Uria Lomvia Research Articles

Four sympatrically nesting auks show clear resource segregation in their foraging environment

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 572:243-254 (2017) - DOI: https://doi.org/10.3354/meps12144 Four sympatrically nesting auks show clear resource segregation in their foraging environment Isabeau Pratte1,*, Gregory J. Robertson2, Mark L. Mallory1 1Department of Biology, Acadia University, Wolfville, Nova Scotia B4P 2R6, Canada 2Wildlife Research Division, Environment and Climate Change Canada, Mount Pearl, Newfoundland A1N 4T3, Canada *Corresponding author: pratteisabeau@gmail.com ABSTRACT: Auks share ecological similarities and are often found in sympatrically nesting assemblages at suitable nesting sites. It is expected that co-existing species would have evolved strategies to reduce niche overlap in response to resource competition. The presence of Atlantic puffins Fratercula arctica, razorbills Alca torda, thick-billed murres Uria lomvia and common murres U. aalge at the Gannet Islands, Labrador, is an opportunity to study interspecific interactions in a major seabird community. We compared the foraging movements of adult breeding birds and the diet of the birds inferred through (1) stable isotopes in the blood of adults, and (2) prey delivered to the chicks, as dimensions in the foraging niche among these 4 auks. Our results revealed that puffins and thick-billed murres headed offshore to forage, while razorbills and common murres were more coastal, heading towards mainland Labrador. The patterns of spatial segregation found among coastal and pelagic birds were mirrored by their stable isotope ratios, with one group of species foraging at a higher trophic level of an inshore food web and the other foraging on a lower trophic level of an offshore, pelagic food web. The ‘pelagic’ species segregated by prey choice for their chicks while differential alternate prey selection was the source of segregation between the ‘coastal’ species. Our research highlights the importance of segregation patterns in both spatial and diet dimensions of the foraging niche among the 4 auks—a potential mechanism for reducing interspecific competition among ecologically similar seabirds and explaining the persistence of such seabird assemblages through time. KEY WORDS: Seabird · Foraging distribution · Niche overlap · Diet · Isotopic niche Full text in pdf format Supplementary material PreviousNextCite this article as: Pratte I, Robertson GJ, Mallory ML (2017) Four sympatrically nesting auks show clear resource segregation in their foraging environment. Mar Ecol Prog Ser 572:243-254. https://doi.org/10.3354/meps12144 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 572. Online publication date: May 31, 2017 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2017 Inter-Research.

Ongoing Research on Herding Agents for In Situ Burning in Arctic Waters: Studies on Fate and Effects

ABSTRACT Research on the fate and effects of herding agents used to contain and thicken oil slicks for in situ burning in Arctic waters continues under the auspices of the International Association of Oil and Gas Producers Arctic Oil Spill Response Technology – Joint Industry Program (JIP). In 2014/2015 laboratory studies were conducted on the fate and effects of herders. The purpose of the studies was to improve the knowledge base used to evaluate the environmental risk of using herders in connection with in situ burning for oil spill response in Arctic seas. Two herding agents were studied (OP 40 and ThickSlick 6535). Laboratory-scale herding and burning experiments were carried out for investigating the physical fate of the two herders during combustion of Alaska North Slope and Grane crude oils (fresh and emulsified). The results showed that after burning, the herder was mainly found on the water surface, and only small concentrations of herders were found in the water column (0.2–22.8 mg/L). The inherent properties of herders in relation to toxicity and bioaccumulation on the high Arctic copepods (Calanus hyperboreus), as well as the biodegradability of herders were studied under arctic conditions. The results indicated that a distinct mortality was seen at the highest test concentrations of the herders. However, the concentration of herders required to produce acute toxicity in the laboratory was approximately three orders of magnitude higher than the concentrations measured in the water column when herders were used to conduct an in situ burn in the laboratory. OP-40 might bio-accumulate whereas TS6535 might not. TS6535 was mostly degraded within 7 days, whereas the degradation of OP-40 was insignificant over 28 days. Since herders are mainly considered as a surface active chemical compound, the potential impacts of herders on Arctic seabird feathers (from legally hunted Thick-Billed Murre and Common Eider) were investigated. Different dosages of herders were tested; high dosages that might be present just after the application of the herder and low dosages (approximately monolayers) likely to occur for a significant time and distance from the operations. Low dosages corresponding to approximately monolayers of OP-40 and TS6535 did not cause feathers to sink; however they did absorb more water than the controls. The high dosages caused measured damages to the feather microstructure. Finally, laboratory burning experiments were carried out to determine if there was a difference in the composition of smoke plumes from mechanically contained burns versus herded oil burns. Herder was not measured in the smoke plumes, and there were no other noticeable differences in combustion between the two methods of containment (herder vs. metal ring).

