No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Diet of black guillemots and northern fulmars breeding beside a High Arctic polynya
Abstract
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.
... In the Canadian Arctic, considerable knowledge has accrued on plastic ingestion by fulmars (Avery-Gomm et al., 2018;Byers et al., 2010;Mallory, 2008;Mallory et al., 2006;Poon et al., 2017;Provencher et al., 2009), but plastic ingestion by kittiwakes, murres and guillemots is less understood (Day et al., 1985;Poon et al., 2017;Provencher et al., 2014;Provencher et al., 2010). However, in the majority of studies, standardized methods for plastic ingestion research (Provencher et al., 2019van Franeker et al., 2011) are not often used, making it difficult to compare data across spatial and temporal scales (Avery-Gomm et al., 2018). ...
... We found that 72% of northern fulmars and 15% of black-legged kittiwakes had plastic debris in their gastrointestinal tract, while black guillemots and thick-billed murres had none. To date, there are no records of plastic ingestion by black guillemots in the Canadian Arctic (Byers et al., 2010;Poon et al., 2017) nor in other Arctic regions (Gjertz et al., 1985;Lydersen et al., 1989;Mehlum and Giertz, 1984;Weslawski et al., 1994). However, in Alaska, pigeon guillemots (Cepphus columba) sampled in 1988-1990 had a 3% frequency of occurrence of ingested Table 1 The frequency of occurrence of plastic ingestion ( ± 95% confidence intervals), mass (g) and number of plastic pieces found in the gastrointestinal tracts of northern fulmars, thick-billed murres, black-legged kittiwakes and black guillemots collected near Qikiqtarjuaq, Nunavut in 2007, 2008. ...
Plastic pollution is a ubiquitous global environmental problem. Plastic ingestion by seabirds is an increasing issue even in remote areas, such as the Arctic, yet research and monitoring of plastic ingestion in Arctic seabird populations is limited and there are large knowledge gaps for many geographic regions. There is currently no standard technique for monitoring plastic debris in the Arctic, making it difficult to compare studies and monitor global trends. Here, we review the current state of knowledge of plastic ingestion by seabirds in the Arctic. We analyzed 38 published records that report plastic ingestion by seabirds in the Arctic region. Of the 51 seabird species examined for plastic ingestion in the Arctic, over half have ingested plastic, however the majority have a limited number of studies, small sample sizes, and/or data are more than 15 years old. Additionally, the spatial distribution of plastic ingestion reports in the Arctic varies widely, with large knowledge gaps in the northernmost areas of most countries. This indicates that we lack recent information on plastic ingestion for the majority of seabird species in the Arctic. Further, less than one third of studies references standardized methods from other regions, making it difficult to assess spatial and temporal trends. Long-term monitoring programs should be established in the Arctic to obtain an accurate assessment of plastic ingestion by seabirds in this region.
... In the Canadian Arctic, considerable knowledge has accrued on plastic ingestion by fulmars (Avery-Gomm et al., 2018;Byers et al., 2010;Mallory, 2008;Mallory et al., 2006;Poon et al., 2017;Provencher et al., 2009), but plastic ingestion by kittiwakes, murres and guillemots is less understood (Day et al., 1985;Poon et al., 2017;Provencher et al., 2014;Provencher et al., 2010). However, in the majority of studies, standardized methods for plastic ingestion research (Provencher et al., 2019van Franeker et al., 2011) are not often used, making it difficult to compare data across spatial and temporal scales (Avery-Gomm et al., 2018). ...
... We found that 72% of northern fulmars and 15% of black-legged kittiwakes had plastic debris in their gastrointestinal tract, while black guillemots and thick-billed murres had none. To date, there are no records of plastic ingestion by black guillemots in the Canadian Arctic (Byers et al., 2010;Poon et al., 2017) nor in other Arctic regions (Gjertz et al., 1985;Lydersen et al., 1989;Mehlum and Giertz, 1984;Weslawski et al., 1994). However, in Alaska, pigeon guillemots (Cepphus columba) sampled in 1988-1990 had a 3% frequency of occurrence of ingested Table 1 The frequency of occurrence of plastic ingestion ( ± 95% confidence intervals), mass (g) and number of plastic pieces found in the gastrointestinal tracts of northern fulmars, thick-billed murres, black-legged kittiwakes and black guillemots collected near Qikiqtarjuaq, Nunavut in 2007, 2008. ...
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.
... Seabirds in this community belong to the same functional group of marine top predators as indicated previously by stable isotope analyses (Hobson & Welch, 1992a). However, each species selects a range of different prey items (Byers, Smith, & Mallory, 2010;Hobson, 1993;Lønne & Gabrielsen, 1992; and thus tends to occupy different trophic positions and has a specific trophic ecology that varies even throughout the year (Hobson & Bond, 2012). For example, murres are surface divers and prey notably on small fish (Arctic cod, capelin Mallotus villosus) and invertebrates such as euphausiids (Gaston & Nettleship, 1981). ...
... Northern fulmars are known to capture small squid, crustaceans (mostly copepods), and polychaete worms (Byers et al., 2010). Our overall objective was to examine the trophic ecology of the seabird community of PLI during the prebreeding season under different seaice conditions using stable isotope measurements in egg tissues. ...
Sea‐ice coverage is a key abiotic driver of annual environmental conditions in Arctic marine ecosystems and could be a major factor affecting seabird trophic dynamics. Using stable isotope ratios of carbon (δ¹³C) and nitrogen (δ¹⁵N) in eggs of thick‐billed murres (Uria lomvia), northern fulmars (Fulmarus glacialis), glaucous gulls (Larus hyperboreus), and black‐legged kittiwakes (Rissa tridactyla), we investigated the trophic ecology of prebreeding seabirds nesting at Prince Leopold Island, Nunavut, and its relationship with sea‐ice conditions. The seabird community of Prince Leopold Island had a broader isotopic niche during lower sea‐ice conditions, thus having a more divergent diet, while the opposite was observed during years with more extensive sea‐ice conditions. Species' trophic position was influenced by sea ice; in years of lower sea‐ice concentration, gulls and kittiwakes foraged at higher trophic levels while the opposite was observed for murres and fulmars. For murres and fulmars over a longer time series, there was no evidence of the effect of sea‐ice concentration on species' isotopic niche. Results suggest a high degree of adaptation in populations of high Arctic species that cope with harsh and unpredictable conditions. Such different responses of the community isotopic niche also show that the effect of variable sea‐ice conditions, despite being subtle at the species level, might have larger implications when considering the trophic ecology of the larger seabird community. Species‐specific responses in foraging patterns, in particular trophic position in relation to sea ice, are critical to understanding effects of ecosystem change predicted for a changing climate.
... However, it is possible that these two birds had been eating prey with a higher lipid content, such as fish, prior to when they were harvested. Fulmars are opportunistic feeders and their diets include a broad range of prey items, in particular, birds from the Canadian High Arctic consume a high proportion of Arctic cod [11,31]. ...
... Concentrations and fugacities of contaminants in the WBH were generally between one and three orders of magnitude higher than in the prey items (Fig. 3), indicating that biomagnification is occurring, i.e., a sequence of solvent switching and solvent reductions that increase both the fugacity and concentration in predators [12]. Crustaceans and Arctic cod are important prey items for northern fulmars in remote areas of the Canadian Arctic [11,31], thus reported contaminant concentrations for these taxa in nearby northern Baffin Bay are included in Figure 3 and are labeled P1 and P2, respectively. The values shown for crustaceans are the mean of four species consumed by fulmars, Calanus hyperboreus, Mysis oculata, Pandalus sp., and Parathemisto libellula. ...
Organochlorine contaminant concentrations, associated fugacities, and stable isotopes of nitrogen (δ(15) N) are reported for liver, whole body homogenate, and opportunistically collected samples of prey (amphipods), stomach oils, digestive tract contents, and guano for northern fulmars (Fulmarus glacialis) collected at Cape Vera, Devon Island in the Canadian High Arctic. Liver concentrations of polychlorinated biphenyls (ΣPCB) and ΣDDT were on average 49.9 ± 35.4 ng g(-1) and 29.9 ± 25.2 ng g(-1) wet weight, respectively. Whole body homogenate concentrations of ΣPCB and ΣDDT were 637 ± 293 ng g(-1) and 365 ± 212 ng g(-1) wet weight, respectively. A mass and energy balance showed that whole body contaminant concentrations, which are seldom reported for Arctic seabirds, are critical in determining contaminant exposure and associated risk to predators such as the Arctic fox (Alopex lagopus). Biomagnification in the fulmars is evident, because concentrations and fugacities of contaminants were generally one to three orders of magnitude higher than those of likely prey items. The fate of diet-derived contaminants along the digestive tract is discussed, in particular with respect to stomach oils, which are used to feed chicks and for defensive purposes. The benefits of considering both concentrations and fugacities are demonstrated and provide information on the absorption and distribution of chemicals within the fulmars and contaminant transfer to offspring and predators.
