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Seabirds that forage within tidal streams may be vulnerable to collision or habitat change due to tidal stream turbines. The black guillemot Cepphus grylle is considered to be the seabird species most at risk from tidal stream turbines in UK waters. Using GPS tracking of adult breeding black guillemots, carried out on the island of Stroma, Caithness, in 2016 and 2017, we examined habitat use within the Inner Sound of the Pentland Firth in relation to the MeyGen tidal lease area (MTLA). We found foraging areas of black guillemots within the Inner Sound to be influenced by tidal velocity and seafloor depth. The velocities and depths which black guillemots selected while foraging within a 1 km boundary of the lease area significantly differed from those concurrently occurring within the MTLA (velocities: foraging = 0.79 m s-1, MTLA = 1.57 m s-1; depths: foraging = 24.55 m, MTLA = 32.09 m). This disparity between the used habitat and the conditions within the MTLA may indicate a reduced potential for interactions with turbines. The potential for collision with turbine blades is further reduced by black guillemots predominantly associating with mean tidal velocities slower than the 1 m s-1 cut-in speeds of the MeyGen turbines. However, as more turbines are constructed within the lease area (up to 398 turbines proposed), habitat and hydrodynamic conditions may be altered to become more suitable for foraging, so monitoring black guillemot foraging behaviour post-construction is strongly recommended.

This map presents the distribution of all bird species which were counted during the 2021 Vigur Island research campaign by Milesi-Gaches, D. and Lhériau, A., Cette carte présente la répartition de toutes les espèces d'oiseaux qui ont été dénombrées lors de la campagne de recherche 2021 de l'île Vigur par Milesi-Gaches, D. et Lhériau, A., Þetta kort sýnir dreifingu allra fuglategunda sem voru taldar í Vigur-eyju rannsóknarátakinu 2021 af Milesi-Gaches, D. og Lhériau, A.

Plastic pollution ingestion by seabirds is an increasing environmental problem even in remote areas such as the Arctic, yet knowledge on plastic pollution ingestion by several Arctic seabirds is limited, making it difficult to assess trends. We examined plastic pollution ingestion by northern fulmars (Fulmarus glacialis), black-legged kittiwakes (Rissa tridactyla), thick-billed murres (Uria lomvia) and black guillemots (Cepphus grylle) in the Canadian Arctic to assess species-specific and temporal differences in plastic ingestion over ten years. Seventy-two percent of fulmars and 15% of kittiwakes ingested plastic, while guillemots and murres did not. The number and mass of plastic ingested by fulmars decreased between the two periods (2008 and 2018), but the frequency of occurrence of plastic ingestion did not change, although sample sizes were less than ideal. Future research with larger samples is recommended to reinforce these trends in plastic ingestion by Arctic seabirds.

Capsule: Using ring recovery records collected in Britain and Ireland from 1935 to 2015, we investigated philopatry and dispersal in Black Guillemots Cepphus grylle ringed as nestlings and ...

Capsule: One of the southernmost populations of the Black Guillemot Cepphus grylle is currently endangered, and the risk may be exacerbated by climate change. Aims: We evaluated the future vulnerability of the Black Guillemot by predicting the impact of climate change on the geographic distribution of its breeding and foraging range in the Baltic Sea. Methods: We used MaxEnt, a species distribution modelling technique, to predict the current and future breeding grounds and foraging sites. Results: We found that although the foraging range is expected to increase in the southern Baltic Sea in future, these areas will no longer be suitable as breeding grounds due to a changing climate, creating a spatial mismatch. Conclusion: Our predictions indicate where threats to the species may be most severe and can be used to guide conservation planning. We advocate conservation measures which integrate potential future threats and focus on breeding sites across the current and future potential geographic range of the Black Guillemot.

The jaw muscles of the thick-billed murre have been described in detail and depicted with comparative notes on the jaw muscles in the common murre and the black guillemot. Owing to adaptation to underwater hunting of mobile prey (first of all, small fish), the composition of the dorsal adductor muscles in the studied species has become simplified in part, compared with their ancestral form, and has become similar to that of another underwater fisher, the great crested grebe (Podiceps cristatus). The attachment of the superficial portion of the external adductor muscle to the postorbital projection was strengthened, especially in both murres. In the external layer of the medial portion of the adductor, the muscle fibers gained secondary insertion by the horizontal aponeurosis, similarly to those of the superficial portion, thus increasing the horizontal (retracting) force component, which lowers the long upper jaw. The caudal part of the deep portion of the external adductor became incorporated in the medial portion, but in the murres, especially in the thickbilled murre, part of it is similar to the posterior adductor, which enhances the retracting force as well. All three species show traces of a transfer of the muscle fascicle from the superficial pseudotemporal muscle to the deep pseudotemporal muscle, giving the same effect. Confirmation of the relatively separated position of the guillemot and of its generalized morphological state were found. The specific features of the murres’ adaptation to fishing, including morphofunctional prerequisites for forage segregation of the two murre species, are understandable as the basis of their sympatric existence.