Declining Trends of Polychlorinated Naphthalenes in Seabird Eggs from the Canadian Arctic, 1975-2014.

There are relatively few studies of polychlorinated naphthalenes (PCNs) for biota in polar regions and even fewer reports of temporal trends. We determined concentrations of PCNs in eggs of thick-billed murres (Uria lomvia) collected from the Canadian high Arctic between 1975 and 2014 and calculated their associated toxic equivalents (TEQs). Concentrations of Σ67PCN decreased significantly in the murre eggs between 1975 and 2014 at an average annual rate of -14.9 pg g-1 wet weight. Although the penta- and tetra-CNs (predominantly CN-52/60 and CN-42) dominated the PCN profile, the hexa-CNs (mainly CN-66/67) accounted for the majority of the Σ67TEQ-PCN, concentrations of which also decreased significantly between 1975 to 2014. On average, Σ67TEQ-PCN in the murre eggs accounted for only 1.9% of the total toxicity calculated for dioxin-like compounds measured in the murre eggs. As such, the TEQ-PCN concentrations calculated for the murre eggs in this study are several orders of magnitude lower than TEQ levels associated with reproductive effects in birds. This is the first published study of temporal trends of PCNs in Canadian Arctic biota.

Reduced activity in middle-aged thick-billed murres: evidence for age related trends in fine-scale foraging behaviour

Several biological functions, such as reproductive success, peak during middle age in long-lived vertebrates. One possible mechanism for that peak is improved foraging performance during middle age, after a period of youthful inexperience and before senescence. Age may be particularly important in relating foraging behaviour to fitness for diving animals as altered skeletal muscle contraction efficiency or cardiovascular function could play a strong role at the scale of a single dive. Miniaturized accelerometers provide the opportunity to measure fine-scale foraging behaviour at the scale of a single wing beat. To examine the relationship between age and foraging behaviour in a diving seabird, whose reproductive success peaks during middle age, we equipped 115 thick-billed murres, Uria lomvia, with accelerometers and depth loggers. Murre activity (i.e. dynamic body acceleration) decreased with increasing dive depth during descent but increased with increasing maximum depth achieved. These patterns were inversed during ascent. After accounting for depth and maximum depth, middle-aged birds had low activity levels during the dive, compared with old and young birds, suggesting that old and young birds were less efficient at diving and foraging than middle-aged birds. Young individuals appeared to struggle at depths above 20 m during descent and throughout ascent when compared to middle-aged birds, while old individuals struggled at the end of deep dives during descent and during the initial parts of ascent when compared to the same middle-age class. We conclude that there is a link between foraging behaviour and age, contrary to previous findings. By examining foraging behaviour at a fine-scale, such as a dive, different energy expenditures across age groups were revealed, giving us insight on how seabirds are affected by senescence in the wild.

Outlier analyses to test for local adaptation to breeding grounds in a migratory arctic seabird