... Matching their coastal diving foraging behaviour, black guillemot diet has been characterised by a number of benthic and kelp-forest associated fish species, varying with latitude, including sculpins (Cottidae), butterfish (Pholis gunnellus), gadoids (Gadiformes), sandeels (Ammodytidae) and squat lobsters (sub-order Anamura) in more temperate climates, and Arctic cod (Boreogadus saida) in the high Arctic (Slater and Slater 1972;Ewins 1990;Lønne and Gabrielsen 1992;Barrett and Anker-Nilssen 1997;Byers et al. 2010;Barrett et al. 2016; this study-see Supplement 1). Most diet data originate from observations of chick-feeding adults at the colonies, and black guillemots typically show a high chickfeeding rate in the early morning and during evening hours (Ewins 1990;Shoji et al. 2015). ...
The intensification of coastal development poses potential threats for coastal seabirds, and understanding their habitat use is a key factor to guide conservation and management. In sub-arctic areas, black guillemots (Cepphus grylle) use coastal habitats year-round, which makes them vulnerable to the increasing human activities in these areas. In mainland Norway, one of the species’ strongholds, black guillemots are red-listed after substantial population declines. However, their fine-scale foraging behaviour has received little attention to date. We collected and analysed GPS tracking data from adult black guillemots at three sites located over a latitudinal gradient of 250 km in central/northern Norway. Maximum foraging ranges of 33 km at Sklinna (65°12′N) for incubating birds, and 18 km at both Vega (65°34′N) and Sklinna for chick-rearing birds, are among the longest reported for this species. At all three sites, foraging probability was highest in shallow waters (< 50 m depth) close to the colony and declined with increasing water depth and distance from colony. However, birds from Vega also foraged over deeper waters. Kelp presence was of high importance at Sklinna, but apparently less important at Røst (67°26’N) and Vega. We also found distinct differences in foraging activity across the day and with tidal height among the sites. Inter-site differences in habitat use and foraging activity may be explained by differences in the availability of habitats and suitable prey. Our study highlights the importance of shallow marine areas for black guillemots and shows that habitat use can vary substantially between sites.
... To do this, information is needed on plastic ingestion in a species over multiple years. For example, at Cape Vera, Nunavut, northern fulmars had no plastic reported in their diet from 1980-1984(Byers et al. 2010, but this increased to 31% by 2003(Mallory 2008, and Provencher et al. (2009) showed that frequency of occurrence of plastic in northern fulmars had also increased in Lancaster Sound from 0% in the 1970s to 80% by 2008. Further, Robards et al. (1995) conducted a direct temporal comparison to the results of Day (1980) in Alaska, and found that the number of seabird species that ingested plastic, the frequency of occurrence of plastic in seabirds, and the mean number of plastic pieces ingested by seabirds increased between the two (2013) found that the number and mass of industrial pellets ingested by northern fulmars have decreased since the 1980s. ...
This literature review assesses information to 2020 on plastic ingestion by Arctic seabirds
... Polymorphus minutus infection is common in freshwater systems across Europe (Medoc et al. 2006), and Gammarus spp. are key detritus processers in freshwater ecosystems (MacNeil et al. 1997;Sutcliffe 2000), comprising important components of the diets of many fish and water fowl around the globe (Byers et al. 2010). ...
Parasites are ecologically ubiquitous and, by modifying the physiology and behavior of their host organisms, act as key regulators of the dynamics and stability of ecosystems. It is, however, as yet unclear how parasitic relationships will act to moderate or accelerate the ecological impacts of global climate change. Here, we explore experimentally how the effects of parasites on both the physiology and behavior of their hosts can be moderated by warming, utilising a well-established aquatic host-parasite model system-the ecologically important amphipod Gammarus duebeni and its acanthocephalan parasite Polymorphus minutus. We show that, while only warming affected measured components of host physiology, parasite infection and warming both supressed predator-avoidance behavior of the host independently, yet in a similar manner. Six degrees of warming altered geotactic behaviors to the same extent as infection with behavior-manipulating parasites. These results indicate a novel mechanism by which parasites impact their ecosystems that could be critical to predicting the ecological impacts of warming. Our findings highlight the need for holistic knowledge of interaction networks, incorporating multiple interaction types and behaviors, to predict the effects of both warming and parasitism on the dynamics and stability of ecosystems.
... Seabirds have been used as biomonitors of pollution for many years, and many arctic seabird colonies are well studied. As a result, a number of reports on plastic ingestion by birds exist [63,64], and some of the longest time series on environmental plastic contamination come from seabirds, including some arctic locations in Canada, northern Iceland, the Faroer Islands and Svalbard [65]. Dietary studies of birds from the Canadian and European Arctic have reported ingestion of plastics, especially by the northern fulmar Fulmarus glacialis [66e69]. ...
Despite an exponential increase in available data on marine plastic debris globally, information on levels and trends of plastic pollution and especially microplastics in the Arctic remains scarce. The few available peer-reviewed scientific works, however, point to a ubiquitous distribution of plastic particles in all environmental compartments, including sea ice. Here, we review the current state of knowledge on the sources, distribution, transport pathways and fate of meso- and microplastics with a focus on the European Arctic and discuss observed and projected impacts on biota and ecosystems. Keywords: Arctic, Litter, Plastic, Distribution, Biota, Ecosystem, Review
... Gammarus spp. are important detritus processers in freshwater ecosystems (MacNeil et al., 1997;Sutcliffe, 2000) and comprise a major component of the diets of many fish and water fowl around the globe (Mortensen, 1982;Byers et al., 2010). ...
Parasites play a critical role in the structure and functioning of ecosystems, contributing to overall ecosystem stability and the provision of ecosystem services. As the global climate changes, it is of considerable importance that ecologists understand and are able to predict shifts in the relationships between parasites and their hosts. Here, I utilize a model system comprising the acanthocephalan parasite Polymorphus minutus and its intermediate host, Gammarus duebeni, in a combination of laboratory and field experiments, to explore how temperature moderates the effects of parasites on ecosystem structure and functioning. My results show that both warming and parasitic infection alter the ecological role played by host organisms. Moreover, these results reveal that the drivers of host functioning are complex and interactive, with intraspecific competition, host sex, and even the mobility status of their prey influencing host behaviour. I conclude that warming and parasitism, through altering host behaviour and modifying predator-prey interactions, could have significant and unforeseen consequences for the structure and dynamics of ecosystems
... Black guillemots are diving, subsurface feeders that switch from offshore Arctic cod (Boreogadus saida) to nearshore and near-nestsite benthic prey such as sculpin (Myoxocephalus scorpioides) or different invertebrates during their breeding season (Cairns, 1987a & b;Mehlum & Gabrielsen, 1993;Byers et al., 2010). While nonbreeding guillemots and guillemots from other Arctic regions share similar contaminant patterns, black guillemots present during the breeding season in Kongsfjorden different patterns of POPs in the plasma ( P DDTs > P PCBs > HCB > P CHL > Mirex> P HCHs) compared to what has been previously reported for liver and muscle of black guillemots from the Barents Sea and in eggs from the Canadian Arctic ( P PCBs > P DDTs > HCB > P CHL > P HCHs > Mirex) (Borgå et al., 2001;Braune et al., 2018). ...
While migratory seabirds dominate ecotoxicological studies within the Arctic, there is limited knowledge about exposure and potential effects from circulating legacy and emerging contaminants in species who reside in the high-Arctic all year round. Here, we focus on the case of the Mandt's Black guillemot (Cepphus grylle mandtii) breeding at Kongsfjorden, Svalbard (79.00°N, 11.66°E) and investigate exposure to legacy and emerging contaminants in relation to individual physiological status, i.e. body condition, oxidative stress and relative telomere length. Despite its benthic-inshore foraging strategy, the Black guillemot displayed overall similar contaminant concentrations in blood during incubation (∑PCB11 (15.7 ng/g w.w.) > ∑PFAS5 (9.9 ng/g w.w.) > ∑Pesticides9 (6.7 ng/g w.w.) > ∑PBDE4 (2.7 ng/g w.w.), and Hg (0.3 μg/g d.w.) compared to an Arctic migratory seabird in which several contaminant-related stress responses have been observed. Black guillemots in poorer condition tended to display higher levels of contaminants, higher levels of reactive oxygen metabolites, lower plasmatic antioxidant capacity, and shorter telomere lengths; however the low sample size restrict any strong conclusions. Nevertheless, our data suggests that nonlinear relationships with a threshold may exist between accumulated contaminant concentrations and physiological status of the birds. These findings were used to build a hypothesis to be applied in future modelling for describing how chronic exposure to contaminants may be linked to telomere dynamics.
... The diet of black guillemots generally consists of a variety of fish and invertebrates (predominantly benthic species , Ewins 1990;Byers et al. 2010). The TP of 3.5, and the fact that the isotopic niche area of black guillemots did not overlap with any of the other species, is in agreement with a diet consisting of a higher percentage of fish than the other birds collected in this study. ...
... The diet of black guillemots generally consists of a variety of fish and invertebrates (predominantly benthic species , Ewins 1990;Byers et al. 2010). The TP of 3.5, and the fact that the isotopic niche area of black guillemots did not overlap with any of the other species, is in agreement with a diet consisting of a higher percentage of fish than the other birds collected in this study. ...