Capsule Dive behaviour in Black Guillemots Cepphus grylle was close to that predicted for a benthic forager by allometry based on body mass.Aims To report the diving behaviour of Black Guillemots in Northern Ireland.Methods A time-depth-recorders and GPS logger were deployed on four chick-rearing breeding Black Guillemots.Results Dive shape implied most dives were benthic with a small number at the start of each bout associated with searching. Diving only occurred during daylight hours, but dive depth was unrelated to light availability outside of the twilight periods. Dive durations (max = 90 s; mean = 54 s) were shorter and dive depths (max = 15 m; mean = 9 m) were shallower than recorded for guillemots elsewhere. The birds dived a maximum of 1.8 km from the colony.Conclusions Black Guillemots' dive duration was similar to the value predicted from allometry, and is therefore likely representative of this species. Bathymetry likely influences the dive behaviour of this benthic-feeding species because mos...

The Black Guillemot (Cepphus grylle) is a monomorphic seabird characterized by its muted plumage and bright red feet, which it prominently displays during courtship. Foot color and oxidative stress were analyzed in a Black Guillemot colony at the Bay of Fundy during the 2006 and 2007 breeding seasons. While no relationship between red intensity of feet and carotenoids was uncovered, the level of plasma oxidative damage was negatively correlated with foot color. Additionally, red intensity of male feet was significantly correlated with the red intensity of their mates' feet, suggesting the possibility of assortative mating by foot color in this species. Further experimental work is necessary to determine whether foot color is used in this species as an honest signal to relay information on the ability of an individual to manage oxidative stress.

Source at: https://doi.org/10.1675/063.040.0301 Visually-oriented predators, such as seabirds, are highly light dependent, and thus their presence and activity under continuously dark conditions of Arctic polar night pose a number of questions about the strategies and mechanisms they use to find prey. Here, opportunistic observations of the behaviors of Thick-billed Murres (Uria lomvia; n = 4) and juvenile Black Guillemots (Cepphus grylle; n = 5) were made in the ocean around Spitsbergen Island, Svalbard Archipelago, off the coast of Norway. These observations were made between 15-23 January 2014-2017 during the darkest period of the polar night. Underwater observations recorded on 23 January 2014 and 19-20 January 2015 revealed that individual birds seemed to be attracted to artificial light. They actively foraged in the sea within the beam of scuba diver lights and harbor lamps indicating that artificial light may create additional feeding opportunities for seabirds present in the area. Other observations of Dovekies (Alle alle; n = 2) made on 15-16 January 2016 may indicate that not all seabird species exhibit such an adaptable behavior. Various seabird reactions might be caused also by different age and intra-specific variation among individuals; however, due to the limited number of observations, future studies are needed to increase our understanding of these behaviors.

Prolonged chasing of an adult reindeer (Rangifer tarandus) by a polar bear (Ursus maritimus) was observed both on land and in the sea, in Magdalenefjorden, northwest Spitsbergen. Polar bears were also observed catching black guillemot (Cepphus grylle) in the sea in northwest Spitsbergen and feeding on chicks in the arctic tern (Sterna paradisea) colony in Hornsund, southwest Spitsbergen. While feeding on seabird species is unsurprising, the prolonged chasing of adult reindeer is unusual for polar bear hunting behaviour. The few documented cases of polar bear hunting reindeer consist of either surprising and killing resting/sleeping prey or stalking and a short rapid chase of the reindeer. Our observations describe new feeding habits of polar bears that may be in response to decreasing seal availability due to shrinking sea-ice cover in the Arctic.

