Grey-headed Albatrosses Research Articles

Boluses: An Effective Method for Assessing the Proportions of Cephalopods in the Diet of Albatrosses

AbstractThe method of collecting and analyzing boluses to characterize the cephalopod diet of albatrosses has been used in many diet studies. However, no study has validated this method. We compared boluses and stomach samples from Gray-headed Albatrosses (Thalassarche chrysostoma) and Black-browed Albatrosses (T. melanophris) to (1) study the consumption and diversity of cephalopods in these species, (2) investigate biases associated with each sampling method, and (3) estimate the number of samples needed to characterize these albatross’s cephalopod diet. We found that collection and analysis of boluses is a simple, efficient, and noninvasive method for assessing the cephalopod diet of these albatross species, but it is inadequate for characterizing the more easily digestible dietary components, such as fish and crustaceans. Both boluses and stomach samples showed that the two albatross species fed on cephalopods of similar sizes and from the same families (Ommastrephidae, Onychoteuthidae, and Cranchiidae). Furthermore, the main prey species (Martialia hyadesi, Kondakovia longimana, and Galiteuthis glacialis) and the total number of cephalopod species consumed (18–24 species) were the same for both albatrosses. To include all cephalopod species, using a sample-randomization technique, a minimum of 61 and 43 boluses were needed for Gray-headed and Black- browed albatrosses, respectively; but to adequately describe the diversity and size frequency of the main prey species, 82 and 371 boluses would be needed.Les Pelotes de Réjection: Une Méthode Efficace pour Évaluer la Proportion de Céphalopodes dans le Régime Alimentaire chez les Albatros

Trends in numbers and survival of Black-browed (Thalassarche melanophrys) and Grey-headed (T. chrysostoma) Albatrosses breeding on Macquarie Island

Black-browed (Thalassarche melanophrys) and Grey-headed (T. chrysostoma) Albatrosses are globally threatened seabirds that breed on remote subantarctic islands. Population trends of Black-browed and Grey-headed Albatrosses breeding on Macquarie Island were described using historical data combined with data from a more intensive 10-year monitoring program. Survival estimates were also calculated for both species over similar time frames. Breeding numbers and survival rates of Black-browed and Grey-headed Albatrosses appear to have remained stable since the mid-1970s. There was no conclusive evidence of survival varying over time and it is unlikely that mortality owing to fisheries’ activities has had a significant impact on these populations. This is in contrast to most other subantarctic populations of these species and may be attributed to their foraging ranges not overlapping significantly with areas of high fishing effort. However, both species forage in areas of new and expanding legal and illegal fishery operations. Owing to their extremely small size, these populations remain chronically vulnerable to any elevated levels of mortality.

Global Circumnavigations: Tracking Year-Round Ranges of Nonbreeding Albatrosses

Although albatrosses are paradigms of oceanic specialization, their foraging areas and migration routes when not breeding remain essentially unknown. Our continuous remote tracking of 22 adult gray-headed albatrosses for over 30 bird-years reveals three distinct strategies: (i) Stay in breeding home range; (ii) make return migrations to a specific area of the southwest Indian Ocean; and (iii) make one or more global circumnavigations (the fastest in just 46 days). The consistencies in patterns, routes, and timings offer the first hope of identifying areas of critical habitat for nonbreeding albatrosses, wherein appropriate management of longline fisheries might alleviate the plight of the world's most threatened family of birds.

