Papers by Sveinn Are Hanssen
Behavioral Ecology
Life history theory states that the resources invested in current reproduction must be traded off... more Life history theory states that the resources invested in current reproduction must be traded off against resources needed for survival and future reproduction. Long-lived organisms have a higher residual reproductive value and are therefore expected to be sensitive to reproductive investments that may reduce survival and future reproduction. Individuals within a population may vary in phenotypic quality, experience, access to resources etc. This may affect their optimal reproductive investment level. In this study we manipulated reproductive costs by shortening and extending the incubation period in common eiders Somateria mollissima without altering clutch size. Females whose incubation time was prolonged experimentally, suffered higher mass loss and increased clutch loss/nest desertion. These females were also more prone to abandon their brood after hatching. Both clutch loss and brood abandonment decreased with clutch size in all treatment categories, indicating higher phenotypi...
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Science of The Total Environment
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PLOS ONE, 2015
<p>Hatching body conditions (hatching weight controlled for egg size) of B-chicks in great ... more <p>Hatching body conditions (hatching weight controlled for egg size) of B-chicks in great skua broods in relation to the mothers’ plasma concentrations of ∑OC and ∑BDE at Bjørnøya in 2010.</p
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Concentrations of POPs in Great skua eggs from Shetland are among the highest in North Atlantic s... more Concentrations of POPs in Great skua eggs from Shetland are among the highest in North Atlantic seabirds, with up to 11,600 µg/kg (ww) DDE and up to 17,900 µg/kg ww SumPCB. Concentrations of legacy POPs were significantly lower in 2008 than 1980. Decreases were greatest for least persistent compounds. Median SumPBDEs increased from 99 µg/kg ww in 1980 to 173 µg/kg ww in 2008. There were changes in Great skua breeding season diet, with more adult Herring and Mackerel and less Sandeel. These changes increase exposure to POPs, since Herring and Mackerel accumulate more POPs than Sandeels. In both years, eggs with higher d15N had higher POP concentrations. In 1980, birds feeding more on demersal discard fish from trawl fisheries and less on Sandeels, had higher POP levels in eggs. In 2008, individuals feeding more on Herring and Mackerel, and less on discards, had higher POP levels in eggs.
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Science of The Total Environment, 2022
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Marine Ecology Progress Series, 2021
Migratory seabirds are exposed to various pollutants throughout their annual cycle. Among them, m... more Migratory seabirds are exposed to various pollutants throughout their annual cycle. Among them, mercury (Hg) is of particular concern given its large impact on animal health. Recent studies suggest that winter is a critical period for seabirds when contamination by Hg can be higher than at other times of year. However, individuals within and between species can have different migration strategies and winter distributions that could affect their exposure. Here, we combined multi-year individual tracking data and Hg measurements from 6 Arctic seabird species. We investigated whether inter-annual variations in individual winter contamination with Hg was related to seabird fidelity to a wintering site over years. First, our results show that Hg concentrations above the toxicity threshold (i.e. 5 µg g-1dry weight in feathers) were observed in variable proportions according to species (from 2% of northern fulmars to 37% of Brünnich’s guillemots). Second, individuals with high fidelity to ...
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Environmental Pollution, 2019
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Canadian Journal of Zoology, 2015
Molluscivore birds that forage on abundant but low-quality food have to ingest large quantities o... more Molluscivore birds that forage on abundant but low-quality food have to ingest large quantities of food to achieve energy balance. Such a strategy is often associated with important digestive constraints limiting predator’s ingestion. Thus, these predators may use prey selection to ingest better-quality individuals among a generally low-quality prey population. Using captive Common Eiders (Somateria mollissima (L., 1758)) diving in a constant environment, we were able to examine their preferences for blue mussels (Mytilus edulis L., 1758) of varying qualities (different sizes or provenances). In addition, we studied the consequences prey selection had on Eiders’ energy intake rates and ingestion of flesh and shell material. Eiders selected 10–20 mm mussels and were able to discriminate and to select cultivated mussels from intertidal mussels. Prey selection allowed, in certain conditions of prey-size abundance, higher flesh and energy intake rates without increasing the ingestion of...