Perfluorinated sulfonates (PFSAs) and perfluorinated carboxylates (PFCAs), as well as selected precursor compounds, were measured in eggs of thick-billed murres (Uria lomvia) and northern fulmars (Fulmarus glacialis) from Prince Leopold Island in the Canadian Arctic between 1975 and 2011 as well as in eggs of three additional species (black guillemot Cepphus grylle, black-legged kittiwake Rissa tridactyla, glaucous gull Larus hyperboreus) sampled in 2008. ΣPFCA concentrations increased significantly from 1975 to 2011 in the murre and fulmar eggs at an average annual rate of 0.56 and 0.91 ng g(-1) ww, respectively, whereas perfluorooctane sulfonate (PFOS) concentrations did not change significantly. The interspecies comparison of eggs sampled in 2008 found that black guillemots had the highest PFOS and lowest ΣPFCA levels, and northern fulmars had the highest ΣPFCA levels. PFUnA (C(11)) and PFTrA (C(13)) were the predominant PFCAs measured in eggs of all five species except for the black guillemot where PFDA (C(10)) contributed almost equally with PFTrA (C(13)) to the PFCA profile. Based on published toxicity thresholds, levels of neither perfluorooctanoate (PFOA) nor PFOS in seabird eggs from the Canadian Arctic are of toxicological concern. These are the first interspecies comparisons for PFASs in seabirds from the Canadian Arctic.

Very few large-scale studies of breeding marine birds have been conducted in Labrador. To address this information deficit, we conducted near-shore aerial surveys of the Labrador coastline between 6–11 and 21–26 June 2006. Our primary species of interest was Somateria mollissima (Common Eider), for which we counted only adult males. In total, we identified 8 species and 5 species categories (alcid colony, mixed tern and gull colony, etc). In total, we counted 40,700 birds, of which Common Eiders were the most widely distributed species, accounting for 88% of all flock/colony observations. Melanitta perspicillata (Surf Scoter) was the second most abundant species, but had a limited distribution, while Cepphus grylle (Black Guillemot) was the third most abundant species observed, but showed the second widest regional distribution. This information is valuable to resource managers and ecosystem researchers.

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.

Canada’s eastern Arctic (Nunavut and Arctic Quebec—Nunavik, N of 60°) supports large numbers of seabirds in summer. Seabird breeding habitat in this region includes steep, rocky coasts and low-lying coasts backed by lowland sedge-meadow tundra. The former areas support colonial cliff- and scree-nesting seabirds, such as murres and fulmars; the latter inland or coastal seabirds, such as terns, gulls and jaegers. The region supports some 4 million breeding seabirds, of which the most numerous are thick-billed murres (Uria lomvia; 75%), black guillemots (Cepphus grylle; 9%), northern fulmars (Fulmarus glacialis; 8%) and black-legged kittiwakes (Rissa tridactyla; 6%). The majority of Arctic seabirds breed in a small number of very large colonies (>10,000 birds), but there are also substantial numbers of non-colonial or small-colony breeding populations that are scattered more widely (e.g. terns, guillemots). Population trends among Canadian Arctic seabirds over the past few decades have been variable, with no strongly negative trends except for the rare ivory gull (Pagophila eburnea): this contrasts with nearby Greenland, where several species have shown steep declines. Although current seabird trends raise only small cause for concern, climate amelioration may enable increased development activities in the north, potentially posing threats to some seabirds on their breeding grounds.

In the Arctic, the availability of early-season open water (shore leads, polynyas) is a key factor influencing annual reproduction by marine birds, as these relatively productive locations provide the only sites where migrating and breeding birds can feed. We examined the diet of two marine birds, black guillemots (Cepphus grylle) and northern fulmars (Fulmarus glacialis), feeding in the Hell Gate–Cardigan Strait Polynya in the Canadian High Arctic during the breeding seasons of 1980–1984. There was little overlap in prey items consumed between these two species, except that both relied on similar sympagic amphipods. Guillemots fed principally on benthic prey, and compared to earlier High Arctic studies, they consumed proportionally more benthic fish, mysids and decapods. Fulmars appeared to feed on swarms of pelagic or surface prey, and in this polynya they consumed proportionally fewer fish and more polychaetes than has been reported for fulmars at other High Arctic locations. Given that climate change may alter marine food webs by changing the types and availability of prey, our results set a baseline of dietary information for these predators against which future conditions can be compared.

We investigated extra-pair paternity (EPP) among 46 young in 32 broods of 19 social pairs of Black Guillemot Cepphus grylle, using a combination of three polymorphic microsatellite markers. The analysis was based on blood samples collected over eight years from a population of individually colour-ringed birds in North Norway. All chicks shared an allele on all three loci with both social parents. Hence, there were no cases of extra-pair parentage. Given our sample sizes, the upper 95% confidence limit of EPP was estimated to 6.2% of the young and 8.9% of the broods. Among seven extra chicks, for which we lacked a DNA sample from the social mother, there was one case of genotype mismatch with the social father, but this could also be because of egg dumping. Low occurrence of EPP has now been documented in five of the six species of Atlantic auks.