The Arctic is facing major environmental changes impacting marine biodiversity and ecosystem functioning. One way of assessing the responses of an ecosystem to these changes is to quantitatively study food web dynamics. Here, we used stable isotope (δ15N and δ13C) analyses of 39 Arctic marine species to investigate trophic relationships and isotopic niches of the West Greenland food web in 2000–2004. The lowest δ15N values were found for suspension feeding blue mussel (Mytilus edulis; 6.1 ‰) and the highest for polar bear (Ursus maritimus; 20.2 ‰). For δ13C, copepods (Calanus spp.) had the lowest values (−20.4 ‰) and snow crab (Chionoecetes opilio) the highest values (−15.8 ‰). Our results show that the three trophic enrichment factor (TEF) approaches used to quantify species trophic positions (fixed TEF of 3.8 and 3.4 ‰ or scaled TEF) did not generally affect trophic modelling and provided similar conclusions. Overall, the findings in this study are in good agreement with previous investigations of other Arctic marine ecosystems. Interestingly, we found little overlap of core isotopic niches used by the four investigated functional groups (mammals, seabirds, fish and invertebrates), except for seabirds and fish where an overlap of 24 % was found. These results provide new insights into species and functional group interactions, as well as into the food web structure and ecosystem functioning of an important Arctic region that can be used as a template to guide future modelling of carbon, energy and contaminant flow in the region.
... In Adventfjorden, the de crease in the catches, especially in the shallow traps, coincides with the time of the year when the light in creases and migrating birds return. Seabirds (black guillemots Cepphus grylle, Arctic terns Sterna para disea, eider ducks Somateria mollissima) feed on amphipods (Węsławski et al. 1994, Byers et al. 2010, as do shore-birds (purple sandpiper Calidris maritima) in the inter-tidal zone (Luukkonen 2009). Interestingly, there is an increase in the trap catches again in June, when the melting season has started and the fjord is receiving high loads of suspended particles. ...
... Avoidance of predation might influence the motility and habitat choice of the amphipods. These large sized amphipods are probably conspicuous prey for visual predators in shallow, clear water, like diving seabirds and shore-birds (Węsławski et al. 1994, Byers et al. 2010, Luukkonen 2009). The size of the catches from ...
The main objective of this study was to increase our knowledge about the ecology of scavenging amphipods, particularly amphipods within the genera Onisimus and Anonyx. Specifically, the emphasis was to increase the knowledge of ice-associated (sympagic) Onisimus-species, but as these species are rather inaccessible, an approach using benthic congeners as proxies was chosen. By studying the shallow-water scavenging amphipods, a high temporal resolution in sampling could be achieved, resulting in detailed descriptions of life cycles and reproduction parameters of Onisimus caricus and O. litoralis. As seasonal studies on the amphipod scavenging guilds in the Arctic are rare, this study also includes a description of the seasonal variations in the amphipod scavenging guild in two fjords in Svalbard, Norway. Feeding strategies of the scavenging amphipods were studied using fatty acid composition and stable isotopes. Extrapolating the knowledge gained on benthic Onisimus-species to sympagic congeners showed that O. nanseni likely follows a similar life strategy as O. litoralis, being an income breeder. Additionally, the extended parental care by investing in a “start pack” of energy to the offspring is likely similar in these two species. Further, it could be hypothesized that O. nanseni and O. glacialis need a higher reproductive output in order to compensate for the high variation in the extent and loss of their sea ice habitat. However, further studies are needed to confirm this. A first step would be to obtain good winter samples, containing ovigerous females of O. nanseni and O. glacialis, that could give information on reproduction parameters and thus illuminate their life strategies and adaptations towards the sea ice habitat.
... These small subsurface feeders dive up to 35 m (Falk et al. 2000) and molt all of their primary flight feathers (hereafter 'primaries') after breeding (Stempniewicz 2001). Black guillemots Cepphus grylle are intermediate-sized diving alcids that feed on ice-associated invertebrates early in the breeding season and on benthic fish during breeding (Bradstreet & Brown 1985, Byers et al. 2010, and replace their primaries following breeding (Ewins 1988). Thick-billed murres Uria lomvia are large subsurface divers that regularly reach depths over 70 m (Falk et al. 2002), and like dovekies, they replace all pri maries at once following breeding in November/December (Huettmann & Diamond 2000). ...
Stable isotope analysis of tissues of seabirds and their prey has proven to be an extremely useful tool in seabird dietary studies in general and in the potential use of seabirds as ecological indicators in particular. The measurement of stable carbon (delta C-13) and nitrogen (delta N-15) isotope values is important since they provide information on source of feeding and trophic position, respectively. However, the stable isotope approach provides information on spatial and trophic ecology of seabirds during a window of temporal integration that depends on the elemental turnover rate in the tissue being measured. Most researchers have relied on only 1 or 2 tissue types to study seabird diets and foraging ecology. Here, the potential for modeling trophic position and habitat use by seabirds over the annual cycle is demonstrated by using multiple tissues from the same individual. Isotopic measurements of bone collagen provide information integrated over the lifetime of the individual and those of feathers during the post-breeding molt period. Analysis of liver provides information integrated over the previous week and that of muscle integrated over a few months. We developed multi-tissue trophic models for thick-billed murre Uria lomvia, dovekie Alle alle, black guillemot Cepphus grylle, glaucous gull Larus hyperboreus, northern fulmar Fulmarus glacialis, black-legged kittiwake Rissa tridactyla, and ivory gull Pagophila eburnea using the Northwater Polynya in Northern Baffin Bay, 1998 to 1999. The careful application of stable isotope methods to a spectrum of tissue types represents a powerful means of extending our ability to investigate diet and potentially to use seabirds as ecological indicators.
... Increases in shipping (Corbett et al. 2010), oil and gas exploration (Fissel et al. 2009) and fishing (Stram and Evans 2009) will introduce new human activities into Gyrfalcon habitats, increase the potential for oil spills (Macdonald et al. 2003), and increase exposure to environmental contaminants (Letcher et al. 2009). Changes in sea ice may also affect the distribution, abundance, and availability of prey species such as seabirds (Tranquilla et al. 2010, Byers et al. 2010) and waterfowl (Chaulk et al. 2007, Loworn et al. 2009, Oppel et al. 2009). Additionally, small-scale wind power projects are currently generating electricity in remote coastal areas of western Alaska (e.g., Tooksook Bay, Wales, Pribilofs, and Kotzebue; Dabo 2008) and similar projects are being proposed for other coastal areas in western Alaska, including several areas used by the radio-tagged Gyrfalcons. ...
... The tendency of morphological diet analysis to underestimate the importance of prey, when only soft tissue has been ingested, or where prey are entirely soft-bodied, has often been noted (Goss-Custard and Jones 1976;Floyd and Jenssen 1983;Dickman and Huang 1988;Reeve 1994;González-Solís et al. 1997;Vincent et al. 1998;Gunzburger 1999;Tsipoura and Burger 1999;Sutela and Huusko 2000;Deagle et al. 2005b;Anderson et al. 2008;Byers et al. 2010;Brown et al. 2012;Boyer et al. 2013). ...
Amphibians are currently the most threatened group of vertebrates, with an estimated 40 % of amphibian species currently in danger of extinction. The global spread of introduced fauna has been accepted as a major factor in the decline of amphibians, as native amphibians often have little or no evolutionary history with introduced predators. In particular, introduced small mammals such as rodents pose a major threat, as they are generalist predators that together have an almost global distribution. Wildlife management decisions regarding the control of introduced predators to protect endangered species are often based on predation rates derived from diet studies of the predators concerned. However, many studies have reported difficulties in identifying amphibians as prey in diet analysis, due to the degraded nature of any diagnostic prey components surviving the mastication and digestion processes of the predator. The aim of the research presented in this thesis was to aid global amphibian conservation by assessing the available tools, and developing further tools, to detect frogs as prey of introduced mammals.
I investigated the feeding behaviour of introduced mammals (ship rats Rattus rattus, Norway rats Rattus norvegicus, house mice Mus musculus and hedgehogs Erinaceus europaeus) when presented with frogs (southern bell frogs Litoria raniformis) as prey and explored the usefulness of two diet analysis methods: traditional morphological analysis and novel DNA-based methods. Using these methods I estimated the impact of ship rats on two endangered New Zealand native frogs (Hochstetter’s frog Leiopelma hochstetteri and Archey’s frog Leiopelma archeyi).
The results show that, using morphological diet analysis, 11 % of stomach and faecal samples collected after small mammals had ingested frogs could be classed as containing frogs as prey, but less than 1 % could be identified to species level. Although very small bones can be used to identify frogs as prey, the odds of successful identification dramatically increase as prey bone length in predator stomach and faecal contents increases.
The use of DNA-based methods increased prey identification (to species level) from less than 1 % to 58 %. Prey detection periods exceeded known gastrointestinal transit times for the small mammal species concerned, indicating that it is primarily the passage of prey material through the gastrointestinal tract that limits the successful detection of DNA, rather than the degradative effects of ingestion or digestion. The DNA-based methods were validated for field-collected samples and were successful where morphological analysis was not. Both Hochstetter’s frogs and Archey’s frogs were identified in the stomach contents of wild ship rats and estimates of predation rates at the study sites ranged from 0.01 – 0.9 frogs/ha/night, but it remains unclear whether ship rats alone threaten them with extinction.
This is the first study to investigate the usefulness of DNA-based diet analysis for detecting amphibians as prey, the first to estimate predation rates on New Zealand’s native frogs, and the first to compare stomach versus faecal prey DNA detection over time in any vertebrate. DNA-based diet analyses are highly adaptable and they offer a reliable and cost-effective approach to conservation managers hoping to make assessments of the impacts of introduced fauna on native amphibians, which are necessary to make informed decisions on the implementation of predator control.