Investigating the extent (or the existence) of local adaptation is crucial to understanding how populations adapt. When experiments or fitness measurements are difficult or impossible to perform in natural populations, genomic techniques allow us to investigate local adaptation through the comparison of allele frequencies and outlier loci along environmental clines. The thick‐billed murre (Uria lomvia) is a highly philopatric colonial arctic seabird that occupies a significant environmental gradient, shows marked phenotypic differences among colonies, and has large effective population sizes. To test whether thick‐billed murres from five colonies along the eastern Canadian Arctic coast show genomic signatures of local adaptation to their breeding grounds, we analyzed geographic variation in genome‐wide markers mapped to a newly assembled thick‐billed murre reference genome. We used outlier analyses to detect loci putatively under selection, and clustering analyses to investigate patterns of differentiation based on 2220 genomewide single nucleotide polymorphisms (SNPs) and 137 outlier SNPs. We found no evidence of population structure among colonies using all loci but found population structure based on outliers only, where birds from the two northernmost colonies (Minarets and Prince Leopold) grouped with birds from the southernmost colony (Gannet), and birds from Coats and Akpatok were distinct from all other colonies. Although results from our analyses did not support local adaptation along the latitudinal cline of breeding colonies, outlier loci grouped birds from different colonies according to their non‐breeding distributions, suggesting that outliers may be informative about adaptation and/or demographic connectivity associated with their migration patterns or nonbreeding grounds.

Density dependence and changes in the carrying capacity of Alaskan seabird populations

Evidence for regulation of animal populations by negative density dependence is ubiquitous across the animal realm, and yet the dynamics of carrying capacity (K) are often overlooked. K acts as a threshold below which population size tends to increase and above which it tends to decrease. Documenting changes in this threshold is particularly important to population viability analysis (PVA). We reconstructed the population sizes of five long-lived seabird species in Alaska, USA, and analyzed their population dynamics from the past four decades: Black-legged (Rissa tridactyla) and Red-legged Kittiwakes (R. brevirostris), Common (Uria aalge) and Thick-billed Murres (U. lomvia) and Tufted Puffins (Fratercula cirrhata). We evaluated a set of models that allowed for either density independence or density dependence, with or without a time trend in K. The best approximating models indicated that these seabird populations behaved in a negative density-dependent fashion. K increased significantly for murres, and remained relatively stable for Red-legged Kittiwakes. It decreased significantly (>40%) for Black-legged Kittiwakes and Tufted Puffins, particularly in the Gulf of Alaska, following the 1989 Exxon Valdez oil spill. Although we have less confidence in the puffin data, our PVA suggests that, in the next 100years, Tufted Puffins may become extirpated from the few colonies that are monitored in the Gulf of Alaska. Negative density dependence can help to prevent population crashes, but time lags and serial correlation in rates of change could suppress the recovery of contracted populations. Therefore, estimating the magnitude of population fluctuations around a changing carrying capacity is essential to managing and conserving declining populations.

Relationship between telomere dynamics and movement and behavior during winter in the thick‑billed murre

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 578:253-261 (2017) - DOI: https://doi.org/10.3354/meps12022 Relationship between telomere dynamics and movement and behavior during winter in the thick‑billed murre Rebecca C. Young1,*, Rachael A. Orben2, Alexis P. Will1, Alexander S. Kitaysky1 1Department of Biology and Wildlife, Institute of Arctic Biology, University of Alaska Fairbanks, Irving 311, Fairbanks, AK 99775, USA 2Department of Fisheries and Wildlife, Oregon State University, Hatfield Marine Science Center, 2030 SE Marine Science Dr., Newport, OR 97365, USA *Corresponding author: rebeccacyoung721@gmail.comAdvance View was available online February 22, 2017 ABSTRACT: Connecting the life history stages of the annual cycle via carry-over effects crucially informs estimates of mortality and reproduction. This study explores variables linking the breeding and wintering seasons in a pursuit-diving seabird, the thick-billed murre Uria lomvia. We deployed global location sensing loggers on chick-rearing murres breeding in the southeastern Bering Sea to examine subsequent overwinter locations and foraging behavior. In the tracked individuals, we measured individual telomere length and longitudinal telomere length changes in blood and used feathers molted during fall and early spring to assess trophic niche (via stable isotopes) and stress levels (as reflected in feather corticosterone levels). Longitudinal changes in telomere length were better predicted by winter diving parameters than by geographic distribution and movement variables, such that birds that foraged more intensely (more time diving, more dive bouts) also experienced higher telomere loss. This indicates that in a pursuit-diving species with high flight costs, patterns of water-column use through diving may be more important than horizontal spatial movement for predicting physiological changes underlying carry-over effects. We conclude that telomere dynamics might be used as an indicator connecting behavior and physiological stress from season to season. KEY WORDS: Telomeres · Carry-over effects · Feather corticosterone · Stable isotope analysis · Migration · Thick-billed murre · Uria lomvia · Wintering grounds · Geolocator Full text in pdf format PreviousCite this article as: Young RC, Orben RA, Will AP, Kitaysky AS (2017) Relationship between telomere dynamics and movement and behavior during winter in the thick‑billed murre. Mar Ecol Prog Ser 578:253-261. https://doi.org/10.3354/meps12022 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 578. Online publication date: August 31, 2017 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2017 Inter-Research.

