Moult in Black-browed and Grey-headed Albatrosses Diomedea melanophris and D. chrysostoma

We recorded the age of individual wing and tail feathers of Black-browed and Grey-headed Albatrosses Diomedea melanophris and D. chrysostoma of known age and breeding status at Bird Island, South Georgia. Breeders and non-breeders of both species moult their rectrices annually. Non-breeders moult primaries biennially. In the first year of a cycle, the outer three and some inner primaries are moulted descendantly; in the next year the inner primaries are moulted ascendantly, starting from primary seven. There is a general progression to moulting equal numbers of primaries in each half of the cycle by the time breeding starts at about 10 years of age. Grey-headed Albatrosses usually moult fewer primaries than Black-browed Albatrosses, particularly as 3-year-olds, when they undertake substantial plumage change in body moult. Most secondaries in Black-browed Albatrosses have been replaced once by age 4 years. Breeding Black-browed Albatrosses continue the moult pattern established as immatures whether they fail or not, as do failed Grey-headed Albatrosses. Successful Grey-headed Albatrosses, which breed again 16 months later, moult their three innermost primaries after breeding in the remainder of the current year and, after a period when moult is interrupted, renew the remaining primaries the following year. Comparisons between species and between failed and successful birds within species indicate that moult rate is not closely linked to the length of the interval between breeding attempts. Interspecies differences are better explained by breeding latitude, with tropical albatrosses moulting twice as fast as sub-Antarctic species, possibly reflecting food availability outside the breeding season.     

Egg formation and the pre-laying period of Black-browed and Grey-headed Albatrosses Diomedea melanophris and D. chrysostoma at Bird Island, South Georgia

Egg composition and factors influencing egg formation were studied in Black-browed and Grey-headed Albatrosses Diomedea melanophris and D. chrysostoma at Bird Island, South Georgia. At nests where eggs were laid, females arrived 6–7 days after males, stayed one day during which 96% of observed copulations occurred, then departed to sea for c. 16 days in D. chrysostoma, c. 10 days in D. melanophris , returning c. two days before laying. Yolk deposition, however, lasted 21 and 20 days, and started 32 and 29 days before laying, in D. chrysostoma and D. melanophris respectively. Therefore, it is probably initiated by environmental factors not by copulation. Egg, albumen and yolk mass are significantly greater in D. chrysostoma but the proportionate composition of the species' eggs is nearly identical. Reduced differences in chick mass at hatching may reflect the longer incubation period in D. chrysostoma or relate to subsequent differences in chick growth rate.     

Chick provisioning rates and growth in Blacklbrowed Albatross Diomedea melanophris and Grey-headed Albatross D. chrysostoma at Bird Island, South Georgia

We compared the parental division of labour and the pattern and rate of parental provisioning by two sympatric species of albatross of similar mass and breeding timetable but differing in diet and in the duration of chick‐rearing. Using electronic weighing platforms inside artificial nests, we recorded chick mass of Black‐browed Albatross and Grey‐headed Albatross at Bird Island, South Georgia every 10 minutes for both species in 1993 and 1994 and for each species in two other years between 1990 and 1996. The chick mass data (nearly one million weighings) were used to calculate meal mass (over 5000 meals) and intervals between meals. Adult birds were fitted with radio‐transmitters which allowed each meal to be allocated to the appropriate parent. The combination of meal mass and foraging trip duration were used to calculate provisioning rates for chicks and individual adults. Overall, Black‐browed Albatrosses delivered significantly lighter meals (569 g) than Grey‐headed Albatrosses (616 g) but more frequently (every 2.07 days and 2.50 days respectively). Thus combining foraging trip data for both parents, Black‐browed Albatross chicks received a meal every 1.22 days compared with 1.26 days for Greyheaded Albatross. These rates did not differ significantly. The contribution of each sex of each species in chick provisioning fluctuated between years, being similar in some years or biased towards males in others. Chicks of both species that failed to fledge received smaller, less frequent meals than successful chicks. In 1990 and 1994, Black‐browed Albatross chick provisioning rates were lower than in 1992 and 1993. In 1990, both meal mass and trip duration were affected, but only in 1994 was trip duration longer. Greyheaded Albatross chick provisioning rate was lower in 1994 than in other years but trip duration was longer. In each species, significant changes in meal mass and trip duration occurred within the chick‐rearing period. Chick provisioning rates invariably declined before chicks attained their peak mass. For both species, chick growth rates and peak and fledging mass, but not fledging age, were affected by differences in provisioning rate.     

