• Analysing diet of small herbivores : the efficiency of DNA barcoding coupled with high-throughput pyrosequencing for deciphering the composition of complex plant mixtures 

      Valentini, Alice; Soininen, Eeva Marjatta; Coissac, Eric; Ims, Rolf Anker; Miquel, Christian; Yoccoz, Nigel Gilles; Gielly, Ludovic; Brochmann, Christian; Brysting, Anne K.; Sønstebø, Jørn H.; Taberlet, Pierre (Journal article; Tidsskriftartikkel; Peer reviewed, 2009-08-20)
      Background: In order to understand the role of herbivores in trophic webs, it is essential to know what they feed on. Diet analysis is, however, a challenge in many small herbivores with a secretive life style. In this paper, we compare novel (high-throughput pyrosequencing) DNA barcoding technology for plant mixture with traditional microhistological method. We analysed stomach contents of two ...
    • Analyzing the proximity to cover in a landscape of fear: A new approach applied to fine-scale habitat use by rabbits facing feral cat predation on Kerguelen archipelago 

      Blanchard, Pierrick; Lauzeral, Christine; Chamaille-Jammes, Simon; Yoccoz, Nigel Gilles; Pontier, Dominique (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-03-07)
      Although proximity to cover has been routinely considered as an explanatory variable in studies investigating prey behavioral adjustments to predation pressure, the way it shapes risk perception still remains equivocal. This paradox arises from both the ambivalent nature of cover as potentially both obstructive and protective, making its impact on risk perception complex and context-dependent, and ...
    • Assessing dental wear in reindeer using geometric morphometrical methods. 

      Rødven, Rolf; Wiig, Øystein; Yoccoz, Nigel Gilles; Ims, Rolf Anker (Journal article; Peer reviewed; Tidsskriftartikkel, 2006)
    • Assessing the effect of predator control on an endangered goose population subjected to predator-mediated food web dynamics 

      Marolla, Filippo; Aarvak, Tomas; Øien, Ingar Jostein; Mellard, Jarad Pope; Henden, John-André; Hamel, Sandra; Stien, Audun; Tveraa, Torkild; Yoccoz, Nigel Gilles; Ims, Rolf Anker (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-01-29)
      <ol> <li>Assessing the effectiveness of conservation actions to halt population declines is challenging when confounded by other factors. We assessed whether culling of red fox, a predator currently increasing in number in the sub‐Arctic, contributed to recent recovery of the critically endangered Fennoscandian population of Lesser White‐fronted Goose <i>Anser erythropus</i>, while controlling for ...
    • Biodiversity may wax or wane depending on metrics or taxa 

      Yoccoz, Nigel Gilles; Ellingsen, Kari Elsa; Tveraa, Torkild (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-02-20)
      <i>Introduction</i>: Biodiversity changes have proven surprisingly complex to estimate and understand. While there are negative trends at a global scale such as the substantial losses of vertebrate species (1), changes at local scales may show large variation, with no clear overall trend (2, 3). Because assessing and improving the status of biodiversity are at the core of international agreements ...
    • Circumpolar dynamics of a marine top-predator track ocean warming rates. 

      Descamps, Sebastian; Anker-Nilssen, Tycho; Barrett, Robert T.; Irons, D.; Merkel, Flemming; Robertson, Gregory J.; Yoccoz, Nigel Gilles; Mallory, Mark L.; Montevecchi, William A.; Boertmann, D.; Artukhin, Yuri; Christensen-Dalsgaard, Signe; Erikstad, Kjell E.; Gilchrist, H. Grant; Labansen, Aili; Lorentsen, Svein Håkon; Mosbech, Anders; Olsen, Bergur; Petersen, Aevar; Rail, Jean-Francois; Renner, Heather M.; Strøm, H.; Systad, Geir Helge; Wilhelm, Sabina I.; Zelenskaya, Larisa (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-04-07)
      Global warming is a nonlinear process, and temperature may increase in a stepwise manner. Periods of abrupt warming can trigger persistent changes in the state of ecosystems, also called regime shifts. The responses of organisms to abrupt warming and associated regime shifts can be unlike responses to periods of slow or moderate change. Understanding of nonlinearity in the biological responses to ...
    • Community-wide mesocarnivore response to partial ungulate migration 

