Puffinus Gravis Research Articles

Breeding biology of the Atlantic Petrel, Pterodroma incerta, and a population estimate of this and other burrowing petrels on Gough Island, South Atlantic Ocean

The Atlantic Petrel, Pterodroma incerta, endemic to the Tristan da Cunha group in the South Atlantic and globally threatened, is one of the least known of the world's seabirds. At Gough Island, Atlantic Petrels are winter breeders, with single eggs laid in June—July and chicks fledging in December. Birds were exclusively nocturnal on land. The pre-egg exodus of ∼50 days and nestling period of almost 140 days are near the longest recorded for Pterodroma species, and support the general pattern of prolonged development found in winter-breeding Procellariiformes. Chicks grew at a very slow rate, suggesting poor at-sea feeding conditions. Breeding success averaged only 20% and introduced House Mice, Mus musculus, were probably responsible for considerable losses of chicks in two breeding seasons. Preliminary population modelling predicts a decline in numbers. The potential impact of introduced mice suggests that the species’ conservation status be upgraded from Vulnerable to Endangered and that further research on this issue is a high priority. The first quantitative estimate of breeding numbers indicates a population of ∼1.8 million pairs of Atlantic Petrels. Provisional population estimates of Great Shearwaters, Puffinus gravis (980000 pairs), Soft-plumaged Petrels, Pterodroma mollis (400000 pairs), and Broad-billed Prions, Pachyptila vittata (1750000 pairs) confirm the international significance of Gough Island as a site for breeding seabirds.

Attendance of scavenging seabirds at trawler discards off Galicia, Spain

The occurrence of scavenger seabirds at fishing trawlers was studied off Galicia, Spain. A total of 9,368 seabirds of 23 species were recorded during 92 fishing operations in 1998 and 1999. The most common species were the yellow-legged and lesser black-backed gull ( Larus cachinnans and L. fuscus ), Sabine´s gull ( L. sabini ), the northern gannet ( Morus bassanus ), the great shearwater ( Puffinus gravis ), sooty shearwater (P. griseus), the Manx and Balearic shearwater ( P. puffinus and P. mauretanicus ), the great skua ( Catharacta skua ) and terns (mainly Sterna hirundo and S. paradisaea ). Other species occurred in small numbers: Leach´s petrel ( Oceanodroma leucorhoa ), the storm petrel ( Hydrobates pelagicus ), the little shearwater ( Puffinus assimilis ), Cory´s shearwater ( Calonectris diomedea ), the parasitic skua ( Stercorarius parasiticus ), the pomarine skua ( S. pomarinus ), the black-headed gull ( Larus ridibundus ), the glaucous gull ( L. hyperboreus ), the kittiwake ( Rissa tridactyla ), the sandwich tern (Sterna sandvicensis), the black tern (Chlidonias niger), the guillemot ( Uria aalge ) and the little auk ( Alle alle ). The maximum number of seabirds recorded at a haul was 320. The maximum number of a particular species ranged from 120 great shearwaters to 250 yellow-legged/lesser black-backed gulls during a single haul. The differences in ship-follower species abundance are related to migratory movements but fisheries could also have a strong influence at a smaller scale on the distribution of seabirds off Galicia. The degree to which seabirds rely on fishery discards as food was not quantified, but may be important for several species.

Ecology of Endoparasites of the Atlantic Puffin (Fratercula arctica grabae) (Alcidae: Charadriiformes)

The first extensive study on the endoparasitic fauna in Ihe Atlantic puffin is reported. A total of 173 puffins were collected at breeding sites at a colony in Nólsoy (Faroe Islands). Host-parasite relationships including life-history characteristics, host fitness and age, prevalence of infestation and seasonal variation are discussed. One digenean species (Gymnophallus sp.), two cestodespecies (Alcataenia sp. and a member of the family Hymenolepidae), three nematode species (Streptocara sp., Seuratia sp. and Contracaecum sp.), and one pentastome species (Reighardia sp.) were found. There was no negative effect on bird fitness owing to the presence of parasites. The prevalence and intensity of parasite infestation in Faroese puffins are lower than in other seabird species, namely, fulmars, great shearwaters and gulls.