BOLUSES: AN EFFECTIVE METHOD FOR ASSESSING THE PROPORTIONS OF CEPHALOPODS IN THE DIET OF ALBATROSSES

The method of collecting and analyzing boluses to characterize the cephalopod diet of albatrosses has been used in many diet studies. However, no study has validated this method. We compared boluses and stomach samples from Gray-headed Albatrosses (Thalassarche chrysostoma) and Black-browed Albatrosses (T. melanophris) to (1) study the consumption and diversity of cephalopods in these species, (2) investigate biases associated with each sampling method, and (3) estimate the number of samples needed to characterize these albatross’s cephalopod diet. We found that collection and analysis of boluses is a simple, efficient, and noninvasive method for assessing the cephalopod diet of these albatross species, but it is inadequate for characterizing the more easily digestible dietary components, such as fish and crustaceans. Both boluses and stomach samples showed that the two albatross species fed on cephalopods of similar sizes and from the same families (Ommastrephidae, Onychoteuthidae, and Cranchiidae). Furthermore, the main prey species (Martialia hyadesi, Kondakovia longimana, and Galiteuthis glacialis) and the total number of cephalopod species consumed (18–24 species) were the same for both albatrosses. To include all cephalopod species, using a sample-randomization technique, a minimum of 61 and 43 boluses were needed for Gray-headed and Black- browed albatrosses, respectively; but to adequately describe the diversity and size frequency of the main prey species, 82 and 371 boluses would be needed. Les Pelotes de Réjection: Une Méthode Efficace pour Évaluer la Proportion de Céphalopodes dans le Régime Alimentaire chez les Albatros

Foraging and provisioning strategies of the light-mantled sooty albatross at South Georgia: competition and co-existence with sympatric pelagic predators

Foraging and provisioning strategies of the light-mantled sooty albatross (LMSA) Phoebetria palpebrata were studied during chick-rearing at Bird Island, South Georgia, in January to May 2003. Virtually all trips of satellite-tracked birds were restricted to Antarctic waters. Individual birds followed a diversity of foraging routes, the majority to shelf and shelf-slope areas along the southern Scotia Arc or to oceanic waters in the mid Scotia Sea, with only a few trips extending as far south as the marginal ice zone in the Weddell Sea. Sympatric white-chinned petrels Procellaria aequinoctialis, black-browed Thalassarche melanophrys and grey-headed albatrosses T. chrysostoma also exploit these areas. Unlike LMSA, these species and the wandering albatross Diomedea exulans, also forage on the shelf and shelf-slope waters surrounding South Georgia, or at the Antarctic Polar Front (APF), where the larger albatrosses and smaller, more manoeuvrable white-chinned petrel may out-compete LMSA for access to prey. As a consequence, foraging distances and maximum ranges are greater, chick-feeding frequencies are lower and chick growth rate is slower in LMSA than in sympatric Thalassarche albatrosses, and adult LMSA appear to have little capacity to regulate provisioning according to chick condition. Nonetheless, LMSA seem well-adapted to exploitation of distant foraging grounds, apparently using the wind to reduce flight costs and, in comparison with other albatrosses, spending more of the night on the wing and returning with food loads that represent a greater proportion of adult mass.

Sustained Fast Travel by a Gray-Headed Albatross (Thalassarche Chrysostoma) Riding an Antarctic Storm

Abstract A Gray-headed Albatross (Thalassarche chrysostoma) was recorded traveling, in the course of a foraging trip, at a minimum average ground speed of >110 km h−1 for ∼9 h with virtually no rest. After taking into account the sinuosity of albatross flight, actual mean ground speed was predicted to be ≥127 km h−1, achieved in association with high tailwinds during an Antarctic storm. Despite its high speed and the storminess of the sea, the albatross still managed to successfully locate and capture prey at a rate comparable to that achieved under less extreme conditions. This individual's performance suggests that albatrosses have the capacity to maintain positive energy budgets while quickly covering long distances and taking advantage of the strong winds that are frequent in the Southern Ocean.

Diet of grey-headed albatrosses at the Diego Ramírez Islands, Chile: ecological implications

The diet of grey-headed albatrosses at Diego Ramírez was analysed and compared to that of the sympatric black-browed albatross. Diet composition was inferred from an analysis of prey hard parts present in 103 chick regurgitates obtained during breeding seasons 2000, 2001 and 2002. The squid Martialia hyadesi predominated in the diet samples in 2001 and 2002 (89% and 81% of reconstituted mass), but was absent from the 2000 samples. Reconstituted mean mass per sample in 2000 was significantly lower than in 2001 and 2002. Chick growth rate during 2000 was also the lowest recorded. This suggests that M. hyadesi plays an important role in the breeding performance of grey-headed albatrosses at Diego Ramírez. Low presence of M. hyadesi in grey-headed albatrosses' diet at South Georgia in 2000, a year with significant low breeding success, suggests ocean-wide processes affecting the availability of this prey to both populations simultaneously. Overlap in diet composition, and inferred feeding areas, between the sympatric albatross species at Diego Ramírez was minimal. Grey-headed albatrosses fed mainly on species associated with the Antarctic Polar Front, whereas black-browed albatrosses consumed benthopelagic species frequently caught in fishing operations in southern Chile.