Weakening of the subpolar gyre as a key driver of North Atlantic seabird demography: a case study with Brünnich’s guillemots in Svalbard

The Arctic is experiencing environmental changes at unprecedented rates. These changes are spreading throughout the entire food web, affecting apex predators such as seabirds. Brunnich’s guillemot Uria lomvia populations in Svalbard archipelago have significantly declined since the mid-1990s. For long-lived species such as seabirds, population growth rate is highly sensitive to changes in adult survival rates, and slight changes in survival may have large consequences at the population level. Adult survival rates, were estimated for Brunnich’s guillemots individually marked and monitored from 1986 to 2011 at Bjornoya, Svalbard. While survival appeared to be repeatedly high (mean ± SE; 95 ± 1%) from 1986 to 1995-98 (transitional years, when Svalbard guillemot colonies started to decline), it dropped by 9-12% over the period 1995-98 to 2011. This decline coincided with the occurrence of an abrupt ecosystem shift in the North Atlantic Ocean in the mid-1990s and the weakening of the Atlantic subpolar gyre. Variations in the subpolar gyre index (SGI) were significantly associated with inter-annual variation in guillemot annual survival, and a strong gyre (i.e. cold waters on guillemot wintering grounds) was associated with high adult survival. Our results, combined with other studies, suggest that the SGI may be an important global proxy to assess oceanographic conditions and changes in marine ecosystems in the North Atlantic.

Levels of ingested debris vary across species in Canadian Arctic seabirds

Plastic debris has become a major pollutant in the world's oceans and is found in many seabird species from low to high latitudes. Here we compare levels of plastic ingestion from two surface feeders, northern fulmars (Fulmarus glacialis) and black-legged kittiwakes (Rissa tridactyla), and two pursuit diving species, thick-billed murres (Uria lomvia) and black guillemots (Cepphus grylle) in the Canadian high Arctic. This is the first report quantifying plastic ingestion in kittiwakes in this region, and as predicted, kittiwakes and fulmars had higher frequency of plastic ingestion than guillemots and murres. Despite this, amounts of plastic ingested by birds remain lower than regions farther south.

Contamination status and accumulation characteristics of heavy metals and arsenic in five seabird species from the central Bering Sea.

Seabirds are marine top predators and accumulate high levels of metals and metalloids in their tissues. Contamination by metals in the highly productive offshore region has become a matter of public concern. It is home to 80% of the seabird population in the U.S.A., 95% of northern fur seals (Callorhinus ursinus), and major populations of Steller sea lions (Eumetopias jubatus), walruses (Odobenus rosmarus) and whales. Here, the concentrations of eight heavy metals (Hg, Cd, Cr, Co, Ni, Cu, Zn and Pb) and a metalloid (As) in the liver and kidneys of the northern fulmar (Fulmarus glacialis), thick-billed murre (Uria lomvia), short-tailed shearwater (Puffinus tenuirostris), tufted puffin (Fratercula cirrhata) and horned puffin (Fratercula corniculata) collected in the Bering Sea were measured. As proxies of trophic level and habitat, nitrogen (δ15N) and carbon (δ13C) stable isotope ratios of breast muscles were also measured. Hepatic Hg concentration was high in northern fulmar, whereas Cd level was high in tufted puffin and northern fulmar. The Hg concentration and δ15N value were positively correlated across individual birds, suggesting that Hg uptake was linked to the trophic status of consumed prey. Furthermore, Hg concentration in our study was higher than those of the same species of seabirds collected in 1990.

