Macronectes Research Articles

Abundance and breeding distribution of seabirds in the northern part of the Danco Coast, Antarctic Peninsula

Seabird abundances and breeding distribution have the potential to serve as ecological indicators. The western Antarctic Peninsula is one of the three sites in the world with the greatest increases in local temperature during the last 50 years. The aim of this study was to monitor the distribution and abundance of breeding populations of seabirds in the northern sector of the Danco Coast, north-west of the Antarctic Peninsula, during the breeding season 2010/11. The birds were the Wilson's storm petrel ( Oceanites oceanicus ), South Polar skua ( Stercorarius maccormicki ), kelp gull ( Larus dominicanus ), Antarctic tern ( Sterna vittata ), snowy sheathbill ( Chionis alba ), chinstrap penguin ( Pygoscelis antarctica ), southern giant petrel ( Macronectes giganteus ), gentoo penguin ( Pygoscelis papua ), Cape petrel ( Daption capense ) and Antarctic shag ( Phalacrocorax bransfieldensis ). Annual breeding population growth increased in pygoscelids, southern giant petrel and sheathbill, and for the remaining species, breeding population trends were stable. Given that seabird populations can provide valuable information on the conditions of their feeding and nesting environments, this study highlights the need to maintain basics monitoring studies. Keywords: Seabird abundances; breeding distribution; Danco Coast; Antarctic Peninsula (Published: 28 February 2013) Citation: Polar Research 2013, 32 , 11133, http://dx.doi.org/10.3402/polar.v32i0.11133

Reducing effects of trawl fishing on seabirds by limiting foraging opportunities provided by fishery waste

By-catch of seabirds on trawl-fishing gear has been reported worldwide, and is exacerbated by the discharge of fisheries waste. We compared the attraction of seabirds to three forms of fishery waste—unprocessed discharge (offal, fish discards), hashed discharge (smaller chunks passed through a hasher pump) and cutter pump discharge (waste passed through the hasher and a cutter pump to further reduce particle size)—to identify the discharge form that most effectively reduced the risk of seabird by-catch. Seabird responses measured within specified areas astern of the vessel were the abundance of: large albatrosses (Diomedea spp.), small albatrosses and giant-petrels (Thalassarche spp.; Southern Giant-Petrels, Macronectes giganteus; and Northern Giant-Petrels, M. halli), Cape Petrels (Daption capense) and all other procellariid species. Seabirds on the water were less numerous during cutter pump and hashed discharge relative to unprocessed discharge (except small albatrosses—cutter treatment). Also, in some cases, the total number of birds decreased, relative to unprocessed discharge treatments (but not small and large albatrosses—cutter treatment). Particle size may be less important for reducing abundances than temporal discharge patterns, which affected how birds tracked the discharge stream. Manipulating discharge characteristics can reduce seabird attraction to fishing vessels. However, the risk of by-catch remained lowest when no discharging occurred.

Stable isotopes identify age- and sex-specific dietary partitioning and foraging habitat segregation in southern giant petrels breeding in Antarctica and southern Patagonia

We examined the isotopic signatures (δ13C, δ15N) of adult body feathers from southern giant petrels Macronectes giganteus collected at two breeding colonies in Antarctica (Potter Peninsula and Cape Geddes) and one in southern Patagonia (Observatorio Island), as well as in whole blood collected from adults of both sexes at each Antarctic colonies and from chicks at Potter Peninsula. As body feather moult is a continuous process in giant petrels, feathers provide an integrated annual signal of an adult’s diets and foraging habitats. In contrast, the stable isotope values of adult and chick blood are reflective of their diets during the breeding season. We found that sex-specific dietary segregation in adults breeding in Antarctica was notable during the breeding season (blood samples) but absent when examined across the entire year (feather samples). In addition, blood stable isotope values differed between chicks and adults, indicating that adults provision their offspring with a relatively higher amount of penguin and seal prey that what they consume themselves. This finding confirms previous work that suggests that chicks are preferentially fed with prey of presumably higher nutritional value such as carrion. Finally, based on isotopic differences between major oceanographic zones in the Southern Ocean, our data indicate population-specific differences in foraging distribution, with Antarctic populations move seasonally between Antarctic and subantarctic zones, while Patagonian populations likely forage in subtropical waters and in continental shelf habitats year-round.