SUSTAINED FAST TRAVEL BY A GRAY-HEADED ALBATROSS (THALASSARCHE CHRYSOSTOMA) RIDING AN ANTARCTIC STORM

Abstract A Gray-headed Albatross (Thalassarche chrysostoma) was recorded traveling, in the course of a foraging trip, at a minimum average ground speed of >110 km h−1 for ∼9 h with virtually no rest. After taking into account the sinuosity of albatross flight, actual mean ground speed was predicted to be ≥127 km h−1, achieved in association with high tailwinds during an Antarctic storm. Despite its high speed and the storminess of the sea, the albatross still managed to successfully locate and capture prey at a rate comparable to that achieved under less extreme conditions. This individual's performance suggests that albatrosses have the capacity to maintain positive energy budgets while quickly covering long distances and taking advantage of the strong winds that are frequent in the Southern Ocean.

Foraging strategies of grey-headed albatrosses Thalassarche chrysostoma: integration of movements, activity and feeding events

We identified a range of foraging strategies adopted by grey-headed albatrosses Tha- lassarche chrysostoma rearing chicks at Bird Island, South Georgia, by simultaneously using satellite telemetry, wet/dry activity recorders and stomach temperature loggers. The albatrosses foraged mostly over oceanic waters, probably associated with the Polar Front north of South Georgia, and also over shelf-slope waters around the Antarctic Peninsula. After leaving the colony, birds commuted to areas with predictable prey concentrations, where they remained for several days. During search periods, birds landed more often and had a higher intake rate, but spent the same proportion of time in flight as on commuting days. Although intake rates were particularly high in shelf-break waters around the Antarctic Peninsula (only one individual foraged in this area), prey were also consumed in reasonable quantities during commuting flights. While at sea, birds spent most (81%) of the day flying, and most (94%) of the night resting on the water. A considerable proportion (26% by mass) of prey was consumed during darkness. The majority of prey were detected and captured during search flights, but 35% were located while sitting on the sea surface. Many ingestion events (up to 27% of the overall food intake) showed temperature signatures characteristic of fluids, suggesting that alba- trosses may feed on gelatinous and rapidly digested prey (e.g. salps and jellyfish) much more often than previously suspected. Diet samples delivered to the chicks comprised mostly squid (particularly Martialia hyadesi) and Antarctic krill Euphausia superba.

Unusual Breeding by Seabirds at Marion Island During 1997/98

In 1997/98, breeding at subantarctic Marion Island was exceptionally good for five species of seabirds capable of foraging over wide areas and for a tern. The number of king penguin Aptenodytes patagonicus chicks surviving to the start of spring in 1997 was considerably more than previously recorded. Greater numbers of wandering Diomedea exulans and grey-headed Thalassarche chrysostoma albatrosses, northern giant petrels Macronectes halli and Kerguelen terns Sterna virgata bred than previously recorded, and more southern giant petrels M. giganteus did so than in any other year since 1994. For southern giant petrels, reproductive success was higher than in any other year, as was survival of chicks of northern giant petrels. Conversely, for two seabirds that feed close to the island, gentoo penguin Pygoscelis papua and Crozet shag Phalacrocorax [atriceps] melanogenis, 1997/98 was a particularly poor breeding season. Gentoo penguins initiated breeding later than usual and fledged few chicks. The number of Crozet shags that bred decreased; probably about 25% of the adult population did not breed. For two species with an intermediate foraging range that eat mainly crustaceans, macaroni Eudyptes chrysolophus and eastern rockhopper E. chrysocome filholi penguins, breeding was not noticeably different from normal except that chicks of rockhopper penguins fledged with a slightly heavier mass than in other years. However, for both these penguins, the mass of adults on arrival at colonies decreased substantially in the following (1998/99) breeding season. The unusual breeding by most of the seabirds coincided with the El Niño Southern Oscillation (ENSO) event of 1997/98. This synchrony contrasts with lagged responses to ENSO events of seabirds that breed farther south in the Southern Ocean. Continued monitoring of seabirds over well-separated sites in the Southern Ocean may elucidate how climatic perturbations operating at a global scale impact seabirds in the region.

