Distribution, abundance and behaviour of Buller's, Chatham Island and Salvin's Albatrosses off Chile and Peru

During 15 cruises between 1980 and 1995, we studied three species of albatross that nest in New Zealand but occur as non‐breeders along the Pacific coast of South America: Buller's Thalassarche bulleri, Chatham Island T. eremita, and Salvin's Albatross T. salvini. We logged 547 h of observation, surveying 7638 km² of ocean surface, and recorded 86, 27, and 475 individuals, respectively, of the three species. Chatham Island and Salvin's Albatrosses occurred throughout the Humboldt Current, but habitats differed. Buller's and Salvin's Albatrosses preferred the continental slope, while Chatham Island Albatrosses frequented mostly pelagic waters. On a latitudinal basis, Salvin's Albatross distribution was skewed northward in the austral autumn and southward in spring; Chatham Island Albatross occurred southward during autumn, but was everywhere scarce in spring; and Buller's Albatross occurred almost exclusively in the south (30°S to 40°S) in both seasons. Upwelling and wind speed were positively correlated with densities of Buller's and Salvin's Albatrosses. Densities of Chatham Island Albatrosses also were positively correlated with wind speed, but they occurred further offshore in more stratified waters (with less mixing/upwelling) than did the other two. Pelagic population estimates for the Humboldt Current system, analysed using generalized additive models, peaked at 26 700 individuals for Buller's Albatross (95% confidence interval (CI) 13 100–37 100); 6790 for Chatham Island Albatross (CI 3900–11 100); and 133 100 for Salvin's Albatross (CI 82 800–183 600). Based on adult:subadult ratios observed in the study area, our best estimates for the number of wintering adults were 9100, 5800 and 114 400 birds, respectively, or 20%, 73% and 75% of the numbers estimated (44 500, 8000 and 153 300 birds) for the breeding populations at respective colonies. If we subtract from the autumn count the number of adult‐plumaged birds seen in spring (assumed to be non‐breeders), then respective percentages were 0%, 73% and 65%. Foraging locations and attraction by these birds to commercial fishing operations makes them susceptible to mortality as a result of the recent development of a long‐line fishery on the continental slope of Chile.     

Factors determining nest-site selection of surface-nesting seabirds: a case study on the world's largest pelagic bird,the Wandering Albatross (Diomedea exulans)

Several factors may drive bird nest-site selection, including predation risk, resource availability, weather conditions and interaction with other individuals. Understanding the drivers affecting where birds nest is important for conservation planning, especially where environmental change may alter the distribution of suitable nest-sites. This study investigates which environmental variables affect nest-site selection by the Wandering Albatross Diomedea exulans, the world's largest pelagic bird. Here, wind characteristics are quantitatively investigated as a driver of nest-site selection in surface-nesting birds, in addition to several topographical variables, vegetation and geological characteristics. Nest locations from three different breeding seasons on sub-Antarctic Marion Island were modelled to assess which environmental factors affect nest-site selection. Elevation was the most important determinant of nest-site selection, with Wandering Albatrosses only nesting at low elevations. Distance from the coast and terrain roughness were also important predictors, with nests more generally found close to the coast and in flatter terrain, followed by wind velocity, which showed a hump-shaped relationship with the probability of nest occurrence. Nests occurred more frequently on coastal vegetation types, and were absent from polar desert vegetation (generally above c. 500 m elevation). Of the variables that influence Wandering Albatross nest location, both vegetation type and wind characteristics are likely to be influenced by climate change, and have already changed over the last 50 years. As a result, the availability of suitable nest-sites needs to be considered in light of future climate change, in addition to the impacts that these changes will have on foraging patterns and prey distribution. More broadly, these results provide insights into how a wide range of environmental variables, including wind, can affect nest-site selection of surface-nesting seabirds.     