The Black Guillemot (Cepphus grylle) is a monomorphic, socially monogamous member of the Alcidae. Although aspects of their breeding and foraging ecology have been extensively studied, less is known about possible sex-based differences in morphology, nor whether Black Guillemots mate assortatively based on body size. Using molecular techniques, we identified the sex of 26 male and 21 female Black Guillemots captured in the Canadian Arctic, and measured six external body measurements: outer tarsus length, wing length, culmen length, bill depth, head plus bill length and body mass to test for sexual size dimorphism (SSD) and assortative mating. Overall, males were 1.7% and 8% larger than females in outer tarsus length and bill depth, respectively. Within breeding pairs, bill depth was the most dimorphic trait. Despite these morphological differences no evidence of assortative mating based upon body size was found. Thus, mate choice for body size does not appear to be an underlying mechanism of SSD...

From existing databases, we compiled and evaluated 604 total mercury (Hg) levels in the eggs and blood of 17 species of marine foraging birds from 35 Gulf of Maine islands to provide baseline data and to determine the best tissue, age class, and species for future biomonitoring. While mean Hg levels in most species did not exceed adverse effects thresholds, levels in some individual eggs did; for all species arithmetic mean egg Hg levels ranged from 0.04 to 0.62 (microg/g, wet weight). Piscivorous birds had higher Hg levels than invertivores. Leach's storm-petrel (Oceanodroma leucorhoa), razorbill (Alca torda), and black guillemot (Cepphus grylle) adult blood and egg Hg levels were higher than other species. Our results indicate that adult blood is preferable to chick blood for detecting long-term temporal trends because adult levels are higher and not confounded by metabolic effects. However, since we found that eggs and adult blood are comparable indicators of methylmercury bioavailability, we determined that eggs are the preferred tissue for long-term Hg monitoring because the relative ease in collecting eggs ensures consistent and robust datasets. We suggest specific sampling methods, and based on our results demonstrate that common eider (Somateria mollissima), Leach's storm-petrel, double-crested cormorant, and black guillemot are the most effective bioindicators of Hg of the Gulf of Maine.

We studied inter-colony natal dispersal in a metapopulation of Black Guillemots Cepphus grylle in the Breidafjordur area in western Iceland 1995-97. About 9000 chicks had beer ringed in a large central colony (Flatey) over the previous 20 years, and by capturing breeding adults in other colonies we collected evidence of emigration from this colony We also included data collected since 1975 on immigration to Flatey from neighbouring colonies. The proportion of Flatey-ringed chicks decreased with distance from the colony, the longest documented dispersal distance was 10.5 km. Over the years, 33 immigrants to Flatey were found, but indirect evidence suggested that about 50% of all breeders on Flatey were immigrants. A Leslie matrix model showed that observed local demographic parameters from the Flatey colony predicted a 7% yearly decline in population size, in contrast to the observed stability. The discrepancy could be resolved by increasing immature survival to account for immigration. Population stability was achieved by assuming 63% of all recruits to be immigrants. Our results support the growing awareness that inter-colony exchanges of immatures are much more important for seabird population dynamics than previously believed.

Kleptoparasitic behaviour of Arctic Skuas was studied at a Black Guillemot colony in northeastern Hudson Bay, Canada. Skuas procured fish in 7-2% and 19-9% of attacks, and Black Guillemots lost fish in 7-2% and 21-2% of chases in 1982 and 1983, respectively. In 1983 chase outcome was related to distance between birds at the end of a chase and number of skuas in pursuit. The skuas' foraging efficiency (energy intake/energy expended during hunting) was estimated at 45 for 1982 and 5–8 for 1983, and total daily energy expenditure was estimated at 2–4 and 2-1 × b.m.r. for these years. Energetic calculations suggested that skuas obtained sufficient food to meet their daily needs in 3–6 h of hunting in 1982 and 2–7 h in 1983. The absence of intensive kleptoparasitic activity by breeding skuas in North America is attributed to the paucity of colonies suitable for both feeding (due to available host species and colony topography) and nesting (due to presence of arctic foxes and/or polar bears).

The breeding biology of Black Guillemots Cepphus grylle was studied from 1982 to 1984 in Shetland, on islands lacking introduced mammalian predators. Adult survival (94%), clutch size (1.75-1.92) and breeding output (1.05-1.34 young fledged per breeding pair) were very high, indicating that conditions were relatively favourable on the islands studied. The timing of breeding varied significantly between years and was somewhat later than in other temperate parts of the range. In 1984 food was probably more readily available (possibly due to better weather conditions) in the pre-breeding period, which enabled more inexperienced birds to reach the condition threshold for breeding. It is likely that these birds tended to lay single-egg clutches in more open sites which were more susceptible to egg predation by crows. Nest-site quality and food availability were the key determinants of breeding productivity.