Feeding strategies and diets of breeding grey-headed and wandering albatrosses at South Georgia

The foraging areas and diets of the grey-headed albatross Thalassarche chrysostoma and wandering albatross Diomedea exulans were studied in March/April 2000 at Bird Island, South Georgia, during their respective chick-rearing and brood-guard periods. Oceanographically, March/April 2000 was abnormal, with warm conditions close to South Georgia. These conditions affected albatross foraging behaviour, particularly that of grey-headed albatrosses. Both species tended to forage in different areas of the ocean, with significant differences in trip durations. Grey-headed albatrosses (n=9) foraged mainly in Antarctic waters (predominantly shelf waters of the South Shetland Islands and Antarctic Peninsula, and also in oceanic waters around South Georgia), feeding mainly on krill (Euphausia superba; 77% by mass). Foraging trips lasted 13.3 days (range: 5–26 days), far longer than the 1–3 days found in previous studies. Only one grey-headed albatross was associated with the APF (Antarctic Polar Front), a reported foraging area in recent studies. Wandering albatrosses (n=9) foraged in Antarctic (South Georgia Shelf) and Antarctic Polar Frontal Zone (APFZ) waters, with trips of 1–4 days trip duration (usual for this species), feeding on fish (46% by mass) and cephalopods (32%). One bird was associated with the APF, and two birds foraged on the shelf/shelf break over the Patagonian shelf. These findings suggest that sea surface temperature anomalies, produced by movement of the APF closer to South Georgia or by eddies, may have had an effect on the foraging strategy of grey-headed albatrosses that year (the main prey of grey-headed albatrosses in previous studies, the ommastrephid Martialia hyadesi, is known to be associated with the APF). Also, when both albatross breeding periods overlap, their foraging areas were complementary, which reflected the prey taken.

Control of provisioning in grey-headed albatrosses (Thalassarche chrysostoma): do adults respond to chick condition?

Recent studies have been equivocal in determining whether long-lived seabirds are able to respond to chick nutritional status and regulate provisioning rates accordingly. With some exceptions, albatrosses and petrels that feed their chicks every 1–3 days seem able to respond to variability in chick condition. In contrast, those with longer overall feeding periodicity and that frequently show a dual foraging strategy, mixing short trips (which most benefit the chick) with longer, pelagic feeding excursions (during which time adults recover lost condition), tend not to regulate provisioning. We used a combined observational and experimental approach to determine whether feeding rates in grey-headed albatrosses (Thalassarche chrysostoma) were determined by parental foraging proficiency and (or) offspring demand. The results indicated that both factors were important. Adults showed consistent differences in provisioning characteristics, but chick satiation and solicitation also influenced the mass of the meal delivered when adults returned. Given a provisioning schedule characterised by relatively frequent colony visits and with no means of assessing the feeding success of their partner in the interim, the adjustment of meal mass upon arrival appears to be a simple means of tailoring prey delivery to changing chick requirements and is likely to be as effective as alternative strategies suggested for other species of Procellariiform.

Seabird mortality in the Patagonian toothfish longline fishery around the Prince Edward Islands, 1996–2000

Sanctioned longline fishing for Patagonian toothfish around the Prince Edward Islands (a globally important seabird breeding site) commenced in 1996 following high levels of Illegal, Unregulated and Unreported (IUU) fishing. Independent fishery observers accompanied all but two sanctioned trips between 1996 and 2000, allowing a thorough understanding of the impact of this fishery on seabirds. Overall, white-chinned petrels Procellaria aequinoctialis were by far the most frequently killed species. However, during the first year, when lines were set during the day and night, a significant number of albatrosses (particularly grey-headed albatrosses Thalassarche chrysostoma) were also killed. Birds were caught almost exclusively during their breeding seasons and most birds killed were breeding adult males from the Prince Edward Islands. Albatrosses and giant petrels were caught almost exclusively during day sets, whereas catch rates of white-chinned petrels did not differ between day and night sets. Albatrosses were caught closer to the islands than white-chinned petrels. Most white-chinned petrel carcasses were hooked in their wings and bodies, whereas albatrosses were caught most frequently in their bills and contained large numbers of baits. Rates of seabird bycatch in the sanctioned fishery decreased from 0.19 birds per 1000 hooks to 0.034 birds per 1000 hooks during the time of this study. This was probably mainly due to stricter implementation of mitigation measures and a progressive movement farther away from the islands over the years. We estimate that the combined impact of legal and IUU longline fishing around the Prince Edward Islands over the past four years could have resulted in between 7000 and 17 000 seabird mortalities and could have had significant impacts on the breeding populations of several seabird species breeding on the Prince Edward Islands. This was mainly due to high levels of IUU fishing during 1996/97.