An effective method for trapping scavenging seabirds at sea

ABSTRACT Most studies of seabirds that involve trapping and marking birds are carried out at breeding colonies. This bias toward the breeding period and colony‐based research is partially caused by difficulties in capturing birds at sea. From 2005 to 2007, we used a cast net thrown by hand from a fishing boat to capture albatrosses and petrels at sea in the southwestern Atlantic Ocean. About 500 birds of 13 species were captured, ranging in size from the 30‐g Wilson's Storm‐petrel (Oceanites oceanicus) to the 10‐kg Wandering Albatross (Diomedea exulans). Cast nets are potentially useful for capturing any seabird that can be attracted close to fishing vessels by bait, such as sardines, squid, offal, or shark liver, thrown into the water. Our method was most effective for capturing bold species, such as Cape (Daption capense), Spectacled (Procellaria conspicillata), and White‐chinned (Procellaria aequinoctialis) petrels and Great Shearwaters (Puffinus gravis), but was not effective for capturing shy species, such as Cory's (Calonectris diomedea), Cape Verde (Calonectris edwardsii) and Manx (Puffinus puffinus) shearwaters, species that rarely sit on the water, such as Wilson's Storm‐petrels, Thin‐billed (Pachyptila belcheri) and Antarctic (Pachyptila desolata) prions and Atlantic Petrels (Pterodroma incerta), and species with excellent diving abilities, such as Sooty Shearwaters (Puffinus griseus). For many species of seabirds, cast nets would likely be more efficient for capturing large numbers of birds than other methods, such as hoop nets.     

An ecological risk assessment for the impacts of offshore wind farms on birds in Australia

An ecological risk assessment, based on life-history and behavioural attributes of 273 bird taxa, was used to identify which of those taxa are at high risk from negative interactions with offshore wind farms in Australia. The marine area of Australia was divided by state/territory boundaries perpendicular to the coast into eight regions, with Western Australia further divided into north and south, and a Bass Strait region bounded by the Victoria coast and the north coast of Tasmania. These regions were subdivided into coastal, inshore and offshore sub-regions and a risk summary for all bird taxa occurring in each of these sub-regions produced. In coastal and inshore sub-regions of Bass Strait, South Australia and Tasmania, the species with the highest risk scores were Orange-bellied Parrot Neophema chrysogaster, Furneaux White-fronted Tern Sterna striata incerta, Swift Parrot Lathamus discolor, Shy Albatross Thalassarche cauta, Far Eastern Curlew Numenius madagascariensis and Anadyr Bar-tailed Godwit Limosa lapponica anadyrensis. In offshore sub-regions in southern Australia, the highest risk species were all albatrosses, comprising Northern Royal Diomedea sanfordi, Eastern Antipodean D. antipodensis antipodensis, Gibson's D. antipodensis gibsoni, Wandering D. exulans, Amsterdam D. amsterdamensis and Grey-headed Albatross T. chrysostoma. Compared to onshore installations, there are logistical challenges to quantifying the potential and realized impacts of offshore wind farms that require different approaches to data collection and analyses. The extensive development of offshore wind farms in the Northern Hemisphere provides examples of best and emerging approaches to quantify and mitigate negative impacts of offshore wind farms that can be applied in an Australian context. Despite differences in the species involved, the same approaches to identifying high-risk species and to the monitoring and mitigation of negative impacts should be applied in a coordinated, regional-scale approach to the development of offshore wind farms in Australia.     

Population structure and biogeography of Hemiphaga pigeons (Aves: Columbidae) on islands in the New Zealand region

