White-capped albatross

The white-capped albatross (Thalassarche cauta steadi) is a mollymawk that breeds on the islands off of New Zealand. Not all experts agree that this form should be recognized as a separate species from the shy albatross, Thalassarche cauta. It is a medium-sized black, slate gray, and white albatross and is the largest of the mollymawks.

Thalassarche cauta steadi
Conservation status
Near Threatened  (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Procellariiformes
Family:	Diomedeidae
Genus:	Thalassarche
Species:	T. cauta
Subspecies:	T. c. steadi
Trinomial name
Thalassarche cauta steadi (Falla, 1933)[1]

Taxonomy

Mollymawks are a type of albatross that belong to family Diomedeidae of the order Procellariiformes, along with shearwaters, fulmars, storm petrels, and diving petrels. They share certain identifying features. First, they have nasal passages that attach to the upper bill called naricorns. Although the nostrils on the albatross are on the sides of the bill. The bills of Procellariiformes are also unique in that they are split into between seven and nine horny plates. Finally, they produce a stomach oil made up of wax esters and triglycerides that is stored in the proventriculus. This is used against predators as well as an energy rich food source for chicks and for the adults during their long flights.[2] They also have a salt gland that is situated above the nasal passage and helps desalinate their bodies, due to the high amount of ocean water that they imbibe. It excretes a high saline solution from their nose.[3]

The white-capped albatross is part of a greater complex of albatrosses consisting of the shy albatross, Thasassarche cauta, Salvin's albatross, Thalassarche salvini, and Chatham albatross, Thalassarche eremita. In 1998, Robertson and Nunn recommended a four-way split,[4] some experts agreed. BirdLife International agreed in 2007,[5] ACAP agreed in 2006,[6] and Brooke agreed in 2004.[7] The SACC agreed to a three-way split, leaving steadi, the white-capped albatross grouped with the shy albatross.[8][9][10] The Clements taxonomy [11] has yet to agree on any of these splits. Finally, following Brooke, this species was shifted from Diomedea to Thalassarche, which was generally agreed upon by most experts.

Description

The white-capped albatross averages 90 to 99 cm (35–39 in) in length, with a wingspan of 220 to 256 cm (87–101 in).[12] It weighs 3.4 to 4.4 kg (7.5–9.7 lb)[13] It has a bold white cap that contrasts with a pale silver gray face and a darker brow. Some adults have a white back with brown tipped feathers.[14] They have a dark gray mantle and a black tail. Most of the rest of the body is white. Its bill is pale gray to blue with a yellow tip. Juveniles have a gray bill with a dark tip, and their head is darker, with gray to the collar.

Range and habitat

Breeding population and trends[5]

Location	Population	Date	Trend
Disappointment Island	72,000 pairs	1993
Auckland Island	3,000 pairs
Antipodes Island	50—100 pairs	1994
Adams Island	100 pairs
Total	150,000	1993	Stable

They are endemic to the islands off the coast of New Zealand, with a population of 75,000 breeding pairs, estimated in 2007,[15][16] and 350,000 to 375,000 total birds.[17] Disappointment Island has 72,000 pairs, Auckland Island has 3,000 pairs, Adams Island (Auckland Islands) has 100 pairs,[17][18] and Bollons Island (Antipodes Islands) has 100 pairs.[19]

Juvenile and non-breeding birds are believed to forage in the southwestern Atlantic[20] and a recent DNA test of a South Georgia bird confirmed it.[21] Also, using different techniques, scientists have proven that they forage off the coast of southwestern Africa.[22][23][24] Juveniles are also believed to go as far as the south Atlantic and the southwestern Indian Ocean.