Differential Responses of Arctic Vegetation to Nutrient Enrichment by Plankton- and Fish-Eating Colonial Seabirds in Spitsbergen.

The role of seabirds as sea-land biovectors of nutrients is well documented. However, no studies have examined whether and how colonial seabirds that differ in diet may influence terrestrial vegetation. Therefore, the purpose of the study was to describe and compare plant communities located in the vicinity of the two most common types of seabird colonies in Arctic, occupied by piscivorous or planktivorous species. Within 46 plots arranged in four transects in the vicinity of planktivorous (little auk, Alle alle) and piscivorous colonies (mixed colony of Brunnich’s guillemot, Uria lomvia, and black-legged kittiwake, Rissa tridactyla) we measured the following: guano deposition, physical and chemical characteristics of soil, total nitrogen and its stable isotope signatures in soil and plants, ground vegetation cover of vascular plants and mosses, and the occurrence of lichens, algae and cyanobacteria. Using LINKTREE analysis, we distinguished five plant communities, which reflected declining influence along a birds fertilization gradient measured as guano deposition. SIMPROOF test revealed that these communities differed significantly in species composition, with the differences related to total soil nitrogen content and δ15N, distinctive levels of phosphates, potassium and nitrates, and physical soil properties, i.e., pH, conductivity and moisture. The communities were also clearly distinguished by distance from the bird colony. The two colony types promoted development of specific plant communities: the immediate vicinity of the planktivorous colony characterized by a Deschampsia alpina–Cerastium arcticum community while under the piscivorous colony a Cochlearia groenlandica–Poa alpina community was present. Despite the similar size of the colonies and similar magnitude of guano input, differences between ornithogenic communities were connected mostly to phosphate content in the soil. Our results show that the guano input from seabirds which have different diets can affect High Arctic vegetation in specific and more complex ways than previously realized.

Cliff-nesting seabirds influence production and sediment chemistry of lakes situated above their colony

Seabirds that congregate in large numbers during the breeding season concentrate marine-derived nutrients to their terrestrial nesting sites, and these nutrients disperse and enhance production in nearby terrestrial, freshwater and marine ecosystems. In the Canadian Arctic, large seabird colonies (>100,000 breeding pairs) nest on cliff faces that drain directly in the ocean, ultimately returning the nutrients back to the marine environment from which they were derived. However, strong winds blowing up cliff faces could transport nutrients up in elevation and onto surrounding terrestrial and aquatic environments. Here, we assess the degree to which seabird nutrients and metals have been delivered to coastal lakes near Hudson Strait (Nunavut, Canada) over the past century. Three lakes located at a higher elevation and increasing distance from a thick-billed murre (Uria lomvia) colony (~400,000 breeding pairs) were sampled for surface water chemistry. In addition, algal assemblages, nitrogen isotopes, and metal/metalloids were analyzed in four dated sediment cores. Elevated nutrients and major ions, as well as an enriched δ15N signature in the sediment cores, were measured in the lake <100m from the cliff, whilst no comparable changes were recorded in lakes >1km from the seabird colony. In contrast, similar oligotrophic and benthic diatom assemblages were identified in all three lakes, suggesting that diatoms were not influenced by enhanced nutrient inputs in this Arctic environment. Chemical tracers (e.g., total mercury) and algal assemblages in the lake near the colony suggest climate warming since ~1950 was the most likely driver of limnological changes, but this effect was muted in the more distant lakes. These pronounced changes in the seabird-impacted lake suggest that, with warming air temperatures and diminished lake ice cover, longer growing seasons may allow for aquatic organisms to more fully exploit the seabird nutrient subsidies.