Aim The New Zealand avifauna includes lineages that lack close relatives elsewhere and have low diversity, characteristics sometimes ascribed to long geographic isolation. However, extinction at the population and species levels could yield the same pattern. A prominent example is the ecologically important pigeon genus Hemiphaga. In this study, we examined the population structure and phylogeography of Hemiphaga across islands in the region. Location New Zealand, Chatham Islands and Norfolk Island. Methods Mitochondrial DNA was sequenced for all species of the genus Hemiphaga. Sixty‐seven individuals from mainland New Zealand (Hemiphaga novaeseelandiae novaeseelandiae), six of the Chatham Islands sister species (Hemiphaga chathamensis), and three of the extinct Norfolk Island subspecies (Hemiphaga novaeseelandiae spadicea) were included in this study. Novel D‐loop and cytochrome b primers were designed to amplify DNA from museum samples. Additionally, five other mitochondrial genes were used to examine placement of the phylogenetic root. Results Analyses of mitochondrial DNA sequences revealed three Hemiphaga clades, consistent with the allopatric populations of recognized (sub)species on oceanic islands. Of the 23 D‐loop haplotypes among 67 New Zealand pigeons (Hemiphaga n. novaeseelandiae), 19 haplotypes were singletons and one haplotype was common and widespread. Population genetic diversity was shallow within and between New Zealand populations, indicating range expansion with high inter‐population exchange. Tentative rooting of the Hemiphaga clade with cyt b data indicates exchange between mainland New Zealand and the Chatham Islands prior to colonization of Norfolk Island. We found low genetic divergence between populations on New Zealand, the Chatham Islands and Norfolk Island, but deep phylogenetic divergence from the closest living relatives of Hemiphaga. Main conclusions The data are consistent with the hypothesis of population reduction during the Pleistocene and subsequent expansion from forest refugia. Observed mobility of Hemiphaga when feeding helps explain the shallow diversity among populations on islands separated by many hundreds of kilometres of ocean. Together with comparison of distribution patterns observed among birds of the New Zealand region, these data suggest that endemicity might represent not long occupancy of an area, but descent from geologically recent colonizations. We consider the role of lineage pruning in creating the impression of old endemicity.     

The impacts of introduced House Mice on the breeding success of nesting seabirds on Gough Island

Invasive species are the main threat to island biodiversity; seabirds are particularly vulnerable and are one of the most threatened groups of birds. Gough Island, a UNESCO World Heritage Site in the South Atlantic Ocean, is an Important Bird and Biodiversity Area, and one of the most important seabird colonies globally. Invasive House Mice Mus musculus depredate eggs and chicks of most seabird species on the island, but the extent of their impact has not been quantified. We used field data and bootstrapped normal distributions to estimate breeding success and the number of surviving chicks for 10 seabird species on Gough Island, and compared estimates with those of analogous species from predator‐free islands. We examined the effects of season and nest‐site location on the breeding success of populations on Gough Island, predicting that the breeding success of Gough birds would be lower than that of analogues, particularly among small burrow‐nesting species. We also predicted that winter‐breeding species would exhibit lower breeding success than summer‐breeding species, because mice have fewer alternative food sources in winter; and below‐ground nesters would have lower breeding success than surface nesters, as below‐ground species are smaller so their chicks are easier prey for mice. We did indeed find that seabirds on Gough Island had low breeding success compared with analogues, losing an estimated 1 739 000 (1 467 000–2 116 000) eggs/chicks annually. Seven of the 10 focal species on Gough Island had particularly high chick mortality and may have been subject to intense mouse predation. Below‐ground and winter breeders had lower breeding success than surface‐ and summer‐breeders. MacGillivray's Prion Pachyptila macgillivrayi, Atlantic Petrel Pterodroma incerta and Tristan Albatross Diomedea dabbenena are endemic or near‐endemic to Gough Island and are likely to be driven to extinction if invasive mice are not removed.     

