Great-winged Petrels Pterodroma Macroptera Research Articles

The status of Great-winged Petrel Pterodroma macroptera in the south-west Atlantic Ocean, with notes on separation from dark-morph Trindade Petrel P. arminjoniana

Great-winged Petrel Pterodroma macroptera is currently considered uncommon in the south-west Atlantic Ocean. However, via a compilation of all recent records available, we found evidence of a regular, wider distribution from breeding colonies in Tristan da Cunha and Gough towards South America. We review these records, report a new beach stranding in Brazil, which is the northernmost record in the south-west Atlantic, and discuss the problems of at-sea separation of Great-winged Petrel from the darkest-plumaged Trindade Petrel P. arminjoniana.

Seabird population changes following mammal eradication at oceanic Saint-Paul Island, Indian Ocean

The eradication of invasive mammals on islands is important for protecting seabird populations and insular ecosystems. However, the impacts of such eradications are insufficiently known because monitoring of potentially beneficiary species is often sporadic and limited. We performed a survey of all seabird species on Saint-Paul Island, southern Indian Ocean, 20 years after successful eradication of invasive black rat (Rattus rattus) and European rabbit (Oryctolagus cuniculus). Using complementary sampling designs including adaptive cluster sampling, stratified random sampling and entire sampling, we estimated population changes and colonization by new seabird species. A total of 13 seabird species were found breeding on Saint-Paul post-eradication compared to six before the eradication. Among the seven species that colonized the island, five (MacGillivray’s prion Pachyptila macgillivrayi, fairy prion P. turtur, white-bellied storm petrel Fregetta grallaria, Antarctic tern Sterna vittata, sooty tern Onychoprion fuscatus) had relictual populations breeding on a nearby islet, and one (brown skua Catharacta antarctica) was a new breeding species. We also found breeding subantarctic little shearwaters Puffinus elegans. For species that were breeding on the Saint Paul pre-eradication, the mean annual population growth rate was 1.030 ± 0.093 (SE). Species known to be vulnerable to rat predation (prions, great-winged petrel Pterodroma macroptera, flesh-footed shearwater Puffinus carneipes, subantarctic little shearwater, white-bellied storm petrel, Antarctic tern) had the highest population growth rates. Two decades after the eradication of invasive mammals on a remote oceanic island, seabird populations were high beneficiaries. These findings further highlight the importance of invasive mammal eradication on islands as a conservation tool. Results are encouraging for the planned eradication of invasive mammals from nearby Amsterdam Island, and suggest this will mainly benefit terns and small burrowing petrels.

A survey of Great-winged Petrels Pterodroma macroptera breeding at sub-Antarctic Marion Island and a revised global population estimate

Although burrow-nesting petrels are the most abundant group of seabirds in the Southern Ocean, their global populations are poorly known, because most species breed on remote islands. For example, there are no accurate estimates for Great-winged Petrel Pterodroma macroptera populations at any of its major breeding sites. Moreover, current global population estimates for Great-winged Petrels of approximately 1.5 million birds include counts of the closely related Grey-faced Petrel P. gouldi, which is now recognised as a different species. On sub-Antarctic Marion Island, Great-winged Petrel burrows found within random strip transects were counted and then burrow densities were extrapolated by GIS-derived habitat attributes to generate an island-wide burrow estimate (33 000 burrows). Burrow occupancy rates at the start of incubation averaged 48 ± 29% (range 10–94%) during one-off surveys at ten sites around the island, and repeat surveys found at least 42% of burrows were occupied by breeders. This suggests there were approximately 14 000 occupied burrows (95% CI 9 500–18 500) on Marion Island in 2015. Collating data from other breeding sites suggests that the global breeding population is perhaps 100 000–150 000 pairs (400 000–600 000 birds).