Declining trends of polychlorinated dibenzo-p-dioxins, dibenzofurans and non-ortho PCBs in Canadian Arctic seabirds

Polychorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (PCBs) such as the non-ortho PCBs (nPCBs) persist in the environment despite international measures to ban their emissions. We determined congener patterns and temporal trends for PCDDs, PCDFs, nPCBs as well as their toxic equivalents (TEQs) in eggs of thick-billed murres (Uria lomvia) and northern fulmars (Fulmarus glacialis) sampled from Prince Leopold Island in the Canadian Arctic between 1975 and 2014. The dominant PCDD congeners were 1,2,3,7,8-PnCDD, 2,3,7,8-TCDD and 1,2,3,6,7,8-HxCDD, and the dominant PCDF congener was 2,3,4,7,8-PnCDF. The nPCB profile was dominated by PCB-126. The TEQ profile in the murre eggs was dominated by nPCB-TEQ whereas in the fulmar eggs, the PCDF-TEQ contribution to ΣTEQ was slightly greater than that of nPCB-TEQ. Concentrations of ΣPCDD, ΣPCDF, ΣnPCB and ΣTEQ declined between 1975 and 2014 in both murre and fulmar eggs. Based on TEQ thresholds in the literature for other species, and taking into account the trend towards declining TEQ levels, it is unlikely that current levels of PCDDs, PCDFs or nPCBs are affecting the reproductive success of thick-billed murres or northern fulmars in the Canadian Arctic.

Telomere length and environmental conditions predict stress levels but not parental investment in a long-lived seabird

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 556:251-259 (2016) - DOI: https://doi.org/10.3354/meps11864 Telomere length and environmental conditions predict stress levels but not parental investment in a long-lived seabird Rebecca C. Young1,4,*, Chris P. Barger1,5, Ine Dorresteijn2,6, Mark F. Haussmann3, Alexander S. Kitaysky1 1University of Alaska Fairbanks, Institute of Arctic Biology; Department of Biology and Wildlife, Fairbanks, AK 99775, USA 2University of Alaska Fairbanks, Institute of Arctic Biology, Fairbanks, AK 99775, USA 3Dept. of Biology, Bucknell University, Lewisburg, PA 17837, USA 4Present address: 3447 Valley Branch Road, Nashville, IN 47448, USA 5Present address: Alaska Department of Fish & Game, 1300 College Road, Fairbanks, AK 99701, USA 6Present address: Leuphana University Lüneburg, Faculty of Sustainability, Scharnhorststr. 1, C11.018, 21335 Lüneburg, Germany *Corresponding author: rebeccacyoung721@gmail.com ABSTRACT: Telomeres are increasingly regarded as viable biomarkers of individual quality, and thus may be associated with other proximate markers of quality. We compared telomere length to such quality markers in a long-lived seabird, the thick-billed murre Uria lomvia, breeding under varying environmental conditions on 3 colonies in the Bering Sea. Individual quality was assessed using behaviors associated with parental investment (trip rate and nest attendance, determined by bird-borne data loggers), body condition, and physiological stress (baseline corticosterone). Telomere length was related to physiological stress and body condition, while parental investment in reproduction was not. This implies that maintenance of consistent levels of parental care was prioritized and that individual quality changes were expressed physiologically (changes in telomere length) rather than behaviorally. Under poor environmental conditions, short telomeres were associated with lower levels of physiological stress. However, under good environmental conditions, they were associated with higher levels of stress. These findings confirm that telomere length variation is related to patterns in stress hormones and support previous findings that environmental conditions are an important mediator of telomere dynamics. KEY WORDS: Individual quality · Brünnich’s guillemot · Corticosterone · Parental investment · Temperature-depth recorder · Telomeres · Thick-billed murre · Uria lomvia Full text in pdf format PreviousNextCite this article as: Young RC, Barger CP, Dorresteijn I, Haussmann MF, Kitaysky AS (2016) Telomere length and environmental conditions predict stress levels but not parental investment in a long-lived seabird. Mar Ecol Prog Ser 556:251-259. https://doi.org/10.3354/meps11864 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 556. Online publication date: September 08, 2016 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2016 Inter-Research.

Sex-specific, inverted rhythms of breeding-site attendance in an Arctic seabird.

