Black-browed Albatross Thalassarche Melanophris Research Articles

Demographic responses to environmental change of the black-browed albatross, sentinel of the Patagonian Shelf Large Marine Ecosystem

In long-lived marine top-predators with delayed sexual maturity such as seabirds, adult survival is predicted to drive population dynamics. Major knowledge gaps exist for the cryptic sub-adult stages of the population. Yet as the oceans undergo dramatic change, investigating the trends of top-predator populations and their responses to environmental variability is key for a process-based understanding of climate change. Using integrated population models based on a longitudinal data set spanning nearly 2 decades, we investigated the demographic rates and environmental drivers shaping the dynamics of a longevous marine top-predator population, the black-browed albatross Thalassarche melanophris in the Falklands. We quantified the dynamics of the whole population, including its cryptic sub-adult stages, and examined the effects of candidate environmental covariates on adult survival and productivity parameters. We found that high survival rates of both adults and juveniles are the main contributors to the growth of this albatross population, the only one that is increasing in the South Atlantic. The breeding parameters were affected by environmental fluctuations through bottom-up processes, with a negative effect of higher sea surface temperatures and a positive effect of wind intensity. The relatively constant adult survival was influenced by deeper ecosystem changes, captured by large-scale indices (Southern Annular Mode). Approximately half of the total population is composed of sub-adults, and the population dynamics are highly sensitive to changes in juvenile survival; addressing current knowledge gaps in these cryptic life-history stages is therefore a conservation goal of primary importance.

Diving behaviour of albatrosses: implications for foraging ecology and bycatch susceptibility

Diving is an ecologically important behaviour that provides air-breathing predators with opportunities to capture prey, but that also increases their exposure to incidental mortality (bycatch) in commercial fisheries. In this study, we characterised the diving behaviour of 26 individuals of three species, the black-browed albatross Thalassarche melanophris, grey-headed albatross T. chrysostoma and light-mantled albatross Phoebetria palpebrata, breeding at Bird Island, South Georgia. Individuals were tracked using Global Location Sensor (GLS)-immersion loggers and time-depth recorders (TDRs) and, for two species, Global Positioning System (GPS) loggers. Although the TDRs recorded 589 dives (defined in this paper as submersion > 1 m), average dive depths and durations were just 1.30–1.49 m and 2.5–3.3 s, respectively, for the three species. In addition, many individuals (22% of black-browed, 20% of grey-headed, and 57% of light-mantled albatrosses; total n = 9, 10 and 7 individuals, respectively) did not dive at all. Most dives occurred at the distal end of foraging trips and were rare during the commuting phase. No dives took place in darkness, despite long periods spent on water at night. The limited and shallow dive activity contrasts with impressions from a previous study using capillary-tube depth gauges (which are less accurate than TDRs) and has implications for the susceptibility of albatrosses to bycatch on longlines. This study provides further support for regulations requiring night setting and increased sink rates of baited hooks to help mitigate albatross bycatch.

The British List: A Checklist of Birds of Britain (9th edition)

The British List: A Checklist of Birds of Britain (9th edition)

Illegal fishing bycatch overshadows climate as a driver of albatross population decline

Effective management of albatross populations requires understanding the impacts of environmental factors on albatross demographics. An integrated modelling approach incorporating multiple data sources can further the understanding of albatross demographics by incorporating error from all components of modeling, and help distinguish between variability related to one factor (e.g. environment) from that of another factor (e.g. density dependence). We applied such an integrated, spatially-explicit population model to quantify the impact of environmental conditions (sea surface temperature, SST), fisheries, and density dependence on a black-browed albatross Thalassarche melanophris population breeding on Kerguelen Island, southern Indian Ocean for the period 1950 to 2011. The model was structured by sex, age-class, and breeding stage, with a 5° × 5° spatial scale and monthly temporal scale. All parameters were estimated within a maximum likelihood framework. This includes estimation of seabird bycatch rates of each of 5 fishing super-fleets, grouped by gear type and reported bycatch rates: (1) Japanese pelagic longline, (2) other pelagic longline, (3) legal demersal longline, (4) trawl, and (5) illegal, unreported, and unregulated (IUU) demersal longline. A decline in the Kerguelen black-browed albatross population occurred between the mid-1990s through the mid-2000s. Our analysis attributes the majority of modelled bycatch to the IUU demersal longline super-fleet operating near Kerguelen Island for this period. Including SST during the incubation period indicated that warm SST favors high breeding success. These results indicate that effective management requires an integrated understanding of the impacts of the environment as well as illegal and legal fishing activities on vulnerable populations.

