Macronectes Research Articles

Factors affecting the number and mortality of seabirds attending trawlers and long-liners in the Kerguelen area

The factors affecting the number and the mortality rates of seabirds attending long-liners and trawlers fishing in the Kerguelen area were studied during four successive seasons (1994–1997), based on observations carried out onboard by dedicated observers. Twenty-four species of seabirds were observed attending fishing vessels, representing an average of 591 birds/census. The total numbers attending varied mainly according to the year, the cloud cover and the presence of offal from long-liners. The dumping of offal increased the numbers of birds attending the vessel, especially when the offal could be easily handled by birds. The activity of the vessels also affected the numbers attending, birds being more abundant during line setting and trawl hauling. White-chinned petrels were the most abundant ship-following seabirds, followed by black-browed albatrosses, giant petrels and cape petrels. The number of white-chinned petrels, black-browed and grey-headed albatrosses attending fishing vessels increased in the time between spring and autumn, whereas it was the reverse situation for giant petrels and cape petrels. Four species of seabirds were caught by fishing gear, mainly by long-lines: white-chinned petrels, and black-browed, grey-headed and wandering albatrosses. Taking into account the number of birds from each species attending long-liners and known to be potential by-catch, some species appear to be more susceptible to being caught than others. White-chinned and grey-headed albatrosses are caught in much higher proportions than the numbers present, whereas black-browed albatrosses are caught in lower numbers. Giant petrels are abundant around long-liners but were never caught. In long-liners, most birds were killed when the lines were set during the day or when the deployment of the scaring device was not successful, with an overall figure of 0.47 birds/1000 hooks. Only one albatross was caught when the lines were set during the night. White-chinned petrels represented 92.2% of all birds killed by long-liners. The number of birds caught varied significantly among months and among years. The type of bait used also affected the catch rate. The catch rate was related to the number of birds attending the long-liner only for black-browed albatrosses. Most birds killed by trawlers were entangled by the netsonde cable. The efficiency of mitigation measures in order to reduce seabird mortality is discussed and it is stressed that night setting is the most efficient way to reduce mortality and should be enforced everywhere when possible. However, further methods should be developed to reduce the mortality of species active at night, especially white-chinned petrels whose populations in the Indian Ocean may by threatened by long-line fisheries.

Foraging partitioning between giant petrels Macronectes spp. and its relationship with breeding population changes at Bird Island, South Georgia

We satellite-tracked the foraging trips of males and females of the 2 sibling species of giant petrels, Macronectes halli and M. giganteus, breeding sympatrically at Bird Island (South Georgia, Antarctica), during the incubation period (November-December). Size of the activity range in addition to speed and distance covered on foraging trips were similar between the species, but were lower for males than for females in both species. Sex-specific differences agree with previous observations on diets and on attendance at seal carcasses, suggesting that females mainly forage at sea, whereas males mainly scavenge on the coast. Overall, however, the foraging ecology of both species seems very similar. Interspecific and intersexual competition may be reduced by the limited overlap in the at-sea range, with southern giant petrels foraging further south than did northern giant petrels, and females further west than males, suggesting some spatial partitioning in foraging areas. Male northern giant petrels foraged almost exclusively on the South Georgia coast; their strong dependence during the brooding and chick-rearing period on Antarctic fur seals, whose population has increased exponentially in recent years, may be reflected in the recent population increase of northern giant petrels at South Georgia. Foraging areas of giant petrels overlapped extensively with longline fishery distribution, highlighting their susceptibility to being caught on longline hooks. Females were at higher risk during the study period since they made longer trips and foraged further west than males, into areas where local longline fisheries are more active.

Sexual dimorphism, moult and body condition of seabirds killed by longline vessels around the Prince Edward Islands, 1996–97

Ryan, P.G. 1999. Sexual dimorphism, moult and body condition of seabirds killed by longline vessels around the Prince Edward Islands, 1996–97. Ostrich 70 (3&4): 187–192. A total of 393 seabirds from nine species killed by longline fishing in South African waters around the Prince Edward Islands during summer 1996–97 were sexed, measured, and their body fat levels and primary moults scored. Males of Whitechinned Petrels Procellaria aequinoctialis and Greyheaded and (Indian Ocean) Yellownosed Mollymawks Thalassarche chrysostoma and T. [chlororhynchosj bassi averaged 1–9% larger than females. Measures of bill depth were the most dimorphic characters in all three species. I recommend that if only a single measure is taken to estimate sex of adults, bill depth at the base be the standard measure for petrels, and bill depth at the nail be the standard measure for mollymawks. Discriminant functions are described for predicting the sex of unknown individuals; the proportion of misclassified birds ranged from 2–10%. With the exception of giant petrels Macronectes spp., only two young birds were actively moulting their primary flight feathers. Analysis of wear patterns among adult Greyheaded Mollymawk primaries conforms with studies of moult in this species at South Georgia. Fat scores did not differ between sexes. They tended to decrease during the breeding season, but trends were masked by great inter-individual variation. There was no significant relationship between fat scores and the presence of ingested plastics. Plastic debris was found in the stomachs of 90 birds from five species. Incidence in Whitechinned Petrel stomachs (37%) was less than that reported from birds collected off South Africa in the early 1980s (57%), but this is probably due to the predominance of breeding adults. The frequency and size of plastic loads decreased through the breeding season, which is consistent with the hypothesis that inter-generational transfer is important in the dynamics of ingested debris.