Chlorinated pesticides and metabolites (CPs) were quantified in the seabird species: little auk (Alle alle), Brunnich's guillemot (Uria lomvia), black guillemot (Cepphus grylle) and black-legged kittiwake (Rissa tridactyla). The purpose was to evaluate avian accumulation of selected CPs based on their concentrations and relative patterns, their relation to dietary descriptors (stable isotopes of carbon and nitrogen), to enzymes in- volved in biotransformation, as well as CPs' accumulation potential relative to the recalcitrant polychlorinated biphenyl PCB-153. In all species, the CP pattern was dominated by p,p 0 -dichlorodiphenyltrichloroethane (DDE) and hexachlorbenzene (HCB). Except for HCB, concentrations were not related to trophic position. Most CPs were quantified in black guillemot, indicating a slower elimination compared to other seabird species. Brunnich's guillemot showed efficient elimination of chlordanes, whereas the opposite was found for little auk. Kittiwake showed higher accumulation of persistent CP and metabolites than auks, whereas accumulation of less recalcitrant CPs was low. 2006 Elsevier Ltd. All rights reserved.

The octa- and nonachlorinated bornanes (toxaphene) CHBs 26, 40, 41, 44, 50 and 62 were analysed in Arctic char ( Salvelinus alpinus ), shorthorn sculpin ( Myoxocephalus scorpius ), ringed seal ( Pusa hispida ) and black guillemot eggs ( Cepphus grylle ) from Greenland. Despite their high trophic level, ringed seals had the lowest concentrations of these species, with a Σ 6 Toxaphene median concentration of 13–20 ng/g lipid weight (lw), suggesting metabolisation. The congener composition also suggests transformation of nona- to octachlorinated congeners. Black guillemot eggs had the highest concentrations (Σ 6 Toxaphene median concentration of 971 ng/g lw). Although concentrations were higher in East than in West Greenland differences were smaller than for other persistent organic pollutants. In a circumpolar context, toxaphene had the highest concentrations in the Canadian Arctic. Time trend analyses showed significant decreases for black guillemot eggs and juvenile ringed seals, with annual rates of −5 to −7% for Σ 6 Toxaphene. The decreases were generally steepest for CHBs 40, 41 and 44.

The importance of the Hell Gate Polynya to marine birds in High Arctic Canada has not been assessed for two decades. Our breeding season surveys in 2002–04 found 19 species of marine birds using the polynya, in annual numbers perhaps reaching 25 000 individuals. The site appears to support nationally significant populations of northern fulmar (Fulmarus glacialis), Thayer’s gull (Larus thayeri) and High Arctic brant (Branta bernicla hrota), as well as locally important numbers of other species including common eiders (Somateria mollissima borealis) and black guillemots (Cepphus grylle). The polynya may be particularly important for migration, as many species are observed here earlier than elsewhere in the High Arctic.

Four seabird species and their prey (zooplankton or fish) were collected in the Barents Sea to determine how dietary exposure, cytochrome P450 (CYP) enzyme activities and sex influenced their hepatic PCB concentrations and accumulation patterns. Five males and five females from each seabird species (little auk (Alle alle), Brunnich's guillemot (Uria lomvia), black guillemot (Cepphus grylle) and black-legged kittiwake (Rissa tridactyla)) were analysed. PCB concentrations could not be explained directly by carbon source (delta13C) or trophic position (delta15N), but by a combination of dietary parameters (delta13C, delta15N, migratory pattern, age) and contaminant metabolism. Contrary to previous studies, the PCB pattern differed among seabirds, with a higher proportion of persistent congeners (% of PCB-153, RPCB-153) in black-legged kittiwake than in auks. The PCB pattern also differed among auks, with little auk as the most efficient biotransformer (highest RPCB-153 values of persistent congeners). Based on high RPCB-153 values, Brunnich's guillemot poorly metabolised ortho-meta-unsubstituted congeners, whereas black guillemot poorly metabolised meta-para unsubstituted congeners. Species-specific differences in PCB biotransformation were confirmed by metabolic indices, where PCB patterns in seabirds were adjusted for PCB pattern in prey. The relative contribution of ortho-meta-unsubstituted congeners to SigmaPCBs decreased with increasing EROD activity. There were no differences in PCB concentrations, PCB patterns or cytochrome P450 enzyme activities between males and females. CYP P450 activities (CYP1A- and CYP2B/3A-like: EROD and testosterone 6beta-hydroxylation, respectively) were low and did not correlate with concentrations of non- or mono-ortho Cl-substituted PCBs (NO- and MO-PCBs), or with total toxic equivalent concentrations (TEQs) for dioxin-like effects of NO- and MO-PCBs.

