Hallvard Strøm

Hallvard Strøm
Norwegian Polar Institute · Scientific Research Department

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161
Publications
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Publications

Publications (161)
Article
Density-dependent prey depletion around breeding colonies has long been considered an important factor controlling the population dynamics of colonial animals.1, 2, 3, 4 Ashmole proposed that as seabird colony size increases, intraspecific competition leads to declines in reproductive success, as breeding adults must spend more time and energy to f...
Article
Full-text available
Since the last Arctic Monitoring and Assessment Programme (AMAP) effort to review biological effects of mercury (Hg) on Arctic biota in 2011 and 2018, there has been a considerable number of new Arctic bird studies. This review article provides contemporary Hg exposure and potential health risk for 36 Arctic seabird and shorebird species, represent...
Article
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Genetic data are useful for detecting sudden population declines in species that are difficult to study in the field. Yet this indirect approach has its own drawbacks, including population structure, mutation patterns, and generation overlap. The ivory gull (Pagophila eburnea), a long-lived Arctic seabird, is currently suffering from rapid alterati...
Article
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Mercury contamination is a major threat to the global environment, and is still increasing in some regions despite international regulations. The methylated form of mercury is hazardous to biota, yet its sublethal effects are difficult to detect in wildlife. Body condition can vary in response to stressors, but previous studies have shown mixed eff...
Article
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In colonially breeding marine predators, individual movements and colonial segregation are influenced by seascape characteristics. Tidewater glacier fronts are important features of the Arctic seascape and are often described as foraging hotspots. Albeit their documented importance for wildlife, little is known about their structuring effect on Arc...
Article
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Tidewater glacier fronts can represent important foraging areas for Arctic predators. Their ecological importance is likely to change in a warmer Arctic. Their profitability and use by consumers are expected to vary in time, but the underlying mechanisms driving such variation remain poorly known. The subglacial plume, originating from meltwater di...
Data
Supplementary data to "Six pelagic seabird species of the North Atlantic engage in a fly-and-forage strategy during their migratory movements"
Article
Atlantic black-legged kittiwakes Rissa tridactyla tridactyla breeding in the Barents Sea have long been considered to winter in the North Atlantic region. Here, we present the first evidence of bi-directional and transpolar migrations of kittiwakes breeding in the south-eastern Barents Sea. Using geolocators, we revealed previously unknown migratio...
Article
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Many seabird species undergo extensive seasonal migrations, often across large marine ecosystems or between marine areas under different national jurisdictions. With the advances of electronic tracking, especially of the application of Global Location Sensors (GLS or geolocators), it is now possible to study the seasonal movements of seabirds and l...
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Each winter, the North Atlantic Ocean is the stage for numerous cyclones, the most severe ones leading to seabird mass-mortality events called ‘‘winter wrecks.’’ During these, thousands of emaciated seabird carcasses are washed ashore along European and North American coasts. Winter cyclones can therefore shape seabird population dynamics by affect...
Article
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Tracking data of marine predators are increasingly used in marine spatial management. We developed a spatial data set with estimates of the monthly distribution of 6 pelagic seabird species breeding in the Northeast Atlantic. The data set was based on year-round global location sensor (GLS) tracking data of 2356 adult seabirds from 2006-2019 from a...
Article
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Bird migration is commonly defined as a seasonal movement between breeding and non-breeding grounds. It generally involves relatively straight and directed large-scale movements, with a latitudinal change, and specific daily activity patterns comprising less or no foraging and more traveling time. Our main objective was to describe how this general...
Article
Migratory seabirds are exposed to various pollutants throughout their annual cycle. Among them, mercury (Hg) is of particular concern given large impacts on animals’ health. Recent studies suggest that winter is a critical period for seabirds when contamination by Hg can be higher than other times of year. However, individuals within and between sp...
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Understanding spatiotemporal variation in vital rates and population growth rates is a central aim of population ecology, and is critical to conservation of migratory species where different populations may spend the non-breeding season in sometimes widely separated areas. However, estimating those parameters and identifying the underlying drivers...