Burrow Wars and Sinister Behaviour among Burrow-Nesting Petrels at Sub-Antarctic Marion Island

Competition for nest sites is relatively common amongst burrow-nesting Procellariiformes, especially on some sub-Antarctic islands where there is limited availability of good burrow-nesting habitat. Where space is limited, petrels may even successfully share a common burrow entrance or nest chamber and burrow densities can reach >7000 burrows/ha. Interspecies burrow competition and chick evictions generally occur as a result of an overlap in breeding seasons, yet there are few documented records of this behaviour and even within study colonies many evictions are unconfirmed or probably go undetected. Here we report on interactions among three burrow-nesting petrels (White-chinned Petrels Procellaria aequinoctialis, Grey Petrels P. cinerea and Great-winged Petrels Pterodroma macroptera) at Marion Island which we observed through regular nest checks with a burrowscope and using infra-red video cameras inside burrow chambers. Despite relatively low petrel densities, White-chinned Petrels were responsible for 17% (8/46) of the Great-winged Petrel chick mortalities over the five breeding seasons (3% of the breeding attempts), but two were also recorded feeding Great-winged Petrel chicks. A pair of White-chinned Petrels evicted a Grey Petrel chick, but then had their own chick killed by Grey Petrels the following season, who went on to breed successfully in the same burrow. Feral Cats Felis catus were eradicated in 1991 and the greatly reduced petrel populations are slowly recovering, which could exacerbate competition for burrows on Marion.

Mouse predation affects breeding success of burrow-nesting petrels at sub-Antarctic Marion Island

AbstractWe report the breeding success of four species of burrow-nesting petrels at sub-Antarctic Marion Island where house miceMus musculusare the sole introduced mammal. Feral catsFelis catuswere present on Marion for four decades from 1949, killing millions of seabirds and greatly reducing petrel populations. Cats were eradicated by 1991, but petrel populations have shown only marginal recoveries. We hypothesize that mice are suppressing their recovery through depredation of petrel eggs and chicks. Breeding success for winter breeders (grey petrelsProcellaria cinerea(34±21%) and great-winged petrelsPterodroma macroptera(52±7%)) were lower than for summer breeders (blue petrelsHalobaena caerulea(61±6%) and white-chinned petrelsProcellaria aequinoctialis(59±6%)) and among winter breeders most chick fatalities were of small chicks up to 14 days old. We assessed the extent of mouse predation by monitoring the inside of 55 burrow chambers with video surveillance cameras (4024 film days from 2012–16) and recorded fatal attacks on grey (3/18 nests filmed, 17%) and great-winged petrel chicks (1/19, 5%). Our results show that burrow-nesting petrels are at risk from mouse predation, providing further motivation for the eradication of mice from Marion Island.

Feather mercury concentrations in Southern Ocean seabirds: Variation by species, site and time

We studied mercury contamination in 25 seabird species breeding along a latitudinal gradient across the Southern Ocean, from Gough Island (40°S) through Marion Island (47°S) to Byers Peninsula (63°S). Total mercury concentrations in body feather samples of adults caught at breeding colonies from 2008 to 2011 were determined. Krill (Euphausia spp.) and other zooplankton consumers had low mercury concentrations (gentoo penguin Pygoscelis papua, chinstrap penguin Pseudomonas Antarctica, common diving petrel Pelecanoides urinatrix, broad-billed prion Pachyptila vittata; mean levels 308–753 ng g−1), whereas seabirds consuming squid or carrion had high mercury concentrations (ascending order: Kerguelen petrel Aphrodroma brevirostris, southern giant petrel Macronectes giganteus, soft-plumaged petrel Pterodroma mollis, sooty albatross Phoebetria fusca, Atlantic petrel Pterodroma incerta, northern giant petrel Macronectes halli, great-winged petrel Pterodroma macroptera; 10,720–28038 ng g−1). The two species with the highest mercury concentrations, northern giant petrels and great-winged petrels, bred at Marion Island. Among species investigated at multiple sites, southern giant petrels had higher mercury levels at Marion than at Gough Island and Byers Peninsula. Mercury levels among Byers Peninsula seabirds were low, in two species even lower than levels measured 10 years before at Bird Island, South Georgia. Replicate measurements after about 25 years at Gough Island showed much higher mercury levels in feathers of sooty albatrosses (by 187%), soft-plumaged petrels (53%) and Atlantic petrels (49%). Concentrations similar to the past were detected in southern giant petrels at Gough and Marion islands, and in northern giant petrels at Marion. There were no clear indications that timing of moult or migratory behavior affected mercury contamination patterns among species. Causes of inter-site or temporal differences in mercury contamination could not be verified due to a lack of long-term data related to species’ diet and trophic levels, which should be collected in future together with data on mercury contamination.