Review of diseases (pathogen isolation, direct recovery and antibodies) in albatrosses and large petrels worldwide

SummaryAlbatrosses (Diomedeidae) and large petrels (MacronectesandProcellariaspp.) are among the world’s most rapidly declining birds. Some of the most endangered species, Amsterdam AlbatrossDiomedea amsterdamensis,Indian Yellow-nosed AlbatrossThalassarche carteriand Sooty AlbatrossPhoebetria fusca, are at risk from recurrent avian cholera outbreaks. Yet little is known about the overall impact of disease in this group. We compiled all available information on pathogens described in albatrosses and large petrel species listed under the Agreement on the Conservation of Albatrosses and Petrels (ACAP) (n= 31). Available reports (n= 53) comprise nearly 60% of ACAP species (18/31). However, only 38% of them focus on threatened species (20/53), and 43% solely report macroparasite findings (23/53). Black-browed AlbatrossThalassarche melanophrys(Near Threatened) and Southern Giant PetrelMacronectes giganteus(Least Concern) are the two species with higher number of publications (29/53, 55% of all papers). Conversely, seven species on the IUCN Red List have three papers or less each. Most existing research has resulted from disease or mortality investigations and baseline studies (28 and 32%, respectively). Pathogens reported in the subset of ACAP species, included bacteria in seven species (39%), viruses in five (28%), protozoa in four (22%), helminths in nine (50%), ectoparasites in 13 (72%) and fungi in one species (5%). Avian cholera, caused by the bacteriumPasteurella multocida, appears as the most severe threat to ACAP species. Infections by poxvirus are the most common viral finding, yet entail lower population level impact. Few serosurveys report pathogen exposure in these species, but add valuable baseline information. There are numerous obvious gaps in species and geographical coverage and likely under-reporting due to remoteness, accessibility and sporadic monitoring. This insufficient knowledge may be hampering effective protection and management of populations at risk. Attention to species currently affected by avian cholera is of utmost priority.

Albatrosses bathe before departing on a foraging trip: implications for risk assessments and marine spatial planning

SummaryTracking studies of seabirds have generally focused in identifying areas used for foraging, in the hope of highlighting regions of energy transfer which may be important for seabird and general ecosystem conservation and special management. However, some sea areas may serve functions other than providing nutritional resources, which may be equally relevant, particularly if used by large numbers of individuals. In this paper, based on a study of 4 breeding colonies in the Falkland Islands and on 314 individuals tracked, we show that virtually all (97.8%) black-browed albatrosses Thalassarche melanophris (BBA) bathe in the close vicinity of the colony, remaining in the area for nearly an hour, before departing on a foraging trip. This compares with only 20 to 40% of the individuals landing close to the colony at the end of a foraging trip. The observed utilization of marine areas by BBA in a radius of 1 to 5 km around the nesting colony is one order of magnitude higher than elsewhere, including foraging hotspots. Clearly, even long-range flying birds such as albatrosses can make an intensive use of the sea-surface in the immediate vicinity of the colonies, and therefore any threats to seabirds in these areas (disturbance, pollutants, collision with artificial structures and light attraction) can potentially have a major impact at the population level. As such, the close neighbourhood of seabird colonies are potentially highly sensitive areas, and this needs to be taken into account when carrying out risk assessments or during marine spatial planning exercises.