In contrast to daily rhythms that are common in the presence of the geophysical light-dark cycle, organisms at polar latitudes exhibit many diel activity patterns during natural periods of continuous solar light or darkness (polar day and night, respectively), from 24 h rhythms to arrhythmicity. In Arctic Greenland (73.7° N, 56.6° W) during polar day, we observed breeding-site attendance rhythms of thick-billed murres (Uria lomvia; n = 21 pairs), a charadriiform seabird, which provide biparental care at the colony. We found that U. lomvia egg-incubation and chick-brooding attendance is rhythmic and synchronized to the geophysical day (mean period length [rhythm duration] ± 95% confidence interval = 24.13 ± 0.52 h). Individual pair members had temporally segregated, sex-specific colony-attendance rhythms that were opposite (inverted) to each other, and these sex-specific rhythms were prominent at the population level. Our results provide a basis for investigating circadian systems at polar latitudes and sex-specific parental-care strategies.

Migration and wintering of a declining seabird, the thick-billed murre Uria lomvia, on an ocean basin scale: Conservation implications

Pelagic seabirds are exposed to an array of potential threats during the non-breeding period, and effective management of these threats on a large scale requires knowledge of which populations winter where. Thick-billed murres (Uria lomvia) are emblematic of this conservation challenge, since they breed widely in the circumpolar Arctic, with many declining populations in the Atlantic. Threats facing murres include hunting, oil spills, bycatch and oceanic change influencing prey availability. Previous knowledge of migration pathways was insufficient to estimate the composition of various wintering populations. We collated tracking data (light-based geolocation) of 320 murres from 18 colonies in Canada, Greenland, Iceland, Svalbard and mainland Norway. Data were combined with breeding population counts to estimate the size and composition of wintering populations. The main wintering areas were off Newfoundland and Labrador, off West Greenland, and around Iceland. Winter areas were associated with the interface between High and Low Arctic ocean regimes. There was strong correspondence between wintering area and breeding population status: stable populations breeding in Canada and Northwest Greenland wintered mainly off Canada, whereas declining populations from Svalbard and Iceland wintered mainly off West Greenland and around Iceland. Many populations used distinct post-breeding areas, presumably for moulting; some of these areas were previously unknown. In some populations, there was a clear tendency for females to migrate south earlier than males, which accompany flightless fledglings when they leave the colony. Our study provides a key example of the urgency of coordinated, transoceanic management of vulnerable migratory species such as seabirds.

First Characterization of Avian Influenza Viruses from Greenland 2014.

In late February 2014, unusually high numbers of wild thick-billed murres (Uria lomvia) were found dead on the coast of South Greenland. To investigate the cause of death, 45 birds were submitted for laboratory examination in Denmark. Avian influenza viruses (AIVs) with subtypes H11N2 and low pathogenic H5N1 were detected in some of the birds. Characterization of the viruses by full genome sequencing revealed that all the gene segments belonged to the North American lineage of AIVs. The seemingly sparse and mixed subtype occurrence of low pathogenic AIVs in these birds, in addition to the emaciated appearance of the birds, suggests that the murre die-off was due to malnutrition as a result of sparse food availability or inclement weather. Here we present the first characterization of AIVs isolated in Greenland, and our results support the idea that wild birds in Greenland may be involved in the movement of AIV between North America and Europe.

Foraging segregation of two congeneric diving seabird species breeding on St. George Island, Bering Sea

Abstract. Subarctic environmental changes are expected to affect the foraging ecology of marine top predators, but the response to such changes may vary among species if they use food resources differently. We examined the characteristics of foraging behavior of two sympatric congeneric diving seabird: common (Uria aalge: hereafter COMUs) and thick-billed (U. lomvia: hereafter TBMUs) murres breeding on St. George Island, located in the seasonal sea-ice region of the Bering Sea. We investigated their foraging trip and flight durations, diel patterns of dive depth, and underwater wing strokes, along with wing morphology and blood stable isotope signatures and stress hormones. Acceleration–temperature–depth loggers were attached to chick-guarding birds, and data were obtained from 7 COMUs and 12 TBMUs. Both species showed similar mean trip duration (13.2 h for COMUs and 10.5 h for TBMUs) and similar diurnal patterns of diving (frequent dives to various depths in the daytime and less frequent dives to shallow depths in the nighttime). During the daytime, the dive depths of COMUs had two peaks in shallow (18.1 m) and deep (74.2 m) depths, while those of TBMUs were 20.2 m and 59.7 m. COMUs showed more frequent wing strokes during the bottom phase of dives (1.90 s−1) than TBMUs (1.66 s−1). Fish occurred more frequently in the bill loads of COMUs (85 %) than those of TBMUs (56 %). The δ15N value of blood was significantly higher in COMUs (14.5 ‰) than in TBMUs (13.1 ‰). The relatively small wing area (0.053 m2) of COMUs compared to TBMUs (0.067 m2) may facilitate their increased agility while foraging and allow them to capture more mobile prey such as larger fishes that inhabit deeper depths. These differences in food resource use may lead to the differential responses of the two murre species to marine environmental changes in the Bering Sea.