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Quantifying withinand between-individual variation in animal migration strategies is a first step... more Quantifying withinand between-individual variation in animal migration strategies is a first step towards our understanding of the ability of migrants to adjust to changes in the en vironment. We studied consistency (or, conversely, flexibility) in movement patterns at large (>1000 km) to meso-scales (100−1000 km) during the non-breeding season of the long-tailed skua Stercorarius longicaudus, a long-distance migratory Arctic seabird, using light-based geolocation. We obtained 97 annual tracks of 38 individuals and quantified similarity between routes. Overall, tracks of the same individual were generally within about 200 to 300 km of their previous year’s route, and more similar than tracks of different individuals. Some flexibility was observed during migration, but individuals were faithful to their staging areas in the North Atlantic and in the Benguela Current off Namibia and South Africa. Over the course of the winter, an increasing number of individuals started to deviate ...
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Hanssen, S.A, & Strand Bakke, K.S. 2021 Overvåking av hekkende horndykker i Troms 2021. NINA Rapp... more Hanssen, S.A, & Strand Bakke, K.S. 2021 Overvåking av hekkende horndykker i Troms 2021. NINA Rapport 2048. Norsk institutt for naturforskning. NINA har overvåket antallet hekkende/territorielle par horndykker Podiceps auritus på 52 lokaliteter fordelt på åtte kommuner i Troms. Siden oppstarten i 2001 har hekkebestanden blitt redusert med rundt 90 % og den sterkeste nedgangen skjedde fra 2009 til 2010. Etter 2010 stoppet denne tilbakegangen noe opp, og tallet er nå relativt stabilt på et lavt nivå. I 2021 ble 51 av 52 opprinnelige lokaliteter fordelt på åtte kommuner overvåket. Ett av vannene i Bardu kommune ble ikke overvåket. I tillegg overvåkes én ny lokalitet (fra 2019) på Hinnøya, Sør-Troms. Dermed ble 52 lokaliteter fordelt på ni kommuner overvåket i 2021 i Troms. Det var et relativt gjennomsnittlig hekkeår for arten med 27 hekkende eller territorielle par innenfor de 51 opprinnelige overvåkingslokalitetene og tre territorielle par horndykkere på lokaliteten på Hinnøya. Horndyk...
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Statens kartverk har drevet geodetisk observatorium i Ny-Ålesund på Svalbard siden 1994. Et nytt ... more Statens kartverk har drevet geodetisk observatorium i Ny-Ålesund på Svalbard siden 1994. Et nytt og oppdatert geodesianlegg bygges ved Brandalslaguna, inkludert bygging av ny vei mellom det nye anlegget og flyplassen i Ny-Ålesund. Veien og geodesianlegget etableres i et område som er verdifullt for fuglelivet. I tillatelsen fra Sysselmannen på Svalbard er det satt vilkår om overvåkningsprogram som følger effekter av inngrepet på hekkende tyvjo og vadefugl, samt fugl i Brandalslaguna og vannene ved Knudsenheia. Norsk institutt for naturforskning (NINA) har designet overvåkningsprogrammet etter oppdrag fra Statens kartverk for å innfri kravene fra Sysselmannen på Svalbard. Overvåkningsprogrammet inkluderer kontroll-områder for å se resultatene i lys av naturlig variasjon og effekten av tiltaket. Programmet er delt inn i ulike faser avhengig av om dataene registreres før anleggstiden, i anleggsfasen eller i driftsfasen. Hovedmålet med overvåkningen i 2013 var å samle inn data for ‘før-...
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12, 2020
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44, 2018
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33, Dec 15, 2020
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46, 2019
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18, 2020
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Data were collected annually on Prins Heinrich Island on the west coast of Svalbard from 1999 to ... more Data were collected annually on Prins Heinrich Island on the west coast of Svalbard from 1999 to 2013. This txt file is the headed format directly usable in E-surge program (see E-surge manual and Appendix S2). Each line represents an individual capture history with 1 when it has been seen and 0 with it has not been seen. The 15 first columns are each year (e.g. A1999 for year 1999). The "S" column is the sample size (i.e. associated number of individuals)
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Papers by Sveinn Are Hanssen