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White-capped Albatross Thalassarche steadi



Justification

Justification of Red List Category
The population trend of this albatross remains poorly known, due to high inter-annual variability in breeding numbers and estimates prior to 2007 are not comparable with those made since. Analysis of recent data suggest that the trend may in fact be stable, but the species remains categorised as Near Threatened given the continuing uncertainty over its trend and because, given its longevity and slow productivity, and a high rate of mortality recorded in longline and trawl fisheries, it may be declining at a moderately rapid rate.

Population justification
The annual breeding population varies considerably, and in recent years adjusted estimates have varied from lows of 73,838 breeding pairs in 2009 and 74,031 breeding pairs in 2013, to highs of 116,025 pairs in 2006 and 102,273 pairs in 2012 (Baker et al. 2014, 2015). The most recent count reported is of 101,798 breeding pairs in 2014 (Baker et al. 2015). This 2014 estimate equates to c.203,600 mature individuals, but this species is now considered to be a biennial breeder, meaning that the total population may in fact be much larger.

Trend justification
Pre-2006/2007 population estimates were not based on comparable methodologies to current census methods and therefore population trends cannot be calculated before this time. Count data over nine years show strong inter-annual fluctuations and trend analysis using regression splines showed no evidence for monotonic decline over the nine years (2006-2014) of the study (Baker et al. 2015). Further data are therefore required to confirm the population trend, which is retained, on a precautionary basis, as a moderately rapid on-going decline.

Distribution and population

Thalassarche steadi is endemic to offshore islands of New Zealand, where it appears to breed biennially, with the annual breeding population estimated at c.101,798 pairs in 2014 (Baker et al. 2015). 95% of breeding pairs are on Disappointment Island (96,242 - 97,486 pairs), with further breeding colonies on Adams (165-221) and Auckland Islands (4,603-4,879) in the Auckland Islands group, and 50-100 pairs on Bollons Island in the Antipodes Islands group (Baker et al. 2015). 'Shy-type' albatrosses (Shy and White-capped Albatrosses at sea that cannot be differentiated from each other) have been recorded in the south-west Atlantic for many years (White et al. 2002, Phalan et al. 2004). Most of the birds recorded are immature, which has hindered specific identification. However, genetic evidence from a bird on South Georgia confirmed the species was T. steadi (Phalan et al. 2004). In addition, tracking studies (Thompson and Sagar 2007), bird band recoveries (Robertson et al. 2003) and DNA-based identification of bycatch specimens (Abbott et al. 2006) have confirmed that this species forages in Tasmania and Southern Africa/Namibia (Robertson et al. 2003), and immature birds are thought to occur regularly throughout the South Atlantic and south-west Indian Ocean. The first tracking studies commenced on Auckland Island in 2006 and are on-going (Thompson and Sagar 2007). Models developed indicated that the estimated bycatch from global fisheries is unsustainable for White-capped Albatross. However, as the observed population trend over the last 10 years has not shown the rate of decline predicted by modelling, it is possible that bycatch estimates used in the models were too high and impacts of bycatch on this species are less severe than predicted (Baker 2016). 

Ecology

Behaviour The breeding frequency and season for this colonially breeding species is poorly known (Petersen 2004), but based on more recent indications, the species appears to breed biennially (ACAP 2009, Baker et al. 2015), with annual probability of breeding estimated at 0.68 (0.58–0.81, 95% CI [Francis 2012]). No information is available about either juvenile survival or the age at first breeding (Francis 2012). Eggs are usually laid mid-November and hatch in February. Chicks depart the breeding site in June at the latest. Some adults remain near the colonies year-round (ACAP 2009). Habitat Breeding Colonies are generally located on rock islands. Diet The main food items include fish, cephalopods, crustaceans and tunicates. It is a ship-follower and fish discharge comprises a significant proportion of its diet. Birds are generally surface feeders, but may undertake shallow surface dives.