Capsule Black Guillemots Cepphus grylle were recorded diving in the Pentland Firth to an average depth of 32 metres and an overall maximal depth of 43 metres. The majority (88%) of dives were benthic with a median dive duration of 95 seconds, and a maximal dive duration of 131 seconds. The results provide empirical evidence that Black Guillemots use depths within the water column at which tidal turbines are likely to operate. Although limited, our data suggest the potential for interactions between Black Guillemots and marine renewable energy devices.

The progression of pre-breeding moult in adult Black Guillemots Cepphus grylle was observed at Bangor, Co. Down. Moult began as soon as early November, which is much earlier than more northerly populations in the UK. Moult was completed within ten weeks. Early return to the breeding colony and early moult may help individuals to obtain breeding sites.

Analysis of cytochrome b nucleotide sequences of the six extant species of Atlantic alcids and a gull revealed an excess of adenines and cytosines and a deficit of guanines at silent sites on the coding strand. Phylogenetic analyses grouped the sequences of the common (Uria aalge) and Brünnich's (U. lomvia) guillemots, followed by the razorbill (Alca torda) and little auk (Alle alle). The black guillemot (Cepphus grylle) sequence formed a sister taxon, and the puffin (Fratercula arctica) fell outside the other alcids. Phylogenetic comparisons of substitutions indicated that mutabilities of bases did not differ, but that C was much more likely to be incorporated than was G. Imbalances in base composition appear to result from a strand bias in replication errors, which may result from selection on secondary RNA structure and/or the energetics of codon-anticodon interactions.

Twenty-seven black guillemot eggs and 39 livers were analysed for polychlorinated biphenyls (PCBs), chlorinated pesticides including chlordane-related compounds and toxaphene, and polybrominated diphenylethers (PBDEs). The samples were collected at Qeqertarsuaq (Godhavn, West Greenland) and Ittoqqortoormiit (Scoresbysund, East Greenland). The concentrations of halogenated organic compounds in samples from East Greenland were somewhat higher than the corresponding concentrations from West Greenland. Differences in compound patterns were found between West and East Greenland, with higher percentages of the heavier PCB molecules, p,p(')-DDE and alpha-HCH in the samples from Ittoqqortoormiit. Similarly, different levels and different compositions were observed for eggs and livers. The eggs had generally higher concentrations of all compounds as well as higher percentages of CHB-50, CHB-62 and alpha-HCH than liver samples from the same area. Dividing the liver samples into age groups revealed increasing concentrations with age.

Competitive interactions among siblings are an important determinant of parental fitness. These are strongly influenced by relative offspring size and therefore also by the extent to which parents can influence offspring size hierarchies. The temporal pattern of hatching in an avian clutch has a large effect on size and developmental disparities among chicks. Hatching spread is generally assumed to be mainly determined by the onset of incubation in relation to egg laying. However, the extent to which factors other than incubation onset, such as development rate, also influence timing of hatching has received little empirical investigation. We compared incubation periods of male and female black guillemot (Cepphus grylle) embryos to ascertain whether the time taken for an egg to hatch varies with embryo sex. Laying date and egg mass had no significant effect on incubation time, but male embryos hatched on average a day sooner than did females. The onset of incubation and hatching spread vary in black guillemots. However, in mixed-sexed clutches in which the first-laid embryo is male, a faster development time of males should mean asynchronous hatching regardless of parental incubation regime. This was supported by empirical investigation. These results demonstrate that factors other than incubation behavior can be important in establishing avian hatching patterns. Whether these sex differences in development rate are a result of constraints on the degree of parental control, or an adaptive strategy to manipulate hatching patterns, remains to be established. Key words: black guillemot, embryo sex, hatching asynchrony, incubation. [Behav Ecol 15:205–209 (2004)]