Population dynamics of Black-browed and Grey-headed Albatrosses Diomedea melanophrys and D. chrysostoma at Campbell Island, New Zealand, 1942–96

The numbers of Black-browed Albatrosses Diomedea melanophrys and Grey-headed Albatrosses D. chrysostoma at Campbell Island, New Zealand, have declined dramatically since the 1940s. Black-browed Albatross numbers went into a steep decline in the 1970s and, since at least 1984, have been increasing slightly at average rates of 1.1% and 2.1% per annum at two colonies. The long-term downward trend in numbers of the Grey-headed Albatross has continued into the 1990s, averaging annually between 3.0% and 4.8% per annum at different colonies. A demographic study carried out between 1984 and 1996 indicates that Black-browed and Grey-headed Albatrosses have similarly high annual adult survival rates (0.945 and 0.953, respectively). Black-browed Albatrosses breed for the first time at a younger average age than do Grey-headed Albatrosses (10 years and 13.5 years, respectively), have a higher average breeding success (0.663 compared with 0.397 for the latter species) and are annual breeders whereas Greyheaded Albatross show a typical biennial pattern of breeding. Both show low survival from fledging to first breeding; averaging 0.186 and 0.162 for Black-browed and Grey-headed Albatrosses, respectively. Both species are accidentally killed in the Japanese long-line fishery for tuna Thunnus sp. in the Australasian region. The steep decline of Black-browed Albatross numbers in the 1970s was concomitant with the development of this fishery in the foraging region of the Campbell Island birds. Currently, the slight increase in numbers is due to high adult survival rates and breeding success, and is coincident with a great reduction in long-line fishing. With stable and high adult survival rates, it is expected that future population trends will be mainly influenced by the recruitment rates. The continuous decline in Grey-headed Albatross numbers since the 1940s, before long-line fishing developed in this region, indicates that natural environmental processes contributed to the downward trend in breeding numbers. Modelling indicates that Grey-headed Albatross numbers will continue to decrease with the present demographic parameters. A comparison between the species breeding at different sites shows that differing environmental conditions influence demographic characteristics.     

Individual quality and reproductive performance in the Grey-headed Albatross Diomedea chrysostoma

The reproductive performances of Grey-headed Albatrosses Diomedea chrysostoma with a previous record (≤5 years) of consistent success (≤70% chicks fledged from eggs laid—"top" birds) or failure (≤ 70% of attempts failed—"bottom" birds) were compared during 1993 -1995. In 1995, top birds arrived back at the colony significantly earlier, had significantly shorter first and second incubation shifts and hatched larger chicks which grew significantly faster than bottom birds. In 1994, top birds also had larger hatchlings with higher rates of growth than bottom birds. In 1994, top birds had significantly higher hatching, fledging and therefore overall breeding success than bottom birds; very similar trends were evident in 1993 and 1995. Chick-rearing success and all indices of chick growth suggested that food availability was high in 1995 (and 1993) and low in 1994. Therefore the superior performance of top birds was maintained in years of very different conditions, with the chick-rearing period particularly critical. A simple model (using published demographic parameters for Grey-headed Albatrosses on South Georgia) suggests that top birds would produce 2.5 more chicks over their lifetime than bottom birds. With the currently declining population numbers, the relative contribution of top birds to the next generation may be even greater than this.     