Habitat-mediated population limitation in a colonial central-place forager: the sky is not the limit for the black-browed albatross

Animal populations are frequently limited by the availability of food or of habitat. In central-place foragers, the cost of accessing these resources is distance-dependent rather than uniform in space. However, in seabirds, a widely studied exemplar of this paradigm, empirical population models have hitherto ignored this cost. In part, this is because non-independence among colonies makes it difficult to define population units. Here, we model the effects of both resource availability and accessibility on populations of a wide-ranging, pelagic seabird, the black-browed albatross Thalassarche melanophris. Adopting a multi-scale approach, we define regional populations objectively as spatial clusters of colonies. We consider two readily quantifiable proxies of resource availability: the extent of neritic waters (the preferred foraging habitat) and net primary production (NPP). We show that the size of regional albatross populations has a strong dependence, after weighting for accessibility, on habitat availability and to a lesser extent, NPP. Our results provide indirect support for the hypothesis that seabird populations are regulated from the bottom-up by food availability during the breeding season, and also suggest that the spatio-temporal predictability of food may be limiting. Moreover, we demonstrate a straightforward, widely applicable method for estimating resource limitation in populations of central-place foragers.

Black-browed Albatross Thalassarche melanophris primary moult timing in the fourth prebasic moult

The aging of immature Black-browed Albatrosses Thalassarche melanophris is reasonably well understood using a combination of primary moult sequence and timing (see Appendix), and progression in plumage aspect (bill colour and pattern, head and neck markings, and whitening of the underwing-coverts). The initial work of Prince et al. (1993) and Prince & Rodwell (1994) studied ringed (known-age) non- breeding Black-browed Albatrosses visiting a study colony on Bird Island, South Georgia between December 1989 and February 1990. Adding to this, Bugoni & Furness (2009) examined and photographed a sample of 33 birds captured at sea off the Brazilian coast in February to June 2006 and July to September 2007. Howell (2010, 2012) provided a number of at-sea photographs illustrating many of the immature age groups. These studies are important to understanding the impact of bycatch on different age groups, and to aging and identification for field birders.

Differences in the timing and extent of annual moult of black-browed albatrosses Thalassarche melanophris living in contrasting environments

Moult entails costs related to the acquisition of energy and nutrients necessary for feather synthesis, as well as the impact of reduced flight performance induced by gaps in the wing plumage. Variation in moult strategies within and between populations may convey valuable information on energetic trade-offs and other responses to differing environmental constraints. We studied the moult strategies of two populations of a pelagic seabird, the black-browed albatross Thalassarche melanophris, nesting in contrasting environments. According to conventional wisdom, it is exceptional for albatrosses (Diomedeidae) to moult while breeding. Here we show that black-browed albatrosses breeding on the Falklands regularly moult primaries, tail and body feathers during chick-rearing, and the majority of those at South Georgia show some body feather moult in late chick-rearing. The greater moult-breeding overlap at the Falklands allows the birds to annually renew more primary feathers than their counterparts at South Georgia. The results of the present paper, pooled with other evidence, suggest that black-browed albatrosses from South Georgia face a more challenging environment during reproduction. They also serve to warn against the uncritical acceptance of conventional ideas about moult patterns when using feathers to study the ecology of seabirds and other migrants for which there is scant information at particular stages of the annual cycle.

Seabird and marine mammal attendance in the Chub mackerel Scomber japonicus semi-industrial Argentinian purse seine fishery