Seabird migration in the Canadian northwest Atlantic Ocean: moulting locations and movement patterns of immature birds

All seabirds in the northwest Atlantic Ocean migrate, but timing and routes are not well understood. We evaluate existing knowledge on seabird migration with data from the Programme intégré de recherches sur les oiseaux pélagiques (PIROP) data base, using observations of immature and moulting seabirds to track migration of the following species: Northern Fulmar (Fulmarus glacialis), Greater Shearwater (Puffinus gravis), Northern Gannet (Morus bassanus), Herring Gull (Larus argentatus), Iceland Gull (Larus glaucoides), Glaucous Gull (Larus hyperboreus), Great Black-backed Gull (Larus marinus), Black-legged Kittiwake (Rissa tridactyla), and Thick-billed Murre (Uria lomvia). The distributions of immature and moulting birds show strong seasonal patterns in the northwest Atlantic, and new transition zones and clear biological borderlines for seabird distribution were found. New data on timing and location of moulting Thick-billed Murres are presented. The southern Labrador Banks and Grand Banks (Thick-billed Murre, Northern Fulmar) and southeast Newfoundland and Georges Bank (Greater Shearwater) were identified as moulting grounds. In terms of marine conservation the following areas seem to be important for part of the life cycle of the species named: western Greenland, Cape Cod, Grand Banks, Labrador Banks, southwest Newfoundland, and the Grand Manan area.

The impact of the hake Merluccius spp. longline fishery off South Africa on procellariiform seabirds

In 1994, an experimental longline fishery for hake Merluccius spp. commenced in the shelf waters off South Africa. Participants were required to record any birds caught, and these data were supplemented by ship-based observers on several vessels. Longlines are set at night, and the white-chinned petrel Procellaria aequinoctialis was the only seabird species caught while attempting to scavenge bait during gear setting. Small numbers of great shearwaters Puffinus gravis and pintado petrels Daption capense were killed during hauling operations. The hake longline fishery is estimated to kill 8000 ± 6400 white-chinned petrels a year in South African waters at a rate of 0.44 birds per 1000 hooks. This represents < 1% of the global white-chinned petrel population, but is cause for concern given (1) the slow reproductive rate among procellariiform seabirds; (2) the projected growth in the longline hake fishery; and (3) the increasing numbers of white-chinned petrels being killed in other longline fisheries. Light intensity was the most important factor for explaining variation in the number of petrels caught during setting; when line shooting was completed prior to the increase in white-chinned petrel activity ( c. 2·5 h before sunrise), few birds were caught. Measures to reduce excessive seabird bycatch include: (1) the introduction of bird lines on all vessels; (2) restricting the setting of lines to times of least bird activity; (3) minimum use of deck lighting during setting; and (4) ensuring that baited hooks sink as fast as possible when deployed. Hauling mortalities can be reduced by diverting offal outlets to the opposite side of the vessel to where the longline is being hauled.

Seabirds attending bottom long‐line fishing off southeastern Brazil

Flocks of seabirds attending commercial bottom long‐line fishing operations on the coastal shelf off southeastern Brazil show a greater species diversity during the summer than the winter (16 v 9 species), although the number of birds per flock tended to be greater during the cold season. During the summer, the Spectacled Petrel Procellaria aequinoctialis conspi‐cillata was the commonest species, followed by the Great Shearwater Puffinus gravis, Cory's Shearwater Calonectris diomedea, skuas Stercorarius spp. and the Yellow‐nosed AlbatrossDiomedea chlororhynchus. During the winter, the White‐chinned Petrel Procellaria aequin‐octialis, Yellow‐nosed Albatross and Black‐browed Albatross Diomedea melanophrys were jointly the commonest species. Marked differences in the relative abundance of species were observed between the different sampling periods, probably because of migratory movements but also because of seasonal shifts of the sea currents and the influence of cold fronts. Waters off southeastern Brazil are important feeding areas for some seabird populations nesting in the Tristan da Cunha and Gough group, especially for nonbreeding Spectacled Petrels and post‐breeding Yellow‐nosed Albatrosses.

