AUSTRALIAN 114 BIRD WATCHER AUSTRALIAN BIRD WATCHER 1989, 13, 114-117 A Bulwer's Petrel Bulweria bulwerii in Victoria by MIKE CARTER1 and TIM REID2 130 Canadian Bay Road, Mt Eliza, Victoria 3930 2Flat 2/61 Fawkner Street, St Kilda, Victoria 3182 Summary A Victorian record of Bulwer's Petrel Bulweria bulwerii is documented and discussed in relation to previous reports in the Australian region and vagrancy in the Atlantic. The observation A Bulwer's Petrel Bulweria bulwerii was seen at sea near Portland in south-western Victoria on 14 September 1986. It was flying among massed feeding seabirds at 38 ~l'S, 141 "34 'E, five nautical miles south-south-east of Cape Nelson. The sounder aboard the 12.8 m long fishing vessel engaged on an RAOU Seabird Group excursion indicated the depth of the ocean floor to be 75 m. Thus we were above the continental shelf in inshore waters. The bird was under observation for only a few minutes just before 0830 h E.S.T., but was well seen and scrutinised for diagnostic characters when it was realised that it was either one of the all-dark 'sooty' storm-petrels Oceanodroma spp. or a Bulwer's Petrel. The closest it approached the boat was about 50 m. The light was dull because of the heavily overcast skies but as the bird passed to the south and west of our position, the sun was behind us so viewing conditions were advantageous. Although the bird hugged the surface of the sea, it was only occasionally lost from view behind waves until it changed direction, headed away from the boat and disappeared. A light southerly wind of around 5 to 7 knots produced a slight sea on a sloppy swell. There were no wind-induced white wave crests. Because the boat was stationary during this observation, it provided a sufficiently stable platform to permit critical examination of the bird. In 'addition to the authors, other observers to see the Bulwer's Petrel included David Anqrew, Rob Drummond, Chris Eastwood, Peter Lansley, Fred Smith and Bill Watson. MJC was the only observer present to have previous experience of the species. The majority of the birds feeding at this location were Fairy Prions Pachyptila turtur, of which there were several hundred. Much smaller numbers of other seabirds were also present. These included four species of albatross Diomedea spp., White-chinned Petrel Procellaria aequinoctialis, Sooty Shearwater Puffinus griseus, Short-tailed Shearwater P. tenuirostris, Fluttering Shearwater P. gavia, Hutton's Shearwater P. huttoni and Common Diving-Petrel Pelecanoides urinatrix. In the area in which the prions were feeding there were concentrations of a pink worm-like organism judged to be 2 mm to 3 mm in diameter and 15 mm in length. This was most likely a polychaete worm, an annelid (Gary Poore pers. comm.). These move to the sea's surface to spawn. One swarm near our boat extended for several square metres over a depth of less than a metre from about half a metre below the surface. VOL. 13 (4) DECEMBER 1989 A Bulwer's Petrel in Victoria 115 Description It was a slender, long-winged, long-tailed, blackish, prion-sized bird. Compared with the surrounding Fairy Prions, it had a longer wing span, was about 2 em longer overall, but had a smaller body. Thus the bird was about Yl em in length. Much of this length consisted of the very long narrow tail which was generally held tightly folded, tapering towards the tip. During banking manoeuvres, the tail was sometimes fanned revealing a wedge-shaped tip in which the outer rectrices were seen to be much shorter than the central feathers. The actual tip was fairly broad, not pointed, and marginally cleft (MJC). In this feature it was slightly reminiscent of a Common Noddy Anous stolidus. The wings were long and narrow, tapering gradually to the very pointed tips (MJC). Both the leading and trailing edges of the outer portion of the wing beyond the carpal were slightly convex, like the sides of a high gothic or lancet arch (TR). The wings were bowed forward to the carpal then swept back to the tip, curved rather than sharply angled like a shearwater Puffinus sp. , but straighter than most Pterodroma species. They were slightly arched such that the carpals were a little above the back whilst the tip of the wing was drooped to about the level of the belly (MJC). A field sketch by Rob Drummond indicated a similar posture. It was short-necked in appearance and TR considered that the head was large and rounded with a steep forehead. Generally the bird appeared to be wholly and uniformly dark, even blackish. This included the bill (Rob Drummond) and the base of the primary shafts. At times TR detected a slightly paler bar passing diagonally across the