Non-Target Species Management for the Macquarie Island Pest Eradication Project

Author(s): Springer, Keith; Carmichael, Noel | Abstract: Mitigation of non-target species impacts is a key challenge of the Macquarie Island Pest Eradication Project (MIPEP). The project aims to eradicate rodents and European rabbits from sub-Antarctic Macquarie Island through the aerial application of cereal-based brodifacoum bait, followed by a hunting program targeting surviving rabbits. Aerial baiting was attempted in winter 2010 but postponed due to sustained adverse weather that suspended helicopter operations. Following limited baiting in 2010 (10% of the island), non-target mortality of 960 individuals across 6 (of 27) seabird and duck species was recorded. In response, the Australian and Tasmanian governments conducted a review of the project. The review established that some species would be adversely affected by the project in the short-term, but that the island’s ecosystem and most other island species would substantially benefit from pest eradication, confirming the assessments in the Environmental Impact Statement prepared prior to the operation. Enhanced mitigation measures were recommended to minimise non-target species impacts. Of several potential mitigation measures assessed, two principal measures were adopted: releasing Rabbit Haemorrhagic Disease Virus to reduce the rabbit population prior to baiting, thus minimising the number of rabbit carcasses containing poison residues available for consumption by scavengers; and increasing the effort of field teams during and after baiting to remove carcasses (the primary 2010 strategy), in an attempt to minimise the exposure of scavengers to toxic residues. Baiting resumed in May 2011 and two island-wide drops were completed by July 2011. Seabird mortality was monitored, with over 1,460 dead birds of the same species found that were affected in 2010, primarily scavenging seabirds such as kelp gulls, giant petrels, and skua. No species was considered to have sustained impacts that threatened the viability of the local population. King penguin colonies were closely monitored during helicopter over-flights and only minor and transitory impacts were observed. Wandering albatross nests were cleared of bait and chicks were not affected. No marine mammal impacts were recorded. If successful, the MIPEP will be the largest and most complex sub-Antarctic island rabbit and rodent eradication yet undertaken.

Responses of an Antarctic Southern Giant Petrel Population to Climate Change

Responses of an Antarctic Southern Giant Petrel Population to Climate Change

Foraging Distribution of an Antarctic Southern Giant Petrel Population

Foraging Distribution of an Antarctic Southern Giant Petrel Population

Beak abnormality in Coturnixcoturnix japonica

A reporting of an abnormality in the beak in a male Japanese quail, Coturnixcoturnix japonica, has been discussed in this paper. During the behavioral study of Japanese quails, a male differed markedly from the others due to its comparatively longer beak. The maxilla was abnormally elongated and curved over the mandible, which made it difficult to feed and drink.Beak deformities has been previously reported in the Antarctic Cormorant,Phalacrocoraxbransfieldensischick; White winged Becard,Pachyramphuspolychopterus; Passerines (Craves); Brown headed Cowbird; Black Wheatears, Oenantheleucura; Southern Giant Petrel, Macronectesgiganteus chick. But no such record of beak deformity in japanese quail has been studied. The reason behind this anomaly can be a subject of research.

Refining Tori lines to further reduce seabird mortality associated with demersal trawlers in the South Atlantic

Fisheries-related mortality of globally threatened albatrosses and petrels in the Falkland Islands is largely attributed to collisions with warp cables on stern trawlers. Following the introduction Tori lines, also known as bird-scaring lines, in 2004, incidental mortality has been substantially reduced. However, there is still a requirement for further development and optimisation of mitigation methods. In this paper, we present results of sea trials to compare the efficacy of a modified Tori line design with the initial (2004) design. The modified design resulted in 28 and 33% fewer warp contacts than the 2004 design for all species, and high-risk species (black-browed albatross and giant petrels), respectively. Surprisingly, these differences were not found to be statistically significant. However, the modified design was more effective at reducing interactions with the Tori lines themselves. The modified design provided better coverage and protection of the warps, particularly in crosswinds, and was safer for the crew to use. Our study highlights the importance of continued research and development in the field of bycatch mitigation and has relevance for trawl fisheries globally.