Threats

The geographic range of T. steadi brings them into contact with a variety of longline and trawl fisheries in New Zealand, the high seas and off the coast of South Africa and Namibia (Baker et al. 2007). The global bycatch of this species (including cryptic mortality) was estimated to exceed 17,000 birds per year (Francis 2012), with c.30% of this bycatch coming from New Zealand fisheries, although this percentage appears to be declining, and lack of data concerning cryptic mortality make these estimates very uncertain. Although 'shy-type' albatrosses comprised 15% of all seabirds returned from longlines in New Zealand waters during 1988-1997 (Taylor 2000), New Zealand demersal and pelagic longline fisheries were considered to have a relatively low impact on T. steadi populations (Baker et al. 2007).  Previously, the impact was higher; the Auckland Islands squid trawl fishery killed 2,300 adults in 1990 alone, mostly through collision with net monitor cables, which were phased out in 1992 (Croxall and Gales 1998, Taylor 2000). However, birds are still killed by entanglement in nets and by collision with warp cables in trawl fisheries (Taylor 2000, Baker et al. 2007). Off South Africa, the White-capped Albatross is the most frequently caught species in pelagic tuna longline operations with an estimated 7,000-11,000 birds killed between 1998-2000 (Ryan et al. 2002), and in 2005, an estimated 500-600 ‘shy-type’ albatrosses were killed (Petersen 2004). In the South African demersal trawl fishery, observer data from 2004-2005 produced an estimate of 7,700 ‘shy-type’ albatrosses killed annually, and subsequent DNA analysis indicated that these were all T. steadi (ACAP 2009). In 2005 and 2006, T. steadi individuals spent 85% of their time in southern African trawl grounds (ACAP 2009). Since the introduction of mandatory permit requirements in August 2006, whereby all vessels must deploy a bird streamer line, the bycatch rate has decreased, but further data collection is required to establish a new catch estimate (Watkins et al. 2006). The impact of the large distant water fleets of Japan, Taiwan and Korea on the species is largely unknown, but Japanese data from 2001-2002 indicate that at least 10% of recorded albatross mortalities were 'shy-type' albatrosses (Baker et al. 2007). In the Uruguayan longline fleet operating in the southwest Atlantic Ocean, 'shy-type' albatrosses made up 25% of all birds observed in association with vessels, mostly immatures. Five individuals caught as bycatch were confirmed as T. steadi, but the numbers caught were not sufficient to predict an overall bycatch level for the fleet (Jimenez et al. 2009).

On Auckland Island, the nesting area was significantly reduced during 1972-1982 due to interference by Domestic Pigs Sus domesticus, and their continued presence on the island poses an ongoing threat to the local population (R. Phillips pers. comm. 2018). Feral cats Felis catus may also take small numbers of chicks on Auckland Island (Croxall and Gales 1998, Taylor 2000, Thompson and Sagar 2007), but the remaining areas are free from introduced mammals (Taylor 2000).

Conservation actions

Conservation Actions Underway
CMS Appendix II and ACAP Annex 1. The aerial survey program of the Disappointment Island population has run continuously from 2006 to 2016/17. The New Zealand Department of Conservation has recently contracted the National Institute of Water and Atmospheric Research to conduct demographic and tracking study of the Auckland Islands populations.

Conservation Actions Proposed
Census populations on all New Zealand islands. Conduct regular monitoring of a representative proportion of the population. Determine the at-sea distribution of the species through tracking studies and the interaction with longline and trawl fisheries (BirdLife International 2004). Promote the adoption of a) monitoring of seabird bycatch associated with longline and trawl fishing and b) best-practice mitigation measures in all fisheries within the species range, including via intergovernmental mechanisms such as ACAP, the Indian Ocean Tuna Commission and FAO.

Identification

90 cm. Medium-sized black, slate-grey and white albatross with a black thumb mark at the base of the leading edge of the underwing.  It has a bold white cap contrasting with a pale silver-grey face and a darker brow. Some adult birds may have a very white back with brown tips to the feathers (B. Watkins in litt. 2008). The mantle is dark grey and tail black. The body plumage is all white and its bill is pale grey/blue with a yellow tip. Immature birds have a grey bill with a dark tip, which lightens with age and a darker head than the adult with grey extending to the collar. Similar spp. Very similar to slightly smaller Shy Albatross T. cauta but T. steadi has paler face and less yellow on the culmen of the bill. Salvin's Albatross T. salvini and Chatham Albatross T. eremita have darker grey heads and lack the white cap.

Acknowledgements

Text account compilers
Small, C., Stuart, A., Sullivan, B., Symes, A., Anderson, O., Calvert, R., Fjagesund, T., Bird, J., Hermes, C., Butchart, S., Martin, R., Moreno, R.

Contributors
Gales, R., Watkins, B., Debski, I., Phillips, R., Double, M., Thompson, D., Baker, B., Ryan, P.G., Robertson, C., Scofield, P., Hitchmough, R.


Recommended citation
BirdLife International (2018) Species factsheet: Thalassarche steadi. Downloaded from http://www.birdlife.org on 19/12/2018. Recommended citation for factsheets for more than one species: BirdLife International (2018) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 19/12/2018.