After an 18-day incubation stint, the second member of the Short-tailed Albatross Phoebastria albatrus pair on Kure Atoll, Hawaii returned on 17 November to relieve its mate of incubation duties. For previous information on the Kure Atoll breeding attempt by Short-tailed Albatrosses click here.
On 31 October 2010 a Short-tailed Albatross nest was discovered on Kure Atoll, 90 km north-west of Midway, with an assumed female in final-phase plumage incubating a single egg. The next day the same individual was seen incubating two freshly laid eggs, but no trace of a partner was seen. At the time of the second egg being laid, Laysan P. immutabilis and Black-footed P. nigripes Albatrosses had not commenced breeding on Kure, so it was assumed that both eggs were laid by Short-tailed Albatrosses.
With the return of the second bird, a ten-year-old banded individual with immature plumage who appears to be the same individual as seen on the island in 2008 and also assumed to be a female, this makes it the first record of a breeding pair of this species in the Hawaiian Islands. Although a single female laid and then abandoned infertile eggs on Midway Atoll from 1989-2001, there was no indication of a male ever attending the nest. Since albatrosses only ever lay one egg a season, the presence of two eggs strongly suggests a pair of females, which likely have each laid an infertile egg that will not hatch. As of 19 November, one of the two eggs was no longer in the nest and the new assumed female was incubating only a single egg.
Female-female pairs are relatively common amongst Laysan Albatrosses, particularly in new colonies, and the phenomenon has also been documented in Black-footed Albatrosses.
These pairs typically lay two eggs, similar to the Short-tailed Albatross pair, but end up incubating only one egg. The second egg either eventually rolls out of the nest cup, or becomes buried in it, but is not actively ejected from the nest (click here for more information on female-pair Laysans). Surprisingly, many of these female-female pairs in Laysan Albatrosses still mate with males and often fledge chicks, so there is still hope that the egg belonging to the Kure Atoll pair of Short-tailed Albatrosses is fertile. We will keep our collective fingers crossed that their egg hatches.
For information on Kure Atoll visit http://www.kureatollconservancy.org/.
With thanks to Cynthia Vanderlip, Field Camp Manager, Kure Atoll Seabird Sanctuary, Papahānaumokuākea Marine National Monument, Hawaii Department of Land and Natural Resources for information by satellite ‘phone from Kure Atoll.
Lindsay Young, ACAP North Pacific News Correspondent, 24 November 2010