Extrapair paternities in black-browed Thalassarche melanophris, grey-headed T. chrysostoma and wandering albatrosses Diomedea exulans at South Georgia

Extrapair paternities (EPP) are relatively common in passerines, but rare in seabirds. Like most seabirds, albatrosses are long lived, form long-term pair bonds and require biparental care for chick-rearing. Microsatellite analyses of 327 chicks from black-browed Thalassarche melanophris , grey-headed T. chrysostoma and wandering albatrosses Diomedea exulans over two breeding seasons revealed the presence of EPP in all three species. Though EPP rates varied between species and years, up to 21% of offspring were the result of extrapair matings. Rates were highest in wandering albatrosses (6–21%) followed by grey-headed (3–10%) and black-browed (0–9%) albatrosses. EPP rates were lower in 1998 compared to 1999 in both black-browed and grey-headed albatrosses, whereas the reverse was true for wandering albatrosses. Interspecific differences in EPP rates may reflect differences in breeding phenology and sexual size dimorphism. Differences in timing and frequency of breeding may promote different opportunities for interactions with birds other than their normal partner. The different breeding habitat, dispersion and mate-attraction rituals in wandering albatross, together with the disparity in size between the sexes may also offer more scope for higher rates of EPP. Despite extensive sampling within each colony, we were unable to identify sires for many of the extrapair young; however males from other colonies were involved, raising interesting questions regarding the timing and nature of such events.     

Fly or die: the role of fat stores in the growth and development of Grey-headed Albatross Diomedea chrysostoma chicks

Chicks of albatrosses, like other Procellariiformes, become independent at a mass similar to their parents but during growth attain a peak mass some 30% or more greater, before losing mass prior to fledging. The current views are that this high peak mass represents chicks storing fat reserves as an energy sink, or as an insurance against periodic food scarcity, or as a Consequence of natural stochastic variation in provisioning rate. We analysed growth and body composition of Grey‐headed Albatross Diomedea chrysostoma chicks at Bird Island, South Georgia in 1984 and 1986, two years of very different food availability. In 1984 when overall breeding success was only 28% (the lowest in 20 years and less than halt that in 1986), chicks were significantly smaller in terms of peak mass (by 37%), primary length (by 25%), liver, lung, heart and kidney size (by 18–34%) and fat (by 75–80%) but not significantly different in terms of skeletal (tarsus, culmen, ulna, sternum) or muscle (pectoral, leg) size. Despite these differences, there were some important similarities in the patterns of growth in both years. Up to the attainment of peak mass, most of the growth of organs and of skeletal structures was completed and little fat was deposited. In the remaining part of the chick‐rearing period, feather growth and acquisition of fat stores were undertaken. Thus Grey‐headed Albatross chicks begin to acquire substantial fat stores only during the later part of the development period; this is contrary to the predictions of any of the existing hypotheses concerning provisioning patterns and the role of fat stores in Procellariiformes. We propose that the deposition of fat in the later stages of chick growth is an adaptation to: (a) ensure against energy demands and/or nutritional stress affecting the quality of flight feathers (many of which are not renewed for up to three years after fledging); and (b) provide an energy reserve for chicks to use in the critical period immediately after independence.     

Utilization of offal and discards from "finfish" trawlers around the Falkland Islands by the Black-browed Albatross Diomedea melanophris

Multinational fisheries operating in the vicinity of the Falkland Islands currently take c. 90,000 tonnes of true fish ("finfish" as opposed to squid) per annum, including hakes Merluccius spp., Southern Blue Whiting Micromesistius australis, Hoki Macruronus magel-lanicus and Red Cod Salilota australis, and generate substantial quantities of fisheries waste in the form of discards and offal. This paper examines the use made of this waste by scavenging Black-browed Albatrosses Diomedea melanophris which breed in the Falklands. The various types of waste produced are described and their consumption by scavenging albatrosses is quantified. The results indicate that Black-browed Albatrosses obtain c. 8000 tonnes of food per annum from this source, of which two-thirds is offal and the remainder whole discards. The energy content of this waste is equivalent to 4.4% of the estimated total annual energy requirements of the Falklands Black-browed Albatross population. However, as the fishery is a greater predator of finfish stocks than are the albatrosses, its long-term impact may be detrimental to these birds.     