... The lack of d 15 N difference between these two arctic seabird species may reflect a change in feeding strategy by the northern fulmar. In Arctic food webs, northern fulmar are known to be a scavenger with a highly plastic diet, able to fly long distances offshore to obtain pelagic fish (i.e., Gadids), fishing discards, and pelagic zooplankton (i.e., Calanus sp.) (Hatch and Nettleship, 1998; Phillips et al., 1999; Byers et al., 2010). During breeding season however, adult seabirds have increased constraints as they provision food for young, resulting in more local (nearshore) food fed to chicks/fledglings compared with that eaten by the adults (nearshore) (Furness and Todd, 1984; Barrett et al., 2007; Ojowski et al., 2001). ...
Persistent organic pollutants (POPs) and stable isotopes were measured in muscle from fledglings of two arctic seabird species, Northern fulmar (Fulmarus glacialis) and Black-legged kittiwakes (Rissa tridactyla). The purpose was to compare POP concentrations between species, in an age class that is highly vulnerable to POPs but little studied, relate to diet using stable isotopes, and quantify differences across life stages (egg to adult). Northern fulmar fledglings had significantly higher POP concentrations than kittiwake, consistent with results reported for adults of these species. Surprisingly, carbon and nitrogen stable isotopes did not differ between species, which does not match data for, or the known feeding ecology, of the adults. Fulmar/kittiwake POP concentration ratios varied across life stages indicating variable POP exposure and accumulation with age in seabirds, indicating that of the use of avian species-specific thresholds should only be done with caution in ecosystem-based POP risk management.
... In Adventfjorden, the de crease in the catches, especially in the shallow traps, coincides with the time of the year when the light in creases and migrating birds return. Seabirds (black guillemots Cepphus grylle, Arctic terns Sterna para disea, eider ducks Somateria mollissima) feed on amphipods (Węsławski et al. 1994, Byers et al. 2010, as do shore-birds (purple sandpiper Calidris maritima) in the inter-tidal zone (Luukkonen 2009). Interestingly, there is an increase in the trap catches again in June, when the melting season has started and the fjord is receiving high loads of suspended particles. ...
Scavenging amphipods are important for the circulation and dispersal of organic material in the marine environment. Despite their dominance in the scavenging guild and importance in the food web, little is known about Arctic amphipods and their feeding preferences. We studied the amphipod scavenging guild using baited traps for one full year to increase our understanding of its seasonal variations. Two Arctic fjords with contrasting hydrographical conditions were studied: Adventfjorden, which is influenced by Atlantic water inflow, and Rijpfjorden, which is dominated by cold Arctic water masses. The species composition clearly differed between the 2 fjords. Onisimus caricus, followed by Anonyx laticoxae, were the dominant species in Adventfjorden. In Rijpfjorden, the species diversity was higher, particularly for Anonyx spp. In both fjords, a clear depth zonation in species distribution was detected, with a seasonal dynamic in species composition. A seasonal pattern in catch sizes was observed in both fjords. The timing of this pattern varied, likely because of the climatic differences between the fjords. Lipid content, lipid classes and fatty acid composition were analyzed for A. nugax, O. caricus, O. litoralis, O. nanseni and O. glacialis, and stable isotopes were also analyzed for the all these species except O. glacialis. A clear difference in the fatty acid and stable isotope composition was found among species. O. glacialis and O. litoralis were primarily omnivorous-herbivorous, while the other species were predominantly carnivorous. O. nanseni and A. nugax preyed extensively on calanoid copepods (Calanus spp.) whereas O. caricus did not.
Breeding seabirds challenge the concept of niche segregation among competing species because similar competitors with comparable life histories can coexist in large multi-species colonies. This makes them an ideal model organism for studying the Hutchisonian niche model, which proposes interspecific niche segregation, across n-dimensions. Recent advances in assessment of ecological niches have improved our understanding of the mechanisms leading to at-sea segregation. We examine 152 published studies investigating one or more of three niche spaces in breeding seabirds: dietary items, stable isotopes (isotopic niche) and spatial distribution (horizontal and vertical). Most studies focused on one rather then multiple niche spaces in combination. When multiple niche spaces were combined, higher segregation than overlap was reported, compared with when niche spaces were assessed individually, as is predicted by the n-dimensional hypervolume concept. Studies investigating vertical (diving) foraging dimensions in addition to the more traditional horizontal (spatial) assessment reported more spatial segregation than overlap, compared with studies focusing only on horizontal or vertical dimensions. Segregation increased with colony size, suggesting an effect of competition. Segregation also increased during chick-rearing, when taxa were more phylogenetically distant, and when foraging ecology was more similar. To gain a comprehensive understanding of sympatric competitors' interactions and their ecological niche space, it is important to combine approaches and standardize methodologies. Embracing multidimensional approaches to assess niche segregation in seabird species can inform effective conservation and management practices in marine ecosystems.
https://www.miljodirektoratet.no/globalassets/publikasjoner/m396/m396.pdf
Contaminant levels and trends have been monitored in eggs of seabirds from the Canadian Arctic since 1975. Nearly 50 years of monitoring have provided key information regarding the temporal and spatial variation of various contaminant classes in different seabird species. However, previous work has primarily assessed individual or related contaminant classes in isolation. There is therefore a need to collectively consider all of the contaminants monitored in seabird eggs to determine where monitoring has been successful, to find areas for improvement, and to identify opportunities for future research. In this review, we evaluated monitoring data for the major legacy and emerging contaminants of concern in five seabird species from three High Arctic and three Low Arctic colonies in Canada. We review the history of Canada’s Arctic seabird egg monitoring program and discuss how monitoring efforts have changed over time; we summarize temporal, spatial, and interspecies variations in Arctic seabird egg contamination and identify important knowledge gaps; and we discuss future directions for ecotoxicology research using seabird eggs in Arctic Canada. Ultimately, this paper provides a high-level overview of the egg contaminant monitoring program and underscores the importance of long-term and continued seabird contaminant monitoring in Arctic Canada.
The northern fulmar Fulmarus glacialis is a medium-sized seabird with a broad, circum-polar range in the northern hemisphere, and is the only petrel that inhabits the High Arctic. We used stomach analysis and stable isotopes (delta N-15, delta C-13) of muscles to examine the diet of 179 fulmars during the breeding season at 4 locations in Arctic Canada, to compare diet to those from studies conducted in these regions >2 decades earlier. Across sampling locations, cephalopods, polychaetes and crustaceans dominated dietary remains in fulmars, although there was some regional variation. Both stable isotopes and stomach dissections showed that a seasonal shift in diet occurred in May, after which fulmars fed at a higher trophic level, suggesting a difference in winter/migration diet and breeding season diet. After migration, fulmar digestive organs decreased markedly in size, and by the time chicks were hatching, these organs were still 17 to 39% smaller than their size when birds arrived at the colony. Despite ongoing changes in the marine environment in much of the Arctic due to global warming, recent fulmar diet samples were similar to samples collected in the 1970s and 1980s, except that a higher proportion of recent collections contained fish.
I examined diet and foraging habitat selection by Black Guillemots (Cepphus grylle) in the eastern Canadian arctic. Birds fed on fish (Boreogadus saida, Stichaeus punctatus, Eumesogrammus praecisus) and mysid, amphipod, and decapod crustaceans. Guillemots concentrated at landfast ice edges early in the breeding season. Open-water foraging occurred principally in waters 10–30 m deep within 13 km of breeding colonies. Guillemots were aggregated on the water, but their distributions were not correlated with those of schooling prey. Guillemots feeding in open water obtained much of their food on the bottom, but some prey was likely taken during transit to and from the bottom.
Bird species from the order Procellariiformes or petrels, including the northern fulmar (Fulmarus glacialis), produce high lipid and high energy content stomach oils from the prey they consume, which enables them to exploit distant marine food sources. Stomach oils are also used as a food source for chicks and for defensive purposes. Samples of stomach oils from two Arctic colonies, St. George Island Alaska, USA and Cape Vera, Devon Island Nunavut, Canada, were collected and analyzed for organochlorine contaminants. SigmaPCB concentrations ranged from 13 to 236 ng g(-1) wet weight (ww) and SigmaDDT concentrations from 5 to 158 ng g(-1) ww and were similar in both sites, though differences in chemical signatures were apparent. Stomach oils are a rich energy source; however, they may also provide a higher dose of contaminants per unit energy than the direct consumption of prey items, as illustrated using mass and energy balance calculations to estimate chick exposure to SigmaDDT for hypothetical stomach oil and whole prey diets. The results of this study suggest that stomach oils are an important vector of organochlorine contaminants to chicks and should be considered in future risk assessments of northern fulmars and other species of petrels. To our knowledge this is the first study of stomach oils as an overlooked vector of organochlorine contaminants to chicks and as a potentially valuable medium for dietary analysis and noninvasive biomonitoring both of petrel dietary exposure and of marine contaminant concentrations.
Thesis (Ph. D.)--Carleton University, 1985. Includes bibliographical references.