coverts of the inner upper-wing. The bird flew low over the sea, passing among the feeding prions with a languid gliding flight more graceful than that of the prions. It did not bank steeply nor tum sharply, instead maintaining a rather level and direct flight (MJC). TR considered the flight to be prion-like but straighter and with looser wing beats. Two or three quick flaps were followed by a glide. It twisted and banked in a similar manner to nearby prions (TR). The ink drawing, Plate 32, has been prepared by TR from a sketch in his field notes. In certain respects, the image this presents differs from the combined description given above. Bulwer's Petrel off Portland, Victoria Plate 32 Drawing: Tim Reid AUSTRALIAN 116 CARTER & REID BIRD WATCHER Identification The size, wholly dark plumage and distinctive shape readily identified the bird as a Bulwer's Petrel. Other seabirds of similar size and all dark plumage are four species of storm-petrel, Markham's Oceanodrom£l m£lrkhami, Tristram's 0. tristrami, Black 0. melania and Matsudaira's 0. m£ltsudairae. However, all these species have forked tails (Harrison 1987). We were aware that Matsudaira's Storm-Petrel was a potential vagrant to the area from north-western Australia, so in addition to carefully studying the shape of the tail, the area at the base of the primaries was scrutinised for any trace of the white displayed by that species. No white was visible. Jouanin's Petrel B. fallax, from the north-western Indian Ocean and beyond, is a closely related and similar species but at 31 em in length would appear distinctly larger (Harrison 1987). Moreover, the tail lacked the distinctive 'step' formed by the shorter outer feathers of that species (Harrison 1987). Another similar species is the little-known Fiji Petrel Pseudobulweria m£lcgillivrayi. This species would also be substantially larger as well as having a shorter tail (Harrison 1987). Some observers may be concerned with separating Bulwer's Petrel from one of the three species of dark-plumaged noddy Anous spp. These too have long tails. However, all species are very much larger, have very long pointed bills and other characteristics typical of terns. Thus confusion should not be a problem for experienced observers if size is positively determined or a reasonable view obtained. Discussion Bulwer's Petrel is a pelagic species of solitary disposition distributed widely in tropical and subtropical seas of the three major oceans, but breeding only on islands in the Atlantic and Pacific Oceans (Harrison 1983). In the northern hemisphere, its breeding range extends to 'J7 °N and vagrants have been recorded to 54 °N in the British Isles (Hollom 1960). Its range in the southern hemisphere is more tropical but sightings to 33 os in the cold waters west of the Cape in South Africa (Brooke & Sinclair 1978, Harrison 1983) indicate the potential for occurrence in the cooler climes of this hemisphere also. Within Australia, Bulwer's Petrels normally occur only in the seas of the north­ west (Harrison 1980, Dunlop et al. 1988, Neil Cheshire pers. comm.). The most southerly report to date is a sighting at 28 Oj7 'S, 112 "06 'E, 80 miles west of the Houtman Abrolhos (Neil Cheshire pers. comm.). The only recorded occurrence in eastern Australia was in the Coral Sea (Cheshire 1989). There are no previous records from southern Australia. Therefore the sighting of this predominantly warm-water pelagic species so close to shore and so far south during winter was a surprise. A previous report '... south of Cape Leeuwin, W.A., Sep. 1910 . .' referred to in Slater et al. (1986) must be rejected. This derives from the claim in Roberts (1967) that Edward Wilson's drawings of a bird seen at 46 °30 'S, 116 007 'E are of a Bulwer's Petrel. The position given is 700 nautical miles south of Point D'Entrecasteaux in south­ west Western Australia and is therefore well beyond any current defmition of oceanic Australia. Moreover, Neil Cheshire (in !itt.) suggested that the bird illustr~. - ~d was not a Bulwer's Petrel but more probably a Kerguelen Petrel Pterodrom£l brevirostris, a species likely to be encountered in the region. We entirely concur with Neil's identification. The tail is far too short for a Bulwer's Petrel and the drawing clearly shows the whitish leading edge on the inner under-wing which is diagnostic of Kerguelen Petrel. VOL. 13 (4) DECEMBER 1989 A Bulwer's Petrel in Victoria 117 The likely age and provenance of our Bulwer's Petrel is cause for considerable conjecture. If of northern hemisphere origin, then it is unlikely that it was an adult because the breeding season there extends from May to September (Harrison 1983).