Foraging interactions between Wandering Albatrosses Diomedea exulans breeding on Marion Island and long-line fisheries in the southern Indian Ocean

Wandering Albatrosses Diomedea exulans are frequently killed when they attempt to scavenge baited hooks deployed by long-line fishing vessels. We studied the foraging ecology of Wandering Albatrosses breeding on Marion Island in order to assess the scale of interactions with known long-line fishing fleets. During incubation and late chick-rearing, birds foraged further away from the island, in warmer waters, and showed high spatial overlap with areas of intense tuna Thunnus spp. long-line fishing. During early chick-rearing, birds made shorter foraging trips and showed higher spatial overlap with the local Patagonian Toothfish Dissostichus eleginoides long-line fishery. Tracks of birds returning with offal from the Toothfish fishery showed a strong association with positions at which Toothfish long-lines were set and most diet samples taken during this stage contained fishery-related items. Independent of these seasonal differences, females foraged further from the islands and in warmer waters than males. Consequently, female distribution overlapped more with tuna long-line fisheries, whereas males interacted more with the Toothfish long-line fishery. These factors could lead to differences in the survival probabilities of males and females. Non-breeding birds foraged in warmer waters and showed the highest spatial overlap with tuna long-line fishing areas. The foraging distribution of Marion Island birds showed most spatial overlap with birds from the neighbouring Crozet Islands during the late chick-rearing and non-breeding periods. These areas of foraging overlap also coincided with areas of intense tuna long-line fishing south of Africa. As the population trends of Wandering Albatrosses at these two localities are very similar, it is possible that incidental mortality during the periods when these two populations show the highest spatial overlap could be driving these trends.     

An extinct nestorid parrot (Aves,Psittaciformes, Nestoridae) from the Chatham Islands,New Zealand

We describe an extinct parrot from late Quaternary fossil bone deposits on the Chatham Islands, located c. 800 km east of mainland New Zealand. Mitochondrial DNA analyses and osteological characters confirm that the Chatham Islands parrot was a sister taxon to the New Zealand kaka (Nestor meridionalis Gmelin, 1788). The relatively large femur : humerus length ratio and broad pelvis of the Chatham Islands parrot indicate that it had a more terrestrial habit than the kaka. Stable dietary isotope analyses (δ ¹⁵N and δ ¹³C) of Chatham Islands parrot bones suggest that the species may have been mainly herbivorous, although further analyses are required to confirm this. The presence of Chatham Islands parrot bones in early midden deposits shows that the species persisted into the post‐settlement era, and became extinct possibly as a result of habitat loss, hunting pressure, and rat predation following initial Polynesian settlement of the islands (sometime between the 13^th and 16^th centuries AD). © 2014 The Linnean Society of London     

Assortative mating in two populations of Short‐tailed Albatross Phoebastria albatrus on Torishima

Assortative mating is an important pre‐mating isolation mechanism that has been observed in some wild populations of seabirds. The Short‐tailed Albatross Phoebastria albatrus is a globally Vulnerable seabird that breeds mainly on Torishima and the Senkaku Islands in the north‐western Pacific Ocean. Our previous studies suggested that two genetically distinct populations exist, one on Torishima and the other on the Senkaku Islands. Recently, however, several un‐ringed birds in subadult plumage have been observed breeding on Torishima in the Hatsunezaki colony. As almost all birds hatched on Torishima since 1979 have been ringed, the natal site of the un‐ringed birds was suspected to be the Senkaku Islands. Genetic differences between the two populations would reveal the natal sites of un‐ringed birds. By observing the ring status (ringed or un‐ringed) of mating pairs and analysing the mitochondrial DNA (mtDNA) control region 2 of un‐ringed birds, we assessed whether birds that originated from Torishima and the Senkaku Islands achieved pre‐mating isolation. There was a small number of pairs on Torishima that consisted of one ringed and one un‐ringed bird, but the observed number was significantly lower than that expected if ringed and un‐ringed birds mated randomly. Furthermore, mtDNA analyses of nine un‐ringed birds demonstrated that all belonged to a particular haplotype clade from the Senkaku Islands. These results show that birds from Torishima and the Senkaku Islands mate assortatively but that there is incomplete pre‐mating isolation between birds from the two island groups. The pre‐mating isolation of these two populations of Short‐tailed Albatross could arise from differences in the timing of breeding and incompatibility in mating displays. As the divergence between the two populations is unlikely to be sufficient to achieve complete post‐mating isolation, the two groups are likely to be hybridizing. Further studies using molecular and/or behavioural analyses would be required to reveal the evolutionary significance of hybridization between these two populations.     