Food samples from 102 seabirds from eight species (fulmar Fulmarus glacialis, common eider Somateria mollissima, glaucous gull Larus hyperboreus, kittiwake Rissa tridaayla, arctic tern Sterna paradisaea, Briinnich's guillemot Uria lorn via, black guillemot Cepphus grylle, little auk Alle alle) were collected during the period August 1991–1993 in the southern part of the Frans Josef Land archipelago, 80°N, 53°E. The pelagic amphipod Parathemisto libellula and polar cod Boreogadus saida were the two most commonly taken food items (frequency of occurrence over 50% and weight contribution more than 70%). Ice-associated crustaceans contributed to some 10% of the weight in the samples. In general, the food composition was very similar to that reported from Svalbard. However, birds from Frans Josef Land fed on a lower diversity of prey compared to Svalbard populations.
Food samples from six High-Arctic seabird species were collected during spring and summer seasons between 1982 and 1990 in the Svalbard region. The material came from coastal localities on the island of Spitsbergen and the marginal ice zone in eastern Svalbard waters. Polar cod Boreogadus saida was the most frequently occurring prey in the ice-covered areas. Analysis of otoliths showed that most polar cod were one-or two-year olds. These year classes are known to associate with sea ice. Other ice-associated (sympagic) organisms, such as gammarid amphipods, were not found to be of high importance as prey for seabirds in the study area. However, the sea ice occurring in the area was mainly one year old. Such ice contains a less developed sympagic fauna than multi-year ice. The pelagic amphipod Parathemisto libellula, which is not sympagic but occurs in the water column, was also found to be an important prey in the marginal ice zone, especially for the Briinnich's guillemot Uria lomuia. The smallest of the seabird species studied, the little auk Alle alle, differed from the other five species in its diet, preying mainly upon smaller items such as copepods and young stages of amphipods, euphausiids and decapods. The diet of the various seabird species was in general more diverse in the coastal areas than in the marginal ice zone.
Northern Fulmars were captured, ringed and released on St Kilda in August 1982. Twelve samples of regurgitated contents of their proventriculus were studied in detail. Velella velella (Siphonophora) were observed twice, Hyperia galba, a small amphipod that is often found in cavities within the umbrella of jellyfish, were recorded four times (72 individuals). All fish found in the samples were apparently taken behind trawlers (discards and offal). Some plastic particles (i.e. pellets) were present and some plant remains were probably taken while at the nest.
Between 10 June and 14 August 1980, Northern Fulmars were captured and either ringed and released (n= 153) or collected (n= 22) on Bjornoya (Bear Island, Norway, western Barents Sea). Food remains of the individuals that regurgitated 'considerable' amounts during handling were collected and analysed (13 samples). In addition, the stomach contents of the collected specimens were studied. From regurgitated food (i.e. contents of proventriculus) an entirely different impression of the diet was obtained than from the complete examination of proventriculus and gizzard contents in collected specimens. Only fish flesh and crustaceans were frequently regurgitated, whereas hard parts such as fish eye-lenses, squid eye-lenses and -beaks, jaws of nereid worms, and plastic particles numerically dominated the prey items in stomachs of collected birds. The absence of crustaceans in an earlier study may thus be attributed to the method of study which was entirely based on stomach contents. In total 18 out of 22 gizzards (i.e. 82%) contained plastic particles (range 1-21 items).
The massive expansion in breeding numbers and range of the northern fulmar Fulmarus glacialis over the last two centuries is generally attributed to an increased availability of fish offal and discarded fishes from commercial fisheries. This implies that discards should be a major component in fulmar diets in the more recently colonised areas in the south of their range. This paper examines the contemporary diet of the northern fulmar at three major breeding sites, Fair Isle (Shetland, UK), Iceland and Disko Fjord (western Greenland). At Fair Isle, 89% of regurgitates contained fishes, with sandeels (Ammodytidae) recorded in 37%; 32% contained crustaceans (mainly decapods); 8% contained squid. There was also a temporal trend; sandeels declining and crustaceans increasing in the diet from July to August. In Iceland, fishes were also the main prey (47 to 93% of wet mass), with sandeels common in the south and west, and capelin (Mallotus villosus) in the north and east. Other fish species were mainly discards, and together with discarded decapods and fish offal formed 5 to 72% of the diet, depending on the sector. Euphausiids, amphipods and copepods constituted 3 to 13% of the diet. At Disko, 39% of samples contained fishes, 64% contained crustaceans (mainly amphipods), 22% contained squid, and 16% contained pteropods. There was a clear temporal trend, with the bulk of the samples made up of crustaceans in mid-June, capelin from late June to late July, and crustaceans and pteropods from late July to late August. An extensive review of published studies was also carried out. The general pattern was for birds in more southerly populations to consume more discarded fishes, fish offal and benthic invertebrates. However, a considerable proportion of their diet also consisted of juvenile gadids, sandeels, capelin and pelagic zooplankton, which fulmars catch for themselves, and we suggest that breeding adults in the south are less dependent on fishing waste than is generally assumed.
Accessible at www.marinespecies.org
Northern fulmars (Fulmarus glacialis) are abundant scavengers at fishing vessels in the North Sea. However, despite their abundance and apparent feeding success
at (some) fishing vessels, the contribution of discards and offal to their food intake cannot be fully estimated in the absence
of less easily gathered data on natural foods. Direct study of fulmar diet has failed to determine the relative importance
of discards and offal in the diet. In this paper, the feeding ecology of, and the importance of fishing activities for, fulmars
across the whole North Sea is evaluated using results from cruises of fishery research vessels and also observations from
a commercial beam trawler. Fulmar and fishery distribution, prey selection and feeding success of scavenging birds, and the
relationship of fulmar distribution with hydrographic parameters are the main topics of this study. We found that: (1) fulmars
were most abundant in regions of the North Sea where the supply of fishery waste was comparatively low; (2) hydrography predicts
fulmar distribution better than fisheries; (3) fulmars at fishing boats obtain discarded offal in proportion to their numerical
abundance, but obtain relatively small amounts of discarded roundfish; (4) roundfish are easily robbed from fulmars, and that
a marked decline in feeding success in autumn and winter might be attributed to increasing numbers of herring gulls (Larus argentatus) at the trawl; and (5) fewer than 50% of the fulmars in the North Sea can be fully supported by fishery waste. These results
indicate that, although fulmars clearly profit from fishery waste, fishing activities are not an important determinant of
their distribution on a North Sea scale.
At ice edges in the Canadian High Arctic, seabirds and marine mammals eat arctic cod (Boreogadus saida) and to a lesser extent, zooplankton (calanoid copepods and Parathemisto) and ice-associated amphipods. Cod eat ice-associated amphipods, other ice-associated taxa (harpacticoid and cyclopoid copepods), and zooplankton. Calanoid copepods, Parathemisto, and the ice-associated amphipods studied (Onisimus glacialis, Apherusa glacialis, Gammarus wilkitzkü) all eat primarily diatom algae characteristic of the under-ice flora. From this information, a food web at the ice edge is constructed.
Key words: trophic relationships, arctic, ice edges, seabirds, marine mammals, cod, epontic community, zooplankton
The Canadian Arctic contains much of Canada's coastal and marine zones, and these areas support tremendous numbers of marine birds. At the start of the 21st century, the Canadian marine zone is the subject of much concern as a result of a variety of anthropogenic threats. The Canadian Wildlife Service (CWS) is the federal agency responsible for the conservation of migratory bird populations and their habitats in Canada. As part of its mandate, CWS has produced this report identifying key marine habitat sites for migratory birds in Nunavut and the Northwest Territories. This report serves as a statement of CWS interest in marine areas where special wildlife conservation measures may be required, and it is offered as a guide to the conservation efforts of other agencies with interests in Nunavut and the Northwest Territories. Approximately 10 million pairs of breeding marine birds use the marine areas in Nunavut and the Northwest Territories annually for breeding, feeding, migration, moulting, or wintering. In addition to breeding birds, hundreds of thousands of nonbreeding birds also inhabit these waters. We have defined a key marine habitat site as an area that upports at least 1% of the Canadian population of at least one migratory bird species, following the protocols used previously in Canada and internationally to identify important bird habitats. Marine habitat sites include coastline, open sea, and polynya-shore lead habitats, although the focus of this report is on the last two categories. The sites identified in this report are essential to the welfare of many migratory birds in Canada. As most of these species migrate across international boundaries, many of these sites are also of international importance. Data for the identification of sites were drawn from existing published and unpublished reports and from personal communications. Portions of some sites listed here were identified in an earlier report that focused on terrestrial areas (CWS Occasional Paper No. 71), where the value of the terrestrial site was integrally linked to the marine component. Currently, CWS manages 18 migratory bird sanctuaries and national wildlife areas in Nunavut and the Northwest Territories. Most of these were set up to protect terrestrial or coastal wildlife resources; only one was set up specifically to protect a large marine zone for seabirds, that being the Nirjutiqavvik (Coburg Island) National Wildlife Area. Nonetheless, the Arctic migratory bird sanctuaries and national wildlife areas contain about 15 000 km2 of marine habitat within their boundaries, providing some protection for selected marine bird colonies. Many key marine habitat sites are not included in these established sites, however. In this report, we have identified 34 key marine habitat sites, 20 of which are in the High Arctic, 13 in the Low Arctic, and 1 in the Boreal oceanographic zones. The total marine area (excluding islands) included in these sites is 161 000 km2. The largest site is Amundsen Gulf and the Cape Bathurst Polynya, which includes 30 700 km2 of marine waters, while the smallest site is East Bay, which encompasses 274 km2. We have also identified those sites where there are known threats, such as cruise ship tourism or potential oil spill concerns. Site identification is the first step in getting key marine habitats for migratory birds recognized and protected at some level. We emphasize that not all of the sites listed in this report are targeted to become protected areas. The first goal will be recognition and incorporation of these sites in land use planning by the Nunavut Planning Commission and in planning documents of other agencies that regulate activities in the Arctic marine environment. Some sites will become national or marine wildlife areas, with community support, and the information provided here will help in the establishment of marine protected areas or marine conservation areas. The identification of key marine habitat sites is a dynamic process, and the importance of each site needs to be reevaluated on a regular basis. As bird populations fluctuate or sea ice conditions change, the value of some sites will change and new sites will be discovered. This report also outlines some of the steps necessary to continue to move the key marine habitat sites process forward, including additional monitoring of some Arctic seabird colonies, research on species that have received little attention in Arctic Canada, renewed offshore survey efforts, and increased collaboration with communities and other partners in marine issues. A review of this report should be conducted each decade to update the status of various sites and list any new ones that have been discovered.