Seasonal patterns of prolactin and corticosterone secretion in an Antarctic seabird that moults during reproduction

In avian species that have evolved life-history strategies wherein molt and breeding overlap, there are potential conflicts between the regulatory roles of baseline prolactin and corticosterone in parental care (positive) and moult (negative). We describe seasonal patterns of hormonal secretion, moult, and parental behaviour in sibling species of giant petrels ( Macronectes spp.) which begin moult during the incubation/early chick-rearing stage of reproduction. With the exception of male Southern giant petrels ( Macronectes giganteus), prolactin secretion and moult in Northern ( Macronectes halli) and female Southern giant petrels conformed to those observed in all other avian species, with the initiation of moult coincident with decreases from peak prolactin levels. However, male Southern giant petrels began moulting early in incubation when prolactin was increasing and had not yet peaked, which suggests a requirement of prolactin for incubation behaviour and a dissociation of prolactin from moult. Corticosterone showed little seasonal variation and no relationship with moult. When comparing prolactin, corticosterone, and moult in failed vs. active breeders, we found that failed breeding enabled a more rapid down-regulation of prolactin, thus facilitating a more rapid moult. We present specific examples of the behavioural ecology of giant petrels which we conclude help mediate any potential hormonal conflicts between parental care and moult.

Recoveries of juvenile Giant Petrels in regions of ocean productivity: potential implications for population change

Explaining long-term population change for migratory seabirds such as Giant Petrels (Macronectes spp.) has proven elusive because only aspects of adult life-histories have been studied. There is a paucity of demographic data for juveniles however; there is a considerable amount of leg-band recovery location data for younger age-classes. Nestlings were leg-banded at two sub-Antarctic islands, and at two higher latitude Antarctic breeding colonies. Bands were most often recovered in winter within six months of liberation. Banded fledglings were recovered in known productive upwelling biomes. The birds had travelled between 350 and 6150 km downwind from their natal colonies to reach these biomes. The distances fledglings travelled to reach the biomes were correlated with the observed population trends at their natal colonies; negative/positive population trends were correlated with great/lesser distances travelled. This study highlights the potential importance juvenile life-history attributes when considering population change for long-lived seabird species, and identifies rich upwelling regions such as the Humboldt and Benguelen Currents that might be important foraging areas for this and other Procellariiform species with high conservation values.

Effectiveness of tori-lines for further reduction of incidental catch of seabirds in pelagic longline fisheries

To improve the performance of tori-lines (bird-scaring lines) in reducing incidental catch of large seabirds (albatrosses and giant petrels) in the pelagic longline fishery, we analyzed factors affecting the performance of tori-lines based on data collected by Japanese scientific observers in the southern bluefin tuna Thunnus maccoyii fishery from 2002 to 2005. We classified the variety of tori-lines by the main tori-line length and the streamer type. Two types of streamers were identified: type A, several long streamers made of nylon cord attached to the main tori-line by metal swivels; type B, many short streamers made of polypropylene packing bands braided into the main tori-line. In a model analysis, we found that the main tori-line length was an important factor affecting tori-line performance, and the two types of streamers had similar effectiveness. Since the light type B streamer has the advantage of practical feasibility, this type can be another option for use in tori-lines if used with a main tori-line of sufficient length.

