Black-browed Thalassarche Melanophris Research Articles

Multi-decadal changes in the at-sea distribution and abundance of black-browed and light-mantled sooty albatrosses in the southwest Pacific Ocean

Abstract Many long-term studies have reported changes in seabird abundance and distribution in response to climate change and various anthropogenic activities. However, a greater understanding of how species are responding to change over large spatial and temporal scales are required—particularly at high latitudes such as the Southern Ocean. We examined black-browed Thalassarche melanophris (BBAL) and light-mantled sooty Phoebetria palpebrata albatross (LMSA) observations spanning over 50 years. Both species have a wide-ranging distribution in a rapidly changing Southern Ocean. We used generalized additive models (GAMs) to investigate environmental drivers of their abundance and occurrence. Our results show that climate indices, sea surface temperature and sea surface height are the main drivers influencing the distribution and abundance of both species. The abundance of BBAL southeast of Australia was observed to be decreased substantially whereas no significant change was observed in the abundance of LMSA. Both species demonstrated contrasting distributions along their latitudinal gradient with BBAL showing early stages of a southward range shift. Our analyses suggest that responses to climate change are species-specific. These rare, long-term data have provided an understanding of species’ responses to past changes in the marine environment and can provide critical information for future conservation and management.

Disentangling the Influence of Three Major Threats on the Demography of an Albatross Community

Climate change, fisheries and invasive species represent three pervasive threats to seabirds, globally. Understanding the relative influence and compounding nature of marine and terrestrial threats on the demography of seabird communities is vital for evidence-based conservation. Using 20 years of capture-mark-recapture data from four sympatric species of albatross (black-browedThalassarche melanophris, gray-headedT. chrysostoma, light-mantledPhoebetria palpebrataand wanderingDiomedea exulans) at subantarctic Macquarie Island, we quantified the temporal variability in survival, breeding probability and success. In three species (excluding the wandering albatross because of their small population), we also assessed the influence of fisheries, oceanographic and terrestrial change on these rates. The Southern Annular Mode (SAM) explained 20.87–29.38% of the temporal variability in survival in all three species and 22.72–28.60% in breeding success for black-browed and gray-headed albatross, with positive SAM events related to higher success. The El Niño Southern Oscillation (ENSO) Index explained 21.14–44.04% of the variability in survival, with higher survival rates following La Niña events. For black-browed albatrosses, effort in south-west Atlantic longline fisheries had a negative relationship with survival and explained 22.75–32.21% of the variability. Whereas increased effort in New Zealand trawl fisheries were related to increases in survival, explaining 21.26–28.29 % of variability. The inclusion of terrestrial covariates, reflecting extreme rainfall events and rabbit-driven habitat degradation, explained greater variability in trends breeding probability than oceanographic or fisheries covariates for all three species. These results indicate managing drivers of demographic trends that are most easily controlled, such as fisheries and habitat degradation, will be a viable option for some species (e.g., black-browed albatross) but less effective for others (e.g., light-mantled albatross). Our results illustrate the need to integrate fisheries, oceanographic and terrestrial processes when assessing demographic variability and formulating the appropriate management response.

Introduced species and extreme weather as key drivers of reproductive output in three sympatric albatrosses

Invasive species present a major conservation threat globally and nowhere are their affects more pronounced than in island ecosystems. Determining how native island populations respond demographically to invasive species can provide information to mitigate the negative effects of invasive species. Using 20 years of mark-recapture data from three sympatric species of albatrosses (black-browed Thalassarche melanophris, grey-headed T. chrysostoma, and light-mantled albatrosses Phoebetria palpebrata), we quantified the influence of invasive European rabbits Oryctolagus cuniculus and extreme weather patterns on breeding probability and success. Temporal variability in rabbit density explained 33–76% of the variability in breeding probability for all three species, with severe decreases in breeding probability observed after a lag period following highest rabbit numbers. For black-browed albatrosses, the combination of extreme rainfall and high rabbit density explained 33% of total trait variability and dramatically reduced breeding success. We showed that invasive rabbits and extreme weather events reduce reproductive output in albatrosses and that eliminating rabbits had a positive effect on albatross reproduction. This illustrates how active animal management at a local breeding site can result in positive population outcomes even for wide ranging animals like albatrosses where influencing vital rates during their at-sea migrations is more challenging.