Article
Full-text available
The factors underlying gene flow and genomic population structure in vagile seabirds are notoriously difficult to understand due to their complex ecology with diverse dispersal barriers and extensive periods at sea. Yet, such understanding is vital for conservation management of seabirds that are globally declining at alarming rates. Here, we eluci...
Article
The Arctic is currently experiencing the most rapid warming on Earth. Arctic species communities are expected to be restructured with species adapted to warmer conditions spreading poleward and, if already present, becoming more abundant. We tested this prediction using long-term monitoring data (2009-2018) from nine of the most common seabird spec...
Article
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The conservation of migratory marine species, including pelagic seabirds, is challenging because their movements span vast distances frequently beyond national jurisdictions. Here, we aim to identify important aggregations of seabirds in the North Atlantic to inform ongoing regional conservation efforts. Using tracking, phenology, and population da...
Article
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Seabird-fishery interactions are a known and common phenomenon of conservation concern. Here, we highlight how light-level geolocators provide promising opportunities to study these interactions. By examining raw light data, it is possible to detect encounters with artificial lights at night, while conductivity data give insight on seabird behaviou...
Technical Report
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This report describes the methods used to obtain positions from geolocators in the SEATRACK project. Using a threshold method, we first identify twilight events from patterns in the recorded light-level data, from the time when light-levels cross a predefined threshold that separate day from night. From twilight events, two positions per day are ca...
Chapter
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Coastal waters are among the most productive regions in the Arctic (Leu et al. 2015; Smola et al. 2017; Ardyna et al. 2020). In these areas, a strong coupling exists between the sea and the land, and the shallow depths create a tight pelagic-benthic coupling (McGovern et al. 2020). These regions are also critical breeding and foraging grounds for m...
Article
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https://arctox.cnrs.fr/en/home/ Mercury (Hg) is a natural trace element found in high concentrations in top predators, including Arctic seabirds. Most current knowledge about Hg concentrations in Arctic seabirds relates to exposure during the summer breeding period when researchers can easily access seabirds at colonies. However, the few studies f...
Article
Full-text available
A wide range of species, including marine mammals, seabirds, birds of prey, fish and bivalves, were investigated for potential population health risks resulting from contemporary (post 2000) mercury (Hg) exposure, using novel risk thresholds based on literature and de novo contamination data. The main geographic focus is on the Baltic Sea, while da...
Article
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We explored the implications of reaching the Paris Agreement Objective of limiting global warming to <2°C for the future winter distribution of the North Atlantic seabird community. We predicted and quantified current and future winter habitats of five North Atlantic Ocean seabird species (Alle alle, Fratercula arctica, Uria aalge, Uria lomvia and...
Article
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The ivory gull Pagophila eburnea is a high-Arctic seabird associated with sea ice throughout the year. It breeds at high latitudes, mostly in the Atlantic sector of the Arctic. It is rare (<11500 breeding pairs globally) and remains one of the most poorly known seabirds in the world. Although Svalbard (Norway) supports breeding populations of inter...
Article
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Sharing the same wintering grounds by avian populations breeding in various areas may synchronize fluctuations in vital rates, which could increase the risk of extinction. Here, by combining multi-colony tracking with long-term capture-recapture data, we studied the winter distribution and annual survival of the most numerous Arctic seabird, the li...
Article
Full-text available
The factors underlying gene flow and genomic population structure in vagile seabirds are notoriously difficult to understand due to their complex ecology with diverse dispersal barriers and extensive periods at sea. Yet, such understanding is vital for conservation management of seabirds that are globally declining at alarming rates. Here, we eluci...
Article
Full-text available
Aim In migratory species, individuals often use fixed and individual‐specific migration strategies, which we term individual migration strategy fidelity (IMSF). Our goal was to test if guillemots have flexible or fixed individual migration strategies (i.e. IMSF), if this behaviour is consistent across large parts of the genus’ range and if they wer...