Incubation energetics of the Laysan Albatross

Summary The energy expenditure of incubating and foraging Laysan Albatross (Diomedea immutabilis, mean body weight 3.07 kg) was estimated by means of the doubly-labelled water technique. During incubation, the energy expenditure was similar to that of resting birds that were not incubating an egg. The energy expenditure of foraging albatross (2072 kJ/day) was 2.6 times that of resting birds. It was concluded that the energy expenditure of the tropical Laysan Albatross was not less than that of species foraging over cold, high-latitude oceans. An energy budget compiled for an incubating pair of albatross revealed that the energy expenditure of the female was greater than that of the male bird, during the incubation period.     

Chemosensory and thermal cue responses in the sub-Antarctic moth Pringleophaga marioni: Do caterpillars choose Wandering Albatross nest proxies?

On the South Indian Ocean Province Islands of the sub-Antarctic, most nutrients are processed through a detritus-based food web. On Marion Island, larvae of the moth Pringleophaga marioni are one of the key decomposers. Abundance of these caterpillars is higher in newly abandoned Wandering Albatross (Diomedea exulans) nests than other habitats, and this observation has been explained by hypotheses regarding the thermal and nutrient advantages of nests. These hypotheses require a mechanism for increasing the abundance of caterpillars, since nests are an ephemeral resource, and here, we determine whether caterpillars respond to chemosensory and thermal cues using a laboratory choice chamber approach. Caterpillars show no significant preference for newly abandoned nest material over no other choice, old nest material, and the common mire moss Sanionia uncinata. Caterpillars that are acclimated to warm (15 °C) conditions do prefer lower (5 °C) to higher (15 °C) temperatures, perhaps reflecting negative effects of prolonged exposure to warm temperatures on growth. Caterpillars also show significant avoidance of conspecifics, possibly because of incidental cannibalism previously reported in this species. Thus, we find no empirical support for nest-finding ability in caterpillars based on chemosensory or thermal cues. It is possible that adult females or very early instar caterpillars show such ability, or high caterpillar density and biomass in nests are an incidental consequence of better conditions in the nests or deposition by the birds during nest construction.     

Harbor seal population decline in the Aleutian Archipelago

Populations of Steller sea lions, northern fur seals, and northern sea otters declined substantially during recent decades in the Bering Sea and Aleutian Islands region, yet the population status of harbor seals has not been assessed adequately. We determined that counts obtained during skiff‐based surveys conducted in 1977–1982 represent the earliest estimate of harbor seal abundance throughout the Aleutian Islands. By comparing counts from 106 islands surveyed in 1977–1982 (8,601 seals) with counts from the same islands during a 1999 aerial survey (2,859 seals), we observed a 67% decline over the ～20‐yr period. Regionally, the largest decline of 86% was in the western Aleutians (n= 7 islands), followed by 66% in the central Aleutians (n= 64 islands), and 45% in the eastern Aleutians (n= 35 islands). Harbor seal counts decreased at the majority of islands in each region, the number of islands with >100 seals decreased ～70%, and the number of islands with no seals counted increased ～80%, indicating that harbor seal abundance throughout the Aleutian Islands was substantially lower in the late 1990s than in the 1970s and 1980s.     