We assessed for the first time marine bird and mammal attendance in the Chub mackerel Scomber japonicus semi-industrial coastal purse seine fishery in northern Argentina. Information was gathered during a fishery run from late spring 2007 to early summer 2008. Sixteen marine top predator species attended vessels, and the most abundant seabirds (percent of overall individuals and percent of occurrence) were the Kelp Gull Larus dominicanus (25% and 40% respectively), and White-chinned Petrel Procellaria aequinoctialis (24% and 47% respectively). Other attending bird species were the Black-browed Albatross Thalassarche melanophrys (18.5% and 12% respectively) and South American Tern Sterna hirundinacea (30% and 22% respectively). The most abundant marine mammal's species was the South American Sea Lion Otaria flavescens (2% and 8% respectively). Analysis of environmental and operational variability affecting the abundance of the four main seabird species indicated a clear spatial variability in the numbers of seabirds attending coastal purse seiners. Other factors included fishing operation, time of day, seasonality, and wind intensity and wind direction. Neither seabird nor marine mammal species were observed to be incidentally taken during 82 fishing operations. The results of this study showed that the semi-industrial purse seine fishery operating in coastal waters in northern Argentina may have a relatively minor impact on some marine top predator populations mainly because (1) the fishing grounds are close to shore, and at relatively shallow depths, and (2) for economic reasons, the fishing fleet operates at considerable distance from dense schooling areas. Still, it has to be stressed that data were obtained during operations in which the levels of discards (<2%) were by far lower than the average of 30% reported in the literature. Given this background, further studies including long-term monitoring are needed for an adequate modeling of the interactions and the identification of core areas for seabirds interacting with purse seiners in the waters of northern Argentina.

Seabird attendance and incidental mortality at shrimp fisheries in Golfo San Jorge, Argentina

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 432:125-135 (2011) - DOI: https://doi.org/10.3354/meps09146 Seabird attendance and incidental mortality at shrimp fisheries in Golfo San Jorge, Argentina Diego González-Zevallos1, Pablo Yorio1,2,*, Walter S. Svagelj1 1Centro Nacional Patagónico (CONICET), Blvd. Brown 2915, U9120ACD, Puerto Madryn, Chubut, Argentina 2Wildlife Conservation Society, Amenabar 1595, P 2, Of. 19, C1426AKC, Ciudad de Buenos Aires, Argentina *Corresponding author. Email: yorio@cenpat.edu.ar ABSTRACT: Many seabirds are attracted to trawl vessels to make use of fishery waste, and often this attraction results in increased incidental mortality. We assessed seabird attendance and associated incidental mortality at the Argentine red shrimp Pleoticus muelleri trawl fishery in Golfo San Jorge, Argentina. Information on seabird numbers was gathered in the autumn and winter 2006 and spring 2008, while information on seabird incidental captures was obtained for the period 2005–2007. Eighteen seabird species attended vessels, and the 2 most frequent and abundant seabirds (percent occurrence, median no. haul–1) were the kelp gull Larus dominicanus (>94%, <100) and black-browed albatross Thalassarche melanophrys (>94%, <55). Seabird numbers were significantly lower in winter than the other 2 seasons and highest during discarding activities. Species incidentally killed in nets were the Magellanic penguin Spheniscus magellanicus and imperial cormorant Phalacrocorax atriceps, with a mean capture rate of 0.048 birds haul–1, and for both species, mortality decreased with distance to the coast. Considering the fishery’s fishing effort during each month, the estimated total mortality in the study period was 895 (95% CI: 572 to 1339) penguins and 172 (95% CI: 69 to 305) cormorants. Over 95% of the recorded mortality occurred in 2005, the year when the trawling moratorium generally implemented in the area was not enforced. No interactions with warp cables were recorded. Results highlight the relevance of complying with the current moratorium scheme, as adjusting it to the penguin and cormorant breeding seasons may by a potentially effective management tool. The proximity to the coast of the recorded incidental mortalities indicates the need to re-evaluate the spatial design of the park and/or the definition of management actions beyond the boundaries of the Marine Protected Area. KEY WORDS: Seabird–fishery interactions · Seabird by-catch · Trawlers · Fishing discards · ­Patagonia Full text in pdf format PreviousNextCite this article as: González-Zevallos D, Yorio P, Svagelj WS (2011) Seabird attendance and incidental mortality at shrimp fisheries in Golfo San Jorge, Argentina. Mar Ecol Prog Ser 432:125-135. https://doi.org/10.3354/meps09146 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 432. Online publication date: June 27, 2011 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2011 Inter-Research.