Article
Despite the limited direct anthropogenic mercury (Hg) inputs in the circumpolar Arctic, elevated concentrations of methylmercury (MeHg) are accumulated in Arctic marine biota. However, the MeHg production and bioaccumulation pathways in these ecosystems have not been completely unraveled. We measured Hg concentrations and stable isotope ratios of H...
Article
Full-text available
The black-legged kittiwake (Rissa tridactyla, hereafter kittiwake) is a small pelagic seabird and is the most numerous gull species in the world. It has a circumpolar distribution, and breeds in the arctic and boreal zones of the Northern Hemisphere. It’s breeding distribution is widespread and ranges across the North Atlantic from the west coast t...
Article
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Identifying drivers of population trends in migratory species is difficult, as they can face many stressors while moving through different areas and environments during the annual cycle. To understand the potential of migrants to adjust to perturbations, it is critical to study the connection of different areas used by different populations during...
Chapter
Full-text available
- The breeding population of ivory gull in the Arctic is declining in parts of its range. Especially dramatic is the situation in Canada, where 70% of the population has been lost since the 1980s. - Satellite tracking of ivory gulls breeding in Canada, Greenland, Svalbard and Russia show that southern Davis Strait and northern Labrador Sea is an in...
Technical Report
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Sammendrag I dette studiet har vi sett på sammenhengen mellom oppvarmingen av Svalbard («Atlantifiseringen») og effekten dette har på naeringsvalg og ungeproduksjon hos to av de mest tallrike sjøfuglartene på øygruppen, nemlig alkekonge og krykkje. Vi fant en sammenheng mellom økende sjøtemperatur (og redusert sjøisutbredelse) i Vest-Spitsbergenst...
Article
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Climate models predict that by 2050 the Arctic Ocean will be sea ice free each summer. Removing this barrier between the Atlantic and the Pacific will modify a wide range of ecological processes, including bird migration. Using published information, we identified 29 arctic-breeding seabird species, which currently migrate in the North Atlantic and...
Article
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Background: Natural environments are dynamic systems with conditions varying across years. Higher trophic level consumers may respond to changes in the distribution and quality of available prey by moving to locate new resources or by switching diets. In order to persist, sympatric species with similar ecological niches may show contrasting foragi...
Article
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A global analysis recently showed that seabird breeding phenology (as the timing of egg-laying and hatching) does not, on average, respond to temperature changes or advance with time (Keogan et al. 2018 Nat. Clim. Change 8, 313–318). This group, the most threatened of all birds, is therefore prone to spatio-temporal mismatches with their food resou...
Article
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The timing of annual events such as reproduction is a critical component of how free‐living organisms respond to ongoing climate change. This may be especially true in the Arctic, which is disproportionally impacted by climate warming. Here, we show that Arctic seabirds responded to climate change by moving the start of their reproduction earlier,...
Technical Report
Full-text available
By positioning a large number of seabirds throughout the year using miniaturized geoloca-tors (GLS), the SEATRACK program provides a unique dataset on the seasonal distribution of seabirds from colonies in Russia (Barents and White Seas), Norway (incl. Svalbard and Jan Mayen), Iceland, Faroe Islands and the British Isles. Combining this extensive d...
Article
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Research in remote locations is more expensive than similar activities at sites with easier access, but these costs have rarely been compared. Using examples from seabird research, we show that conducting research in the Arctic is typically eight times more expensive than pursuing similar studies at a southern location. The differences in costs are...
Technical Report
Full-text available
I Tildelingsbrev 2016 fra Klima- og miljødepartementet (KLD) fikk Norsk Polarinstitutt følgende oppdrag med frist 1. april 2017: «Etter bestilling fra Sysselmannen levere kunnskapsgrunnlag for forvaltningsplaner for nasjonalparkene på Sentral-Spitsbergen (Nordre Isfjorden, Sassen-Bünsow Land, Indre Wijdefjorden og Nordenskiöld Land), samt Festning...
Article
Many pelagic seabirds moult their feathers while at sea, which is an energetically costly behaviour. Mortality rates during moult can be high, so spatial and trophic ecology during this critical period is important for understanding demographic patterns. Unfortunately, individual foraging behaviours specifically linked to at-sea moult are commonly...