Where two oceans meet: distribution and offshore interactions of great-winged petrels Pterodroma macroptera and Leach’s storm petrels Oceanodroma leucorhoa off southern Africa

Abstract During seabird surveys off southern Africa, great-winged petrel Pterodroma macroptera and Leach’s storm petrel Oceanodroma leucorhoa were widespread and relatively common. Similar aerial displays, frequent (social) interactions, a tendency to “huddle” in tight (mixed) gatherings and interactions during foraging inspired a study of their behaviour and distribution. Both species peaked at >2,000-m-deep ocean waters, with lower densities over the shelf and with Leach’s storm petrels (ca. 0.5 km−2) twice as abundant as great-winged petrels (ca. 0.25 km−2). The results suggest half a million great-winged petrels and well over a million Leach’s storm petrels occurring over deep waters off southern Africa. Active fishing vessels elevated background densities of petrels in some areas, indicating the utilisation of discarded material, but in most areas hardly any fisheries were encountered and on the shelf with no discernable effect on petrel densities. Both species showed an association with meso-scale hydrographic features in the Agulhas current retroflection region. High densities of Leach’s storm petrels occurred in offshore areas with steep salinity and sea surface temperature gradients. No such tendency was found in great-winged petrels. Great-winged petrels spent relatively little time feeding during daylight (10.3% of birds observed) in comparison to Leach’s storm petrels (66.2%), but were frequently seen to join feeding Leach’s storm petrels where they profited from the searching skills of Leach’s. Both species performed displays as individuals, in pairs, in larger groups and in mixed-species groups. Tight gatherings of petrels swimming at sea (huddling) occurred, consisting either of one species or both. When disturbed, such flocks would disperse after take off and often engage in aerial displays. It is speculated that the formation of these flocks is part of the anti-predator strategy of petrels against attacks from under water.

Seabird associations with mesoscale eddies: the subtropical Indian Ocean

We investigated seabird-eddy associations in subtropical waters of the southern Indian Ocean during a summer (January) cruise from Amsterdam Island to Western Australia. To determine habitat associations and to enable predictions about foraging strategies, we related the distributions of satellite altimetry data (sea surface height anomalies) to the 3 most abundant taxa in the study area: terns (sooty Sterna fuscata and bridled S. anaethetus) and shearwaters (wedge-tailed Puffinus pacificus) were significantly more common and numerous within convergence zones. However, a step-wise logistic regression model revealed that these seabirds were more strongly associated with other habitat variables, including the distance to breeding colonies and warm sea surface temperature conditions. Great-winged petrels Pterodroma macroptera were widely scattered and did not show associations with convergences or divergences. These contrasting results highlight the need to consider smaller-scale hydrographic features, such as frontal systems, when guantifying seabird associations with mesoscale eddies. Large-scale patterns of ocean circulation and mesoscale variability also seem to play a critical role in determining the extent of seabird-eddy associations. In contrast with previous studies, which have focused on dynamic frontal regions and energetic current systems, we surveyed a region of weak mesoscale variability north of the Subtropical Convergence zone. © Inter-Research 2006.

Improved breeding success of great-winged petrels Pterodroma macroptera following control of feral cats Felis catus at subantarctic Marion Island : J. Cooper & A. Fourie, Bird Conservation International, 1(2), 1991, pp 171–175

Improved breeding success of great-winged petrels Pterodroma macroptera following control of feral cats Felis catus at subantarctic Marion Island : J. Cooper & A. Fourie, Bird Conservation International, 1(2), 1991, pp 171–175

Improved breeding success of Great-winged Petrels Pterodroma macroptera following control of feral cats Felis catus at subantarctic Marion Island

SummaryA population of feral domestic cats Felis catus has existed at subantarctic Marion Island since 1951. From 1977 to 1990 an ongoing programme has utilized an introduced disease, shooting and gin-trapping in an endeavour to control cat numbers, with the eventual aim of their eradication. Burrowing petrels (Procellariidae) form the majority of the cats' diet. The breeding success of the winter-breeding Great-winged Petrel Pterodroma macroptera has varied between nil and 20.5% in the period from 1979 to 1984, due primarily to cat predation of chicks causing up to 100% mortality. In 1990, by which time cat numbers had been greatly reduced from their 1970s' peak, Great-winged Petrels had a breeding success of 59.6%, with chick mortality being zero. No signs of cat predation were observed. This finding provides good reason to continue the control programme until cats are finally eradicated from Marion Island.