New perspectives on harvesting as one driver of ecosystem dynamics

New perspectives on harvesting as one driver of ecosystem dynamics

Seabird bycatch in the Brazilian pelagic longline fishery and a review of capture rates in the southwestern Atlantic Ocean

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 5:137-147 (2008) - DOI: https://doi.org/10.3354/esr00115 Seabird bycatch in the Brazilian pelagic longline fishery and a review of capture rates in the southwestern Atlantic Ocean Leandro Bugoni1, 2,*, Patricia L. Mancini1, Danielle S. Monteiro3, 4, Loretha Nascimento1, Tatiana S. Neves1 1Projeto Albatroz, Av. dos Bancários 76/22, Ponta da Praia, CEP 11030-300, Santos-SP, Brazil 2Institute of Biomedical and Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, UK 3Núcleo de Educação e Monitoramento Ambiental – NEMA, R. Maria Araújo 450, Cassino, CEP 96207-480, Rio Grande-RS, Brazil 4Fundação Universidade Federal do Rio Grande, Laboratório de Elasmobrânquios e Aves Marinhas, C.P. 474, CEP 96201-900, Rio Grande-RS, Brazil *Email: l.bugoni.1@research.gla.ac.uk ABSTRACT: The southwestern Atlantic Ocean is an important foraging ground throughout the year for several albatross and petrel species. Longline fishing fleets in the region currently pose the main threat for this group of seabirds at sea, and conservation measures are urgently required. We present information on bycatch rates of seabirds in the Brazilian domestic pelagic longline fishery from 2001 to 2007, and review bycatch rates reported for the demersal and pelagic longline fisheries in the southwestern Atlantic Ocean. Overall seabird capture rate for the Brazilian pelagic longline fleet during 63 cruises (656 sets and 788446 hooks) was 0.229 birds per 1000 hooks, varying from 0 to 0.542 according to season. Capture rates were higher between June and November (cold season) and affected mainly the black-browed albatross Thalassarche melanophris (55% of birds captured), the white-chinned petrel Procellaria aequinoctialis, the spectacled petrel Procellaria conspicillata and the Atlantic yellow-nosed albatross Thalassarche chlororhynchos. Capture rates previously reported in the SW Atlantic varied from 0 to 5.03 birds per 1000 hooks, with those reports based on logbooks or fishermen interviews tending to underestimate capture rates, whereas those based on small numbers of hooks or short time periods tend to greatly overestimate rates in both pelagic and demersal longline fisheries. Previous studies have played an important role in delimiting the seabird bycatch problem, forming a baseline for mitigation actions and serving as a guide for improvements in data collection. However, data collected by onboard seabird-dedicated observers are more reliable, provide a greater range of information relating to bycatch, and form a baseline for more robust analysis and addressing further questions. The current study highlights the stochastic nature of seabird fatalities in longline fisheries and the need for extensive sampling to obtain realistic estimates of capture rates covering different years, seasons, vessels, and the range of fishing gear and practices. KEY WORDS: Albatrosses · Petrels · Longline · Incidental capture · Review · Brazil · Fisheries Full text in pdf format PreviousNextCite this article as: Bugoni L, Mancini PL, Monteiro DS, Nascimento L, Neves TS (2008) Seabird bycatch in the Brazilian pelagic longline fishery and a review of capture rates in the southwestern Atlantic Ocean. Endang Species Res 5:137-147. https://doi.org/10.3354/esr00115 Export citation Mail this link - Contents Mailing Lists - RSS Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 5, No. 2-3. Online publication date: December 23, 2008 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2008 Inter-Research.

