Date(s) and time(s) of observation: 28 June 2015, 11:22am
Site Location: Continental shelf break, off Southport, QLD; coordinates: 27 52.30S/153 52.12E
Habitat: Pelagic waters at the continental shelf break.
Weather conditions: A slow moving high over south eastern Australia brought moderate S to SE winds to the SEQ coast, abating somewhat on the day, with light SW winds early, rising to 15+ knots from the SE by mid morning, then dying off late afternoon. Moderate cloud cover with rain squalls inshore, cloud lightening off slightly off the shelf but still with the occasional rainsquall. Visibility very good, barometer 1031 hPa, maximum air temperature 23 °C.
Sea conditions: Fairly calm seas on a low swell on leaving the seaway, rising to 1.5 m sea on up to 1.7 m swell out wide, with the wind picking up and dying down again on approaching the coast later in the afternoon. Sea surface temps. 21 °C at the seaway, 23 °C across the shelf and rising to 23.6 °C at the widest point in slope waters. EAC running at 1.6 knots out wide.
Other species seen: Wilson’s Storm-Petrel 10; White-faced Storm-Petrel 4; Black-bellied Storm-Petrel 7; Gibson’s Albatross 1 imm.; Antipodean Albatross 1 juv.; Wandering Albatross 1 imm.; Black-browed Albatross 5; Campbell Albatross 1; Light-mantled Sooty Albatross 1; Northern Giant Petrel 2; Cape Petrel 1 (capense); Fairy Prion 44; Antarctic Prion 47 (one was killed by a NGP); Kermadec Petrel 2; Great-winged Petrel 1; Providence Petrel 44; Australasian Gannet 3; Pied Cormorant 1; Crested Tern 7; Caspian Tern 1; Silver Gull 6.
Sighting conditions: Good light conditions, clear visibility, overcast, sun in the back. See attached photographs.
Optical aids used: RWS: Canon 7D mark II, Canon EF 100-400mm f/4.5-5.6L IS USM (RWS); EL: Nikon Monarch 10x42, RM: Swarovski 12x50 ED; NKH: Leica 12x50 BA
To your knowledge, is the species seen frequently at this site?
There are 5 documented observations of LSP in Australia: HANZAB: (1) one beachcast June 1965 Tower Hill, VIC, (2) one beachcast April 1978 Pelican Pt. WA, (3) one sighted May 1979 off Freemantle, WA, (4) one exhausted (later died) July 1984, Bremer Bay, WA. BARC: (5) May 1974 near Ivanhoe, NSW. In New Zealand: April, August (x2) [plus the famous pair prospecting for nest sites on Chatham in November 1980 (IMBER & LOVEGROVE 1982) and again a sighting there in December 1983] (HANZAB). At least 7 further undocumented Australian observations: 6 from Broome/Ashmore Reef, WA (Sept 1996, 2000, 2001, 2004, and April 2010; Rohan Clarke pers. comm.) and one off Robe, SA (1990’s). A recent BARC submission for a bird at sea off northern Western Australia (13°11’S, 126°37’E) on the 3rd September 2015 was not accepted.
Did you use a field guide?
