Bonin Petrel – birdfinding.info

Birdfinding.info ⇒ Locally common around its remote, mid-oceanic nesting islands, but rarely seen otherwise. Small numbers occur off the east-central coast of Honshu in June and July, including around the Izu Islands, accessible by ferry from Tokyo and Shimodo. In Hawaii it breeds abundantly in parts of the Northwest Chain but is almost entirely unknown from the main islands. However, a breeding colony formed by the translocation of chicks to James Campbell National Wildlife Refuge has shown signs of becoming self-sustaining, which seems likely to result in viewing opportunities around Oahu.

Bonin Petrel

Pterodroma hypoleuca

Family: Procellariidae

Breeds on Japan’s Ogasawara and Iwo Islands, and the Northwest Chain of Hawaii. Disperses to the western North Pacific and adjacent seas.

Breeds in large colonies over a somewhat protracted period, from July to April.

From March to July or so, some portion of the population apparently disperses west and north across the northwestern Pacific to the East China Sea, the Sea of Okhotsk, and possibly the Sea of Japan.

In the Northwest Chain of Hawaii, the largest colonies are on Lisianski (~200,000 pairs), Midway (~150,000), and Laysan (~70,000). Much smaller numbers nest on Kure, Pearl and Hermes Reefs, and French Frigate Shoals.

In the main Hawaiian Islands, a new breeding colony has been established at James Campbell National Wildlife Refuge on the north shore of Oahu. In 2018, conservation biologists began translocating newly-hatched chicks from the Northwest Chain. By 2021, translocated individuals had bred successfully and fledged young. This reintroduces the Bonin Petrel to an island where it was extirpated by the Polynesian colonists roughly 800 years ago, and enhances the species’ long-term survival prospects by leading it to nesting areas that are not imminently susceptible to a rising sea level.

Identification

A small but long-tailed gadfly petrel, strongly patterned above and below, with a gray cowl and a diagnostic combination of dark patches on the underwing.

Bonin Petrel, showing diagnostic underwing pattern—also note white forehead and gray cowl on neck. (Offshore from Chichijima, Ogasawara Islands, Japan; September 22, 2020.) © Hiroyuki & Shoko Tanoi

On the upperparts, shows a blackish “M” pattern with a pale-gray back and rump, and a darker gray or blackish hood and tail-tip. The forehead is white or whitish. In worn plumage, however, the upperparts pattern can be nearly imperceptible.

Bonin Petrel, dorsal view showing black M-pattern—also note white forehead and gray cowl on neck. (Sand Island, Midway Atoll National Wildlife Refuge, Hawaii; August 22, 2017.) © Eric VanderWerf

The undersides of the wings have a unique pattern: the inner portion of the wing-lining is mostly white and the outer two-thirds has a wide blackish leading edge with a bold white indentation.

Bonin Petrel, in worn plumage, showing an indistinct washed-out dorsal pattern in this view. (Offshore from Kita-iwo-jima, Iwo Islands, Japan; July 5, 2013.) © Hiroyuki Tanoi

Bonin Petrel at breeding colony, showing gray upperparts, black wings, white forehead, and gray cowl on neck. (Sand Island, Midway Atoll National Wildlife Refuge, Hawaii; December 31, 2012.) © Bettina Arrigoni

Voice. Calls on breeding grounds include raspy squeaks, buzzy rattles, high piping whistles, wheezy hisses, deep growls, percussive pops, and shrill screams. These various sounds are sometimes issued in phrases, often three-note phrases with two clipped notes followed by a much longer one. E.g.:

Notes

Monotypic species.

See below for comparisons of the Bonin Petrel with Black-winged, Collared, and Hawaiian Petrels.

Cf. Black-winged Petrel. Bonin and Black-winged Petrels are similar overall and overlap widely in the central North Pacific. The most striking difference is in their underwing patterns. Bonin has mostly dark primary coverts with one white row, which creates an unusual impression, whereas Black-winged has a less distinctive pattern: blackish leading and trailing edges with a white central stripe. Black-winged also lacks Bonin’s extensive dark-gray cowl, and instead has a pale-gray head and throat collar.

Cf. Collared Petrel. Bonin and Collared Petrels are not known to overlap, but their ranges approach one another in the central Pacific. Collared is more similar to Black-winged than to Bonin, but is also variable and has a dark-gray hood and collar, which could be mistaken for Bonin’s dark-gray cowl. Bonin differs from both because of its unique underwing pattern, whereas Collared and Black-winged have essentially the same simple pattern: blackish leading and trailing edges with a white central stripe.

Cf. Hawaiian Petrel. Bonin and Hawaiian Petrels both breed in Hawaii (but on different islands) and range widely across the western and central North Pacific. Hawaiian is larger and heavier-bodied, although this distinction is not very useful in isolation. The two are most similar in their head and neck pattern: a dark-gray cowl. They differ in the rest of their upperparts: Hawaiian is mostly uniform dark-gray, whereas Bonin usually shows strongly contrasting pale and dark areas—in particular, a contrastingly pale rump and back. Bonin’s unique underwing pattern is diagnostic, whereas Hawaiian has a simple pattern: blackish leading and trailing edges with a white central stripe.

