Species names in all available languages
|English (United States)||Murphy's Petrel|
|French||Pétrel de Murphy|
|Spanish||Petrel de Murphy|
|Spanish (Chile)||Petrel de Murphy|
|Spanish (Spain)||Petrel de Murphy|
Pterodroma ultima Murphy, 1949
- ultima / ultimum / ultimus
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34·5–41 cm (1); 335–435 g (2, 3); wingspan 89–97 cm (1). Dark with small bill, full forebody and only weak pattern on both wing surfaces . Feathers of foreface have dusky brownish-grey tips and usually a variable number of whitish bases, especially on cheeks to lower ear-coverts and throat, rest of head and body dusky brownish grey, slightly darker on head and darkest on small patch before eye, paler and greyer on mantle, back and scapulars, upperwing and tail dusky brownish grey with diffuse, broad but often weak dark M pattern on upperwings meeting on tertials , primary shafts paler but not eye-catching; underwing dusky brown-grey with clearly paler primary bases, forming a usually obvious (but not white) panel, greater primary-coverts usually slightly darker grey but paler than lesser coverts; underparts slightly paler brown-grey than upperparts except diffusely on foreneck and upper breast; generally may appear browner or greyer, even bluish grey in some areas ; iris dark brown; bill black; legs and inner base of feet pink-flesh to pale fleshy grey, rest of feet greyish black. Sexes alike, but male typically larger in most measurements except tail (3). Juvenile as adult, but in fresh plumage in Nov–Dec when adults very worn (1). Similar to other dark congeners, but relatively small bill, full forebody and diffuse dark M pattern are useful characters; P. macroptera similar in size and proportions but stronger-billed and has more uniform wing above and below, legs all dark; P. caribbaea has slightly stronger bill and appears slenderer (less full-breasted) and longer-tailed; dark morph of P. arminjoniana especially similar in bill size, but has slenderer forebody, darker face, plainer above and clearly more contrasting underwing pattern; other dark species less similar in size, Pseudobulweria aterrima marginally smaller, with uniform dark head and upperparts, and proportionately larger bill, while Pseudobulweria macgillivrayi is clearly smaller and slenderer, wings long and plainer on both surfaces, head all dark with proportionately larger bill; Procellaria parkinsoni has similar underwing, but is slightly larger overall, with evenly dark head, plainer upperparts, different proportions and an obviously larger pale bill.
SC Pacific Ocean, breeding on Austral Is, Tuamotu, Pitcairn Is and Easter I (4).
Marine and pelagic, rarely approaching land except at colonies. Breeds on rocky islets off tropical oceanic islands .
Probably disperses within tropical Pacific, from CS Pacific towards the W coast of North America, being recorded N to Hawaii (Oct–Nov) and to 54º N in Gulf of Alaska (mainly well offshore) (1), and it is possibly regular off W North America (sometimes 100s) in Feb–Jun (mainly Apr–May), but also even more rarely in Jul to early Dec (1), as well as being also recorded from S Cook Is (Raratonga) (5) and off Peru (3). It has been suggested that birds perform clockwise loop migration around NE Pacific, moving N through C Pacific then returning S through far E Pacific (1). Feeding grounds during breeding period poorly known, but given lack of Antarctic species in its diet, it has been suggested that P. ultima travels N to feed (6). There is an exceptional record from S Atlantic Ocean, at St Helena, in late Mar 1988, involving a bird that had apparently been visiting the same area of the island on and off for up to two years (7).
Diet and Foraging
Very little known, with most data based on study of 37 stomach samples, principally from mid-sized chicks on Oeno; this study found that squid of c. 20 species were represented in 92% of samples, fish in 32%, crustaceans in 38% and insects in 66%, with offal also being recorded in some samples (8, 3).
Sounds and Vocal Behavior
Two principal vocalizations have been described: a soft, owl-like “hoo-hoo-hoo-hoooooooooo” or “uh-uh-uh-uh-uh -uuuuuuuuuu -uh-uh” lasting c. 2·5 seconds (7), which is mainly given from the ground and made with the bill closed, and a three- or four-syllable yelping call that is given either on the ground or in flight (9), while a shrill “ki-ki-ki” has also been reported (3).
First nests recently found on Austral Is, where incubation during Mar, and on Easter I (Chile), where eggs in Aug (10); elsewhere, in Pitcairns, comes ashore in late Mar, while on Henderson I egg-laying occurred 28 May to 9 Jul in 1991 season, with hatching between 17 Jul and 28 Aug, and fledging occurs on Oeno and Ducie is in Oct–Nov (11, 3). Activity at colonies usually greatest between late afternoon and early evening, i.e. before complete darkness (11, 3). Birds on Austral Is nest on rocky cliffs of offshore stack and species is also surface nester, but rarely in direct sunlight, on Henderson, while on Oeno and Ducie (Pitcairns) it nests under canopy of Argusia argentea trees, sometimes protected by fallen tree (11, 3), and on Manui (Gambiers) it nests under tussocks of grass and groves of Pisonia (12). Single white egg, mean size 63·6 mm × 47·3 mm; incubation c. 50 days, in three notably long mean shifts of 19 days (11, 3); chick has sooty-brown to sooty-grey down and is fed about every fifth day (3); fledging c. 100 days (3). Hatching success on Henderson during 1991 season was < 86% (n = 36 eggs), but fledging success was just < 5% (in 1991 and 2003) due to predation by black rats (Rattus exulans), although fledging rates were reportedly higher on Oeno and Ducie (11, 3).
Not globally threatened. Currently considered Near Threatened, with an overall population estimated at perhaps 800,000–1,000,000 birds (3). Major colonies are in Pitcairn group, where c. 2500 pairs on Henderson I, c. 12,500 pairs on Oeno and c. 250,000 pairs on Ducie, with much smaller numbers elsewhere, e.g. just 5–10 pairs in the Gambiers (12) and 10–99 pairs on Rapa in the Austral Is, while the present status of colonies in the Tuamotus is unknown (3). Also recently discovered breeding on Easter I (Chile), in Aug 2009 (10). Species discovered as recently in late 1940s, and comparatively little studied since; rats abundant on some of breeding islands, but have been recently (1997) eradicated from major colonies of Oeno and Ducie (3), while an egg of this species was discovered on Pitcairn itself following temporary reduction in numbers of cats and rats there (3). Major rat eradication campaign has also been launched on Henderson I, which should potentially benefit this species and several other petrels (6). Main priorities include thorough survey of potential breeding grounds, estimate of numbers and study of impact of introduced predators.