ANTARCTIC AND SUB-ANTARCTIC SEABIRDS IN SOUTH AMERICA: A REVIEW

We analyzed the reports of Antarctic and Sub-antarctic birds in South American Countries according to scientific papers and gray literature. Forty-eight species were found, and they were observed to occur over oceanic and/or coastal areas of the countries surveyed. Chile was found to present the highest number of seabird species (39), followed by Brazil (38). Species that were less frequently found were Pygoscelis adeliae , Thalassoica antarctica , Pagodroma nivea , Pachyptila salvini and Pterodroma inexpectata, and these were observed only in a single country each. Diomedea exulans , D. epomophora , Thalassarche melanophris , Macronectes giganteus , Fulmarus glacialoides , Pachyptila desolota and Oceanites oceanicus were the seabird species most frequently observed, and were found in six out of the seven countries analysed. Of all species found, three are considered endangered species, eight are considered vulnerable, another eight are considered near threatened, according IUCN.

Oceanographic and biological landscapes used by the Southern Giant Petrel during the breeding season at the Patagonian Shelf

The study of how and why marine animals distribute themselves at sea has important conservation and management implications of the species and their habitats. We characterize the oceanographic and biological landscapes of the marine areas used by breeding Southern Giant Petrels (Macronectes giganteus) at Patagonian colonies and explore inter-sexual and inter-colony differences. The at-sea movements of 16 adults (7 males and 9 females) were studied by means of satellite telemetry techniques during 1999, 2000, 2002, and 2004 breeding seasons. Southern Giant Petrels utilized an oceanographic scenario characterized by high productivity, warm sea surface temperature, and shallow waters. The biological landscape was characterized by a high availability of squid and carrion nearby colonies. Females spent more time in the shelf break and exploited deeper waters than males. In contrast, males spent more time in coastal areas and they showed a higher spatial overlap with areas of high squid density than females. Such a prosperous foraging scenario for both sexes may play a key role in the growth of the breeding population of Southern Giant Petrel Patagonian colonies.

Isolation and characterization of Salmonella enterica from Antarctic wildlife

In recent years, the human presence in Antarctica has increased and as a consequence, the possibility of microorganisms’ introduction. The aims of this work were to determine the presence of Salmonella enterica in Antarctic seabirds and sea mammals, to characterize the isolates identified, and to determine the genetic relation of Antarctic S. enterica isolates among them and compare with isolates of human, animal, and food sources recovered in Argentina. During the summer 2000 and 2002 in Potter Peninsula, and during the summer 2001 and 2003 in Hope Bay, a total of 1,739 fecal samples from Antarctic animals were collected and analyzed. In summer 2000, S. Newport and S. Enteritidis were isolated from 8.9% of southern giant petrels (Macronectes giganteus). In summer 2003, S. Enteritidis was isolated from 1.5% of Adelie penguins (Pygoscelis adeliae), from 5.5% of skuas (Stercorarius sp.), from 5.4% of kelp gulls (Larus dominicanus), and from 5.6% of Weddell seals (Leptonychotes weddelli). All the isolates belonging to the same serovar showed indistinguishable genomic profiles by Pulse-Field Gel Electrophoresis (PFGE) with XbaI and BlnI restriction enzymes and by Random Amplified Polymorphic DNA (RAPD-PCR). In addition, these Antarctic strains were different from S. enterica isolates from different sources identified in Argentina during the same or close time periods.

Individual state and survival prospects: age, sex, and telomere length in a long-lived seabird

Identifying markers that are indicative of individual state, related to fitness, and which could be used to study life-history tradeoffs in wild populations is extremely difficult. Recently, it has been suggested that telomeres, the ends of eukaryote chromosomes, might be useful in this context. However, little is known of the link between telomere length and fitness in natural populations and whether it is a useful indicator of biological state. We measured average telomere length in red blood cell samples taken from a wide age range of individuals of a very long-lived and highly sexually dimorphic seabird, the southern giant petrel (Macronectes giganteus). We examined the relationship with age, sex, and subsequent survival over an 8-year period. Telomere length was longer in chicks than adults. Within the adult group, which ranged in age from 12 to 40 years, telomere length was not related to age. For the first time in birds, there was some evidence of a sex difference. Male giant petrels, which are substantially larger than females, had significantly shorter telomere lengths than females. This difference was evident from an early stage in life and is likely to relate to differences in growth trajectories. Those adults that died during the 8-year time window following the telomere length measurement had significantly shorter telomere lengths than those that survived this period, irrespective of age or sex, neither of which were significant predictors of survival. These results show that relatively short telomere length is related to future life expectancy at any adult age, demonstrating its usefulness as a state variable.