This paper synthesizes the trophic dynamics of a Canadian arctic marine ecosystem in so far as it is known, using new data on primary production, zooFlankton, the bivalve Mya truncata, and arctic cod (Boreogadus saida), as well as literature values for marine mammals and seabirds. The 98 000 km reglon has a high rate of primary production relative to other parts of arctic Canada. About 60 g Cm-' are fixed annually, of which approximately 90% is contributed by phytoplankton, 10% by ice algae, and 1% by kelp. Phytoplankton production is twofold higher along the south coast of Comwallis Island than elsewhere in Barrow Strait. Four copepod species, of which Pseudocalanus acuspes is the most important energeti- cally, graze about one-third of the phytoplankton production. Bivalves maintain high biomass but low energy flow, acting as sedimenting agents. Arctic cod is a major component, with 125 000 tonnes bein consumed by marine mammals and 23 000 tonnes by seabirds annually. Our hydro- acoustic estimate for mean arctic cod density, 0.0022 fish.m', is probably too low, partly because we have been unable to quantify dense aggrega- tions of schooling fish. The ecological efficiency of ringed seal is near maximum, with 5% of ringed seal ingestion going to bears and man as seal flesh. The data on total kill and prey consumption in whales and birds is incomplete because they migrate out of the Lancaster Sound region in win- ter. The food chain is very long, with bears occupying the fifth trophic level; this is reflected by high biomagnification factors for persistent lipophilic pollutants such as PCBs. There are major data gaps for some zooplankton and most of the benthos, as well as for winter populations and energetics. This trophic analysis is therefore incomplete and efficiencies for entire trophic levels cannot be calculated.
Summary • We compared the reproduction of a marine diving bird, Brunnich's guillemot (Uria lomvia), breeding at two Arctic colonies close to the northern and southern limits of the species’ range in the Canadian Arctic. • At both colonies, timing of breeding for Brunnich's guillemots was positively correlated with summer ice cover, which was determined by winter and spring temperatures. Spring temperatures also modified the effects of ice conditions on timing of breeding. • At Coats Island, northern Hudson Bay, in low Arctic waters, the date of egg-laying has advanced since 1981, simultaneous with a decrease in summer ice cover in surrounding waters. Lower ice cover in this region is correlated with lower chick growth rates and lower adult body mass, suggesting that reduction in summer ice extent is having a negative effect on reproduction. • Conversely, at Prince Leopold Island, in the High Arctic, there has been no trend in summer ice cover and no detectable change in timing of breeding. Reproduction there is less successful in years of late ice than in years of early ice break-up. • Current trends suggest that continued warming should benefit birds breeding on the northern limit of the species range, while adversely affecting reproduction for those on the southern margin. The probable result will be an eventual northward displacement of the population. Although this type of effect has been widely predicted, this study is among the first to demonstrate a potential causal mechanism. Journal of Animal Ecology (2005) 74, 832–841 doi: 10.1111/j.1365-2656.2005.00982.x
Trends in the composition of nestling thick-billed murre diets were analyzed for the period 1980-2002 on the basis of observations of food delivered to nestlings at two breeding colonies in northern Hudson Bay. The incidence of arctic cod, sculpins, and benthic Zoarcidae decreased and the incidence of capelin and sandlance increased over the period considered. Arctic cod fell from a mean of 43% of deliveries in the mid-1980s to 15% in the late 1990s; benthic species (zoarcids and sculpins) fell from 36% to 15%, while capelin increased from 15% to 50% over the same period. July ice cover in Hudson Bay approximately halved during 1981-99. We suggest that the observed changes in diet composition reflect changes in the relative abundance of the fish species involved and that the decline in arctic cod and increase in capelin and sandlance were associated with a general warming of Hudson Bay waters, the result of ongoing climate change in the region.
Garthe, S. 1997. An evaluation of the distribution and scavenging habits of northern fulmars (Fulmarus glacialis) in the North Sea. – ICES Journal of Marine Science, 54: 654–683. Northern fulmars (Fulmarus glacialis) are abundant scavengers at fishing vessels in the North Sea. However, despite their abundance and apparent feeding success at (some) fishing vessels, the contribution of discards and offal to their food intake cannot be fully estimated in the absence of less easily gathered data on natural foods. Direct study of fulmar diet has failed to determine the relative importance of discards and offal in the diet. In this paper, the feeding ecology of, and the importance of fishing activities for, fulmars across the whole North Sea is evaluated using results from cruises of fishery research vessels and also observations from a commercial beam trawler. Fulmar and fishery distribution, prey selection and feeding success of scavenging birds, and the relationship of fulmar distribution with hydrographic parameters are the main topics of this study. We found that: (1) fulmars were most abundant in regions of the North Sea where the supply of fishery waste was comparatively low; (2) hydrography predicts fulmar distribution better than fisheries; (3) fulmars at fishing boats obtain discarded offal in proportion to their numerical abundance, but obtain relatively small amounts of discarded roundfish; (4) roundfish are easily robbed from fulmars, and that a marked decline in feeding success in autumn and winter might be attributed to increasing numbers of herring gulls (Larus argentatus) at the trawl; and (5) fewer than 50% of the fulmars in the North Sea can be fully supported by fishery waste. These results indicate that, although fulmars clearly profit from fishery waste, fishing activities are not an important determinant of their distribution on a North Sea scale.
Food samples from 102 seabirds from eight species (fulmar Fulmarus glacialis, common eider Somateria mollissima, glaucous gull Larus hyperboreus, kittiwake Rissa tridaayla, arctic tern Sterna paradisaea, Briinnich's guillemot Uria lorn via, black guillemot Cepphus grylle, little auk Alle alle) were collected during the period August 1991–1993 in the southern part of the Frans Josef Land archipelago, 80°N, 53°E. The pelagic amphipod Parathemisto libellula and polar cod Boreogadus saida were the two most commonly taken food items (frequency of occurrence over 50% and weight contribution more than 70%). Ice-associated crustaceans contributed to some 10% of the weight in the samples. In general, the food composition was very similar to that reported from Svalbard. However, birds from Frans Josef Land fed on a lower diversity of prey compared to Svalbard populations.
Northern fulmars (Fulmarus glacialis) have recently expanded their breeding range in the northwest Atlantic Ocean. We studied their diet in their largest colony in the northwest Atlantic on Funk Island, eastern Canada, by collecting dietary samples from chicks during 1999 and 2000. Fish, primarily capelin (Mallotus villosus), and offal from commercial fisheries were the most common foods in the diets of fulmar chicks. Crustaceans were also common prey fed to the chicks. Squids (Gonatus fabricii) were an important food in 2000. Chick diets varied considerably between the 2years of the study. The diets of northern fulmar chicks on Funk Island were opportunistic and similar to those of chicks at other colonies in the eastern and northern North Atlantic Ocean. Compared to other regions in the North Atlantic Ocean, the diet of birds on Funk Island seems to be most similar to those from Iceland, and least resemble those from Shetland. Long-term studies of the feeding ecology on northern fulmars may be helpful in discerning factors influencing changes in the species distribution and abundance.
Several different techniques have been used to study the diet composition of skuas and gulls in polar regions. In this study, we assessed the diet of great skuas using five techniques (pellets, prey remains, spontaneous regurgitates, observed feeds and water off-loading). The estimates of diet derived from each sampling technique during a single breeding season were generally similar. Although it is easy to collect large samples of pellets and remains, these over-estimate the amount of indigestible material in the diet. Prey remains provide a high degree of taxonomic accuracy, but may under-estimate prey swallowed whole. Water off-loading provides unbiased estimates of chick diet but only during a short period in the breeding season. It may also stress birds, and is labour-intensive. Spontaneous regurgitates are useful for assessing chick and adult diet but are difficult to collect systematically, and differing prey digestibility may bias results. Observed feeds are time consuming to record and over-represent easily identifiable prey. Technique-dependent biases highlight that sampling methods should be selected on the basis of sample sizes, time, taxonomic detail and age of study birds. Biomass may be estimated using pellets with correction factors, and also spontaneous regurgitates and water off-loading, but prey remains and observed feeds may be more inaccurate.
