• Ambient temperature effects on stress-induced hyperthermia in Svalbard ptarmigan 

      Nord, Andreas; Folkow, Lars (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-06-20)
      Stress-induced hyperthermia (SIH) is commonly observed during handling in homeotherms. However, in birds, handling in cold environments typically elicits hypothermia. It is unclear whether this indicates that SIH is differently regulated in this taxon or if it is due to size, because body temperature changes during handling in low temperatures have only been measured in small birds <0.03 kg (that ...
    • Does posture explain the kinematic differences in a grounded running gait between male and female Svalbard rock ptarmigan (Lagopus muta hyperborea) moving on snow? 

      Marmol-Guijarro, Andres; Nudds, Robert; Folkow, Lars; Lees, John; Codd, Jonathan (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-05-05)
      The majority of locomotor research is conducted on treadmills and few studies attempt to understand the differences between this and animals moving in the wild. For example, animals may adjust their gait kinematics or limb posture, to a more compliant limb, to increase stability of locomotion to prevent limb failure or falling on different substrates. Here, using video recordings, we compared locomotor ...
    • Elevated antioxidant defence in the brain of deep-diving pinnipeds 

      Martens, Gerrit A.; Folkow, Lars; Burmester, Thorsten; Geßner, Cornelia (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-12-16)
      While foraging, marine mammals undertake repetitive diving bouts. When the animal surfaces, reperfusion makes oxygen readily available for the electron transport chain, which leads to increased production of reactive oxygen species and risk of oxidative damage. In blood and several tissues, such as heart, lung, muscle and kidney, marine mammals generally exhibit an elevated antioxidant defence. ...
    • Energy efficiency of respiration in mature and newborn reindeer 

      Solberg, Simon Birger Byremo; Kjelstrup, Signe; Magnanelli, Elisa; Kizilova, Nataliya; Barroso, Iratxe Lorea Casado; Acquarone, Mario; Folkow, Lars (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-25)
      Reindeer (<i>Rangifer tarandus</i>) have evolved elaborate nasal turbinate structures that are perfused via a complex vascular network. These are subject to thermoregulatory control, shifting between heat conservation and dissipation, according to the animal’s needs. The three-dimensional design of the turbinate structures is essential in the sense that they determine the efficiency with which heat ...
    • Environmental drivers of population-level variation in the migratory and diving ontogeny of an Arctic top predator 

      Grecian, W. James; Stenson, Garry B.; Biuw, Martin; Boehme, Lars; Folkow, Lars; Goulet, Pierre J.; Jonsen, Ian D.; Malde, Aleksander; Nordøy, Erling Sverre; Rosing-Asvid, Aqqalu; Smout, Sophie (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-03-02)
      The development of migratory strategies that enable juveniles to survive to sexual maturity is critical for species that exploit seasonal niches. For animals that forage via breath-hold diving, this requires a combination of both physiological and foraging skill development. Here, we assess how migratory and dive behaviour develop over the first year of life for a migratory Arctic top predator, the ...
    • Examining the accuracy of trackways for predicting gait selection and speed of locomotion 

      Marmol-Guijarro, Andres; Nudds, Robert; Folkow, Lars; Codd, Jonathan (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-27)
      Using Froude numbers (<i>Fr</i>) and relative stride length (stride length: hip height), trackways have been widely used to determine the speed and gait of an animal. This approach, however, is limited by the ability to estimate hip height accurately and by the lack of information related to the substrate properties when the tracks were made, in particular for extinct fauna. By studying the Svalbard ...
    • The eyes of the deep diving hooded seal (Cystophora cristata) enhance sensitivity to ultraviolet light 

      Hogg, Chris; Neveu, Magella; Folkow, Lars; Stokkan, Karl-Arne; Kam, Jaimie Hoh; Douglas, Ron H; Jeffery, Glen (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-05-11)
      The mammalian visual range is approximately 400–700 nm, although recent evidence suggests varying ultraviolet (UV) extensions in diverse terrestrial species. UV sensitivity may have advantages in the dim, blue light shifted environment experienced by submerged marine mammals. It may also be advantageous when seals are on land as UV is reflected by snow and ice but absorbed by fur, enhancing visual ...
    • The influence of snow properties on speed and gait choice in the Svalbard rock ptarmigan (Lagopus muta hyperborea) 