Black guillemots (Cepphus grylle) in Saglek Bay, Labrador have elevated polychlorinated biphenyl (PCB) concentrations due to marine sediment contamination around a former military site. We measured liver biomarkers and ΣPCB concentrations in 31 nestlings from three PCB-exposure groups: Reference group (range: 15–46 ng/g liver, wet wt.), moderately exposed Islands group (24–150 ng/g), and highly exposed Beach group (170–6200 ng/g). Biomarker responses were dose-dependent and in some cases sex-dependent. Livers of female Beach nestlings were enlarged 36% relative to Reference females. In both sexes, Beach nestlings had liver ethoxyresorufin-O-deethylase (EROD) activities elevated 79% and liver retinol concentrations reduced 47%. Retinyl palmitate concentrations were reduced 50% but only among female nestlings. Island nestlings also exhibited EROD induction (57%) and reductions in retinol and retinyl palmitate concentrations (28 and 58%, respectively). Liver lipid content increased with ΣPCBs in both sexes, and correlated with liver mass in males. Malic enzyme activity and porphyrin concentrations showed little association with ΣPCBs. Although similar associations between liver biomarkers and organochlorine exposure in fish-eating birds are well documented, typically exposures involve multiple contaminants and there is uncertainty about specific PCB effects. Our findings indicate that liver biomarkers respond to relatively low PCB exposures (∼73 ng/g liver) in guillemots.

Boat disturbance of foraging black guillemots (Cepphus grylle) was studied at a breeding colony in the Bay of Fundy, Canada. Using observations from a cliff top, flushing behaviour was examined in relation to boat characteristics, guillemot behaviour, and environment conditions. The distance guillemots foraged from shore and the size, speed, and approach distance of boats were important factors predicting flushing probability. Guillemots foraged further from shore at low tide presumably making them more vulnerable to disturbance then. Using these results to identify the conditions that would minimize disturbance, management recommendations on boat speed and set-back distance were developed. At this site, a set-back distance of 600 m from shore with a speed limit of 25 km/h would reduce guillemot flushing probability to 10% most of the time. Although specific management options are proposed for this particular colony, the analytical approach used to identify an appropriate set back distance and some of the specific results are relevant to other locations and colonial waterbird species.

Siblings in a diversity of species are facultatively aggressive, yet the proximate control of the aggressive response and the ecological conditions selecting for such systems are poorly understood. In this study, we investigated the effects of food amount (food amount hypothesis) and competitive asymmetry on sibling aggression in black guillemot broods. Parental provisioning rates were experimentally manipulated in broods comprising a range of hatching intervals over a 12-h period. Aggression became evident only after parental provisioning rates were experimentally reduced. When parental provisioning resumed, adults did not increase their feeding rate to compensate for the induced food deficit, and the result of sibling rivalry was a change in the allocation of parental deliveries from one of equality to one in favor of the dominant chick. Food-deprived chicks from synchronous broods were more aggressive than those from asynchronous broods, suggesting that one benefit of hatching asynchrony in the black guillemot is to establish an efficient competitive hierarchy among siblings which minimizes the need for costly aggressive interactions. On the following day, sibling aggression ceased, and chicks regained an equal share of parental feeds. Our results provide the first evidence that short-term food shortage per se acts as an initial trigger for aggression and also show that the aggressive response is complicated by factors associated with hatching and laying order. Key words: black guillemot, Cepphus grylle, competitive asymmetry, facultative aggression, hatching asynchrony, provisioning, sibling rivalry. [Behav Ecol 11: 282–287 (2000)]

Concentrations and patterns of several chloro compounds including polychlorinated dibenzo p-dioxins (PCDD), dibenzofurans (PCDF), biphenyls (PCB) and diphenyl ethers (PCDE) were determined in black guillemots ( Cepphus grylle L.) and white-tailed sea-eagles ( Hallaeetus albicilla L.) from the Baltic Sea environment. Three breast muscles of eagles were analyzed and had different concentrations and patterns of the studied compounds, whereas the three guillemot eggs were found to have more similar levels and patterns. The concentrations of individual PCDE congeners varied from

Previous studies have indicated the presence of high levels of organochlorines, especially PCBs, in some species of arctic seabirds. The glaucous gull (Larus hyperboreus) in particular has shown high levels of organochlorine contamination. We present data on total PCB and isomer specific PCBs in liver samples from four species of seabirds from the Svalbard region. Two of the species were sampled both in the vicinity of the mining town Longyearbyen, where PCBs have been used in the past, and in the remote region of Nordaustlandet. We compared the levels obtained from these two localities in order to test for any indication of local contamination in the Longyearbyen area. No significant difference was found in total hepatic PCB between glaucous gulls collected at Longyearbyen and those collected at Nordaustlandet (grand mean ± S.D.: 15.59 ± 21.53 μg/g wet wt.; n = 22). Similarly, no difference was found in black guillemots (Cepphus grylle) from these two regions (grand mean ± S.D.: 0.14 ± 0.05 μg/g wet wt.; n = 20). However, in both species, we found significantly higher levels of higher chlorinated biphenyls in the Longyearbyen samples, and higher levels of lower chlorinated biphenyls in the samples from Nordaustlandet. This finding indicates that the birds sampled at the two localities might have been contaminated by different sources. Local contamination in the Longyearbyen area is one of several possible explanations for this difference. Total PCB levels in common eiders (Somateria mollissima) and Bru¨nnich's guillemots (Uria lomvia) were in the same order of magnitude as those for the black guillemots (mean ± S.D.: 0.04 ± 0.04 μg/g; n = 11 and 0.08 ± 0.04 μg/g; n = 8, respectively).