Preprint
Full-text available
Seabirds provide ecosystem services, notably as human food in many Arctic regions, major tourist attractions, as well as being an important link to the Arctic food web and returning nutrients from the oceans to coastal areas. Changes in seabird populations and diversity will affect regional sustainability for Arctic communities and ecosystems. The...
Preprint
Full-text available
Seabirds provide ecosystem services, notably as human food in many Arctic regions, major tourist attractions, as well as being an important link to the Arctic food web and returning nutrients from the oceans to coastal areas. Changes in seabird populations and diversity will affect regional sustainability for Arctic communities and ecosystems. The...
Article
Full-text available
Background: Foraging strategies of seabird species often vary considerably between and within individuals. This variability is influenced by a multitude of factors including age, sex, stage of annual life cycle, reproductive status, individual specialization and environmental conditions. Results: Using GPS-loggers, we investigated factors affecting...
Article
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In the original publication of the article, the linear discriminate Eq. (1) was mistyped. We provide below the correct equation to use to discriminate male and female in Ivory Gull Pagophila eburnea (Phipps, 1774).
Article
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Here, we model current and future distribution of a foraging Arctic endemic species, the little auk (Alle alle), a small zooplanktivorous Arctic seabird. We characterized environmental conditions [sea depth, sea surface temperature (SST), marginal sea ice zone (MIZ)] at foraging positions of GPS-tracked individuals from three breeding colonies in S...
Article
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Carry-over effects, whereby events in one season have consequences in subsequent seasons, have important demographic implications. Although most studies examine carry-over effects across 2 seasons in single populations, the effects may persist beyond the following season and vary across a species’ range. To assess potential carry-over effects acros...
Article
Conducting multi-species studies is important when assessing current ecosystem state and predicting climate change impacts, as altered biological interactions can affect the wider ecosystem. The marginal-ice zone (MIZ, transition zone between the sea-ice edge and areas with complete sea-ice coverage) is an important foraging area for Arctic marine...
Article
The Arctic is warming more rapidly than other region on the planet, and the northern Barents Sea, including the Svalbard Archipelago, is experiencing the fastest temperature increases within the circumpolar Arctic, along with the highest rate of sea ice loss. These physical changes are affecting a broad array of resident Arctic organisms as well as...
Article
Full-text available
The ivory gull (Pagophila eburnea) is a high-Arctic species considered endangered in most parts of its breeding range. Ivory gulls must cope with not only the reduction in sea ice cover triggered by climate change but also increasing contaminant loads due to changes in global contaminant pathways and the release of previously stored pollutants from...
Article
Full-text available
During its population recovery in the North Atlantic in the early 1900s, the northern gannet (Morus bassanus) established its first colony in Norway at Runde in 1946. Since the 1960s, gannets have established (and later abandoned) several small colonies in the north of the country. These colonies have been regularly monitored, and in 2015–16 ca. 33...
Article
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Background The use of light level loggers (geolocators) to understand movements and distributions in terrestrial and marine vertebrates, particularly during the non-breeding period, has increased dramatically in recent years. However, inferring positions from light data is not straightforward, often relies on assumptions that are difficult to test,...
Article
The ongoing decline of sea ice threatens many Arctic taxa, including the ivory gull. Understanding how ice-edges and ice concentrations influence the distribution of the endangered ivory gulls is a prerequisite to the implementation of adequate conservation strategies. From 2007 to 2013, we used satellite transmitters to monitor the movements of 10...
Article
Full-text available
The Arctic is a highly seasonal environment with a harsh climate and extensive sea ice cover during the winter. Consequently, most Arctic-breeding seabirds migrate south to reach more benign environmental conditions. Knowledge of migration routes and wintering areas is integral for successful conservation of these globally important breeding popula...
Article
Full-text available
The ivory gull is a high-Arctic species considered endangered in most parts of its breeding range. Ivory gulls must cope with both the reduction of sea ice cover triggered by climate change and increasing contaminant loads due to changes in global contaminant pathways. The objective of this study was to assess the concentration of 14 essential and...