      Henden, John-André; Stien, Audun; Bårdsen, Bård-Jørgen; Yoccoz, Nigel Gilles; Ims, Rolf Anker (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
    • Comparison of budburst phenology trends and precision among participants in a citizen science program 

      Bison, M; Yoccoz, Nigel Gilles; Carlson, BZ; Delestrade, Anne (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-01)
      Quantifying shifts in plant phenology in response to climate change represents an ongoing challenge, particularly in mountain ecosystems. Because climate change and phenological responses vary in space and time, we need long-term observations collected at a broad spatial scale. While data collection by volunteers is a promising approach to achieve this goal, one major concern with citizen science ...
    • Deepened winter snow significantly influences the availability and forms of nitrogen taken up by plants in High Arctic tundra 

      Mörsdorf, Martin Alfons; Baggesen, Nanna Schrøder; Yoccoz, Nigel Gilles; Michelsen, Anders; Elberling, Bo; Ambus, Per Lennart; Cooper, Elisabeth J. (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-05-13)
      Climate change may alter nutrient cycling in Arctic soils and plants. Deeper snow during winter, as well as summer warming, could increase soil temperatures and thereby the availability of otherwise limiting nutrients such as nitrogen (N). We used fences to manipulate snow depths in Svalbard for 9 consecutive years, resulting in three snow regimes: 1) <i>Ambient</i> with a maximum snow depth of ...
    • Definition of sampling units begets conclusions in ecology: The case of habitats for plant communities 

      Mörsdorf, Martin Alfons; Ravolainen, Virve; Støvern, Einar; Yoccoz, Nigel Gilles; Jonsdottir, Ingibjørg; Bråthen, Kari Anne (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-03-05)
      In ecology, expert knowledge on habitat characteristics is often used to define sampling units such as study sites. Ecologists are especially prone to such approaches when prior sampling frames are not accessible. Here we ask to what extent can different approaches to the definition of sampling units influence the conclusions that are drawn from an ecological study? We do this by comparing a ...
    • Demersal fish assemblages in the boreo-Arctic shelf waters around Svalbard during the warm period 2007–2014 

      Bergstad, Odd Aksel; Johannesen, Edda; Høines, Åge Sigurd; Ellingsen, Kari Elsa; Lien, Vidar Surén; Byrkjedal, Ingvar; Yoccoz, Nigel Gilles; Tveraa, Torkild; Wienerroither, Rupert; Langhelle, Gunnar; Wenneck, Thomas de Lange (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-07-17)
      The temporal and spatial resilience of abundance patterns of assemblages of organisms inhabiting transition zones between Arctic and boreal regions is an issue of concern in relation to climate change. The recognition that baseline information spanning such transition zones is required to facilitate future monitoring and assessments of temporal dynamics provided the motivation for the present study. ...
    • Demographic effects of extreme weather events: snow storms, breeding success, and population growth rate in a long-lived Antarctic seabird 

      Descamps, Sebastian; Tarroux, Arnaud; Varpe, Øystein; Yoccoz, Nigel Gilles; Tveraa, Torkild; Lorentsen, Svein-Håkon (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-12-23)
      Weather extremes are one important element of ongoing climate change, but their impacts are poorly understood because they are, by definition, rare events. If the frequency and severity of extreme weather events increase, there is an urgent need to understand and predict the ecological consequences of such events. In this study, we aimed to quantify the effects of snow storms on nest survival ...
    • Earlier colony arrival but no trend in hatching timing in two congeneric seabirds (Uria spp.) across the North Atlantic 

      Merkel, Benjamin; Descamps, Sebastien; Yoccoz, Nigel Gilles; Danielsen, Jóhannis; Daunt, Francis; Erikstad, Kjell E; Ezhov, Aleksey V.; Grémillet, David; Gavrilo, Maria; Lorentsen, Svein Håkon; Reiertsen, Tone Kristin; Steen, Harald; Systad, Geir Helge Rødli; Þórarinsson, Þorkell Lindberg; Wanless, Sarah; Strøm, Hallvard (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-10-23)
      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 <i>et al.</i> 2018 <i>Nat. Clim. Change</i> <b>8</b>, 313–318). This group, the most threatened of all birds, is therefore prone to spatio-temporal mismatches with their food resources. Yet, other aspects of ...
    • Ecosystem drivers of an Arctic fox population at the western fringe of the Eurasian Arctic 

