Variations of snow petrel breeding success in relation to sea-ice extent: detecting local response to large-scale processes?

Demographic parameters were estimated for snow petrels Pagodroma nivea nesting at the study colony of Reeve Hill near Casey station, Antarctica between 1984 and 2003. Average breeding success for the colony varied from 18.2% to 76.5%. Breeding effort, hatching and fledging success were subject to a high interannual variability. We examined the influence of regional sea-ice extent on the breeding performance of snow petrels at Reeve Hill. Fewer birds were breeding when sea-ice had been extensive during April–May. Overall breeding success and fledging success were improved during years with extensive sea-ice cover in winter. Successful breeding effort and breeding success were depressed when there was extensive sea-ice cover during January–February. Sea surface temperatures also correlated to snow petrel breeding performance parameters. Previous work showed that large-scale climatic events (ENSO, Antarctic circumpolar wave) and the related sea-ice cover around the Antarctic might affect the lower trophic levels of the marine environment and consequently food availability for snow petrels. A comparison with the long-term study conducted at Ile des Pétrels (Terre Adélie) suggests that despite similarities in the underlying biological processes that control snow petrel breeding performance, the nature of the correlation of large-scale environmental factors with breeding performance differs substantially between the two colonies, probably because of the confounding effects of other environmental factors acting at a local scale (local weather, nest quality), which also affect bird body condition.     

First census of breeding seabirds between Cap Bienvenue (Terre Adélie) and Moyes Islands (King George V Land), Antarctica: new records for Antarctic seabird populations

Breeding population sizes of penguins, fulmarine etrels and skuas were estimated for the first time on a major part of the Terre Adélie coast and a section of the King George V Land coast during the 1997/1998 austral summer. We counted 106,400 breeding pairs and 12,400 Adélie penguin (Pygoscelis adeliae) chicks by direct counts, and 6960 breeding pairs from aerial photographs. Minimum breeding populations for other species are (direct counts): Antarctic fulmar (Fulmarus glacialoides) 6861 pairs, Antarctic petrel (Thalassoica antarctica) 4574 pairs, cape petrel (Daption capense) 194 pairs, snow petrel (Pagodroma nivea) 767 pairs, south polar skua (Catharacta maccormicki) 129 pairs and subantarctic skua (Catharacta lonnbergi) 1 breeding bird. We discovered 29 new seabird breeding locations in King George V Land, including 6 Antarctic fulmar, 4 Antarctic petrel, 3 cape petrel, 6 snow petrel and 10 south polar skua colonies. The largest colonies found contained up to 4205 breeding pairs of Antarctic fulmars. Population sizes of all species obtained in this study are higher than those found during previous partial surveys. Although these differences are in great part due to differences in survey methods, they also reflect real population changes. Our minimum population sizes obtained for a small portion of the Antarctic coast (<2%) suggest an underestimation of the estimated world breeding populations for several species of Antarctic seabirds. Accepted: 28 August 1998     

Demographic effects of extreme weather events: snow storms,breeding success,and population growth rate in a long‐lived Antarctic seabird

Weather extremes are one important element of ongoing climate change, but their impacts are poorly understood because they are, by definition, rare events. If the frequency and severity of extreme weather events increase, there is an urgent need to understand and predict the ecological consequences of such events. In this study, we aimed to quantify the effects of snow storms on nest survival in Antarctic petrels and assess whether snow storms are an important driver of annual breeding success and population growth rate. We used detailed data on daily individual nest survival in a year with frequent and heavy snow storms, and long term data on petrel productivity (i.e., number of chicks produced) at the colony level. Our results indicated that snow storms are an important determinant of nest survival and overall productivity. Snow storm events explained 30% of the daily nest survival within the 2011/2012 season and nearly 30% of the interannual variation in colony productivity in period 1985–2014. Snow storms are a key driver of Antarctic petrel breeding success, and potentially population dynamics. We also found state‐dependent effects of snow storms and chicks in poor condition were more likely to die during a snow storm than chicks in good condition. This stresses the importance of considering interactions between individual heterogeneity and extreme weather events to understand both individual and population responses to climate change.     