The massive expansion in breeding numbers and range of the northern fulmar Fulmarus glacialis over the last two centuries is generally attributed to an increased availability of fish offal and discarded fishes from
commercial fisheries. This implies that discards should be a major component in fulmar diets in the more recently colonised
areas in the south of their range. This paper examines the contemporary diet of the northern fulmar at three major breeding
sites, Fair Isle (Shetland, UK), Iceland and Disko Fjord (western Greenland). At Fair Isle, 89% of regurgitates contained
fishes, with sandeels (Ammodytidae) recorded in 37%; 32% contained crustaceans (mainly decapods); 8% contained squid. There
was also a temporal trend; sandeels declining and crustaceans increasing in the diet from July to August. In Iceland, fishes
were also the main prey (47 to 93% of wet mass), with sandeels common in the south and west, and capelin (Mallotus villosus) in the north and east. Other fish species were mainly discards, and together with discarded decapods and fish offal formed
5 to 72% of the diet, depending on the sector. Euphausiids, amphipods and copepods constituted 3 to 13% of the diet. At Disko,
39% of samples contained fishes, 64% contained crustaceans (mainly amphipods), 22% contained squid, and 16% contained pteropods.
There was a clear temporal trend, with the bulk of the samples made up of crustaceans in mid-June, capelin from late June
to late July, and crustaceans and pteropods from late July to late August. An extensive review of published studies was also
carried out. The general pattern was for birds in more southerly populations to consume more discarded fishes, fish offal
and benthic invertebrates. However, a considerable proportion of their diet also consisted of juvenile gadids, sandeels, capelin
and pelagic zooplankton, which fulmars catch for themselves, and we suggest that breeding adults in the south are less dependent
on fishing waste than is generally assumed.
The correlation between areas of open water in ice-covered seas and increased biological productivity has been noted for some time. To date, most attention has been focused on larger polynyas, such as the Northeast Water and the Northwater. Although spectacular in their own right, these large polynyas represent only part of a vitally important continuum of biological productivity that varies significantly between geographic areas and ice habitats, that includes the multi-year pack of the polar ocean and small localized polynyas in annual ice. Surveys of the distribution and abundance of ringed seals in the Canadian Arctic Archipelago have shown differences in density that are correlated with the presence or absence of polynyas. There is also significant variation in the biological productivity of polynya areas of the Canadian High Arctic Archipelago and northern Greenland, all of which receive inflow from the polar basin. Long-term studies of polar bears and ringed seals in western Hudson Bay and the eastern Beaufort Sea show significant but dissimilar patterns of change in condition and reproductive rates between the two regions and suggest that fundamentally different climatic or oceanographic processes may be involved. Projections of climate models suggest that, if warming occurs, then the extent of ice cover in Hudson Bay may be among the first things affected. Long-term studies of polar bears and ringed seals in the eastern Beaufort Sea and Hudson Bay would suggest these two species to be suitable indicators of significant climatic or oceanographic changes in the marine ecosystem.
BLDSC reference no.: D45069/83. Thesis (doctoral)--University of Oxford, 1981.
Barrett, R. T., Camphuysen, C. J., Anker-Nilssen, T., Chardine, J. W., Furness, R. W., Garthe, S., Hüppop, O., Leopold, M.
F., Montevecchi, W. A., and Veit, R. R. 2007. Diet studies of seabirds: a review and recommendations. – ICES Journal of Marine
Science, 64.
We review the different methods that are used to collect dietary data from marine birds. We consider their limitations and
practicalities and emphasize critical data gaps in our knowledge of the feeding ecology of seabirds (na mely diets outside
breeding seasons). To enhance comparability of findings among studies, species, and oceanographic regions, we make recommendations
on standards for the reporting of results in the literature.
Examination of survival rdtes of nestlings and fledglings of some species show that there is a strong tendency for those young which are hatched earliest in the season to have the greatest chance of surviving to breed. Since natural selection so strongly favours parents who leave many surviving young, the question arises as to why other birds breed later than the date at which they could most successfully raise their young.
It is suggested that the food supply for the breeding females immediately prior to the breeding season may limit their ability to form eggs and the females may thus not be able to lay at the time which would result in young being in the nest at the best time for raising them, but as soon after this time as the female is able to produce her eggs. Not all species are likely to be prevented, by food shortage, from breeding at the best time for raising young and the groups of birds most likely to be affected are discussed.
Many aspects of the reproductive ecology of seabirds are linked to the phenology, quantity and accessibility of marine food supplies. In polar regions, annual sea ice constrains these aspects of marine productivity, and thus seabirds breeding at high latitudes may exhibit adaptations to accommodate these constraints. Like most petrels, northern fulmars Fulmarus glacialis undertake an exodus from their breeding colony just before egg-laying. To assess whether this exodus was related to energetic needs and stored nutrient reserves, we studied changes in body mass and composition of male and female fulmars breeding in the Canadian High Arctic, by comparing birds collected just before and just after the pre-laying exodus. Males gained body mass over this period, accumulating water, fat and protein, whereas females lost body mass, particularly protein and fat. Declines in female fat and protein approximated the amounts contributed to eggs, but water and mineral reserves in pre-exodus females appeared insufficient for egg production. We hypothesize that female fulmars leave the colony before egg-laying to meet mineral demands for egg production, possibly focusing on calcium-rich prey. In contrast, we hypothesize that males use a different strategy for resource acquisition and allocation, which seeks to maximize fat and protein accumulation to meet forthcoming incubation demands. Differences in typical marine environmental conditions at breeding colonies across the species' range probably account for observed behavioral variation in breeding schedules, and may also result in different nutrient dynamics.
Young-of-the-year rock bass and smallmouth bass were studied in 1977 along the west shore of Grand Island in the upper Niagara River, New York. Fish were collected every 2 weeks by shore scining. The average summer growth rate of smallmouth bass was 1.15 mm/day and of rock bass, 0.51 mm/day. Population estimates and laboratory habitat preference studies indicated that smallmouth bass preferred a rocky substrate whereas rock bass preferred a heavily vegetated substrate. Smallmouth bass less than 40 mm in total length (TL) fed mainly on zooplankton, chironomid larvae, mayfly nymphs, and amphipods, and when greater than 40 mm TL fed on amphipods, adult caddis flies, and small fish. Rock bass young of the year of all sizes fed on amphipods, copepods, and several other aquatic invertebrates. Levins' average niche breadth or dietary diversity value for smallmouth bass was 2.51, and for rock bass, 3.78. Levins' dietary overlap values were highest early in the season, 0.71–0.88, and decreased to 0.05–0.17 as the season progressed. Ecological segregation was by both food and habitat partitioning.
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.
Aerial surveys of Jones Sound reveal a highly clumped distribution of Cepphus grylle 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 polynya located in W Jones Sound. Annual variation in the distribution of ice edges in Jones Sound may influence distribution of breeding birds among suitable breeding sites. -from Authors
(1) The breeding success and timing of laying of manx shearwaters breeding on Skokholm Island, Wales, are discussed. (2) Newly formed pairs have a lower hatching success (66.2%) than established pairs (79.1%). This is due to the fact that new pairs include birds without prior breeding experience and not to the newly formed pair bond per se. (3) When forming new pairs experienced breeding birds tend to mate with other experienced breeding birds rather than new breeders. (4) Divorce and burrow movement are both more likely after breeding failure than after success. (5) The timing of laying and the size of eggs laid are very constant from year to year, both for the population as a whole and for individual females. (6) The relationship of laying date and egg size to female age is described. (7) It is suggested that birds do not lay earlier than they do because, early in the season, the food supply would be inadequate to enable the adults to maintain continuous incubation. (8) Circumstantial evidence is presented suggesting that conditions for incubation improve during the incubation period.
Fulmarus glacialis es un ave marina pelágica que se reproduce en las zonas oceanográficas desde los 25° de latitud norte hasta altas latitudes en el Ártico. Examinamos la fenología reproductiva de individuos de F. glacialis en la colonia remota de Cabo Vera ubicada a altas latitudes en el Ártico canadiense, una región marina cubierta por hielo durante gran parte del año. Trabajamos allí para determinar si el inicio de la reproducción y los patrones de presencia de aves en las colonias difería de la fenología reproductiva de colonias de F. glacialis que se encuentran más al sur. Los individuos de Cabo Vera llegaron a las colonias más tarde, permanecieron por menos tiempo en las colonias antes de comenzar la puesta de huevos y se ausentaron antes de la postura por un período significativamente más largo que los individuos que nidificaron en colonias más sureñas. Sin embargo, después del periodo de postura de huevos, los patrones de presencia de individuos fueron similares entre las colonias del ártico y las sureñas; esta parte del periodo reproductivo podría ser inflexible. Estas diferencias en la fenología reproductiva en el área de distribución de esta especie pueden reflejar adaptaciones de comportamiento por parte de las aves que nidifican en el Ártico para hacer frente a las limitaciones físicas y biológicas impuestas por las extensas áreas de hielo en el mar cercanas a las colonias del Ártico, especialmente durante las etapas tempranas de la época reproductiva. Debido al calentamiento climático y la consecuente reducción del hielo marino que está ocurriendo en el Ártico, es aún necesario determinar si los individuos que se reproducen a altas latitudes en el Ártico tienen la flexibilidad conductual en su fenología reproductiva necesaria para compensar los cambios que están ocurriendo repentinamente en su ambiente.