Olfactory foraging in Antarctic seabirds:a species-specific attraction to krill odors

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 177:235-241 (1999) - doi:10.3354/meps177235 Olfactory foraging in Antarctic seabirds: a species-specific attraction to krill odors Gabrielle Nevitt* Section of Neurobiology, Physiology and Behavior, Division of Biological Sciences, University of California, Davis, California 95616, USA *E-mail: ganevitt @ucdavis.edu ABSTRACT: Antarctic procellariiform seabirds are known for their well-developed sense of smell, yet few behavioral experiments have addressed how these birds use olfactory cues to forage at sea. I describe results from controlled, shipboard experiments performed in Antarctic waters near Elephant Island. Birds were presented with plain or krill-scented (Euphausia superba) vegetable oil slicks, and their behavioral responses were compared. Krill-scented vegetable oil slicks were highly attractive to some but not all procellariiform species foraging in this area (p < 0.001, G-test). Cape petrels Daption capense and southern giant petrels Macronectes giganteus appeared at krill-scented slicks within 1 min, whereas black-browed albatrosses Diomedea melanophris appeared within 3 min. Cape petrels D. capense showed the strongest attraction: these birds were observed as much as 5 times as frequently at krill-scented slicks as compared to unscented control slicks (p < 0.001, G-test), while storm-petrels (Oceanites oceanicus and Fregetta tropica) and Antarctic Fulmars Fulmarus glacialoides responded in equal numbers to krill-scented and unscented slicks. When considered with respect to previously published findings, these results suggest a greater complexity in the significance of odors to the foraging ecology of different tube-nosed species than has commonly been assumed. KEY WORDS: Procellariiform · Olfaction · Antarctica · Petrels · Seabirds · Foraging · Krill Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 177. Publication date: February 11, 1999 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1999 Inter-Research.

Distribution of 14 elements in tissues and organs of oceanic seabirds.

The concentrations of 14 trace elements (Li, V, Mn, Co, Cu, Zn, Se, Rb, Sr, Ag, Cd, Cs, Pb, and Hg) were determined in tissues and organs of three species and in the liver of 11 species of seabirds. Comparatively high concentrations of Li, Co, Sr, and V were found in the femur. Cd, Se, Cu, and Mn concentrations were relatively higher in the kidney than in other tissues and organs. Rb, Cs, and Pb concentrations were rather uniform among tissues. Concentrations of essential elements such as Mn, Cu, and Co were comparable among seabird species, except high Cu concentrations in northern giant petrel. Among nonessential elements, concentrations of Cd and Hg were variable according to seabird species. Pb levels were low in all the species. High Se levels (100 microg/g dry weight) were found in the liver of black-footed albatross and grey petrel. There were significant positive correlations between Se and Cd concentrations in three species and between Se and Hg in black-footed albatross, suggesting that Se has an antagonistic action on the toxic effects of Cd and Hg. Concentrations of Li, V, Ag, and Cs were usually low (less than 1 microg/g dry weight).

Cytochrome-B Evidence for Validity and Phylogenetic Relationships of Pseudobulweria and Bulweria (Procellariidae)