Changes in seabird species abundance near South Georgia during a period of rapid change in sea surface temperature

During a three month research cruise near the island of South Georgia, sea surface temperature (SST) increased from c. 2°C to over 4°C. Satellite derived SST show that this corresponded to a rapid southward and eastward shift of isotherms in the northern Scotia Sea, which could have resulted from changes in the wind field. At the same time, observation from the ship of seabirds close to the island indicated changes in the abundance of some non-resident species, whereas resident breeders from South Georgia, such as black-browed albatrosses (Diomedea melanophris) and prions (Pachyptila spp.) which were foraging locally, were present at consistent density in both halves of the survey. Blue petrels (Halobaena caerulea) left the area after breeding, so were associated only with the low water temperatures during the first part of the cruise. In contrast, great shearwaters (Puffinus gravis) and soft-plumaged petrels (Pterodroma mollis) migrated into the area later in the survey. These birds were almost certainly non-breeders which were feeding in the warmer water which had moved towards the island.

PREY SELECTION AND TEMPORAL VARIATION IN THE DIET OF SUBANTARCTIC SKUAS AT INACCESSIBLE ISLAND, TRISTAN DA CUNHA

Summary Ryan, P.G., & Moloney, C.L. 1991. Prey selection and temporal variation in the diet of Subantarctic Skuas at Inaccessible Island, Tristan da Cunha. Ostrich 62:52-58. More than 2 500 prey items of Subantarctic Skuas Cuthuructa anturcricu were identified from regurgitated pellets collected at a roost of non-breeding skuas during summer 1989–90 at West Point, Inaccessible'Is-land. Most prey items (96,5%) were birds, primarily burrow-nesting procellariiforms. Sixteen bird species were recorfed in the diet, but five secies accounted for 94,6% of identifiable prey remains: Whitebellied Storm Petrel Fieettu grullariu (53,5%), Whitefaced Storm Petrel Pelugodrorna marina 15,1%), Broad-billed Prion Pacaptilu vittutu (14,0%), Great Shearwater Puffinus gruvis (7,3%), and Iommon Diving Petrel Pelecunoids urinutrix (4,7%). Petrel chicks were important in the diet, particularly Great Shearwaters. The main non-avian prey were fish and goose barnacles Lepas sp., but their importance may have been underestimated. T...

Novel Area Serving Binocular Vision in the Retinae of Procellariiform Seabirds

Procellariiforms are pelagic seabirds which fly close to the sea surface and feed either by taking items from the surface or by shallow diving. The retinal ganglion cells in five species (Manx shearwater, Puffinus puffinus, Kerguelen petrel, Pterodroma brevirostris, great shearwater, Puffinus gravis, broad-billed prion, Pachyptila vittata, and common diving petrel, Pelecanoides urinatrix) were examined by Nissl staining and also by silver staining in the case of the common diving petrel. In all five species, a well-defined region in the dorsotemporal retina, close to the ora, was identified. This region is characterized by the presence of ganglion cells which are both regularly arrayed and larger than those found in the rest of the retina. These cells also have a large dendritic field of sparsely branched dendrites with much dendritic overlap between cells, thick axons, and dendrites confined to the proximal inner plexiform layer. Morphologically, they appear similar to the alpha cells of the retina in cats. It is suggested that the region containing these cells should be regarded as a retinal area, and the name area giganto cellularis is proposed. In the Manx shearwater, it is found that this novel area projects visually into the binocular field below the bill. Unlike previously described areas in avian retinae, it seems that this novel area is not concerned with high spatial resolution. It may function in the detection of objects on the sea surface and/or be concerned with the detection of the actual sea surface as a bird flies low over it.