Factors influencing the habitat use of sympatric albatrosses from Macquarie Island, Australia

Differences in habitat use of sympatric species are influenced by variability in functional morphology and life history trade-offs and are expected to shape species resilience to environmental change. To determine differences in year-round habitat use and gain insight into how morphological and life history traits influence foraging of an albatross community from subantarctic Macquarie Island, Australia (54.6°S, 158.9°E), we quantified the physical features associated with high residence time for 10 black-browed Thalassarche melanophris; 10 grey-headed T. chrysostoma; 15 light-mantled Phoebetria palpebrata; and 12 wandering albatrosses Diomedea exulans tracked in 1994-2009. Overlap among the 4 species was greatest close to the island during the breeding season, extending north into the Tasman Sea. Nevertheless, black-browed albatrosses ranged more locally than the other species, perhaps because they have a shorter breeding cycle and morphological traits that result in less efficient flight and greater capacity to outcompete other species for prey. Nonbreeding albatrosses showed high variability in habitat use across wide ocean expanses, but all used productive frontal regions and mesoscale eddies. Increased residence times during the breeding and nonbreeding periods were associated with moderate wind speeds for all species (excluding breeding black-browed albatrosses), indicating that birds used areas where aerodynamic performance was enhanced. Given patterns in residence time at sea, and the functional and life history adaptations of each species, we suggest that black-browed albatrosses breeding on Macquarie Island will be more vulnerable to expected future climate-driven changes to wind patterns in the Southern Ocean, and potential latitudinal shifts in the Subantarctic Front.

Cephalopods in the diet of nonbreeding black-browed and grey-headed albatrosses from South Georgia

The food and feeding ecology of albatrosses during the nonbreeding season is still poorly known, particularly with regard to the cephalopod component. This was studied in black-browed Thalassarche melanophris and grey-headed T. chrysostoma albatrosses by analysing boluses collected shortly after adults returned to colonies at Bird Island, South Georgia (54°S, 38°W), in 2009. Based on stable isotopic analyses of the lower beaks, we determined the habitat and trophic level (from δ13C and δ15N, respectively) of the most important cephalopods and assessed the relative importance of scavenging in terms of the albatrosses’ feeding regimes. Based on lower rostral lengths (LRLs), the main cephalopod species in the diets of both albatrosses was Kondakovia longimana, by frequency of occurrence (F > 90 %), number (N > 40 %) and mass (M > 80 %). The large estimated mass of many squid, including K. longimana, suggests that a high proportion (>80 % by mass) was scavenged, and that scavenging is much more important during the nonbreeding season than would be expected from breeding-season diets. The diversity of cephalopods consumed by nonbreeding birds in our study was similar to that recorded during previous breeding seasons, but included two new species [Moroteuthis sp. B (Imber) and ?Mastigoteuthis A (Clarke)]. Based on similarities in LRL, δ13C and δ15N, the squid consumed may have been from the same oceanic populations or region, with the exception of Taonius sp. B (Voss) and K. longimana, which, based on significant differences in δ15N values, suggest that they may have originated from different stocks, indicating differences in the albatrosses’ feeding regimes.

Foraging areas of black-browed and grey-headed albatrosses breeding on Macquarie Island in relation to marine protected areas

1. Although marine protected areas (MPAs) are often established to protect threatened top-order predators, there is a paucity of data that can be used to evaluate their efficacy in achieving this purpose. 2. We assessed the effectiveness of a network of MPAs around Macquarie Island in the Southern Ocean by examining the foraging areas of breeding black-browed Thalassarche melanophrys and grey-headed albatrosses T. chrysostoma. 3. During late incubation and brood periods over 90% of time spent foraging by black-browed albatrosses was contained within MPAs, principally the Economic Exclusion Zone (EEZ) around Macquarie Island. In contrast, grey-headed albatrosses spent only 34% of their time foraging in MPAs. 4. Black-browed and grey-headed albatrosses spent 30% and 15% of their respective foraging times in the Marine Park around Macquarie Island. 5. Both black-browed and grey-headed albatrosses foraged in Antarctic waters under the jurisdiction of the Convention for the Conservation of Antarctic Marine Living Resources (CCAMLR), accounting for 5% and 12% of the total foraging times respectively. 6. The spatial extent of MPAs around Macquarie Island appear to adequately cover much of the foraging distribution of breeding black-browed albatrosses from Macquarie Island. 7. Breeding grey-headed albatrosses spend significantly more time in waters outside the spatial extent of the surrounding MPAs and are at higher risk from fisheries activities and other threats. 8. Further information on the foraging movements both of albatrosses outside the breeding season and of juvenile albatrosses is required to more fully assess the efficacy of MPAs in protecting foraging habitats of these species. Copyright © 2005 John Wiley & Sons, Ltd.

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.