Contrasted patterns of age-specific reproduction in long-lived seabirds

While the number of studies providing evidence of actuarial senescence is increasing, and covers a wide range of taxa, the process of reproductive senescence remains poorly understood. In fact, quite high reproductive output until the last years of life has been reported in several vertebrate species, so that whether or not reproductive senescence is widespread remains unknown. We compared age-specific changes of reproductive parameters between two closely related species of long-lived seabirds: the small-sized snow petrel Pagodroma nivea, and the medium-sized southern fulmar Fulmarus glacialoides. Both are sympatric in Antarctica. We used an exceptional dataset collected over more than 40 years to assess age-specific variations of both breeding probability and breeding success. We found contrasted age-specific reproductive patterns between the two species. Reproductive senescence clearly occurred from 21 years of age onwards in the southern fulmar, in both breeding probability and success, whereas we did not report any decline in the breeding success of the snow petrel, although a very late decrease in the proportion of breeders occurred at 34 years. Such a contrasted age-specific reproductive pattern was rather unexpected. Differences in life history including size or migratory behaviour are the most likely candidates to account for the difference we reported in reproductive senescence between these sympatric seabird species.     

Insular bird populations can be saved from rats: a long-term experimental study of white-chinned petrels<Emphasis Type="Italic"> Procellaria aequinoctialis</Emphasis> on Ile de la Possession (Crozet archipelago)

The white-chinned petrel is a subantarctic seabird that requires urgent implementation of conservation measures for the species. At sea, adults suffer heavy mortality due to fisheries' practices. On land, introduced rats prey on chicks at several localities, and we test here if and how rats can be efficiently controlled. Since 1994, we have conducted an intensive rat-control program during each breeding season in a white-chinned petrel colony on Ile de la Possession (150 km²; Crozet archipelago, southern Indian Ocean), which had been monitored since 1986. On the same island, a control white-chinned petrel colony, where no poisoning occurred, was also monitored, and we assessed the seasonal variations of rat abundance. We compared three situations: high rat-poisoning, low rat-poisoning and control conditions without poisoning. Low-poisoning trials performed in our experimental colony between 1988 and 1991 did not lead to higher chick production than for the previous two control years. However, petrel-breeding success was significantly higher when intensive poisoning occurred (50%) than for the previous years (16%). The duration of our study (8 years before intensive poisoning, plus 8 years afterwards), combined with a comparison of petrel annual breeding success between our experimental and control colonies, allowed us to assess more effectively the impact of rats. Forty-one per cent of breeding failures occurring in non-poisoned areas were attributed to rats. We conclude that threatened insular bird populations can be conserved and restored in localities even where total rat eradication is not possible. However, only intensive and repeated (long-term) poisoning will control rats sufficiently.     

Selection against immigrants in wild seabird populations

Immigration is a major demographic parameter shaping population dynamics and is an important driver of eco‐evolutionary patterns, but the fitness consequences for individuals following their settlement to a new population (immigrants) remain poorly tested in wild animal populations, particularly among long‐lived species. Here we show that immigrants have a lower fitness than residents in three wild seabird populations (wandering albatross Diomedea exulans, southern fulmar Fulmarus glacialoides, snow petrel Pagodroma nivea). Across all species and during a 32‐year period, immigrants made on average ?9 to 29% fewer breeding attempts, had 5–31% fewer fledglings, had 2–16% lower breeding success and produced 6–46% fewer recruits. Female immigration and male residency were also favored through differences in breeding performance. We provide evidence for selection against immigrants in wild populations of long‐lived species and our results are consistent with female‐biased dispersal in birds being driven by asymmetric limiting resources and the competitive ability of dispersers vs. non‐dispersers.     