Levantamento das aves marinhas no percurso Rio de Janeiro: Bahia (Brasil)

Marine birds were surveyed between Rio de Janeiro and Bahia, latitudes 24o44'S and 17o50'S, from July to September 1984. Sixteen species were recorded belonging to six families, with most sightings occurring between 24o44'S and 22o3$'S. Data suggest two distinct communities, the more southerly one is represented by Daption capense and the one further north by Puffinus gravis.

Ecology of helminth parasitism in Puffinus gravis (Procellariiformes) on the breeding grounds at Gough Island

Great shearwaters, Puffinus gravis, on the breeding grounds at Gough Island in the central South Atlantic were hosts for seven species of gastrointestinal helminths (range, two to five species per host; abundance = 114–4016 parasites per host). Cestodes, including Tetrabothrius laccocephalus, Tetrabothrius diomedea, Tetrabothrius filiformis, and metacestodes of Tetrabothrius sp., a strigeid trematode, Cardiocephaloides physalis, and an acanthocephalan, Corynosoma australe, occurred in the small intestine. Nematodes, Seuratia shipleyi and larvae of Contracaecum sp., were found in the proventriculus. Great shearwaters had not previously been recognized as hosts for T. filiformis, T. diomedea, and Cardiocephaloides, while C. australe is reported for the first time in an avian host. Populations of the five most abundant and prevalent helminths (Tetrabothrius spp. and Cardiocephaloides) were overdispersed. The patterns of diversity (measured by Brillouin's index), species richness, and abundance in the intestinal helminth community from P. gravis were at the lower end of a continuum for equivalent communities in avian hosts from terrestrial and aquatic habitats. The predictable breeding phenology of P. gravis at Gough Island and the distribution of immature or recently acquired helminths indicated that the major component of the parasite fauna was derived in the South Atlantic Ocean adjacent to the breeding grounds during the austral spring. The distribution of helminth parasites of great shearwaters is discussed with reference to food habits and long-range migration of the hosts.

Plastic ingestion and PCBs in seabirds: Is there a relationship?

Multivariate analyses were used to assess the independent determinants of four organochlorines (OCs) in the fat and eggs of breeding female Great Shearwaters Puffinus gravis. The amounts of polychlorinated biphenyls (PCBs), DDE, DDT, and dieldrin, in both adult fat tissue and in eggs were positively correlated. However, there was no correlation between the amounts of OCs in adults and their eggs. Positive correlations between the amounts of different OCs in adults and in eggs suggest that individual differences in non-breeding range, diet and age are determinants of pollutant levels within a species. The mass of ingested plastic was positively correlated only with PCBs, a group of chemicals commonly found in plastics. It is probable that seabirds assimilate PCBs and other toxic chemicals partly from ingested plastic particles.

The incidence and characteristics of plastic particles ingested by seabirds

The ingestion of plastic was recorded for 36 of 60 seabird species sampled in the southern hemisphere (mostly off southern Africa). Biases of different sampling techniques were considered. Plastic was most frequent in procellariiforms, notably Blue Petrels, Great Shearwaters, White-faced Storm-petrels and Pintado Petrels. Particles were compared with those found at sea. The size of ingested particles was related to body size, and this affected the proportions of plastic types ingested. Pale particles were underrepresented, suggesting selection for darker-coloured particles. Small species were less colour-selective and exhibited a higher incidence of plastic ingestion than did large species. The incidence of ingested plastic was directly related to foraging technique and inversely related to the frequency of egestion of indigestible stomach contents. Secondary ingestion of plastic through contaminated prey was important in only one species sampled.