The diet of black guillemots Cepphus grylle (L.) was studied in Shetland between 1982 and 1985, both during and outside the breeding season. Full-grown birds consumed a wide variety of fish and invertebrate species in summer, broadly reflecting the diversity of the inshore benthic fauna. In winter a greater diversity of invertebrates was taken, which assumed increased importance in the diet as the availability of benthic fish probably declined. Chicks were fed a diet of fish, with 70–80% being sandeels Ammodytes marinus and butterfish Pholis gunnellus on the island of Mousa. Sandeels were delivered more frequently in the early morning, coincident with a peak in their feeding activity. Older chicks were fed significantly longer fish. The composition of chick diet varied significantly with date, not chick age. A seasonal decline in the proportion of sandeels in the chick diet may have reflected changes in Zooplankton abundance, but the possibility that intensive industrial fishing of sandeels had adversely affected local stocks can not be ruled out.

Livers and kidneys were collected for five seabird species from the Canadian Arctic during the 1983 and 1991 to 1993 breeding seasons. Livers were analyzed for Cd, Hg, Pb, and Se, and kidneys were analyzed for Cd, Cu, Zn, and metallothionein (MT). Concentrations of the essential elements, Cu and Zn, were in agreement with those previously published in the literature. Thick-billed murres (Uria lomvia) from Ivujivik on the Hudson Strait/Hudson Bay coast in northwestern Quebec (Canada) had the highest mean renal concentrations of Cu, Zn, and Cd. Among the four species collected from Prince Leopold Island, northern fulmars (Fulmarus glacialis) had the highest hepatic concentrations of both Cd and Hg. The highest Se concentrations were found in northern fulmars and black-legged kittiwakes (Rissa tridactyla) from Prince Leopold Island. Hepatic Pb concentrations were low (0.3 microg/g dry wt) in all species at all locations. Metallothionein concentrations were positively correlated with Cd and Zn for all species combined but were not correlated with Cu in any species. No significant relationships were found between MT and Cu or Zn in black guillemots (Cepphus grylle) or glaucous gulls (Larus hyperboreus). To our knowledge, this is the first report of MT concentrations and their relationships with trace metals in Arctic seabirds.

We describe the summer diets of four seabird species. Kittiwake (Rissa tridactyla), Little Auk (Alle alle), Black Guillemot (Cepphus grylle) and Brunnich's Guillemot (Uria lomvia) collected in sea-ice-covered waters near Svalbard. Birds collected in an area filled with young sea-ice, within the seasonal sea-ice zone, were compared with birds collected from the perennial sea-ice zone dominated by multiyear ice. Pelagic Crustacea and fish dominated the diet of birds feeding in young ice, while sympagic Crustacea and fish were most important in the diet of birds feeding in multiyear ice. Boreogadus saida was the most important fish food item. B. Saida was present in the ice in both areas, while sympagic Crustacea were lacking in the area filled with young ice. Important food items in young ice were B. saida (Black Guillemots and Kittiwakes), Cajanus sp. (Little Auks) and Pandalus borealis (Brunnich's Guillemot). B. saida (Black Guillemots, Kittiwakes, Brunnich's Guillemots), Gammarus wilkitzkii (Brunnich's Guillemot, Black Guillemot) and Apherusa glacialis (Little Auk) were most important in multiyear ice. In general, Black Guillemots and Kittiwakes fed on fish, whereas Brunnich's Guillemots fed on the larger, and Little Auks on the smaller, Crustacea. The importance of sympagic species in the diet of seabirds is thought to be closely related to the age and history of the ice in the feeding area.

Aerial surveys of Jones Sound, N.W.T., reveal a highly clumped distribution of black guillemots in the early spring and throughout the breeding season. Black guillemots are uncommon throughout much of Jones Sound except at its mouth and in the western portion. By September most guillemots have left the area. Both early spring and breeding distributions appear to be influenced by the Hell Gate and Cardigan Strait polynya located in western Jones Sound between Ellesmere and Devon islands. Evidence presented suggests that annual variation in the distribution of ice edges in Jones Sound may influence distribution of breeding birds among suitable breeding sites. Key words: black guillemot, Cepphus grylle , breeding distribution, Jones Sound, aerial surveys