Geographical variation in morphometry of black-browed and grey-headed albatrosses from four sites

Differences in morphometry between five populations of black-browed albatrosses (Diomedea melanophrys) and four populations of grey-headed albatrosses (D. chrysostoma) are examined. Two clear groups of black-browed albatrosses are evident, with birds from the subspecies Diomedea melanophrys impavida showing significant differences in several variables from those from the subspecies Diomedea melanophrys melanophrys. For groups from the latter subspecies, birds from South Georgia had larger measures than those from Kerguelen. A similar pattern to that of Diomedea melanophrys melanophrys was found between the groups of grey-headed albatrosses. Analysis of foraging distances relative to adult body-size index and the duration of chick-rearing periods suggests that differences in chick-provisioning rates between populations of conspecifics could account for at least some of the observed differences in adult morphometry. Accepted: 5 April 1999     

Interannual variation in the diets of two albatross species breeding at South Georgia: implications for breeding performance

The diet and breeding performance of Grey‐headed Albatrosses Thalassarche chrysostoma and Black‐browed Albatrosses Diomedea melanophris breeding at Bird Island, South Georgia, were studied simultaneously during the chick‐rearing period between 1996 and 2000. When samples for all years were combined, cephalopods and crustaceans were the main components in the diet of Grey‐headed and Black‐browed Albatrosses, respectively. However, their diets exhibited interannual variations. Cephalopods were the most important component in the diet of Grey‐headed Albatrosses between 1996 and 1999 (60–75% by mass) but decreased significantly in 2000 (17%), when crustaceans dominated (61%). The Black‐browed Albatross diet varied greatly, with cephalopods being the most important component in 1996 (49% by mass) and 1997 (48%), fish in 1998 (32%) and 1999 (40%), and crustaceans in 2000 (63%). In 1998 and 2000 there was a significant change in the cephalopod species present in the diet of both albatross species, when their breeding success was low. The consumption of the ommastrephid Martialia hyadesi was significantly and positively correlated with Grey‐headed Albatross breeding success. For Black‐browed Albatrosses significant correlations were found between its consumption of the Icefish Champsocephalus gunnari and breeding success, and between its consumption of M. hyadesi and M. hyadesi CPUE (Catch per Unit Effort). These findings suggest that Grey‐headed Albatrosses are more reliant on Antarctic Polar Frontal Zone prey (M. hyadesi and Lamprey Geotria australis) whereas Black‐browed Albatrosses are more dependent on Antarctic prey (Icefish and Antarctic Krill Euphausia superba). The differences between diets of Grey‐headed and Black‐browed Albatrosses breeding on different islands of the Southern Ocean showed that Grey‐headed Albatrosses feed more on oceanic cephalopods (e.g. M. hyadesi) whereas Black‐browed Albatrosses feed primarily on shelf fish (e.g. Blue Whiting Micromesistius australis), suggesting that albatross diets are likely to be influenced by the geographical position of those islands, albatross foraging preference and prey availability.     

Foraging location and range of White-chinned Petrels Procellaria aequinoctialis breeding in the South Atlantic

The foraging range and principal feeding areas of White‐chinned Petrels breeding at South Georgia were determined using satellite telemetry. Foraging trips during incubation lasted 12–15 days and covered 3000–8000 km and 2–11 days and 1100–5900 km during chick‐rearing. Adults covered less distance per day during chick‐rearing (71 km) than during incubation (91 km) but the proportion covered at night (47%) was the same. Mean (31–34 km/h) and maximum (80 km/h) flight velocities were similar during both periods of the breeding season and during day and night. Between incubation shifts, White‐chinned Petrels travelled to the Patagonian shelf; during chick‐rearing they foraged more extensively. Most locations were between 30° to 55°W and 52° to 60°W around South Georgia/Shag Rocks and south to the South Orkney Islands. Diet samples from known foraging locations suggested birds fed mainly on krill and squid. They caught the squid Brachioteuthis? picta and Galiteuthis glacialis around Shag Rocks/South Georgia and also at sites close to the South Orkney Islands; Illex argentinus on the Patagonian shelf. Dispersal of adults after breeding failure was south to the South Orkney Islands then west to the Falkland Islands. This study confirms that breeding White‐chinned Petrels are amongst the widest‐ranging of seabirds; they may minimise competition with other Procellariiformes in the South Atlantic by their more extensive foraging range. The nature and extent of their range also brings substantial risk of high mortality rate in South Atlantic long‐line fisheries.     

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.     