The effects of ingested plastic on seabirds: Correlations between plastic load and body condition

Multivariate analyses were used to assess the indepedent influences of body size, ingested plastic load and parasite load on bird mass and on an index of fat reserves in great shearwaters and blue petrels. PLastic load was negatively correlated with body condition in the sample of blue petrels collected after the post-nuptial moult, but diffrences oin reproductive status may account for this negative correlation. Ingested plastic loads had no apparent effect on blue petrels and great shearwaters collected at the same stage of reproduction, despite high plastic loads in some individuals. The limitations of using correlations to demonstrate the effects of plastic ingestion are discussed.

Ingestion of plastic particles by seabirds at Gough Island, South Atlantic Ocean

A survey of the occurrence of plastic in the gizzardz of seabirds at Gough Island indicated that high levels were present in white-faced storm petrels, great shearwaters, and broad-billed prions, while several other species carried small numbers of particles. Larger species tended to carry larger particles. No clear influence of ingested plastic on body condition could be demonstrated although there is some evidence to suggest that Procellariiformes may be susceptible to a build-up of plastic because of their small and constricted gizzard anatomy.

Plastic particles in three procellariiform seabirds from the Benguela Current, South Africa

Small plastic particles were found in White-chinned Petrels and Great Shearwaters collected in the Benguela Current, but not in Sooty Shearwaters collected in the same region. The origin of these particles is unclear. They may have originated in the Antarctic or subantarctic, or, in the case of those found in the Great Shearwaters, in the North Atlantic. Plastic particle pollution of seabirds is an increasing phenomenon, and of concern in view of the possible damage caused to the birds. As such it should be carefully monitored.

THE FOODS OF GREAT AND SOOTY SHEARWATERSPUFFINUS GRAVISANDP. GRISEUSIN EASTERN CANADIAN WATERS

SummaryThe foods of Great and Sooty ShearwatersPuffinus gravisandP. griseusare described from birds collected off eastern Canada. There was a broad overlap in diet, but Great Shearwaters tended to take more squid and tough‐bodied fish such as mackerelScomber scombruswhile Sooties took more euphausiidsMeganyctiphanes norvegicaand soft‐bodied fish such as HerringClupea harengus. These differences are apparently related to differences in bill structure and in the degree of adaptation to underwater swimming.The birds appeared to feed opportunistically on whatever prey was locally available in the size‐range between euphausiids and small fish and squid:Meganyctiphanesoff southwest Nova Scotia, spawning and post‐spawning capelinMallotus villosusoff eastern Newfoundland, and migrating squidIllex illecebrosuson the Grand Bank. Possible factors influencing prey selection are discussed. It is suggested that the timing and routes of the birds' migrations in the North Atlantic are related to the exploitation of such local concentrations.Despite the overlap in diets, differences in the distributions of the two species rule out the possibility of significant competition for common food resources.

Daytime surface swarming by Meganyctiphanes norvegica (M. Sars) (Crustacea, Euphausiacea) off Brier Island, Bay of Fundy

In July–September the euphausiid Meganyctiphanes norvegica (M. Sars) swarms at the surface in daytime off Brier Island, Nova Scotia (ca. 44°15′ N 66°23′ W). Systematic observations of swarming were made, mainly in late August 1974, 1975, 1976, and 1978, supplemented in 1974 and 1975 by the frequency of occurrence of the euphatisiids in the proventriculi of collected greater shearwaters, Puffinus gravis (O'Reilly). Swarms, consisting mostly of immature animals, occurred near an area of turbulence where strong tidal streams ran up against steep underwater ledges, bringing cool subsurface water and also copepods to the surface. Swarming was apparently not an attempt to avoid underwater predators or unfavourable oceanographic conditions, nor was it a means of advancing gonad maturation through exposure to solar irradiation. Swarming was most common in spring tide periods when tidal streams were strongest, and did not occur at all during a neap tide period in late August 1975. It is suggested that M. norvegica swarms were transported passively to the surface by strong vertical turbulence. However, the possibility that they swam actively to the surface in search of copepods and other food passively transported in that way could not be ruled out. It is suggested that the surface swarming of Euphausia pacifica Hansen, the other well-documented survey of the phenomenon, by Y. Komaki in 1967, be reexamined in the light of these conclusions. The significance of surface swarms as food sources for a variety of marine predators is discussed.