Quantitative analysis of the use of discards from squid trawlers by Black-browed Albatrosses Diomedea melanophris in the vicinity of the Falkland Islands

In the past decade, a major trawl fishery for the squid Loligo gahi has developed in the vicinity of Beauchêne Island, an internationally important breeding site for the Black-browed Albatross Diomedea melanophris. The breeding season diet of this albatross in the Falklands and its use of discards generated by the Loligo fishery were investigated. Albatross chicks are fed extensively on commercially exploited species of squid and fish including Loligo gahi and southern blue whiting Micromesistius australis. The quantity of waste generated by the Loligo fishery amounts to c. 5% of the reported catch and just over 50% of this waste, mainly Loligo and nototheniid fish, is scavenged by adult Black-browed Albatrosses. The total quantity scavenged during the chick rearing period amounts to 1000–2000 tonnes per year. This is equivalent to 10–15% of the total food requirement of the breeding Black-browed Albatross population on Beauchene Island during the period when the fishery is operating. Although the Loligo fishery currently provides a significant quantity of food to these albatrosses, its net effect may be detrimental to them, as it is a much greater predator of Loligo stocks than the albatrosses are estimated to have been prior to the fishery's development.     

Physiological conditions of parent and offspring Black-browed Albatrosses Thalassarche melanophris

Capsule: In Black-browed Albatrosses Thalassarche melanophris nutritional condition is correlated between parents and their offspring.

Aims: To test resource allocation hypotheses analysing the relationship between parental and offspring nutritional condition.

Methods: We measured blood chemistry parameters related with nutritional condition in 24 parents and their nestlings in a colony of Black-browed Albatrosses.

Results: There were no significant differences in blood parameters between sexes or location of the nest within the colony, neither among adults nor among nestlings. We found a significant positive correlation between parents and the nutritional condition of their offspring, measured as urea, uric acid and beta-hydroxybutyrate concentrations in blood.

Discussion: These relationships demonstrate that condition of the young seems to be merely a reflection of parental condition. An interesting relationship between alkaline phosphatase concentration in adults and nutritional condition of their nestlings was found, suggesting that age of the parents would be a key factor explaining quality of the nestling.     

Development and maturation of plumage in the wandering albatross Diomedea exulans

Changes in the plumage of the wandering albatross Diomedea exulans were studied on the Crozet Islands, using a population of birds of known sex and age and including some birds more than 32 years old. Plumage phases of a cross-section of the male and female populations are presented. Males and females fledge with a dark brown plumage. Between the first and fourth year the male's plumage becomes much whiter than the female's. Between five and 15–18 years old the whitening of plumage in either sex develops in parallel though still separated by the extent of the initial divergence. Male plumage probably attains a definitive snowy stage after 30 years while the plumage of the female does not mature beyond an intermediate stage, which is reached after 20 to 25 years. Maturation of the plumage of head, back and wing are compared. In birds of similar age, breeding birds tend to have a whiter plumage than non-breeders. In the oceanic range of the species, white birds, i.e. mostly adult males, favour cold antarctic waters while dark birds, i.e. mostly adult females and juveniles, are observed in warmer subtropical and subantarctic waters. We discuss the possible adaptive significance of the slow maturation in the plumage of the wandering albatross and of the differences in plumage between sexes and between populations.     

Ten polymorphic microsatellite markers in the wandering albatross Diomedea exulans

We describe 10 new variable dinucleotide microsatellites in the wandering albatross Diomedea exulans, as well as conditions for multiplexing and simultaneous genotyping sets of loci. Their variability was assessed in two and one populations from the Crozet and Kerguelen archipelagos (southern Indian Ocean), respectively. Two to 13 alleles were detected per population, and the mean gene diversity was around 0.4. The low genetic differentiation suggests that these populations constitute a single panmictic unit. Cross‐species amplification provided some variability at three and five loci in two other marine birds (Bulweria bulwerii and Pagodroma nivea), but none in Calonectris diomedea.     