Behavior

Feeding

They are a surface feeder, but may utilize shallow dives for their food which is fish, cephalopods, tunicates, and crustacea.[5]

Reproduction

The white-capped albatross breeds annually on rocks on small islands.[5]

Conservation

The IUCN classifies this species as near threatened,[1] with an occurrence range of 77,700,000 km² (30,000,000 sq mi) and a breeding range of 22 km² (8.5 sq mi). The largest threat for this bird is longline and trawl fisheries.[16] Net monitor cables were responsible for large numbers of deaths; however, they were phased out in 1992.[17][18] Commercial exploitation of squid in Bass Strait may present a threat by reducing the food supply. Also, pigs on Auckland Island reduced nesting from 1972–1982, and feral cats also take small number of chicks.[17][18][25]

Since 2006, Auckland Island birds have been tracked, and this will continue.[23]

Footnotes

1. BirdLife International (2008)
2. Double, M. C. (2003)
3. Ehrlich, Paul R. (1988)
4. Robertson C. J. R. & Nunn G. B. (1998)
5. BirdLfie International (2008a)
6. ACAP (2006)
7. Brooke, M. (2004)
8. Remsen Jr., J. V. (2004)
9. Remsen Jr., J. V. (2005)
10. Remsen Jr., J. V. (2008)
11. Cornell Lab of Ornithology (2018)
12. Dunn, Jon L. & Alderfer, Jonathan (2006)
13. "White-capped mollymawk". New Zealand Birds Online. Retrieved 18 November 2016.
14. Watkins, B. (2008)
15. Gales, R., et al. (1998)
16. Baker, G. B., et al. (2007)
17. Taylor, G. A. (2000)
18. Croxall, J. P. & Gales, R. (1998)
19. Tennyson, A., et al. (1998)
20. White, R. W., et al. (2002))
21. Phalan, B., et al. (2004)
22. Abbott, C. L., et al. (2006)
23. Thompson, D. R. & Sagar, P. M. (2007)
24. Robertson, C. J. R., et al. (2003)
25. Thompson, D. R. & Sagar, P. M. (2006)