Heteroblasty on Chatham Island: A comparison with New Zealand and New Caledonia

We used a comparative approach to investigate heteroblasty in the Chatham Islands. Heteroblasty refers to abrupt changes in the morphology of leaves and shoots with plant height. Common on isolated islands such as New Caledonia and New Zealand, which once had flightless, browsing birds, heteroblasty is hypothesised to be an adaptation to deter bird browsing. The Chatham Islands are a small archipelago located 800 km off the east coast of New Zealand, which has clear floristic links to New Zealand. However, unlike New Caledonia and New Zealand, the Chathams never had flightless, browsing birds. We investigated heteroblasty on the Chatham Islands by: (1) comparing height-related changes in leaf morphology and branching architecture in several plant taxa with heteroblastic relatives on the New Zealand mainland; (2) characterising changes in leaf morphology in heteroblastic tree species endemic to the Chathams; and (3) comparing overall trends in leaf heteroblasty on the Chathams with New Caledonia and New Zealand. Reversions to homoblasty were observed in the three Chatham Island taxa with heteroblastic relatives on the New Zealand mainland. However, two endemic tree species were clearly heteroblastic; both produced dramatically larger leaves as juveniles than as adults. Inter-archipelago comparisons showed that this trend in leaf morphology is rare among heteroblastic species in New Caledonia and New Zealand. Therefore, while some of our results were consistent with the hypothesis that heteroblasty is an adaptation to avoid bird browsing, other processes also appear to have shaped the expression of heteroblasty on Chatham Island.     

Seabirds attending bottom long-line fishing off southeastern Brazil

Flocks of seabirds attending commercial bottom long-line fishing operations on the coastal shelf off southeastern Brazil show a greater species diversity during the summer than the winter (16 v 9 species), although the number of birds per flock tended to be greater during the cold season. During the summer, the Spectacled Petrel Procellaria aequinoctialis conspi-cillata was the commonest species, followed by the Great Shearwater Puffinus gravis, Cory's Shearwater Calonectris diomedea, skuas Stercorarius spp. and the Yellow-nosed Albatross Diomedea chlororhynchus. During the winter, the White-chinned Petrel Procellaria aequin-octialis, Yellow-nosed Albatross and Black-browed Albatross Diomedea melanophrys were jointly the commonest species. Marked differences in the relative abundance of species were observed between the different sampling periods, probably because of migratory movements but also because of seasonal shifts of the sea currents and the influence of cold fronts. Waters off southeastern Brazil are important feeding areas for some seabird populations nesting in the Tristan da Cunha and Gough group, especially for nonbreeding Spectacled Petrels and post-breeding Yellow-nosed Albatrosses.     

Allozyme and mitochondrial DNA variability within the New Zealand damselfly genera Xanthocnemis,Austrolestes, and Ischnura (Odonata)

Abstract

We collected larval damselflies from 17 sites in the North, South and Chatham Islands, and tested the hypotheses that: (1) genetic markers (e.g., allozymes, mtDNA) would successfully discriminate taxa; and (2) the dispersal capabilities of adult damselflies would limit differentiation among locations. Four species from three genera were identified based on available taxonomic keys. Using 11 allozyme loci and the mitochondrial cytochrome c‐oxidase subunit I (COI) gene, we confirmed that all taxa were clearly discernible. We found evidence for low to moderate differentiation among locations based on allozyme (meani F _ST = 0.09) and sequence (COI) divergence (<0.034). No obvious patterns with respect to geographic location were detected, although slight differences were found between New Zealand's main islands (North Island, South Island) and the Chatham Islands for A. colensonis (sequence divergence 0.030–0.034). We also found limited intraspecific genetic variability based on allozyme data (H_exp < 0.06 in all cases). We conclude that levels of gene flow/dispersal on the main islands may have been sufficient to maintain the observed homogeneous population structure, and that genetic techniques, particularly the COI gene locus, will be a useful aid in future identifications.     

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.