Reproductive endocrinology of the Wandering Albatross Diomedea exulans in relation to biennial breeding and deferred sexual maturity

The reproductive endocrinology of the Wandering Albatross Diomedea exulans was studied at South Georgia to investigate the potential endocrine correlates of biennial breeding and of the acquisition of sexual maturity. Gonads of breeding birds and of known-age immature birds of both sexes were examined by laparoscopy throughout the period that they were at the nest site. Blood samples, subsequently analysed to determine concentrations of luteinizing hormone (LH), prolactin, progesterone, testosterone and oestradiol-17/i, were obtained from samples of breeding birds of both sexes at regular intervals from first arrival until the chicks fledged nearly a year later. Before laying in December, breeding birds had mature testes and ovarian follicles and high concentrations of LH, prolactin and sex steroids. Gonadal regression and a rapid drop in hormone levels (except for LH in females) occurred in early incubation (January). Testes (and follicles to a lesser extent) enlarged in mid-incubation, coinciding with high levels of LH and increases in prolactin and testosterone. Gonads finally regressed completely near hatching time. LH, prolactin and testosterone remained at low levels throughout chick rearing (April to November), but females had several periods of active progesterone and oestradiol secretion, and progesterone was detectable in males only late in the chick-rearing period. Although some changes in hormone levels are difficult to explain, the patterns are fairly typical of temperate birds. The persistence of progesterone secretion in both female breeders and non-breeding ‘immature’ birds is viewed as part of a mechanism inhibiting an ovary from becoming vitellogenic. Although testis size and testosterone concentrations increased with age in immature males (of ages 4–10 years), birds of 5 years and older are probably physiologically mature, even though breeding does not start until they are 7 years of age and only half an age group has bred by an age of 11 years. Immature females (of age 4–7 years) had undeveloped follicles, very low oestradiol concentrations but high progesterone levels, providing further support for the role of this hormone in inhibiting gonadotropin secretion. The condition of the female is therefore probably decisive in determining when a pair first attempts to breed but it is unknown what factors initiate normal ovarian development.     

Foraging energetics of Grey-headed Albatrosses Diotnedea chrysostoma at Bird Island,South Georgia

At-sea metabolism (CO₂ production) and water turnover of six breeding Grey-headed Albatrosses Diomedea chrysostoma were measured, using the doubly labelled water method, at Bird Island, South Georgia, Mean food consumption (estimated from a water influx rate of 1.01 1 d^-1 and data on dietary composition) was 1200gd^-1 or 50.4 W. At-sea metabolism (derived from a rate of CO₂ production of 3.98 1 h^-1) was 27.7 W, 2.5 times the estimated basal metabolic rate (BMR). On average the birds ingested nearly twice as much food energy as they expended to obtain it. The metabolic rate during flight (estimated from at-sea metabolism and activity budget data) was 36.3 W (range 34.7–39.0 W) or 3.2 (range 3.0–3.4) times the predicted BMR. This is the lowest cost of flight yet measured, but consistent with the highly developed adaptations for economic flight shown by albatrosses. These results are briefly compared with data for other polar vertebrates (penguins, fur seals) exploiting similar prey.     

Foraging energetics of Grey-headed Albatrosses Diotnedea chrysostoma at Bird Island, South Georgia

At-sea metabolism (CO₂ production) and water turnover of six breeding Grey-headed Albatrosses Diomedea chrysostoma were measured, using the doubly labelled water method, at Bird Island, South Georgia, Mean food consumption (estimated from a water influx rate of 1.01 1 d^-1 and data on dietary composition) was 1200gd^-1 or 50.4 W. At-sea metabolism (derived from a rate of CO₂ production of 3.98 1 h^-1) was 27.7 W, 2.5 times the estimated basal metabolic rate (BMR). On average the birds ingested nearly twice as much food energy as they expended to obtain it. The metabolic rate during flight (estimated from at-sea metabolism and activity budget data) was 36.3 W (range 34.7–39.0 W) or 3.2 (range 3.0–3.4) times the predicted BMR. This is the lowest cost of flight yet measured, but consistent with the highly developed adaptations for economic flight shown by albatrosses. These results are briefly compared with data for other polar vertebrates (penguins, fur seals) exploiting similar prey.     