Distribution of cephalopods recorded in the diet of the Patagonian toothfish (Dissostichus eleginoides) around South Georgia

The cephalopod component of the diet of Patagonian toothfish, Dissostichus eleginoides, around South Georgia was analysed from stomach contents collected between March and May 2000. Cephalopods occurred in 7% of D. eleginoides stomachs. A total of 363 cephalopod beaks were found, comprising 16 cephalopod species, of which 15 had not been previously recorded in the diet. Octopodid A (probably Pareledone turqueti) was the most important cephalopod species by number of lower beaks (36 beaks; 20.2% of the lower beaks) and Kondakovia longimana was the most important in terms of estimated mass (76% of the cephalopod component). When the cephalopod component of D. eleginoides was compared with other predators between March and May 2000, D. eleginoides fed more on octopods (25% of the lower beaks) than black-browed and grey-headed albatrosses (<1% of the lower beaks). The low frequency of the squid Martialia hyadesi in the diet of D. eleginoides around South Georgia was also noticed in the diet of albatrosses, and suggests that M. hyadesi was not present in these waters in 2000 (probably due to migratory movements or reproduction failure), despite being a candidate for commercial exploitation. The presence of the squid Mesonychoteuthis hamiltoni in the diet of D. eleginoides and being caught by a longline hook whilst presumably feeding on D. eleginoides, may indicate that juveniles of Mesonychoteuthis hamiltoni are prey of D. eleginoides adults, and when Mesonychoteuthis hamiltoni reach a large size as adults, they become the predator.

Population trends of albatrosses and petrels at sub-Antarctic Marion Island

We report on the population changes of five species of Procellariiform seabirds breeding at Marion Island: wandering albatross (Diomedea exulans), grey-headed albatross (Thalassarche chrysostoma), northern giant petrel (Macronectes halli), southern giant petrel (M. giganteus), and white-chinned petrel (Procellaria aequinoctalis). The four large surface-nesting species (wandering albatross, grey-headed albatross and the northern and southern giant petrel) show similar population trends over the last 16–18 years. All were stable or decreasing during the 1980s, followed by a recovery period during the early to mid-1990s. Recently, all species have once again stabilized or decreased in numbers. Population trends of wandering albatross at Marion Island were strongly correlated with other Indian Ocean populations, but were different from the Atlantic Ocean population. These similarities suggest a common cause and can be explained by changes in tuna (Thunnus spp.) longline fishing effort in the southern Indian Ocean. A recent increase in tuna longlining, as well as recent large-scale Illegal, Unregulated and Unreported (IUU) longline fishing for Patagonian toothfish (Dissostichus eleginoides) close to Marion Island, could be contributing to the recent decreases in some of these species. Adoption of mitigation measures and an effective means of dealing with IUU longline fishing seem necessary to reduce the potential impacts of longline fishing on populations of albatross and petrel.

Feather mercury levels in seabirds at South Georgia: influence of trophic position, sex and age