More Images of the Bonin Petrel

Bonin Petrel. (Offshore from Chichijima, Ogasawara Islands, Japan; September 22, 2020.) © Hiroyuki Tanoi

Bonin Petrel. (Offshore from Lisianski Atoll, Hawaii; November 21, 2010.) © Sophie Webb

Bonin Petrel. (East of Midway Atoll, Hawaii; April 12, 2018.) © Eric VanderWerf

Bonin Petrel. (Offshore from Muko-jima, Ogasawara Islands, Japan; September 21, 2020.) © Hiroyuki Tanoi

Bonin Petrel. (Midway Atoll National Wildlife Refuge, Hawaii; October 2, 2019.) © Eric VanderWerf

Bonin Petrel. (East of Midway Atoll, Hawaii; April 12, 2018.) © Eric VanderWerf

Bonin Petrel. (Offshore from Lisianski Atoll, Hawaii; November 20, 2010.) © Sophie Webb

Bonin Petrel, molting feathers on its back. (Offshore from Hachijyo-jima, Izu Islands, Japan; August 3, 2017.) © Hiroyuki Tanoi

Bonin Petrel. (Offshore from Minami Iwo Jima, Iwo Islands, Japan; July 6, 2018.) © Yann Muzika

Bonin Petrel. (Offshore from the Ogasawara Islands, Japan; September 21, 2020.) © Yann Muzika

Bonin Petrel, in worn plumage, showing indistinct pattern on the upperparts. (Offshore from Muko-jima, Ogasawara Islands, Japan; July 28, 2018.) © Hiroyuki Tanoi

Bonin Petrel. (Offshore from Hachijyo-jima, Izu Islands, Japan; August 3, 2017.) © Hiroyuki Tanoi

Bonin Petrel. (Offshore from the Ogasawara Islands, Japan; May 2015.) © Jemi & John Holmes

Bonin Petrel. (Midway Atoll National Wildlife Refuge, Hawaii; January 2012.) © Dan Maxwell

Bonin Petrel. (Offshore from the Ogasawara Islands, Japan; May 6, 2015.) © Jemi & John Holmes

Bonin Petrel. (Ogasawara Islands, Japan; May 27, 2017.) © Lars Petersson

Bonin Petrel. (Sand Island, Midway Atoll National Wildlife Refuge, Hawaii; October 2, 2019.) © Eric VanderWerf

Bonin Petrel. (East of Midway Atoll, Hawaii; April 12, 2018.) © Eric VanderWerf

Bonin Petrel. (West of Midway Atoll, Hawaii; September 8, 2011.) © Sophie Webb

Bonin Petrel. (Offshore from Minami Iwo Jima, Iwo Islands, Japan; July 6, 2018.) © Yann Muzika

Bonin Petrel. (Offshore from the Ogasawara Islands, Japan; May 2015.) © Jemi & John Holmes

Bonin Petrel. (Offshore from Chichijima, Ogasawara Islands, Japan; September 11, 2012.) © Hiroyuki Tanoi

Bonin Petrel. (Sand Island, Midway Atoll National Wildlife Refuge, Hawaii; October 2, 2019.) © Eric VanderWerf

Bonin Petrel, in worn plumage, showing an atypical partial white collar. (Offshore from Muko-jima, Ogasawara Islands, Japan; July 28, 2018.) © Hiroyuki Tanoi

Bonin Petrel, pair displaying. (Sand Island, Midway Atoll National Wildlife Refuge, Hawaii; October 2, 2019.) © Eric VanderWerf

References

BirdLife International. 2018. Pterodroma hypoleuca. The IUCN Red List of Threatened Species 2018: e.T22697967A132615616. https://dx.doi.org/10.2305/IUCN.UK.2018-2.RLTS.T22697967A132615616.en. (Accessed November 22, 2020.)

Brazil, M. 2009. Birds of East Asia. Princeton University Press.

eBird. 2020. eBird: An online database of bird distribution and abundance. Cornell Lab of Ornithology, Ithaca, N.Y. http://www.ebird.org. (Accessed December 8, 2021.)

Harrison, P. 1983. Seabirds: An Identification Guide. Houghton Mifflin, Boston.

Howell, S.N.G. 2012. Petrels, Albatrosses & Storm-Petrels of North America. Princeton University Press.

Howell, S.N.G., and K. Zufelt. 2019. Oceanic Birds of the World. Princeton University Press.

Pratt, H.D., P.L. Bruner, and D.G. Berrett. 1987. A Field Guide to the Birds of Hawaii and the Tropical Pacific. Princeton University Press.

Pyle, R.L., and P. Pyle. 2017. The Birds of the Hawaiian Islands: Occurrence, History, Distribution, and Status. Version 2 (January 1, 2017). http://hbs.bishopmuseum.org/birds/rlp-monograph/. B.P. Bishop Museum, Honolulu, Hawaii.

Seabirding of Japan. 2020. Bonin Petrel. http://seabirding-japan.com/bonin-petrel/. (Accessed November 22, 2020.)

Wu, N. 2021. 1st wild Bonin petrels fledged from their nests on Oahu’s North Shore. https://www.staradvertiser.com/2021/08/03/breaking-news/1st-wild-bonin-petrels-fledged-from-their-nests-on-oahus-north-shore/. Star Advertiser. (Posted August 3, 2021.)

Xeno-Canto. 2020. Bonin Petrel – Pterodroma hypoleuca. https://www.xeno-canto.org/species/Pterodroma-hypoleuca. (Accessed December 8, 2021.)

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