Although the genus Pseudobulweria was described in 1936 for the Fiji Petrel (Ps. macgillivrayi), its validity, phylogenetic relationships, and the number of constituent taxa it contains remain controversial. We tried to clarify these issues with 496 bp sequences from the mitochondrial cytochrome-b gene of 12 taxa representing three putative subspecies of Pseudobulweria, seven species in six other genera of the Procellariidae (fulmars, petrels, and shearwaters), and one species each from the Hydrobatidae (storm-petrels) and Pelecanoidi- dae (diving-petrels). We also include published sequences for two other petrels (Procellaria cinerea and Macronectes giganteus) and use Diomedea exulans and Pelecanus erythrorhynchos as outgroups. Based on the pronounced sequence divergence (5 to 5.5%) and separate phylo- genetic history from other genera that have been thought to be closely related to or have been synonymized with Pseudobulweria, we conclude that the genus is valid, and that the Mascarene Petrel (Pseudobulweria aterrima) and the Tahiti Petrel (Ps. rostrata) are distinct spe- cies. In trees constructed with maximum parsimony and maximum likelihood, Pseudobul- weria is the sister taxon to Puffinus and Calonectris, and these genera in turn are most closely related to Bulweria (and Procellaria in the maximum-parsimony tree). Pseudobulweria is not closely related to Pterodroma in either tree. Because Ps. r. trouessarti from New Caledonia, and Ps. r. rostrata from Polynesia differ by only 0.6%, these taxa do not deserve species status and should be regarded as valid subspecies. Received 7 October 1996, accepted 23 July 1997.

Interactions between longline vessels and seabirds in Kerguelen waters and a method to reduce seabird mortality

A longline fishery for Dissostichus eleginoides has recently developed in the vicinity of South Georgia and Kerguelen islands, two internationally important breeding areas for procellariiform birds. The number of hooked birds and a method to reduce mortality were investigated during 13 days of fishing activity in Kerguelen waters in February 1994. Between 100 and 600 seabirds were always observed behind the longline vessel during daytime. The main ship-following species were the white-chinned petrel Procellaria aequinoctialis (67% of counts), giant petrels Macronectes spp. (8%) and the wandering albatross Diomedea exulans (11%), black-browed albatross D. melanophris (6%) and grey-headed albatross D. chrysostoma (2%). Only diving species were caught on the lines, i.e. the white-chinned petrel ( n = 36) and the grey-headed albatross ( n = 2). Marked differences in the mortality rate were observed between day and night (1·00 versus 0·38 birds per 1000 hooks), and at night when the decklights were on or off (0·59 versus 0·15 birds per 1000 hooks). Dumping of homogenized offal during line settings greatly reduced incidental capture of seabirds, mainly because birds were more attracted by offal than by hooked baits. We therefore propose that the dumping of offal during line settings should be included in the regulations of the longline fishery for Dissostichus in order to minimize seabird mortality.

Flight tracks and speeds of Antarctic and Atlantic seabirds: radar and optical measurements

A tracking radar and an optical range-finder, placed on a ship, were used to register the flight of eleven species of seabirds, in waters off the Antarctic Peninsula and in the Atlantic Ocean. Albatrosses under calm conditions used swell soaring, turning and twisting extensively within a width of 300-500 m laterally from the overall direction of movement. Their resulting travel speed was on average 10 m s-1. In windy conditions the albatrosses as well as giant petrels travelled faster, with resulting speeds up to 22.5 m s-1, by a combination of wave soaring and dynamic soaring. Shearwaters and the antarctic fulmar proceeded by flap-gliding, along tracks that were only slightly zigzag within 50-60 m from the resulting course of movement. The little shearwater flew faster, with an airspeed about 14 m s-1, than larger-sized shearwaters and fulmars, using continuous flapping flight to a higher degree than its larger relatives. South polar skuas and Wilson’s storm-petrels were tracked on foraging flights, and flocks of imperial shags on commuting flights between feeding and breeding-roosting areas. The south polar skua was able to accelerate to airspeeds exceeding 20 m s-1in pursuit flights after shags. Wilson’s storm-petrels showed significantly slower airspeeds in foraging flights as compared to non-foraging flights. Average airspeeds of most species fell between the minimum power and maximum range speeds estimated from aerodynamical theory. Species using gliding or flap-gliding flight showed a mean airspeed close to the gliding speed for best glide ratio. Optimal speeds in foraging flights, as expected for the south polar skuas and Wilson’s storm-petrels, are unlikely to coincide with the minimum power and maximum range speeds. Albatrosses reached the fastest resulting travel speeds when moving at angles 120°-150° from the wind (partly following winds), with strong wind forces. They predominantly travelled with the wind from their left side which, in the southern hemisphere, would lead them away from low pressure centres and towards high pressure areas.

Seabird mortality in longline fisheries around South Georgia

Incidental mortality of Southern Ocean seabirds due to fishing activities well away from the breeding grounds has been implicated in the population declines of wandering albatross (Diomedea exulans) on South Georgia (Croxall and others 1990) and lies Crozet, black-browed albatross (Diomedea melanophris) on lies Kerguelen, and possibly the southern giant petrel (Macronectes giganteus) (Jouventin and Weimerskirch 1990). Albatrosses are particularly at risk from longline fisheries, based on the high proportion in recoveries of banded birds from longline fishing vessels off Brazil (Croxall and Prince 1990), and on direct observation of albatross during surface and midwater longline fishing for tuna in the Tasman Sea (Brothers 1991).