      Ims, Rolf Anker; Killengreen, Siw Turid; Ehrich, Dorothee; Flagstad, Øystein; Hamel, Sandra; Henden, John-André; Jensvoll, Ingrid; Yoccoz, Nigel Gilles (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-08-16)
      The distribution of traditional breeding dens on the Varanger Peninsula (70–71°N) in northernmost Fennoscandia indicates that this area once harboured a large Arctic fox population. Early 20th century naturalists regarded the coastal tundra of the Fennoscandian Low Arctic to be a stronghold for the species. At the start of our research in 2004, however, the local Arctic fox population was ...
    • Effects of changing permafrost and snow conditions on tundra wildlife: critical places and times 

      Berteaux, Dominique; Gauthier, Gilles; Dominé, Florent; Ims, Rolf Anker; Lamoureux, Scott F; Lévesque, Esther; Yoccoz, Nigel Gilles (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-12-21)
      The change of water phase around 0 °C has considerable impacts on wildlife ecology because liquid and solid water strongly differ in their insulating capability, mechanical resistance, and light reflectance. Freeze and melt events thus have strong ecological relevance, particularly in the Arctic where snow and ice are omnipresent and their conditions are changing due to climate warming. We first ...
    • Expected Climate Change in the High Arctic—Good or Bad for Arctic Charr? 

      Svenning, Martin; Bjørvik, Eigil T.; Godiksen, Jane Aanestad; Hammar, Johan; Kohler, Jack; Borgstrøm, Reidar; Yoccoz, Nigel Gilles (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-12-23)
      Lakes in the High Arctic are characterized by their low water temperature, long-term ice cover, low levels of nutrients, and low biodiversity. These conditions mean that minor climatic changes may be of great importance to Arctic freshwater organisms, including fish, by influencing vital life history parameters such as individual growth rates. In this study, Arctic charr sampled from two Svalbard ...
    • Feeding at the front line: Interannual variation in the use of glacier fronts by foraging black-legged kittiwakes 

      Bertrand, Philip; Strøm, Hallvard; Bêty, Joël; Steen, Harald; Kohler, Jack; Vihtakari, Mikko; Van Pelt, Ward; Yoccoz, Nigel Gilles; Hop, Haakon; Harris, Stephanie M.; Patrick, Samantha C.; Assmy, Philipp; Wold, Anette; Duarte, Pedro; Moholdt, Geir; Descamps, Sébastien (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-10-28)
      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 discharge, is responsible for the entrainment and ...
    • Fjellrev i Finnmark : Årsrapport 2013 

      Ims, Rolf Anker; Killengreen, Siw Turid; Jensvoll, Ingrid; Yoccoz, Nigel Gilles; Henden, John-André; Arriola, Aline; Mørk, Torill; Sarre, Arne Petter; Ørjebu, Alfred; Kristoffersen, Bjørn Hugo; Bye, Åshild (Research report; Forskningsrapport, 2013)
      Prosjekt Fjellrev i Finnmark har pågått siden 2004. Prosjektet har fra starten av hatt to målsetninger: Å gjøre grunnleggende forskning på økosystembetingelser som begrenser fjellrevenbestandens nåværende utbredelse og bestandsvekst i Øst-Finnmark spesielt, og i sub- og lav-Arktis generelt, med fokus på to hypoteser; a) mer uregelmessige og dempede smågnagersykler og b) øket konkurranse med ...
    • Fjellrev i Finnmark : årsrapport for 2008 

      Ims, Rolf Anker; Knutsen, Kjartan; Mørk, T.; Killengreen, Siw Turid; Yoccoz, Nigel Gilles; Sarre, Arne Petter; Ørjebu, Alfred; Henden, John-André (Research report; Forskningsrapport, 2008)
    • Fjellrev i Finnmark : forskning og tiltak 2004 

      Langeland, K.; Ims, Rolf Anker; Killengreen, Siw Turid; Skog, E.; Scheie, J.O.; Yoccoz, Nigel Gilles; Bråthen, Kari Anne (Research report; Forskningsrapport, 2004)