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 243:261-269 (2002) - doi:10.3354/meps243261 Feather mercury levels in seabirds at South Georgia: influence of trophic position, sex and age Peter H. Becker1,*, Jacob González-Solís2, Brigitte Behrends1, John Croxall3 1Institut für Vogelforschung ŒVogelwarte Helgoland¹, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany 2Departamento Biología Animal (Vertebrats), Universitat de Barcelona, Avenida Diagonal 645, 08028 Barcelona, Spain 3British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge CB3 0ET, United Kingdom *Email: peter.becker@ifv.terramare.de ABSTRACT: We studied the mercury contamination of 13 species of seabirds breeding on Bird Island, South Georgia, in 1998. Total mercury concentrations in body feather samples of birds caught at their breeding colonies were determined. Among the species, grey-headed albatross (8933 ng g-1) and southern giant petrel (7774 ng g-1) showed the highest, and gentoo penguin (948 ng g-1) the lowest body feather mercury concentrations. Mercury levels were negatively correlated with the proportion of crustaceans (mainly krill) in the species¹ diets, suggesting that the trophic level is the most important factor in explaining the variation of mercury concentrations in Antarctic seabirds. In 4 species studied for age effects among adult birds (grey-headed and black-browed albatross, northern and southern giant petrel), no age-dependent variation in mercury levels was found. Sex differences were also assessed: female gentoo penguins had lower mercury levels than males, which may be related to the elimination of part of the mercury body burden by females into eggs. In contrast, northern giant petrel males had lower levels than females, which may be related to a higher consumption by males of carrion from Antarctic fur seals. In grey-headed albatrosses, mercury levels were 113% higher than in 1989, when this species was investigated at the same site, indicating a possible increase in mercury pollution of the Southern Ocean during the last decade. KEY WORDS: Interspecific variability · Intraspecific variability · Trophic position · Krill diet · Foraging · Temporal trend · Total mercury · Body feathers Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 243. Online publication date: November 13, 2002 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2002 Inter-Research.

The importance of the Patagonian Shelf for top predator species breeding at South Georgia

1. The rich zooplankton, fish and squid resources on the Patagonian Shelf sustain substantial populations of largely resident seabirds and marine mammals. These habitats are also visited seasonally by similar species from elsewhere but few data exist on their status and origin. Recent studies, using satellite-tracking to determine foraging ranges and feeding areas of seabirds and marine mammals breeding at South Georgia, have shown that several species make substantial use of the waters of the Patagonian Shelf. 2. Wandering albatrosses use shelf-edge areas year-round with direct observations of both sexes of almost all age classes, including, breeding, pre-breeding and non-breeding individuals. White-chinned petrels and female Northern and Southern giant petrels mainly visit during incubation and post-breeding, particularly to the Falklands Current (White-chinned petrels) and to upwelling areas around the southern shelf-break from the Burdwood Bank in the east to Staten Island and Diego Ramirez in the west (giant petrels). Northern giant petrel males during incubation and Antarctic fur seals in winter reach inner shelf habitats in the northern sector. In contrast, South Georgia populations of black-browed and grey-headed albatrosses do not appear to use the Patagonian Shelf at any stage of their breeding cycle. 3. Although the use of the Patagonian Shelf by visiting species is now best documented for South Georgia species, recent observational data confirm that seabirds from Diego Ramirez, Tristan da Cunha and Gough visit the southern and northern sectors, during both breeding and non-breeding seasons respectively. Several Antarctic species (notably Antarctic fulmar and cape petrel) winter in the region as do at least two albatross species from New Zealand; other species (especially Wilson's storm petrels) use it as a staging ground on migration, as do several species of baleen whales and possibly other cetacean species. 4. Three of the seabird species which breed on the Patagonian Shelf are Globally Threatened; seven of the visiting species (and four baleen whale species) also have this status. The Patagonian Shelf is, therefore, not only of global importance for the diversity and abundance of its resident top predators but is just as critical for the survival of many visiting species, some of which are even more endangered. 5. Combining data from satellite-tracking with conventional mapping from direct observations offers the prospect of defining the foraging ranges (and the main feeding areas within these) of a range of key top predator species. Such data should be used, in conjunction with similar information of the distributions of fish, squid and zooplankton resources and of fishing effort, to identify critical marine habitats whose precautionary, multiple-use sustainable management will be vital to protect the interests of both commercial fishers and top predators. Copyright © 2002 John Wiley & Sons, Ltd.

Exploitation of mesoscale oceanographic features by grey-headed albatross Thalassarche chrysostoma in the southern Indian Ocean