Ventilatory Oxygen Extraction in Relation to Ambient Temperature in Four Antarctic Seabirds

We tested the hypothesis that at low ambient temperatures (Ta) birds reduce ventilatory heat loss by increasing ventilatory oxygen extraction (Eo2). We examined relationships between Ta, body temperature, oxygen consumption (V̇o2), carbon dioxide production (V̇co2), evaporative water loss (ṁH2O), respiratory frequency, tidal volume (VT), minute volume, and Eo2, in four species of Antarctic marine birds ranging in body mass from 33-4,915 g The factorial increases in V̇o2 ranged from 1.8 to 5.2 between the lower critical temperature (Tlc; 10° -30° C, depending on species) and a Ta of -23°C. The respiratory exchange ratio (V̇co2/V̇o2) did not change with Ta. The ṁH2O was independent of Ta between 10° and 30° C in kelp gulls and giant petrels but was positively correlated with Ta between 10° and 35° C in Wilson's storm-petrels and between 10° and 30° C in South Polar skuas. Thermal conductance (C) was minimal at Ta's of 10° or 20° C depending on the species and was constant and low at Ta's below this minimum. In all four species C increased significantly at high Ta's. In storm-petrels, gulls, and skuas, the increase in V̇o2, resulting from a change in Ta from Tlc down to -23°C was accommodated mainly by increasing VT. In contrast, in giant petrels the increase in V̇o2 resulting from a change in Ta from Tlc down to -23°C was accommodated mainly by increasing Eo2, and the increase in VT was of secondary importance. Our data suggest that increasing Eo2, as a means of reducing ventilatory heat loss is not a general phenomenon in cold-adapted birds.

Field Energy Expenditures of the Southern Giant-Petrel

Field Energy Expenditures of the Southern Giant-Petrel

The Diet of Giant Petrels Macronectes spp. at Marion Island, Southern Indian Ocean

The Diet of Giant Petrels Macronectes spp. at Marion Island, Southern Indian Ocean

The impact of avian predator‐scavengers on King Penguin Aptenodytes patagonicus chicks at Marion Island

While ashore King Penguins Aptenodytes patagonicus are fed upon by a guild of five predator‐scavenger seabirds. During the winter (April‐October) male Southern Giant Petrels Macronectes giganteus killed an estimated 6430 (11.2%) of Marion Island's King Penguin chicks, although most birds only scavenged in the colonies. The rate of predation varied, with peaks in April‐May and in September. The proportion of successful attacks was 22.7%. There was a strong correlation between colony size and the rate of accumulation of chick corpses. Kelp Gulls Larus dominicanus and Lesser Sheathbills Chionis minor also scavenged penguin corpses but Northern Giant Petrels M. halli and female Southern Giant Petrels rarely entered the colonies. During the summer predation was mainly by Sub‐Antarctic Skuas Catharacta lonnbergi which took eggs and small chicks.

A further contribution on the biology of the Antarctic flea, Glaciopsyllus antarcticus (Siphonaptera: Ceratophyllidae)

Experiments showed that adult Antarctic Fleas Gladopsyllus antarcticus preferred dark over light conditions, dry over wet conditions, and fine substrate over coarse substrate. Examination of seabird chicks and collections of nest material indicated that the Southern Fulmar Fulmarus glacialoides, is the major host species of the Antarctic Flea, while Snow Petrels Pagodroma nivea, Cape Petrels Daption capense, Antarctic Petrels Thalassoica antarctica, and Wilson's Storm-Petrels Oceanites oceanicus are minor hosts. This is the first report of Antarctic Fleas occuring on either Antarctic Petrels or Wilson's Storm-Petrels. No fleas were found associated with Southern Giant Petrels Macronectes giganteus, Antarctic Skuas Catharacta maccormicki, or Adelie Penguins Pygoscelis adeliae. No live fleas were found in Southern Fulmar nest material during their period of dispersal over the winter months, supporting the hypothesis that Antarctic Fleas survive the winter period by remaining on their seabird host.