References

• Abbott, C. L.; Double, M. C.; Gales, R.; Baker, G. B.; Lashko, A.; Robertson, C. J. R.; Ryan, P. G. (2006). "Molecular provenance analysis for Shy and White-capped Albatrosses killed by fisheries interactions in Australia, New Zealand and South Africa". Conservation Genetics. 7: 531–542. doi:10.1007/s10592-005-9064-y.
• ACAP (2007). "Agreement on the Conservation of Albatrosses and Petrels : ACAP Species". ACAP. Archived from the original on January 5, 2009. Retrieved 22 Feb 2009.
• Baker, G. B.; Double, M. C.; Gales, R.; Tuck, G. N.; Abbott, C. L.; Ryan, P. G.; Petersen, S. L.; Robertson, C. J. R.; Alderman, R. (2007). "A global assessment of the impact of fisheries-related mortality on Shy and White-capped Albatrosses: conservation implications". Biological Conservation. 137: 319–333. doi:10.1016/j.biocon.2007.02.012.
• BirdLife International (2008). "Thalassarche steadi". IUCN Red List of Threatened Species. 2008. Retrieved 22 Feb 2009.CS1 maint: ref=harv (link)old-form url
• BirdLife International (2008a). "White-capped Albatross - BirdLife Species Factsheet". Data Zone. Retrieved 22 Feb 2009.
• Brooke, M. (2004). "Procellariidae". Albatrosses And Petrels Across The World. Oxford, UK: Oxford University Press. ISBN 0-19-850125-0.
• Clements, James (2007). The Clements Checklist of the Birds of the World (6th ed.). Ithaca, NY: Cornell University Press. ISBN 978-0-8014-4501-9.
• Croxall, J. P.; Gales, R. (1998). "Assessment of the conservation status of albatrosses". In Robertson, G.; Gales, R. (eds.). Albatross biology and conservation. Chipping Norton, Australia: Surrey Beatty & Sons.
• Double, M. C. (2003). "Procellariiformes (Tubenosed Seabirds)". In Hutchins, Michael; Jackson, Jerome A.; Bock, Walter J.; Olendorf, Donna (eds.). Grzimek's Animal Life Encyclopedia. 8 Birds I Tinamous and Ratites to Hoatzins. Joseph E. Trumpey, Chief Scientific Illustrator (2nd ed.). Farmington Hills, MI: Gale Group. pp. 107–111. ISBN 0-7876-5784-0.
• Dunn, Jon L.; Alderfer, Jonathan (2006). "Albatrosses". In Levitt, Barbara (ed.). National Geographic Field Guide to the Birds of North America (fifth ed.). Washington D.C.: National Geographic Society. p. 80. ISBN 978-0-7922-5314-3.
• Ehrlich, Paul R.; Dobkin, David, S.; Wheye, Darryl (1988). The Birders Handbook (First ed.). New York, NY: Simon & Schuster. pp. 29–31. ISBN 0-671-65989-8.
• Gales, R.; Brothers, N.; Reid, T. (1998). "Seabird mortality in the Japanese tuna longline fishery around Australia, 1988-1995". Biological Conservation. 86: 37–56. doi:10.1016/s0006-3207(98)00011-1.
• Phalan, B.; Phillips, R. A.; Double, M. C. (2004). "A White-capped Albatross, Thalassarche [cuata] steadi, at South Georgia: first confirmed record in the south-western Atlantic". Emu. 104: 359–361. doi:10.1071/MU03057.
• Remsen Jr., J. V.; et al. (December 2004). "Proposal #155 to South American Check-list Committee: Split Shy Albatross Thalassarche cauta into two or three species". South American Classification Committee. American Ornithologists' Union. Retrieved 18 Feb 2009.
• Remsen Jr., J. V.; et al. (February 2005). "Proposal (#166) to South American Classification Committee: Re-lump Thalassarche eremita and Thalassarche salvini with Thalassarche cauta". South American Classification Committee. American Ornithologists' Union. Retrieved 18 Feb 2009.
• Remsen Jr., J. V.; et al. (28 Feb 2008). "Proposal (#255) to South American Classification Committee : Follow-up to Proposal 155: Split Thalassarche cauta into three species". South American Classification Committee. American Ornithologists' Union. Retrieved 18 Feb 2009.
• Robertson, C. J. R.; Bell, D.; Sinclair, N.; Bell, B. D. (2003). "Distribution of seabirds from New Zealand that overlap with fisheries worldwide". Science for Conservation. Wellington, New Zealand: Department of Conservation. 233.
• Robertson, C. J. R.; Nunn, G. B. (1998). "Towards a new taxonomy for albatrosses". In Robertson, G.; Gales, R. (eds.). Albatross biology and conservation. Chipping Norton, Australia: Surrey Beatty & Sons. pp. 13–19.
• Taylor, G. A. (2000). "Action plan for seabird conservation in New Zealand. Wellington: Department of Conservation". Threatened Species Occasional Publication. 16.
• Tennyson, A.; Imber, M.; Taylor, R. (1998). "Numbers of Black-browed Mollymawks (Diomedea m. melanophrys) and White-capped Mollymawks (D. cauta steadi) at the Antipodes Islands in 1994-95 and their population trends in the New Zealand region". Notornis. 45: 157–166.
• Thompson, D. R.; Sagar, P. M. (2006). "Conduct a population and distributional study on White-capped Albatross at the Auckland Islands". Unpublished annual report to the Conservation Services Programme, Department of Conservation.
• Thompson, D. R.; Sagar, P. M. (2007). "Conduct a population and distributional study on White-capped Albatross at the Auckland Islands". Unpublished annual report to the Conservation Services Programme, Department of Conservation.
• Watkins, B. (2008) in litt
• White, R. W.; Gillon, K. W.; Black, A. D.; Reid, J. B. (2002). The distribution of seabirds and marine mammals in Falkland Islands waters. Peterborough, U.K.: Joint Nature Conservation Committee.

External links