Seabird bycatch in the Brazilian pelagic longline fishery and a review of capture rates in the southwestern Atlantic Ocean

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 5:137-147 (2008) - DOI: https://doi.org/10.3354/esr00115 Seabird bycatch in the Brazilian pelagic longline fishery and a review of capture rates in the southwestern Atlantic Ocean Leandro Bugoni1, 2,*, Patricia L. Mancini1, Danielle S. Monteiro3, 4, Loretha Nascimento1, Tatiana S. Neves1 1Projeto Albatroz, Av. dos Bancários 76/22, Ponta da Praia, CEP 11030-300, Santos-SP, Brazil 2Institute of Biomedical and Life Sciences, Graham Kerr Building, University of Glasgow, Glasgow G12 8QQ, UK 3Núcleo de Educação e Monitoramento Ambiental – NEMA, R. Maria Araújo 450, Cassino, CEP 96207-480, Rio Grande-RS, Brazil 4Fundação Universidade Federal do Rio Grande, Laboratório de Elasmobrânquios e Aves Marinhas, C.P. 474, CEP 96201-900, Rio Grande-RS, Brazil *Email: l.bugoni.1@research.gla.ac.uk ABSTRACT: The southwestern Atlantic Ocean is an important foraging ground throughout the year for several albatross and petrel species. Longline fishing fleets in the region currently pose the main threat for this group of seabirds at sea, and conservation measures are urgently required. We present information on bycatch rates of seabirds in the Brazilian domestic pelagic longline fishery from 2001 to 2007, and review bycatch rates reported for the demersal and pelagic longline fisheries in the southwestern Atlantic Ocean. Overall seabird capture rate for the Brazilian pelagic longline fleet during 63 cruises (656 sets and 788446 hooks) was 0.229 birds per 1000 hooks, varying from 0 to 0.542 according to season. Capture rates were higher between June and November (cold season) and affected mainly the black-browed albatross Thalassarche melanophris (55% of birds captured), the white-chinned petrel Procellaria aequinoctialis, the spectacled petrel Procellaria conspicillata and the Atlantic yellow-nosed albatross Thalassarche chlororhynchos. Capture rates previously reported in the SW Atlantic varied from 0 to 5.03 birds per 1000 hooks, with those reports based on logbooks or fishermen interviews tending to underestimate capture rates, whereas those based on small numbers of hooks or short time periods tend to greatly overestimate rates in both pelagic and demersal longline fisheries. Previous studies have played an important role in delimiting the seabird bycatch problem, forming a baseline for mitigation actions and serving as a guide for improvements in data collection. However, data collected by onboard seabird-dedicated observers are more reliable, provide a greater range of information relating to bycatch, and form a baseline for more robust analysis and addressing further questions. The current study highlights the stochastic nature of seabird fatalities in longline fisheries and the need for extensive sampling to obtain realistic estimates of capture rates covering different years, seasons, vessels, and the range of fishing gear and practices. KEY WORDS: Albatrosses · Petrels · Longline · Incidental capture · Review · Brazil · Fisheries Full text in pdf format PreviousNextCite this article as: Bugoni L, Mancini PL, Monteiro DS, Nascimento L, Neves TS (2008) Seabird bycatch in the Brazilian pelagic longline fishery and a review of capture rates in the southwestern Atlantic Ocean. Endang Species Res 5:137-147. https://doi.org/10.3354/esr00115 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 5, No. 2-3. Online publication date: December 23, 2008 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2008 Inter-Research.

Seabird mortality at trawler warp cables and a proposed mitigation measure: A case of study in Golfo San Jorge, Patagonia, Argentina

We studied the interaction between seabirds and warp cables in the high-seas Argentine hake Merluccius hubbsi trawl fishery operating in Golfo San Jorge, Argentina, and tested the efficacy of a simple mitigation measure designed to reduce mortality at warp cables. Observations were made onboard hake trawlers during the height of the fishing season, between December 2004 and April 2005. Thirteen seabird species used food made available by fishing operations. The most frequent and abundant seabirds (% occurrence, mean maximum number per haul) were the Kelp gull Larus dominicanus (98.1%, 348.5) and the Black-browed albatross Thalassarche melanophrys (96.1%, 132.2). Contacts with warp cables were recorded for six species in 81.4% of hauls, with a mean number of contacts per haul of 14.4 ± 23.8 (range = 0–127). A total of 53 individuals were killed due to interactions with nets and cables, resulting in a total cable mortality rate of 0.14 birds/haul. Considering the fishery’s fishing effort, the estimated total number of birds killed during the study was 2703 (CV = 0.8), of which 306 (CV = 0.9) were killed due to contacts with warp cables (255 Kelp gulls and 51 Black-browed albatross). The tested device consisted of a plastic cone attached to each warp cable. In hauls with mitigation device, the number of contacts was reduced by 89% and no seabirds were killed. Mean distances between seabirds and cables were significantly larger in hauls with than without mitigation device (2.6 vs 0.9 m). The proposed device could be easily applied in this and other trawl fisheries operating in Argentine waters. Increased effort should be placed in implementing mitigation measures and the monitoring of cable related mortality associated to high-seas trawlers operating in the Argentine Continental Shelf.