Occurrence of the cephalopod Martialia hyadesi (Teuthoidea: Ommastrephidae) at the Kerguelen Islands in the Indian Ocean sector of the Southern Ocean

In the Atlantic sector of the Southern Ocean, data from vertebrate predators and commercial fisheries suggests that the distribution of the ommast rephid squid Martialia hyadesi is related to the Antarctic Polar Frontal Zone, but it spreads further to the north in some years (Rodhouse, in press). A mass stranding of M. hyadesi occurred on Macquarie Island in 1971 (O'Sullivan et al. 1983) suggesting that its distribution is c ircumpolar (Rodhouse and Yeatman 1990). However, apart from a single beak collected from the s tomach of a wandering albatross at Mar ion Island (Imber and Berruti 1981) its presence has not, until now, been confirmed in the Indian Ocean sector and in particular it is not included in the list of cephalopods from the Kerguelenian Province (Lu and Mangold 1978). M. hyadesi is a major prey item of the grey-headed albatross, Diomedea chrysostoma, and the southern elephant seal, Mirounoa leonina, at South Georgia (Rodhouse et al. 1990; Rodhouse et al., unpublished data) and is present in the diet o f several other predators in the Scotia Sea area including the wandering albatross, Diomedea exulans (Rodhouse et al. 1987) and the giant petrels, Macronectes halli and M. gioanteus (Hunter 1983). It occasionally occurs as a significant by-catch in the lllex argentinus fishery on the Pa tagonian Shelf and has been taken during commercial squid jigging trials in the Scotia Sea at the Antarctic Polar Frontal Zone (Rodhouse, in press). It appears to have potential for commercial exploitation in the sub-Antarctic waters of the Atlantic sector of the Southern Ocean (Rodhouse 1990). In view of the ecological importance of M. hyadesi to Antarctic predators, and the likelihood that it will be commercially exploited in the future, it is important to thoroughly establish its geographical range, and in particular to confirm its circumpolar distribution.

The Avifauna of the Kerguelen Islands

The status of the 35 bird species breeding on the Kerguelen Islands in the south-western Indian Ocean is reviewed in view of recent discoveries and censuses made between 1984 and 1987. Aspects of the breeding biology of most of the species are described, together with weights and measures for 17 species for which data were previously scarce or unavailable. Four new breeding species have been recently discovered on the archipelago: the Yellow-nosed Albatross, the Southern Giant Petrel, the Soft-plumaged Petrel and the Fairy Prion. The population sizes of King and Macaroni Penguins and albatrosses were monitored: the first two species increased in number during the last 20 years, while Wandering and Black-browed Albatrosses decreased. The status of the three prion species is reviewed and the study validates the previously debated specific status of Kerguelen Antarctic and Thin-billed Prions. The taxonomic status of several Kerguelen seabird populations is discussed. Most of the burrowing petrels breeding on the mainland are today threatened by predation from recently introduced feral Cats and by degradation of their habitat caused by introduced Rabbits and other herbivorous mammals. The presence of 300 islands and islets around the mainland, mostly yet unmodified, will ensure the safety of much of the Kerguelen avifauna if they are protected now from further interference.

Temporal Progression of the Giant Petrel Courtship

AbstractThe courtship behaviour of the giant petrel Macronectes giganteus is described after a 15‐months field study in Adélie Land, Antarctica. The five sexual displays are briefly summarized. Sequences of these displays given by both partners form the courtship. Analysis of 1122 sequences shows that their structure varies during the two months before laying. The biological function of this temporal evolution is discussed, focusing on two particular aspects: the synchronization of partners and the diminution of aggressivity leading to copulation.

SOCIAL BEHAVIOUR OF THE SOUTHERN GIANT PETREL

Summary Bretagnolle, V. 1988. Social behaviour of the Southern Giant Petrel, Ostrich 59: 116–125. The social behaviour of Southern Giant Petrels Macronectes giganteus is described after a 15-month field study in Adélie Land, Antarctica. Elementary acts are briefly listed and vocalizations are described for both adults and chicks. All the social displays are described, some for the first time. Social communication is analysed from sequences of “stimulus” and “answer”, as a function of sex, distance separating the birds, and the type of stimulus (agonistic or movement) or answer (agonistic, movement and appeasement). The meaning and function of each display is given, and its structural components are discussed. Comparisons with other species of the order including albatrosses and fulmarine petrels, show that the giant petrels are unique in having an elaborate social system. It is suggested that this results from their large size, diet, breeding behaviour, and diurnal habits.

Banding studies of giant petrels, macronectes spp, at Macquarie Island

Between 1 July 1967 and 3 June 1987, totals of giant petrels banded at Macquarie Island (54 degrees South, 158.57 East) were northern giant petrel (Macronectes halli)-3056 chicks, 583 adults; southern giant petre (Macronectes giganteus)-369 chicks, 47 adults.

Banding studies of giant petrels, macronectes spp, at Macquarie Island

Banding studies of giant petrels, macronectes spp, at Macquarie Island