Burrow densities and nest site preferences of petrels (Procellariidae) at the Prince Edwards Islands

The nest-site preferences of six burrowing petrel species, Salvin's prion Pachyptila vittata salvini, blue petrel Halobaena caerulea, great-winged petrel Pterodroma macroptera, Kerguelen petrel Pterodroma brevirostris, soft-plumaged petrel Pterodroma mollis and white-chinned petrel Procellaria aequinoctialis, in the northeastern part of Marion Island (Prince Edward Island group, southern Indian Ocean) were analyzed by step-wise multiple regression. The nest-site characteristics measured were slope angle, soil depth and moisture content, percentage cover by stones or boulders and percentage cover by each of seven major plant species. The major nest-site preferences were: exposed areas with shallow soil (Salvin's prion); steep coastal slopes (blue petrel); sheltered well-drained slopes with deep soil (great-winged petrels); wet areas along drainage lines (Kerguelen petrel); steep slopes (soft-plumaged petrel); and areas with deep soil (white-chinned petrel). Similar species showed no significant avoidance of nest sites where there were burrows of potential competitors but did tend to nest spread out over different habitats. Burrow densities were determined in six habitat and seven vegetation types. Salvin's prion was the most abundant species (81% of burrows, with a maximum density of 279 burrows ha-1) and used both burrows and natural cavities for nesting. For all species combined, burrow densities at Marion Island were lower than in comparable habitats and vegetation types at neighbouring Prince Edward Island. Depredation by feral house cats Felis catus, absent from Prince Edward Island, is assumed to be largely responsible for this difference.

THE DIET OF CHICKS OF GREATWINGED, KERGUELEN AND SOFTPLUMAGED PETRELS AT THE PRINCE EDWARD ISLANDS

Summary Schramm, M. 1986. The diet of chicks of Greatwinged, Kerguelen and Softplumaged Petrels at the Prince Edward Islands. Ostrich 57: 9–15. Stomach contents of chicks of Greatwinged Petrels Pterodroma macroptera, Kerguelen Petrels P. brevirostris and Softplumaged Petrels P. mollis collected at the Prince Edward Islands were analysed. Chicks of all three species were fed primarily on cephalopods (90%, 70% and 89% by mass of solids in the stomach contents, respectively) supplemented by crustaceans (6% in P. macroptera, 24% in P. brevirostris and 10% in P. mollis) and fishes. The prey species taken are broadly similar but potential interspecific competition for food is presumably reduced, since the petrels have different breeding seasons with non-overlapping chick-rearing periods.

The Breeding Biologies of the PetrelsPterodroma Macroptera, P. BrevirostrisandP. Mollisat Marion Island

SUMMARYSCHRAMM, M. 1983. The breeding biologies of the petrels Pterodroma macroptera, P. brevirostris and P. mollis at Marion Island. Emu 83: 75–81.The Great-winged Petrel Pterodroma macroptera, Kerguelen Petrel P. brevirostris and Soft-plumaged Petrel P. mollis breed in different habitats at different times of the year at Marion Island. P. macroptera breeds in inland slopes during winter, brevirostris breeds in flat marshy areas during early summer and mollis breeds during late summer in coastal slopes. Nesting-burrows of macroptera and mollis have a similar simple design but burrows of brevirostris have a drainage system to cope with their waterlogged breeding habitat.Incubation periods are similar (56, 49 and 50 days in macroptera, brevirostris and mollis respectively), but fledging periods are very different (61 days in brevirostris and 91 days in mollis). The species rear chicks at different times, presumably to help reduce interspecific competition for food. In all species, the chicks are fed mostly squid, but meals of brevirostris chicks contain most crustaceans and fish. Differences in quality of meals in part explain the faster growth of brevirostris compared to macroptera or mollis. The timing of breeding influences the vulnerability of each species to predators, which is reflected in differences in breeding success (53%, 7% and 0% in brevirostris, mollis and macroptera respectively).