Seabird mortality associated with ice trawlers in the Patagonian shelf: effect of discards on the occurrence of interactions with fishing gear

This study investigated the level of seabird mortality caused by the domestic trawl fleet (freshies) for hake (among other less important targets) operating in waters off central Patagonia (37–48°S), analyzing the effect of environmental and operational variability on the level of seabird interactions. With a total of 135 vessels, the fleet is one of the largest in Argentina. Specifically tasked seabird observers were placed onboard trawlers during the summer and winter seasons of the years 2006 and 2007. The type and number of seabird interactions (i.e. contacts with fishing gear) were recorded during shooting and hauling operations, covering 72 days of observation and 328 trawls. Black-browed albatrosses, white-chinned petrels Procellaria aequinoctialis, southern giant petrels Marconectes giganteus and southern royal albatrosses Diomedea epomophora were the most abundant species interacting with trawlers. Confirmed mortalities of black-browed and southern royal albatrosses were the result of collisions and entanglement with the warp cable while birds were scavenging. The estimated total mortality rate was 0.017 birds h−1 and 0.105 birds per vessel per day. The intensity of interactions (in terms of the number of contacts per unit time) was largely explained by the distribution of the fishing effort. Seasonality and the incidence of discards were the strongest factors explaining the occurrence of seabird interactions. The total annual mortality in the trawl fleet under investigation was roughly estimated to be from several hundred to over a thousand albatrosses. However, these figures should be considered preliminary due to the limited spatial and temporal coverage of data and the fact that estimations were based on a low number of observed mortalities. The implementation of a strategic discard management may significantly reduce the number of seabird mortalities from collisions with warp cables or improve the effectiveness of other complementary mitigation methods. Urgent implementation of mitigation measures is needed in this fleet to reduce the mortality of albatrosses and petrels along the Patagonian shelf.

Reducing interactions between seabirds and trawl fisheries: Responses to foraging patches provided by fish waste batches

Seabird bycatch in trawl fisheries is driven by the attraction of birds to foraging opportunities, i.e., the discharge of catch processing waste and the contents of trawl nets. The risk of seabird captures increases with seabird abundance and exposure to fishing gear. We investigated (1) how quickly seabirds responded to discharges of trawl catch processing waste and (2) whether decreasing numbers of seabirds attended trawlers during processing waste discharge events as the time interval between these events increased. Waste was retained onboard the vessel for four different holding periods (30 min, 2 h, 4 h, 8 h), one of which was applied each day using a randomised block design. We determined seabird responses to batch discharge events after the prescribed holding periods using the abundance of large (albatrossses and giant petrels Macronectes spp.) and small (all other petrels except cape petrels Daption capense, shearwaters and prions) seabirds in a semi-circle of 40 m radius, centred on the stern of the experimental trawler. Seabird responses reflected the type of discharge released: birds moved from the air to the water, as the amount of food available increased from no discharge, through sump discharge to batch discharge. When discharge occurred, seabird abundance increased faster than could be resolved with the 5 min sampling period. However, abundance decreased more slowly over a 10–15 min period after the discharge event. The number of large seabirds attending the vessel during discharge events decreased significantly when waste was held for 4 h. For small birds, significant decrease occurred after 8 h. Such holding periods emphasise the tenacity of foraging seabirds, although we have not evaluated any long-term habituation to a particular discharge regime. While holding waste for less than 4 h may not reduce seabird attendance during discharge events, holding for shorter intervals can still reduce bycatch risk, e.g., prior to and during net shooting and hauling.