Long-term population trends in seven Antarctic seabirds at Pointe Géologie (Terre Adélie) Human impact compared with environmental change

Antarctic seabird populations have been much studied over the last decades as bioindicators of the nature of variability in the Southern Ocean marine ecosystem, and most attention has been focused on the role of food supply and the extent of sea ice. In addition, the rapid spread of tourism and the activities of researchers since the early 1960s have raised questions related to their real and potential impact on bird populations. Our data sets start in 1952 for several species of Antarctic seabirds and this study documents the trends over a 14-year period (1985–1999) in seven species breeding on Pointe Géologie archipelago (Terre Adélie, Antarctica). This is the first study where the direct impact of destruction of breeding sites (for building of an airstrip) is examined and where such long-term populations trends have been assessed in such a number of Antarctic species at one site. Trends from 1985 show that for the whole archipelago and when excluding islands destroyed, Adélie penguins and south polar skuas were the only species to show a significant increase (>3.5% annual change). The others species showed opposite trends, three increasing slightly (southern fulmars +0.4%, cape petrels +2.3%, snow petrels +0.9%) and two decreasing (emperor penguin −0.9%, southern giant petrel −3.9%). Three species particularly affected by the destruction of their breeding habitat (Adélie penguin, cape petrel, snow petrel) showed the capability to restore their populations. The availability of food and nesting sites is discussed in relation to environmental change. Species feeding on krill (Adélie penguins and cape petrels) increased more than other species; however, decrease of ice cover can increase availability of nesting sites. The importance of long-term studies is shown when assessing the role of human activities in Antarctica compared to larger-scale changes. Accepted: 18 September 2000     

One House Two Families: Petrel Squatters Get a Sniff of Low‐Cost Breeding Opportunities

Burrowing is a widespread nesting behaviour, found in vertebrates and invertebrates. It is particularly common in small procellariiform seabirds such as blue petrels (Halobaena caerulea) and Antarctic prions (Pachyptila desolata), two closely related petrel species. However, digging a burrow is costly and alternative strategies may evolve. Accordingly, blue petrel males can adopt two alternative nesting strategies: digging a new burrow or squatting in an empty one. Importantly, a blue petrel squatter arriving at the colony to breed is more likely to find empty Antarctic prion burrows than empty blue petrel burrows, since the former species only start breeding a month later. However, squatting in a prion’s burrow is risky for blue petrels as the legitimate owner very often returns and claims the burrow back, thus ruining the squatter’s breeding attempt. We present here results of a survey of two sympatric colonies of blue petrels and Antarctic prions on Kerguelen Island. Our data show that blue petrel squatters preferentially occupy blue petrel empty burrows. To investigate potential underlying mechanisms behind this preference, we used a simple Y‐maze design to show that blue petrels can discriminate and prefer their specific odour over the prion odour. Our results confirm the existence of alternative burrowing strategies in blue petrels and suggest that squatters could use olfaction to avoid the less suitable Antarctic prion burrows.     

Early body condition and hatching success in the snow petrel Pagodroma nivea

We examined how variations in parental quality affect the reproductive success of a long-lived seabird, the snow petrel (Pagodroma nivea). In particular, we focused on how prebreeding body condition (prebreeding body mass adjusted for structural size) influences the hatching success of male and female snow petrel. Condition in females, but not in males, had a significant effect on hatching success. Among breeding pairs, early body condition of pairs was not significantly related to their hatching success. Laying date had a significant effect on hatching success, but this was due to heavy snowfalls during the beginning of the laying period. We suggest that females in poor early condition would not be able to build up sufficient body reserves necessary for successful incubation during the energy-demanding egg formation period. Moreover males, being structurally larger, would have a higher fasting capacity. These results show that the hatching success of the snow petrel is clearly influenced by female condition and suggest that effects of variations in environmental conditions may depend on body condition of individuals. However, the year of the study appeared to be an unusually poor year for reproduction, which may be why female body condition appears to be important. Accepted: 24 June 1998     