AINLEY DG (1980): Geographic variation in Leach’s Storm-Petrel. Auk 97:837–853. • BAUER KM & GLUTZ VON BLOTZHEIM U (eds) (1966): Handbuch der Vögel Mitteleuropas, Bd. 1, Frankfurt. • BEAMAN M & MADGE S (1998): The Handbook of Bird Identification for Europe and the Western Palearctic. Helm; London. • BOLTON M, SMITH AL, GÓMEZ-DIAZ E, FRIESEN VL, MEDEIROS R, BRIED J, ROSCALES JL & FURNESS RW (2008): Monteiro’s Storm-Petrel Oceanodroma monteiroi: a new species from the Azores. Ibis 150:717–727. • BROOKE M (2004): Albatrosses and Petrels across the World (Bird Families of the World). Oxford. • COLLINS C (undated): 'New Caledonian' Band-rumped Storm-petrel. http://www.birdsandwildlife.com/new-cal-band-rumped-storm-petrel. • CRAMP S & SIMMONS KEL (eds) (1977): Handbook of the Birds of Europe, the Middle East, and North Africa: The Birds of the Western Palearctic, Volume 1. Oxford. • ENTICOTT J & TIPLING D (1997): Seabirds of the World. London. • FLOOD B, FISHER A & LEWINGTON I (2011): Multimedia ID Guides to North Atlantic Seabirds - Storm-petrels & Bulwer's Petrel. Hockley. • FLOOD B, FISHER A & LEWINGTON I (2013): Multimedia ID Guides to North Atlantic Seabirds - Storm-petrels & Bulwer's Petrel. Revised Edition. Hockley. • FLOOD RL & THOMAS B (2007): Identification of ‘black-and-white’ storm-petrels of the North Atlantic. Brit. Birds 100: 407–442 • HARRISON P (1983a): Identification of white-rumped North Atlantic petrels. Brit. Birds 76: 161–174. • HARRISON P (1983b): Seabirds, an identification guide. Beckenham. • HARRISON P (1987): Seabirds of the World. A Photographic Guide. London. • HOWELL SNG (2012): Petrels, Albatrosses, and Storm-Petrels of North America: A Photographic Guide. Princeton. • HOWELL SNG, MCGRATH T, HUNEFELD WT & FEENSTRA JS (2009): Occurrence and identification of the Leach’s Storm-Petrel (Oceanodroma leucorhoa) complex off southern California. North American Birds 63: 540-549 • HOWELL SNG, PATTESON JB, SUTHERLAND K & SHOCH DT (2010): Occurrence and identification of the Band-rumped Storm-Petrel (Oceanodroma castro) complex off North Carolina. North American Birds 64: 196-207 • DEL HOYO J, ELLIOTT A & SARGATAL J (eds) (1992): Handbook of the Birds of the World. Vol. 1. - Barcelona. • IMBER MJ & LOVEGROVE TG (1982): Leach’s Storm-petrels (Oceanodroma leucorhoa) prospecting for nest sites on the Chatham Islands. Notornis 29: 101–108. • MARCHANT S & HIGGINS PJ (eds) (1990): Handbook of Australian, New Zealand and Antarctic Birds. Volume 1: Ratites to Ducks. Melbourne. • MULLARNEY K, SVENSSON L, ZETTERSTRÖM D & GRANT P (1999): Collins Bird Guide. London. • ONLEY D & SCOFIELD P (2007): Albatrosses, Petrels & Shearwaters of the World. Princeton. • PYLE P, WEBSTER DL & BAIRD RW (2016): White-rumped Dark Storm-petrels in Hawaiian Island Waters - The quandary of Leach’s vs. Band-rumped storm-petrels throughout the world. Birding 48: 58-73 • ROBB M, MULLARNEY K & THE SOUND APPROACH (2008): Petrels Night and Day: A Sound Approach Guide. Dorset. • SHIRIHAI, H. (2007, 2nd ed.): A Complete Guide to Antarctic Wildlife. London. • SMITH AL, MONTEIRO L, HASEGAWA O & FRIESEN VL (2007): Global phylogeny of the Band-rumped Storm-Petrel (Oceanodroma castro; Procellariiformes: Hydrobatidae). Molecular Phylogenetics and Evolution 43:755–773.
How confident are you of your identification?
100% Leach’s Storm-Petrel complex; according to the current literature most likely nominate O. l. leucorhoa.
The bird was only seen briefly by RWS, EL, RM & NKH. In the field RWS, EL and RM immediately noted the flight style and distinctly larger size cf Wilson’s Storm-Petrel. In addition, RWS noted the carpal bar and NKH the rump pattern. The bird was conclusively identified by RWS when reviewing her photographs and instantly confirmed by EL & NKH and later RM and subsequently – based on the photographs only – by Paul Walbridge, Jeff Davies, Rohan Clarke, Tony Palliser, Daniel Mantle and Andrew Sutherland and others.