      Marmol-Guijarro, Andres C; Nudds, R; Folkow, Lars; Sellers, William R.; Falkingham, P; Codd, J (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-08-14)
      Substrate supportiveness is linked to the metabolic cost of locomotion, as it influences the depth to which the foot of a moving animal will sink. As track depth increases, animals typically reduce their speed to minimize any potential energetic imbalance. Here, we examine how self-selected speed in the Svalbard rock ptarmigan is affected by snow supportiveness and subsequent footprint depth measured ...
    • A life after Research? First Release of Harp Seals (Phoca groenlandica) after Temporary Captivity for Scientific Purposes 

      Blanchet, Marie-Anne; Acquarone, Mario; Biuw, Martin; Larsen, Roger B.; Nordøy, Erling Sverre; Folkow, Lars (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-08)
      Three wild-caught female harp seals (Pagophilus groenlandicus) from the Greenland Sea stock were brought into temporary captivity in connection with a controlled validation study on energetics. The two pups and one adult were kept in two indoor and outdoor experimental facilities approved by the Norwegian Animal Research Authority. They were trained daily using operant conditioning to participate ...
    • Marine mammal hotspots across the circumpolar Arctic 

      Hamilton, Charmain D.; Lydersen, Christian; Aars, Jon; Acquarone, Mario; Atwood, Todd; Baylis, Alastair; Biuw, Martin; Boltunov, Andrei N.; Born, Erik W.; Boveng, Peter; Brown, Tanya M.; Cameron, Michael; Citta, John; Crawford, Justin; Dietz, Rune; Elias, Jim; Ferguson, Steven H.; Fisk, Aaron; Folkow, Lars; Frost, Kathryn J.; Glazov, Dmitri M.; Granquist, Sandra M.; Gryba, Rowenna; Harwood, Lois; Haug, Tore; Heide-Jørgensen, Mads Peter; Hussey, Nigel E.; Kalinek, Jimmy; Laidre, Kristin L.; Litovka, Dennis I.; London, Josh M.; Loseto, Lisa L.; MacPhee, Shannon; Marcoux, Marianne; Matthews, Cory J. D.; Nilssen, Kjell Tormod; Nordøy, Erling Sverre; O’Corry-Crowe, Greg; Øien, Nils Inge; Olsen, Morten Tange; Quakenbush, Lori; Rosing-Asvid, Aqqalu; Semenova, Varvara; Shelden, Kim E. W.; Shpak, Olga V.; Stenson, Garry; Storrie, Luke; Sveegaard, Signe; Teilmann, Jonas; Ugarte, Fernando; Von Duyke, Andrew L.; Watt, Cortney; Wiig, Øystein; Wilson, Ryan R.; Yurkowski, David J.; Kovacs, Kit M. (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-05-11)
      Aim: Identify hotspots and areas of high species richness for Arctic marine mammals.<p><p> Location: Circumpolar Arctic. <p>Methods: A total of 2115 biologging devices were deployed on marine mammals from 13 species in the Arctic from 2005 to 2019. Getis-Ord Gi* hotspots were calculated based on the number of individuals in grid cells for each species and for phyloge-netic groups (nine pinnipeds, ...
    • Marine mammal hotspots in the Greenland and Barents Seas 

      Hamilton, Charmain Danielle; Lydersen, Christian; Aars, Jon; Biuw, Martin; Boltunov, Andrei; Born, Erik W.; Dietz, Rune; Folkow, Lars; Glazov, Dmitry M.; Haug, Tore; Heide-Jørgensen, Mads-Peter; Kettemer, Lisa Elena; Laidre, Kristin L.; Øien, Nils Inge; Nordøy, Erling Sverre; Rikardsen, Audun H.; Rosing-Asvid, Aqqalu; Semenova, Varvara; Shpak, Olga V.; Sveegaard, Signe; Ugarte, Fernando; Wiig, Øystein; Kovacs, Kit M. (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-02-04)
      Environmental change and increasing levels of human activity are threats to marine mam- mals in the Arctic. Identifying marine mammal hot - spots and areas of high species richness are essential to help guide management and conservation efforts. Herein, space use based on biotelemetric tracking devices deployed on 13 species (ringed seal <i>Pusa hispida</i>, bearded seal <i>Erignathus ...
    • Methane emissions are lower from reindeer fed lichens compared to a concentrate feed 