Predictive habitat modelling to estimate petrel breeding colony sizes: Sooty shearwaters (Puffinus griseus) and mottled petrels (Pterodroma inexpectata) on Whenua Hou Island

Abstract

Between 2001 and 2006, we systematically sampled the entire coast of Whenua Hou, a rugged offshore island in southern New Zealand, to estimate the population densities of sooty shearwaters (Puffinus griseus) and mottled petrels (Pterodroma inexpectata) by counting the entrances of breeding burrows. A two‐step regression modelling process using binomial errors was used to predict the presence of a colony, and a normal general linear model was used to predict the density of entrances within colonies. Aerial photography, GIS and a Digital Elevation Model were used to extract relevant habitat and location variables, and a combination of both regression models was used to predict the density of breeding burrows within each 5.32 m² pixel on the island. This complex GIS and habitat prediction modelling approach gave population estimates very similar to a more traditional simple area extrapolation method and gave no improvement in precision. However, correction for the slope of the land increased our simple area estimates of population size by 11%. We estimate populations of sooty shearwater and mottled petrel breeding pairs at 173 000 (162 000–190 000) and 160 000 (123 000–197 000) respectively. Based on this number of breeding pairs, we calculate that Whenua Hou supports a total population of 868 000 (554 000–1 270 000) sooty shearwaters. Our estimate of the total mottled petrel population 202 000 pairs (162 000–242 000) is comparable with the only published estimate, but could be an underestimate because mottled petrels are sometimes found in large burrows. More research for robust estimation of population trends is needed to assess the conservation status of mottled petrels.     

Winter Fidelity and Apparent Survival of Lesser Snow Goose Populations in the Pacific Flyway

Abstract The Beringia region of the Arctic contains 2 colonies of lesser snow geese (Chen caerulescens caerulescens) breeding on Wrangel Island, Russia, and Banks Island, Canada, and wintering in North America. The Wrangel Island population is composed of 2 subpopulations from a sympatric breeding colony but separate wintering areas, whereas the Banks Island population shares a sympatric wintering area in California, USA, with one of the Wrangel Island subpopulations. The Wrangel Island colony represents the last major snow goose population in Russia and has fluctuated considerably since 1970, whereas the Banks Island population has more than doubled. The reasons for these changes are unclear, but hypotheses include independent population demographics (survival and recruitment) and immigration and emigration among breeding or wintering populations. These demographic and movement patterns have important ecological and management implications for understanding goose population structure, harvest of admixed populations, and gene flow among populations with separate breeding or wintering areas. From 1993 to 1996, we neckbanded molting birds at their breeding colonies and resighted birds on the wintering grounds. We used multistate mark-recapture models to evaluate apparent survival rates, resighting rates, winter fidelity, and potential exchange among these populations. We also compared the utility of face stain in Wrangel Island breeding geese as a predictor of their wintering area. Our results showed similar apparent survival rates between subpopulations of Wrangel Island snow geese and lower apparent survival, but higher emigration, for the Banks Island birds. Males had lower apparent survival than females, most likely due to differences in neckband loss. Transition between wintering areas was low (<3%), with equal movement between northern and southern wintering areas for Wrangel Island birds and little evidence of exchange between the Banks and northern Wrangel Island populations. Face staining was an unreliable indicator of wintering area. Our findings suggest that northern and southern Wrangel Island subpopulations should be considered a metapopulation in better understanding and managing Pacific Flyway lesser snow geese. Yet the absence of a strong population connection between Banks Island and Wrangel Island geese suggests that these breeding colonies can be managed as separate but overlapping populations. Additionally, winter population fidelity may be more important in lesser snow geese than in other species, and both breeding and wintering areas are important components of population management for sympatric wintering populations.     