(1) Number: one individual was observed
(2) Age, sex: Moulting outer rectrices implies that the bird was at least one year old. Moult starts in October, main moult is in winter quarters, November-February, and finishes in April (adult tail moult usually finishes in December), but non-breeders start primary moult in August-September (CRAMP & SIMMONS 1977; FLOOD et al. 2013). However birds of unknown age off NC were in tail moult late May to early June (FLOOD et al. 2013). According to HAZELWOOD & GORTON (Bull. Brit. Orn. Club 74, 1954) Leach’s Storm-petrel moults between August and November, males before females (cited in BAUER & GLUTZ VON BLOTZHEIM, 1966). Based on this, the bird might be a 1+ year old male. However, this needs to be taken with care as vagrants often show aberrant moult cycles.
(3) Size and shape: Medium-sized, long-winged storm-petrel. Even though Wilson’s Storm-petrels were nearby, we were unable to compare absolute body length and wingspan directly. Body: long and slim, creating a tail-heavy jizz. Wing: Long hand, short arm, pointed tip. Conspicuously back-angled at carpal joint, resulting in strongly angular leading and trailing edges. P9 longest primary. Head-on travelling profile with wings slightly bowed, forming shallow-M can be appreciated even in some of the side-on photographs. Tail: Long, notched and scooped. Outermost rectrix appeared short, indicating it was growing in. This moult stage could explain the rather shallow notch of the tail (rather than a more pronounced fork). Legs/feet: Far short of the tail tip. Bill: Long, slender, slightly drooping.
(4) Plumage colour and pattern: Cool-toned dark brown head, upperparts and underparts. Dark brown tail and upperwings with conspicuous broad ‘teardrop-shaped’, cream-coloured panel across the greater and median coverts reaching the leading edge of the wing at the carpal joint and the trailing edge at the inner secondaries/tertials. Primary shafts all dark. Dark brown underwings with inconspicuous band generated by slightly paler greater coverts. The large white rump patch that was longer than wide and v-shaped with a dark dividing line down the centre (Ainley scale (1-11): 3-4, AINLEY 1980; Howell score (1-5): 2, HOWELL et al. 2009; HOWELL 2012) was noted by NKH at sea. It wrapped around just slightly to the underparts due to white outer undertail coverts (small thigh patch). Neither the field observation nor the photographs allowed assessment of the exact pattern of individual uppertail coverts.
(5) Colour of bill, eyes and legs/feet: black bill, iris and feet
(6) Calls: none heard
(7) Behaviour, movements, flight pattern, feeding, interactions with other birds
At sea RWS immediately noted the flight style that differed profoundly from that of the nearby Wilson’s Storm-petrels - this prompted her to photograph the bird. Both EL and RM noted the flight style that reminded EL [quote] “of a small sandpiper or a falcon flying quickly - swiping and slicing at the air and driving it backwards”. The flight style was indeed swift and erratic (reminiscent of that of a Common Nighthawk Chordeiles minor or a Chlidonias tern as described in the literature and as experienced by RM & NKH on multiple occasions elsewhere; RM also thinks of them looking like a ‘mini jaeger’ flying low to the sea). The deep wing beats are demonstrated in the chronological series of photographs (Figures 1-3). No pattering was performed during the short observation time.
Other species with which you think it might be confused and how these were eliminated?
There are a number of white-rumped storm-petrels with dark underparts:
Wilson’s Storm-Petrel Oceanites oceanicus: The common white-rumped storm-petrels with dark underparts in the area. 10 Wilson’s Storm-Petrels were seen at the same time as the bird reported here. Wilson’s Storm-Petrel is smaller, long-legged with feet usually projecting well beyond tail tip. It has shorter, broader and more rounded wings, less back-angled at carpal joint, straight trailing edge and smoothly curved leading edge and a shorter bill. Plumage: overall darker blackish-brown, broader and shorter upperwing bar that does not reach the leading edge of the wing; conspicuous rectangular to slightly u-shaped rump patch.