Greater Shearwater in Costa Rica

In June 1977, Karen Bjorndal of the University of Florida collected the pelvis and leg bones of a single shearwater at Tortuguero beach on the Caribbean coast of Costa Rica (10'30'N, 83'30'W). The specimen is on deposit at the University of Florida (GSC 290). I compared the bones with skeletons of the eight species of Puffinus listed by Palmer (Handbook of North American birds, Yale University Press, New Haven, Connecticut, 1962). The following species were eliminated because their bones were smaller than the Tortuguero specimen: assimilis, bulleri, carneipes, iherminieri, puffinus, and tenuirostris. Puffinus gravis and P. griseus averaged just slightly larger than the specimen. The leg measurements for these two species overlap considerably, except for the height of the cnemial crest (Tortuguero Puffinus: 13.8 mm; P. gravis: 14.9-17.6 mm, N = 8; P. griseus: 18.8-20.9 mm, N = 8). The specimen agrees with P. gravis, the Greater Shearwater, in the following characters. Pelvis: the proximal, dorsal edge of the ilium is broad and rounded (narrow and pointed in griseus). Femur: the posterior intermuscular line extends onethird the length of the shaft from the distal end (onehalf the length in griseus). Tibiotarsus: (1) the proximal tip of the inner cnemial crest is more rounded (more pointed in griseus); (2) the internal ligamental prominence is high and rounded (low and ridgelike in griseus); (3) on the proximal end, in external view, the prominence extending distally from the head is indistinct (distinct in griseus). Tarsometatarsus: (1) the anterior lip of the external cotyla dips slightly towards the distal end (dips steeply in griseus); (2) in external view, the external calcaneal ridge is long (short in griseus). The Greater Shearwater ranges in open Atlantic waters from Tierra del Fuego to Labrador and Greenland. The Gulf of Mexico was not included in its range in the Check-list of North American Birds (Fifth ed., American Ornithologists' Union, Baltimore, Maryland, 1957). Arnold (Auk 92:394-395, 1975) first reported this species in the Gulf at Galveston, Texas. Eastern Caribbean records (Trinidad and Los Roques, Venezuela) were reviewed by Collins and Tikasingh (Bull. Br. Ornithol. Club 94:96-99, 1974). It was not listed by Slud (The birds of Costa Rica, American Museum of Natural History, New York, 1964). This then is the first record of the Greater Shearwater for Costa Rica and the western Caribbean. I thank Pierce Brodkorb for checking the identification of the specimen and for loaning comparative material.

Parasites of the greater shearwater (Puffinus gravis) from Newfoundland, Canada.

Two groups of ectoparasites (Mallophaga and Acarina) and two groups of helminths (Cestoda and Nematoda) were recovered from 49 Puffinus gravis collected off the coast of insular Newfoundland, in 1974 and 1975. Mallophagans of the genera Ancistrona, Austromenopon, Docophoroides, Halipeurus, Naubates, Saemundssonia, and Trabeculus, and acarines belonging to the genera Brephosceles, Microspalax, and Zachvatkinia were recovered. Of the 10 genera and 12 species collected, 3 genera (Docophoroides, Microspalax, Zachvatkinia) and 2 species (Saemundssonia peusi, Halipeurus diversus) had not previously been recorded on this host.Cestodes of the genus Tetrabothrius and nematodes of the genera Contracaecum, Seuratia, Stegophorus, Tetrameres, and the subfamily Dicheilonematinae were also obtained. Before this study no nematodes had been recovered from this host.Details of the degree of infestation of the birds are given, as well as the distribution of each ectoparasite species on the host.