Interdecadal changes in at‐sea distribution and abundance of subantarctic seabirds along a latitudinal gradient in the Southern Indian Ocean

AbstractLong‐term demographic studies have recently shown that global climate change together with increasing direct impacts of human activities, such as fisheries, are affecting the population dynamics of marine top predators. However, the effects of these factors on species distribution and abundance at sea are still poorly understood, particularly in marine ecosystems of the southern hemisphere. Using a unique long‐term data set of at‐sea observations, we tested for interdecadal (1980s vs. 2000s) changes in summer abundance and distribution of 12 species of Albatrosses and Petrels along a 30° latitudinal gradient between tropical and Antarctic waters of the southern Indian Ocean. There were contrasting effects of climate change on subantarctic seabird distribution and abundance at sea. While subtropical waters showed the highest rate of warming, the species that visited this water mass showed the greatest changes in distribution and abundance. The abundance of Wandering Albatrosses (Diomedea exulans), White‐chinned Petrels (Procellaria aequinoctialis) and Giant Petrels (Macronectes sp.) declined markedly, whereas the other species showed contrasting trends or did not change. With the exception of the White‐chinned Petrel, these decreases were at least partly related to regional increase in sea surface temperature. The southward shift of Wandering Albatross and Prions (Pachyptila spp.) distributions could be ascribed to species redistribution or decrease in abundance due to warming of the subtropical waters. Surprisingly, White‐chinned Petrel distribution shifted northward, suggesting more complex mechanisms. This study is the first to document a shift in species range in the Southern Ocean related to climate change and contrasting abundance changes. It suggests that some species might experience more severe impacts from climate change depending on the water masses they visit. As climate changes are predicted to continue in the next decades, understanding species responses to climate change is crucial for conservation management, especially when their conservation status is critical or unknown.

Ecogeographical variation in the Southern Giant Petrel (Macronectes giganteus)

The Southern Giant Petrel ( Macronectes giganteus (Gmelin, 1789); Aves, Procellariiformes), ranging from New Zealand to the Graham Peninsula and Patagonia and also from coastal Antarctica to Gough Island, displays significant geographic variation throughout its range. Six breeding provinces were identified, which show significant interpopulational variation. The formerly proposed subspecies Macronectes giganteus giganteus and Macronectes giganteus solanderi were confirmed. Macronectes giganteus solanderi has smaller homologuous parts than M. g. giganteus. Two of the provinces belong to the subspecies M. g. solanderi. Females are smaller and have shorter bills than males. In M. g. giganteus, outer appendages are longer in the sub-Antarctic than in the Antarctic, which is consistent with Allen’s rule. Moreover, an east-to-west cline shows a gradual decrease in body size. Within M. g. solanderi, the Chubut River Estuary (Argentina) and the Falkland Islands form the southern province, and Gough Island the northern province. The birds have shallower bills in Argentina than in the Falklands or Gough, but tarsi are longest in Gough. Macronectes giganteus giganteus is morphologically polymorphic but taxonomically stable, whereas M. g. solanderi, which is biometrically less variable, could undergo taxonomical differentiation. This paper gives arguments for further morphometric and genetic studies on the taxon.

Distance associations among antarctic and ­subantarctic seabirds

Seabirds seek environmental cues for find food at sea. One of the cues is the behaviour of other seabirds. The present study aims to demonstrate through spatial correlation analysis, the distance at which species of seabirds are able to associate. Seabird counting was conducted onboard the Brazilian Polar Ship NPo Almirante Maximiano between Southern Argentina and South Shetland Islands, Antarctica. Birds were counted during 10 minutes censuses at intervals of one and half hours during the whole day. Abundances of Daption capense, Macronectes giganteus, Thalassarche melanophrys, Petrels and Albatrosses in spatial correlations were used. We tested if there were any intra-specific associations (autocorrelation) and/or any inter-specific associations (cross-correlation). The coefficients of auto and cross-correlation were used in linear regression with average distance lags to estimate the distance at which seabirds influence each other. All the Autocorrelation coefficients of the evaluated species were negatively related with lag average distance, that is, the further away the seabirds are the less they are able to detect each other. Even so, there were marked differences among species, since R2 varied from 0.3 (all petrels added together) and close to 0.9 for Southern Giant Petrels. But the inter-specific association does not appear to be related with distance, since from the nine possible pairs, for only three, were the spatial cross-correlations related with the distance.