European Storm-petrel Hydrobates pelagicus: Smaller; more compact with shorter body; shorter, broader and more rounded wings; especially shorter hand; shorter square to rounded tail; shorter bill; plumage: overall darker blackish-brown, faint upperwing bar, conspicuous and diagnostic contrasting white underwing bar (visible even at large distances); conspicuous rectangular to slightly u-shaped rump patch.
Wedge-rumped Storm-petrel Oceanodroma tethys: Smaller and blacker than Leach’s, with a broader and brighter white rump band, a shorter, (less deeply forked) tail and longer legs.
Band-rumped Storm-Petrel complex: This complex comprises numerous taxa, some of which are treated as subspecies, others have recently been elevated to species level: Grant’s Storm-Petrel Oceanodroma [castro] ssp. nov. (widespread in the Atlantic; winter-breeder); Madeiran Storm-Petrel Oceanodroma [castro] castro (Madeira and the Canaries; summer-breeder); Monteiro’s Storm-petrel Oceanodroma monteiroi (BOLTON et al. 2008; Azores; summer-breeder); Cape Verde Storm-petrel Oceanodroma jabejabe (SMITH et al. 2007; apparently comprises two genetically distinct populations). Further Atlantic populations breed on Ascension, St. Helena and Sao Tomé. In the Pacific, there are distinct (but unnamed) cool-season and hot-season populations on the Galapagos Islands (Darwin’s Storm-Petrel Oceanodroma [castro] bangsi; HOWELL 2012), plus distinct summer-breeding populations in Hawaii and Japan (SMITH ET AL. 2007, SMITH & FRIESEN 2007) and apparently a population in New Caledonia (COLLINS, undated web article).
The Band-rumped Storm-Petrel complex is the ID contender for the Leach’s Storm-Petrel complex (FLOOD & THOMAS 2007; HOWELL et al. 2010; HOWELL 2012). As most taxa of the Band-rumped Storm-Petrel complex are relatively similar to each other, but differ in similar field characters from the Leach’s Storm-Petrel complex, the following description is for the entire complex rather than for individual taxa: Overall jizz less slender and more front-heavy due to bigger head and shorter tail; shorter and broader wings with more rounded tips, less back-angled at carpal joint, resulting in straighter trailing edge and only moderately angled leading edge; overall warmer-toned brown; duller panel across the greater coverts NOT reaching the leading edge of the wing, conspicuous square-cut rump patch wider than long and wrapping further down onto the lateral undertail coverts (‘band rump’ and larger thigh patches); no dark centre line (unless moulting central upper tail coverts), shorter tail; shorter and stubbier bill; usually less erratic flight style (cf. CLARKE et al. BARC submission of Australia’s first Band-rumped Storm-petrel; COLLINS (undated web article).
Other taxa within the Leach’s Storm-Petrel complex: This complex comprises numerous taxa, some of which are treated as subspecies; others have recently been elevated to species level. The at-sea identification of the taxa within this complex is still not well-known, even though there are some subtle differences reported (HOWELL et al. 2009; HOWELL 2012).
Chapman’s Storm-petrel O. l. chapmani (Coronado and San Benito Islands, Mexico; summer-breeder): Smaller than Leach’s and usually with dark rump. “The wintering range of Chapman’s is mainly in the eastern tropical Pacific (Crossin 1974, Spear and Ainley 2007), but some birds may occur north to waters off southern California (P. Pyle, pers. comm.)” (quoted from HOWELL et al. 2009).
Townsend’s Storm-petrel Oceanodroma socorroensis (Guadalupe Island, Mexico; summer-breeder): Smaller and blacker than Leach’s, with a broader white rump band and shorter, (less deeply forked) tail. Thus, somewhat more similar to Wedge-rumped Storm-petrel. A dark-rumped morph occurs as well. “The known at-sea range lies in the eastern Pacific between 35° N and 10° N (Crossin 1974), but seasonal movements are not well known” (quoted from HOWELL et al. 2009).