Differential responses of seabirds to environmental variability over 2 years in the continental shelf and oceanic habitats of southeastern Bering Sea

Abstract. Seasonal sea-ice cover has been decreasing in the southeastern Bering Sea shelf, which might affect ecosystem dynamics and availability of food resources to marine top predators breeding in the region. In this study, we investigated the foraging responses of two seabird species, surface-foraging red-legged kittiwakes Rissa brevirostris (hereafter, RLKI) and pursuit-diving foraging thick-billed murres Uria lomvia (TBMU) to different marine environmental conditions over 2 years. At-sea distributions of RLKI and TBMU breeding on St. George Island, the largest seabird colony in the region, were recorded using GPS loggers, and blood samples were taken to examine their physiological condition and isotopic foraging niche in a given year. Between the study years, winter ice retreated earlier and summer water temperatures were relatively warmer in 2014 compared to those in 2013. RLKI foraging occurred mostly over the oceanic basin in both years. TBMU, however, foraged mostly over the shelf but showed a relatively higher use of the shelf break and oceanic basin in 2013. The foraging distances from the colony peaked at 250–300 km in 2013 and bimodally at 150–250 and 300–350 km in 2014 for RLKI and tended to be farther in 2013 compared to those in 2014 for TBMU. Plasma levels of corticosterone did not differ between the years in RLKI but differed in TBMU, showing higher levels of physiological stress incurred by murres in 2013, the year of relatively cooler sea surface temperatures with later sea-ice retreat. δ13N (a proxy of trophic level of prey) did not differ between the years in either RLKI or TBMU. These results suggest that the response of ecosystem dynamics to climate variability in the southeastern Bering Sea may differ between the ocean basin and continental shelf regions, which, in turn, may generate differential responses in seabirds relying on those habitats for foraging.

Temporal trends of mercury in eggs of five sympatrically breeding seabird species in the Canadian Arctic

We compared temporal trends of total mercury (Hg) in eggs of five seabird species breeding at Prince Leopold Island in the Canadian high Arctic. As changes in trophic position over time have the potential to influence contaminant temporal trends, Hg concentrations were adjusted for trophic position (measured as δ15N). Adjusted Hg concentrations in eggs of thick-billed murres (Uria lomvia) and northern fulmars (Fulmarus glacialis) increased from 1975 to the 1990s, followed by a plateauing of levels from the 1990s to 2014. Trends of adjusted Hg concentrations in eggs of murres, fulmars, black guillemots (Cepphus grylle) and black-legged kittiwakes (Rissa tridactyla) had negative slopes between 1993 and 2013. Adjusted Hg concentrations in glaucous gull (Larus hyperboreus) eggs decreased by 50% from 1993 to 2003 before starting to increase again. Glaucous gull eggs had the highest Hg concentrations followed by black guillemot eggs, and black-legged kittiwake eggs had the lowest concentrations consistently in the five years compared between 1993 and 2013. Based on published toxicological thresholds for Hg in eggs, there is little concern for adverse reproductive effects due to Hg exposure in these birds, although the levels in glaucous gull eggs warrant future scrutiny given the increase in Hg concentrations observed in recent years. There is evidence that the Hg trends observed reflect changing anthropogenic Hg emissions. It remains unclear, however, to what extent exposure to Hg on the overwintering grounds influences the Hg trends observed in the seabird eggs at Prince Leopold Island. Future research should focus on determining the extent to which Hg exposure on the breeding grounds versus the overwintering areas contribute to the trends observed in the eggs.