Stomachs of 171 vertebrates (two species offish, eight of birds and twoof seals) from Hornsund, Svalbard, were collected between 7 September and 5 October 1984. Arctic cod Boreogadus saida and the amphipod Pamthemisto libellula were the main prey species of black guillemots Cepphus grylle, little auks Alle alle, puffins Fratercula arctica, Brunnich's guillemots Uria lomvia, kittiwakes Rissa tridactyla and ringed seals Phoca hispida. Fulmars Fulmarus glacialis preyed mainly on the squid Gonatusfabricii and the polychaete Nereis irrorata. Eiders Somateria mollissima preyed mainly on bivalves and on the amphipod Gammarellus homari. G. homari and Gammarus oceanicus were the most important prey species of striped snailfish Liparis liparis, while shorthorn sculpin Myoxocephalus scorpius mainly preyed upon G. homari and Anonyx sarsi. Glaucous gulls LOTUS hyperboreus took many different prey including birds and tundra plants. Only one bearded seal Erignathus barbatus stomach with content was available for this study.
The food and feeding ecology of northern fulmars Fulmarus glacialis was investigated in July 1999 at Bjørnøya (Bear Island). Fulmars relied almost exclusively on fish during the brooding period.
The main fish prey was capelin Mallotus villosus (87.0% by reconstituted mass), Atlantic cod Gadus morhua accounting for most of the remainder (9.7% by reconstituted mass). The estimated total length of capelin and Atlantic cod
eaten averaged 15 and 17 cm, respectively. Adult fulmars performed short foraging trips averaging 8 hours when brooding chicks,
and they foraged at a mean maximum distance of about 60 km, the birds being concentrated on the shelf surrounding the island.
The study emphasizes the importance of capelin as a key link between zooplankton and top predators, including seabirds, in
the pelagic ecosystem of the Barents Sea.
The maximum extent of sea ice in the northern hemisphere has been contracting for several decades, with implications for all ice-associated biota. To determine how variation in ice conditions affects reproduction in marine birds, we studied the effects of ice conditions on breeding of four species of seabirds over four years at Prince Leopold Island, Nunavut, a colony close to the limits of ice conditions where breeding is feasible. In 2000 and 2003, open water was present close to the colony in June, when the birds began to lay eggs. In 2001 and 2002, the ice edge in June was >200 km to the east of the colony, forcing birds to commute long distances to open water to feed. Egg-laying by thick-billed murres, black-legged kittiwakes and glaucous gulls was delayed and eggs and clutches were smaller in 2001 and 2002. However, northern fulmars laid at the same time in all years, although their incubation shifts were longer in 2001 and 2002 than in 2003. Open water was present close to the colony by the time of hatching in all years. Despite this, nestling survival of northern fulmars, body condition and nestling growth of thick-billed murres and body condition and nestling survival of black-legged kittiwakes were lower in 2001 and 2002 than in –2000 and 2003. All these indicators suggest that feeding conditions in the years of late ice break-up continued to be worse than usual even after open water was available at the colony. Our study suggests that current trends towards earlier ice break-up in the Arctic may be beneficial for marine birds at Prince Leopold Island, at least in the short-term.
Food samples from six high-arctic seabird species were collected during spring and summer seasons between 1982 and 1990 in the Svalbard region. The material came from coastal localities on the island of Spitsbergen and the marginal ice zone in eastern Svalbard waters. Polar cod Boreogadus saida was the most frequently occurring prey in the ice-covered areas. Analysis of otoliths showed that most polar cod were one-or two-year olds. These year classes are known to associate with sea ice. Other ice-associated (sympagic) organisms, such as gammarid amphipods, were not found to be of high importance as prey for seabirds in the study area. However, the sea ice occurring in the area was mainly one year old. Such ice contains a less developed sympagic fauna than multi-year ice. The pelagic amphipod Parathemisto libellula, which is not sympagic but occurs in the water column, was also found to be an important prey in the marginal ice zone, especially for the Briinnich's guillemot Uria lomuia. The smallest of the seabird species studied, the little auk Alle alle, differed from the other five species in its diet, preying mainly upon smaller items such as copepods and young stages of amphipods, euphausiids and decapods. The diet of the various seabird species was in general more diverse in the coastal areas than in the marginal ice zone.
Five northern fulmars (Fulmarus glacialis) were tracked by satellite transmitters from their breeding colony in the Canadian high Arctic (Cape Vera, Devon Island,
NT) to their wintering grounds in the northwest Atlantic Ocean. In both 2004 and 2005, fulmars left northern Baffin Bay in
mid- to late September, and migrated south to Davis Strait in less than 1week, after which movements were erratic. In October
and November, the birds were widely distributed, but by December through March, they tended to remain in the Labrador Sea
between 50 and 55°N. Average flight speed was 35km/h with a maximum of 64km/h, and over their entire transmission periods,
the five traveled on average 84km/day. Our work suggests that the North Atlantic northern fulmar population may be panmictic
in winter, with the Labrador Sea as a key wintering site for fulmars from high Arctic Canada.
Concentrations of total mercury, selenium and a suite of organochlorine compounds were measured in eggs of thick-billed murres (Uria lomvia), northern fulmars (Fulmarus glacialis) and black-legged kittiwakes (Rissa tridactyla) collected on Prince Leopold Island in Lancaster Sound, Nunavut, Canada, between 1975 and 1998. Mercury levels in thick-billed murre and northern fulmar eggs increased significantly during this period while selenium concentrations decreased significantly in northern fulmar eggs. Mercury and selenium concentrations in black-legged kittiwake eggs exhibited no significant temporal trends. Concentrations of sigma PCB, sigma DDT and total chlorobenzenes decreased over time for all three species and there was a shift in the PCB congener pattern as the hexachlorobiphenyl fraction of sigma PCB increased and the lower chlorinated biphenyl fraction decreased. Total chlordane, dieldrin and mirex concentrations decreased in kittiwake eggs while no significant trends were observed for the other two species. Increases in sigma HCH levels were detected in thick-billed murre eggs but not in northern fulmar and black-legged kittiwake eggs. Levels of the beta-HCH isomer, however, increased significantly in murres and fulmars. Stable-nitrogen isotope analyses (delta 15N) indicate that the temporal trends observed for contaminant concentrations in eggs were not the result of shifts in trophic level. Changing deposition patterns of xenobiotic compounds over the summer and winter ranges of these birds provide a likely explanation for differing exposures through time.
Eggs of glaucous gulls (Larus hyperboreus), black-legged kittiwakes (Rissa tridactyla), thick-billed murres (Uria lomvia) and black guillemots (Cepphus grylle) were collected from several sites throughout the Canadian Arctic. Samples were analyzed for organochlorines as well as mercury and selenium. Glaucous gulls breeding at sites in the High Arctic showed higher levels of organochlorine contamination than those in the western Low Arctic. This was likely due to dietary differences among colonies as suggested by stable isotope data, although different overwintering areas may also play a role. Levels of sigmaPCB, sigmaDDT, sigmaCHLOR, sigmaCBz and dieldrin were significantly lower in thick-billed murres from Prince Leopold Island in the High Arctic compared with colonies in the eastcrn Low Arctic. This difference was likely due to the combined effects of different atmospheric deposition patterns in the High and Low Arctic and different overwintering areas since murres from Prince Leopold Island may winter farther north than murres from the other colonies sampled. Eggs from colonies at higher latitudes generally contained higher concentrations of mercury. The trophic and dietary differences/similarities suggested by stable-nitrogen and carbon isotope data in this study were useful in explaining the spatial patterns of contaminant concentrations observed among colonies of seabirds such as the glaucous gull and the black-legged kittiwake where variation in latitudinal atmospheric deposition patterns and different overwintering grounds did not appear to be confounding factors.
Organochlorine contaminants (OCs) were determined in liver and fat of seven species of seabirds (Alle alle, Uria lomvia, Cepphus grylle, Rissa tridactyla, Pagophila eburnea, Larus hyperboreus, and Fulmaris glacialis) collected in May/June 1998 from the Northwater Polynya in northern Baffin Bay. OC concentrations ranged over an order of magnitude between seabird species and OC groups, with PCBs having the highest concentrations followed by DDT, chlordane, HCH and ClBz. Positive relationships between delta15N (estimator of trophic level) and OC concentrations (lipid basis) were found for all OC groups, showing that trophic position and biomagnification significantly influence OC concentrations in Arctic seabirds. Concentrations of a number of OCs in particular species (e.g., HCH in P. eburnean) were lower than expected based on delta15N and was attributed to biotransformation. P. eburnea and F. glacialis, which scavenge, and R. tridactyla, which migrate from the south, were consistently above the delta15N-OC regression providing evidence that these variables can elevate OC concentrations. Stable isotope measurements in muscle may not be suitable for identifying past scavenging events by seabirds. OC relative proportions were related to trophic position and phylogeny, showing that OC biotransformation varies between seabird groups. Trophic level, migration, scavenging and biotransformation all play important roles in the OCs found in Arctic seabirds.
Black guillemot (Cepphus grylle) In: Poole A, Gill F (eds) The Birds of North America, No 675
- Rg Butler
- Buckley
Ecology of sea colony birds of the Barents Sea
- Belopol
The bird bazaars of Novaya Zemlya
- S M Uspenski
- SM Uspenski