Ainley’s Storm-petrel Oceanodroma cheimomnestes (Guadalupe Island, Mexico; winter-breeder): Slightly larger than Townsend’s, white-rumped. At-sea identification criteria from Leach’s Storm-Petrel unknown (HOWELL 2012). Limited numbers of specimens during non-breeding season were documented within a range of 550 km from the breeding islands (HOWELL et al. 2009).
There is no confusion risk with any other storm-petrels. Four White-faced (Pelagodroma marina) and 7 Black-bellied Storm-Petrels (Fregetta tropica) were observed during this pelagic.
Taken alone, some of the described field marks are subjective and should be taken with care. The same applies for the ‘diagnostic’ flight style. E.g. when we later observed Australia’s first Band-rumped Storm-petrel (cf. Clarke et al. BARC submission) it showed the ‘classic’ flight style during the day but at dusk it (or a second Band-rumped Storm-petrel) tricked us by displaying a Leach’s-like flight style. Indeed, a recent article described a Leach’s Storm-Petrel that looked like a Band-rumped Storm-Petrel and a Band-rumped Storm-Petrel that looked like a Leach’s Storm-Petrel (PYLE et al. 2016). The authors come the conclusion “Careful analyses of CRC’s images and specimens indicate that the above-mentioned plumage marks [HOWELL et al. 2010; HOWELL 2012] are nearly useless on their own because (1) they can overlap extensively between species and (2) plumage wear can mask any intrinsic differences. There is also the widely known truth that flight style can be used to identify any given storm-petrel species as any other species by birders not considering wind speed and direction relative to a bird’s path of fight, not to mention a bird’s wing-molt status.” While we agree partially with this statement, we are not convinced that the different photographs discussed are indeed of the same individual, n=93 (for BRSP-like LSP) and n=122 (for LSP-like BRSP). Moreover, similarly to PYLE et al. (2016) we have also a set of 15 photographs documenting the field marks of Leach’s Storm-Petrel (see Figures 1-3). Unfortunately in our case neither the at-sea observation nor the photographs allowed assessment of the exact pattern of individual uppertail coverts as proposed by PYLE et al. (2016). However, all documented field marks above taken together in combination with the observed flight style leave no doubt that the bird was indeed a Leach’s Storm-petrel and allow to rule out other white-rumped storm-petrels with dark underparts, including all known taxa of the Band-rumped complex. Interestingly, HOWELL (2012) shows a presumed Grant’s (Band-rumped) Storm-Petrel in fresh plumage in Figure S3.6 that shows a similar arm/hand ratio and a similar pattern of the upperwing panel and of the white wrapping around the rump to the lateral underparts. However, this bird shows a typical ‘Band-rump’ rather than the elongated Leach’s-type rump of our bird. As with the exception of the smaller dark-rumped Chapman’s Storm-Petrel the at-sea identification of the taxa within the Leach’s complex is still not well-known, it is harder to rule out Townsend’s and especially Ainley’s Storm-Petrels with certainty. However, in RM’s experience Townsend’s Storm-Petrel appears shorter-tailed than the bird reported here. Moreover, nominate leucorhoa is known to migrate south to winter in regions of the tropical convergences (CRAMP & SIMMONS 1977) and central South Atlantic to 30˚S (FLOOD et al. 2013) and “the larger northern-breeding Leach’s (with longer and relatively pointed wings) winters mainly in the central tropical and equatorial Pacific (Crossin 1974, Spear and Ainley 2007); Leach’s wintering off California (Briggs et al. 1987, P. Pyle, pers. comm.) have been attributed to the smaller “beali” (with shorter and blunter-tipped wings), which winters mainly in the eastern Pacific (Crossin 1974)” (quoted from HOWELL et al. 2009). Hence nominate leucorhoa is the most likely to occur in Australian waters.