Senescence effects in an extremely long-lived bird: the grey-headed albatross Thalassarche chrysostoma

Studies attempting to document reproductive or other pre-lethal senescence effects in wild birds typically face an array of problems, including flaws in statistical analyses, non-adaptive philopatry to deteriorating environments, confounding effects arising from cohort heterogeneity and differential death rates of phenotypes and the frequent pairing of old birds to younger mates. Furthermore, recent studies suggest that birds could maintain a high level of physical fitness until old age, before being struck by a catastrophic illness leading quickly to their demise. The presence of terminally ill individuals in most datasets (and their greater incidence in older age categories) may therefore provide a false impression of progressive senescence in cross-sectional analyses. This study was designed explicitly to avoid all the known pitfalls linked to the demonstration of progressive senescence in wild populations, and involved one of the very longest-lived bird species. We show that, during incubation, old (aged 35 years and over) male grey-headed albatrosses Thalassarche chrysostoma make longer foraging trips, and have lower daily mass gains, than experienced mid-aged individuals (aged up to 28 years). This is, to our knowledge, the first report documenting reduced foraging performance with old age. Hatching and breeding success of pairs composed of two old individuals were reduced in comparison to mid-aged pairs. Overall results were very similar when analyses were repeated using only individuals known to have survived 1 or 2 years beyond field measurements (hence probably not suffering from the effects of an advanced terminal illness). We conclude that extremely long-lived individuals usually experience some degree of general physical deterioration, leading to reduced foraging and breeding performance, long before their final demise.     

Diatom communities in soils influenced by the wandering albatross (Diomedea exulans)

Soil diatom communities within two breeding colonies of the wandering albatross (Diomedea exulans) on Île de la Possession (Crozet Archipelago) were investigated. Samples were collected around occupied and abandoned nests and compared with control samples taken from soils lacking any animal influence. A total of 163 diatom taxa has been identified. Differences in the diatom flora were recorded between the two colonies, but the results show that it is almost impossible to identify a single diatom community typical for albatross-influenced areas. Diatom species composition varied markedly between control samples, occupied and abandoned nests. A turnover in the diatom community (shift from eutraphentic to oligotraphentic taxa) was observed when moving away from both occupied and abandoned nests, although no significant differences in diversity have been found. In summary, soil diatom species composition seems to indicate the impact of animal perturbations. However, it is too early to draw sound conclusions and further studies regarding the topic should be performed to confirm the results of the present study.     

Distribution and movements of Buller's albatross (Diomedea bulleri) in Australasian seas

Abstract

The distribution and movements of Buller's albatross in Australasian seas are analysed using results of shipborne surveys (13 238 10‐min counts), counts from trawlers, banding data, recoveries on beaches and fishing vessels, and records from the literature. Patterns of marine distribution are documented by monthly accounts and maps. During the breeding season, highest abundances are recorded over shelves and slopes off southern New Zealand (The Snares shelf to 41–43°S off the South Island, D. b. bulleri), around the Chatham Islands and over oceanic subtropical waters east of New Zealand (probably D. b. platei), with marked seasonal variations observed off southern New Zealand. Both subspecies disperse mostly outside Australasian waters during the non‐breeding season. Birds banded on The Snares were recovered off south‐eastern New Zealand (Stewart Island to Cook Strait) and in the eastern tropical Pacific. Immatures accounted for only 0.25% of birds censused during the ship‐borne surveys; they are recorded around the New Zealand mainland in August‐October and February‐May, off south‐eastern Australia and in the Tasman Sea in November‐December, February, and June‐July. Around New Zealand, males predominate among birds recovered along the eastern seaboard, whereas the sex ratio in south‐western waters tends to vary according to water depth and season. Distribution patterns and movements in New Zealand and Australian seas are discussed in relation to breeding events and breeding status.