 Shirihai, H. (2008). Rediscovery of Beck’s Petrel Pseudobulweria becki, and other observations of tubenoses from the Bismarck archipelago, Papua New Guinea. Bull. Brit. Orn. Club 128(1):3–16. Close ), c. 100 individuals off southern New Ireland in March 2012 (15 Bird, J.P., Carlile, N. and Miller, M.G.R. (2014). A review of records and research actions for the Critically Endangered Beck’s Petrel Pseudobulweria becki. Bird Conservation International 24(3):287–298. Close ) and up to 24 in a single day in the same area in January 2017 (2 Flood, R. L., A. C. Wilson, and K. Zufelt (2017). Observations of five little-known tubenoses from Melanesia in January 2017. Bulletin of the British Ornithologists’ Club 137(3):226–236. Close ), with two near Efate, Vanuatu, in February 2010, and a possible photographed in the Coral Sea east of Australia’s Great Barrier Reef in 2006 (1 Shirihai, H. (2008). Rediscovery of Beck’s Petrel Pseudobulweria becki, and other observations of tubenoses from the Bismarck archipelago, Papua New Guinea. Bull. Brit. Orn. Club 128(1):3–16. Close ). At least some previous records of Tahiti Petrel Pseudobulweria rostrata from the seas around New Guinea, where both taxa occur, might have involved the present species (16 Bourne, W. R. P. & Dixon, T. J. (1971). Observations of sea birds 1967–1969. Sea Swallow 22:29–60. Close ,1 Shirihai, H. (2008). Rediscovery of Beck’s Petrel Pseudobulweria becki, and other observations of tubenoses from the Bismarck archipelago, Papua New Guinea. Bull. Brit. Orn. Club 128(1):3–16. Close ).

The immediate priority is to locate the species’ breeding grounds, which necessitates dedicated nocturnal surveys at appropriate (high) elevations (the Hans Meyer Range in southeast New Ireland reaches up to c. 2,380 m), and perhaps use of dogs to search for burrows (15 Bird, J.P., Carlile, N. and Miller, M.G.R. (2014). A review of records and research actions for the Critically Endangered Beck’s Petrel Pseudobulweria becki. Bird Conservation International 24(3):287–298. Close ); details on population size and main threats also essential.