Monteiro's Storm‐petrel Oceanodroma monteiroi: a new species from the Azores

The existence of two seasonally distinct breeding populations of Oceanodroma storm‐petrels in the Azores islands was first documented in 1996. The discovery of morphological differences between the populations led to the suggestion that they may represent cryptic sibling species. Recent mtDNA and microsatellite analysis from storm‐petrel populations has considerably advanced our understanding of their taxonomic relationships. Here we present new information on the timing of breeding and moult of the two Azores populations, the extent of exchange of individuals between seasons, and diet from feather isotopes. We conclude that the hot‐season Azores population should be considered a new species for which we propose the name Oceanodroma monteiroi, Monteiro's Storm‐petrel. The species is both genetically distinct and genetically isolated from the sympatric cool‐season population of Madeiran Storm‐petrel Oceanodroma castro, and from all other populations of Oceanodroma castro in the Atlantic and Pacific Oceans examined to date. Differences in the vocalizations permit species recognition, and the extent of primary feather wear and stage of moult aids separation of the two species in the Azores, which is especially valuable during August when both attend the breeding colonies in large numbers. Feather carbon and nitrogen isotopes reveal that the diet of Monteiro's Storm‐petrel differs from that of the sympatric Madeiran Storm‐petrel during both breeding and non‐breeding seasons, and unlike the Madeiran Storm‐petrel, Monteiro's Storm‐petrel appears to maintain the same foraging environment during the summer and winter months, though it shows a dietary shift to higher trophic levels during the non‐breeding season. Monteiro's Storm‐petrel is thought to be confined to the Azores archipelago, where it is currently known to nest on just two small neighbouring islets. The total population size was estimated at 250–300 pairs in 1999.     

The persistence of the snow petrel (Pagodroma nivea) in Dronning Maud Land (Antarctica) for over 37,000?years

Two samples of snow petrel Pagodroma nivea mumiyo (solidified stomach oil) from Heimefrontfjella (74°34′36″S, 11°13′24″W) in Dronning Maud Land, Antarctica, were radiocarbon dated at 37,400 ± 1,500 and 3,120 ± 70 years old (dates are corrected for the ‘reservoir effect’). The age of the older sample provides further evidence that snow petrel colonies have existed in the mountain peaks of Dronning Maud Land since before the last glacial maximum (approx. 20,000–16,000 years ago). This finding also pushes back the estimated timing of establishment of snow petrel breeding colonies in this part of the continent by several thousand years. The variation in the accumulation rates of these two samples (1.6 and 35.2 mm per millennium, respectively) supports previous observations that mumiyo accumulation rates are highly variable and probably relate to site-specific factors affecting accumulation and degradation of the oil. Studies that help us understand historical bird population distributions in continental Antarctica can significantly aid the development and refinement of models that explain glacial advancement and retreat, the relationship between sea ice and population viability and, perhaps, predict species responses to future climate shifts.     

Hybridization and Back-Crossing in Giant Petrels (Macronectes giganteus and M. halli) at Bird Island,South Georgia,and a Summary of Hybridization in Seabirds

Hybridization in natural populations provides an opportunity to study the evolutionary processes that shape divergence and genetic isolation of species. The emergence of pre-mating barriers is often the precursor to complete reproductive isolation. However, in recently diverged species, pre-mating barriers may be incomplete, leading to hybridization between seemingly distinct taxa. Here we report results of a long-term study at Bird Island, South Georgia, of the extent of hybridization, mate fidelity, timing of breeding and breeding success in mixed and conspecific pairs of the sibling species, Macronectes halli (northern giant petrel) and M. giganteus (southern giant petrel). The proportion of mixed-species pairs varied annually from 0.4–2.4% (mean of 1.5%), and showed no linear trend with time. Mean laying date in mixed-species pairs tended to be later than in northern giant petrel, and always earlier than in southern giant petrel pairs, and their breeding success (15.6%) was lower than that of conspecific pairs. By comparison, mixed-species pairs at both Marion and Macquarie islands always failed before hatching. Histories of birds in mixed-species pairs at Bird Island were variable; some bred previously or subsequently with a conspecific partner, others subsequently with a different allospecific partner, and some mixed-species pairs remained together for multiple seasons. We also report the first verified back-crossing of a hybrid giant petrel with a female northern giant petrel. We discuss the potential causes and evolutionary consequences of hybridization and back-crossing in giant petrels and summarize the incidence of back-crossing in other seabird species.     