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 217:15-26 (2001) - doi:10.3354/meps217015 Exploitation of mesoscale oceanographic features by grey-headed albatross Thalassarche chrysostoma in the southern Indian Ocean D. C. Nel1,*, J. R. E. Lutjeharms2, E. A. Pakhomov3, I. J. Ansorge2, P. G. Ryan1, N. T. W. Klages4 1Percy FitzPatrick Institute and 2Department of Oceanography, University of Cape Town, Rondebosch 7701, South Africa 3Southern Ocean Group, Department of Zoology & Entomology, Rhodes University, PO Box 94, Grahamstown 6140, South Africa 4Port Elizabeth Museum at Bayworld, PO Box 13147, Humewood 6013, South Africa *E-mail: dnel@botzoo.uct.ac.za ABSTRACT: Breeding grey-headed albatross Thalassarche chrysostoma, tracked from Marion Island (Prince Edward Islands) during November-December 1997 and January-February 1998, showed a strong association with mesoscale oceanographic features, as identified by sea surface height anomalies, in the southern Indian Ocean. During incubation, most birds foraged to the north of the island, at the edges of anomalies created by the Agulhas Return Current in the Subtropical Convergence and the Subantarctic zones. In contrast, during chick-rearing all tracked birds foraged to the southwest of the island, at the edges of anomalies along the South-West Indian Ridge. Previous work in this area has shown that these anomalies are in fact eddies that are created as the Antarctic Circumpolar Current crosses the South-West Indian Ridge. Diet samples taken during the chick-rearing period showed a predominance of fresh specimens of the predatory fish Magnisudis prionosa and the squid Martialia hyadesi. Myctophid fish and amphipods Themisto gaudichaudii, both known prey of M. hyadesi, were also well represented in our samples. Diet samples taken from tracked birds showed birds feeding at edges of positive anomalies returning with fresh specimens of M. prionosa and M. hyadesi. Predatory fish and squid are thus presumably concentrated at these features. Eddies formed at the South-West Indian Ridge have also been shown to drift closer to Marion Island, within the foraging range of penguins and seals breeding on Marion Island. We therefore suggest that these mesoscale oceanographic features may be an important component of the Œlife-support¹ system enabling globally significant populations of seabirds and seals to breed at the Prince Edward Islands. KEY WORDS: Albatross · Foraging ecology · Diet · Oceanography Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 217. Online publication date: July 31, 2001 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2001 Inter-Research.

Contrasting Strategies of Provisioning and Chick Growth in two Sympatrically Breeding Albatrosses at Campbell Island, New Zealand

AbstractThe provisioning strategies of two closely related species of albatross breeding sympatrically were studied at Campbell Island, New Zealand. Black-browed Albatrosses (Diomedea melanophrys) had a higher provisioning rate of chicks than Grey-headed Albatrosses (D. chrysostoma) as a result of a higher feeding frequency. Provisioning and satellite-tracking data suggest that Black-browed Albatrosses forage over neritic waters in trips of up to 5 days, in combination with longer trips over oceanic waters. In contrast, it was not possible to separate clearly short and long trips in Grey-headed Albatrosses, but they probably forage mostly over oceanic waters, combined with rafting or feeding near the colony during stays of short duration at sea. No inter-annual differences in foraging trip duration were apparent between years for either species. Chicks were fed larger meals at older ages and when in poorer condition, probably due to a limitation on the rate of assimilation of food. For both species, chick condition after feeding did not influence the duration of foraging trips. Black-browed Albatrosses from Campbell Island feed locally in neritic waters and up to 2,000 km from the colony, in contrast to conspecifics from other sites which feed principally over neritic waters. Grey-headed Albatrosses were largely dependent on oceanic resources as for conspecifics studied elsewhere. This study shows that foraging and provisioning strategies are flexible within species, allowing them to exploit more or less distant resources.

Salmonella in sub-Antarctica: low heterogeneity in Salmonella serotypes in South Georgian seals and birds.

The number of human visitors to Antarctica is increasing rapidly, and with it a risk of introducing infectious organisms to native animals. To study the occurrence of salmonella serotypes in sub-Antarctic wildlife, faecal samples were collected from gentoo penguins, macaroni penguins, gray-headed albatrosses, black-browed albatrosses and Antarctic fur seals on Bird Island in the South Georgian archipelago during the austral summer of 1996 and 1998. In 1996, S. havana, S. typhimurium and S. enteritidis were isolated from 7% of gentoo penguins and 4% of fur seals. In 1998, however, 22% of fur seals were found to be infected with S. havana, S. enteritidis and S. newport. All isolates, except one, showed identical pulsed-field gel electrophoresis-patterns within each serotype, irrespective of sampling year and animal reservoir. No significant antibiotic resistance was found. The very low heterogeneity in the salmonella isolates found could either indicate a high genetic adaptation of the bacteria to the environment or a recent introduction of salmonella into the area.