Environmental variation and experience‐related differences in the demography of the long‐lived black‐browed albatross

1. It has been largely demonstrated that demographic performances of animals increase with age or experience as a result of an improvement of foraging skills, an increasing reproductive effort or a selection process. However, little is known about the age or experience-related response of populations to environmental variations. Theoretical studies consider that age-related variations of the performances are greater under more restricting conditions, but this has rarely been tested. 2. We tested this hypothesis on a long-lived species, black browed albatross Thalassarche melanophrys Temminck, using a long-term capture-mark-recapture data set. We investigated the responses of a population to climate, by studying the effects of climatic factors and breeding experience on survival and breeding success. 3. First-time breeders appear to be poorer performers compared with experienced adults, with lower reproductive success and lower survival. In addition, interannual variations of demographic traits were partly explained by climatic indices, reflecting environmental variations. The survival probability of black-browed albatrosses varied with experience and climate, and differences being greater under harsh conditions. By contrast, the reproductive success of inexperienced individuals was affected by climatic fluctuations in the same way as the experienced ones. 4. First breeding event acts as a strong selective process on the highly heterogeneous class of inexperienced individuals, suggesting the increase in survival and breeding success with experience may mainly reflect a reduction in the heterogeneity among individual qualities.

Nearest neighbors as foraging cues: information transfer in a patchy environment

To assess the importance of both conspecifics and heterospecifics as cues to prey loca- tion, we analyzed patterns of seabird species co-occurrence along shipboard transects conducted near South Georgia (55° S, 35° W) during the austral summer. Using data collected over 9 d and 1500 km ocean, we focused on the behavior of 4 seabird species that are abundant in Antarctic waters: black-browed albatross Thalassarche melanophrys, white-chinned petrel Procellaria aequinoctialis, prion Pachyptila spp., and diving petrel Pelecanoides spp. We identified and recorded the behavior of the nearest neighbors of focal, flying individuals and demonstrated strong intraspecific associa- tions for all 4 species. More conspecific neighbors of prions and diving petrels were also observed fly- ing than expected due to chance. This result suggests that these birds may forage co-operatively with conspecifics. In contrast, more heterospecific neighbors were feeding than expected, and more heterospecific neighbors of white-chinned petrels, prions, and diving petrels were black-browed albatross and groups of penguins and Antarctic fur seals Arctocephalus gazella than expected by chance. We show that associations among foraging birds are not random and are not due to species- specific differences in foraging habitat. We present methods that can be used to measure and com- pare the strength of intra- and interspecific association among predators at sea. Our results suggest that local enhancement is an important component of the foraging strategies of Antarctic seabirds.

Long-term population increase of black-browed albatrosses Thalassarche melanophrys at Heard Island, 1947/1948 – 2000/2001

The breeding population of the black-browed albatross Thalassarche melanophrys has increased at Heard Island since the first census data were obtained in 1947/1948. Four breeding localities are known, and all populations have increased in the period 1947/1948–2000/2001. The breeding population is estimated to have been approximately 200 pairs in 1947/1948. Based on 2000/2001 census data, the population has increased to a minimum of approximately 600 pairs over the 53 years. Two mechanisms, that of increased prey availability through scavenging discards from trawlers operating within their foraging range, and climatic amelioration, are proposed as hypotheses for this increase.