Distribution and abundance of Wilson’s storm petrels Oceanites oceanicus at two locations in East Antarctica: testing habitat selection models

Over the last decades, Antarctic seabird populations have been studied as bioindicators of the variability in the Southern Ocean marine ecosystem. Little information is available on the distribution and abundance of Wilson’s storm petrel (Oceanites oceanicus) in East Antarctica although the bioindicator value of this species has been investigated. Regional surveys were conducted at two coastal locations, Casey (66°S, 110°E) and Mawson (67°S, 62°E), to locate Wilson’s storm petrel nests using systematic searches in sites selected with a balanced random sampling design. Conducted in ice-free areas of similar size, searches located 553 Wilson’s storm petrel nests at Mawson and 630 at Casey. Comparable densities were observed between locations but regional estimates suggest that Wilson’s storm petrels are more abundant at Casey. Habitat preferences of Wilson’s storm petrels were investigated using resource selection functions based on Generalized Additive and Linear Models (GAMs and GLMs), which allow their ecological niche to be graphically and quantitatively described. The orientation of nests in relation to the prevailing winds was identified as a determinant of nest distribution at both locations. However, selected rock substrate types differed between Mawson and Casey. Snow was confirmed to constrain the spatial distribution of nests, especially at Casey where snow precipitations and accumulation are more common in summer, confirming the results of previous temporal surveys focusing on breeding success. At the southern edge of its geographic distribution, the Wilson’s storm petrel may be subject to more obvious climate related habitat changes in East Antarctica. Such models may provide valuable information to detect the potential effect of climate variations on this species and others, in the context of a broad Antarctic ecosystem monitoring.     

Differences in habitat selection between Chatham petrels (

The Chatham petrel (Pterodroma axillaris) is an endangered species restricted to a single population on South East Island, Chatham Islands, New Zealand. The key threat to Chatham petrel breeding success is interference with chicks by broad-billed prions (Pachyptila vittata) prospecting for burrows for their oncoming breeding season. This burrow competition has resulted from alteration to breeding habitat by humans throughout the Chatham Islands. Understanding habitat preferences may enable managers to manipulate habitat to reduce burrow competition and will be essential in order to translocate Chatham petrels to a proposed second colony. Habitat characteristics surrounding both Chatham petrel and broad-billed prion burrows were quantified and selection ratios compared. Both Chatham petrels and broad-billed prions selected habitat factors associated with mature forest. Chatham petrels avoided a large number of habitat characteristics, which suggests they were habitat specific, and their preferred habitat is now limited. Broad- billed prions used a wide range of habitat characteristics, which suggests they are not habitat specific. This study recommends that selection values be used when deciding on the best location to establish a second Chatham petrel colony.     

Exploitation of inland-breeding Antarctic petrels by south polar skuas

During the austral summer of 1996/1997 we studied south polar skuas at Svarthamaren, Dronning Maud Land, Antarctica, where the world's largest known colony of Antarctic petrels is found. Our censuses suggested approximately 250 full-grown skuas and 140,000 breeding pairs of petrels were present. During their breeding season, skuas did not visit the open sea at least 200 km from the site; they relied entirely on prey caught and scavenged from the petrel colony. Because the site is so isolated, we asked whether the prey (petrels) had swamped the predators (skuas), or whether there was evidence that predator numbers were limited by the size of the prey population. Particularly at the end of the petrel incubation period, we found a close correspondence between the energy required by adult skuas and their chicks, ascertained from time budget studies, and the rate at which petrel eggs disappeared from the colony. This suggests that, in this closed system, the predator population was limited by the prey population, and that predator swamping was not an advantage that petrels gained by nesting in this remote location. Received: 12 April 1999 / Accepted: 30 June 1999     

The diets of five summer breeding seabirds in Adélie Land,Antarctica

Summary The diets of five breeding seabird species were investigated on Adélie Land in January–February 1982. Stomach contents of Adélie penguins, Pygoscelis adeliae, were sampled by a water off-loading method and of Procellariiformes by spontaneous regurgitation. Diet compositions by mass were: Adélie penguin (79% euphausiid, 18% fish, 3% squid); Cape pigeon, Daption capense, (64% euphausiid, 29% fish, 7% carrion); Antarctic fulmar, Fulmarus glacialoides, (64% euphausiid, 20% carrion, 16% fish); snow petrel, Pagodroma nivea, (95% fish, 2% euphausiid, 1% carrion) and Wilson's stormpetrel, Oceanites oceanicus, (39% fish, 37% euphausiid, 13% carrion, 12% various crustaceans). The present Adélie penguin diet is consistent with those reported in other studies, given our knowledge of geographical variation in food availability. Differences in the diets of fulmarine petrels appear to relate to differences in foraging areas. The snow petrel is a fish-eating bird associated with pack-ice. Cape pigeon and Antarctic fulmar are mainly krill-eaters and we infer segregation along a neritic/oceanic gradient because of the importance of the neritic Euphausia crystallorophias in the former and the oceanic E. superba in the latter.     

Foods of the south polar skua Catharacta maccormicki in the eastern Larsemann Hills,Princess Elizabeth Land,East Antarctica

Regurgitated pellets and food remains were collected near nest sites, and from a club site, of south polar skuas Catharacta maccormicki in the eastern Larsemann Hills, Princess Elizabeth Land, East Antarctica, during the skuas' presence in the area. The samples indicated that the snow petrel Pagodroma nivea, the most abundant seabird species breeding locally, formed the major dietary component, comprising some 66% of food items identified in pellets and 80% of the food remains obtained. Adélie penguins Pygoscelis adeliae (which do not breed in the Larsemann Hills), other seabirds, fish and marine foods were rarely found as remains or in pellets. However, refuse (meat, fish and vegetable remains) taken as food by skuas from nearby stations occurred in pellets at all sites and formed about 12% of the food remains collected and identified. In this study, foods taken by skuas were related both to the local breeding distribution of snow petrels, and to the possession of a feeding territory. Birds without feeding territories took somewhat fewer snow petrels and included more refuse from local stations in their diet, as did those at the club site. Future monitoring of the influence of anthropogenic foods (and inedible waste materials) on the species' ecology is considered important.     

Occurrence of the flea Glaciopsyllus antarcticus and avian lice in central Dronning Maud Land

The flea Glaciopsyllus antarcticus is endemic to the Antarctic continent, where it is known to parasitise a number of seabird species. This paper reports the occurrence of the flea and two species of lice from snow petrel (Pagodroma nivea) colonies in central Dronning Maud Land, Antarctica, and extends considerably the recorded distribution of the flea. Flea adults, pupae and larvae were recovered from 10 of 11 samples of organic material collected from snow petrel nests at Svarthamaren (71°53^′S, 05°10^′E) in the Mühlig-Hofmannfjella. Specimens of two philopterid lice species, Saemundssonia antarctica and Pseudonirmus charcoti, were recovered from three of these samples. Specimens of the Antarctic flea and of the louse S. antarctica were recovered from carcasses of snow petrel chicks collected both at Svarthamaren and Robertskollen (71°28^′S, 03°15^′W) in the northern Ahlmannryggen; the louse Pseudonirmus charcoti was recovered from Robertskollen only. Received: 30 January 1996 / Accepted: 28 April 1997