      Hansen, Kia Krarup; Sundset, Monica Alterskjær; Folkow, Lars; Nilsen, Marte; Mathiesen, Svein Disch (Journal article; Tidsskriftartikkel; Peer reviewed, 2018)
      Methane emissions from reindeer (Rangifer tarandus tarandus) fed lichens (mainly Cladonia stellaris) and a concentrate feed were determined using open-circuit respirometry. The lichen diet was low in crude protein (< 2.6% of dry matter [DM]), starch (6.0% DM) and acid detergent lignin (2.0% DM) compared to the concentrate feed (12.7, 22.5 and 7.2% DM, respectively), and high in neutral detergent ...
    • The Nasal Geometry of the Reindeer Gives Energy-Efficient Respiration 

      Magnanelli, Elisa; Wilhelmsen, Øivind; Acquarone, Mario; Folkow, Lars; Kjelstrup, Signe (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-07-14)
      Reindeer in the arctic region live under very harsh conditions and may face temperatures below 233 K. Therefore, efficient conservation of body heat and water is important for their survival. Alongside their insulating fur, the reindeer nasal mechanism for heat and mass exchange during respiration plays a fundamental role. We present a dynamic model to describe the heat and mass transport that takes ...
    • Pharmacokinetics of a long-acting subcutaneous eprinomectin injection in semi-domesticated reindeer (Rangifer tarandus tarandus) - a pilot study 

      Davidson, Rebecca K.; Fæste, Christiane Kruse; Uhlig, Silvio; Tukun, Feng-Ling; Lian, Hans Edvin; Solvang, Hans Arne; Thorvaldsen, Renate; Folkow, Lars; Sanchez Romano, Javier; Kilvær, Marianne V.; Holmgren, Karin Elisabeth; Nymo, Ingebjørg Helena (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-12-17)
      Reindeer (Rangifer tarandus tarandus) are exposed to the pathogenic parasitic nematode Elaphostrongylus rangiferi during grazing. The severity of disease is dose-dependent. Prophylactic anthelmintic treatment is needed to improve animal health and reindeer herding sustainability. Herds are traditionally only gathered once during the summer, requiring a drug with a persistent effect. In this study ...
    • Reduced immune responsiveness contributes to winter energy conservation in an Arctic bird 

      Nord, Andreas; Arne, Hegemann; Folkow, Lars (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-04-27)
      Animals in seasonal environments must prudently manage energy expenditure to survive the winter. This may be achieved through reductions in the allocation of energy for various purposes (e.g. thermoregulation, locomotion, etc.). We studied whether such trade-offs also include suppression of the innate immune response, by subjecting captive male Svalbard ptarmigan (<i>Lagopus muta hyperborea</i>) to ...
    • Reduced Metabolic Cost of Locomotion in Svalbard Rock Ptarmigan (Lagopus muta hyperborea) during Winter 

      Lees, J; Nudds, R; Stokkan, Karl-Arne; Folkow, Lars; Codd, J (Journal article; Tidsskriftartikkel; Peer reviewed, 2010)
    • The roles of brain lipids and polar metabolites in the hypoxia tolerance of deep-diving pinnipeds 

      Martens, Gerrit A.; Geßner, Cornelia; Folkow, Lars; Creydt, Marina; Fischer, Markus; Burmester, Thorsten (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-14)
      Lipids make up more than half of the human brain's dry weight, yet the composition and function of the brain lipidome is not well characterized. Lipids not only provide the structural basis of cell membranes, but also take part in a wide variety of biochemical processes. In neurodegenerative diseases, lipids can facilitate neuroprotection and serve as diagnostic biomarkers. The study of organisms ...
    • Seasonal changes in plumage density, plumage mass, and feather morphology in the world’s northernmost land bird, the Svalbard Rock Ptarmigan (Lagopus muta hyperborea) 

      Nord, Andreas; Holje, Vidar; Judik, Benjamin; Folkow, Lars; Pap, Péter L. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-24)
      The Svalbard Rock Ptarmigan, Lagopus muta hyperborea, is the only year-round resident terrestrial bird in the high Arctic. Many of the physiological and morphological adaptations permitting its winter endurance in this harsh environment are well understood. However, it remains unknown how the conspicuous moult from a greyish brown summer to a white winter plumage, and any underlying changes in ...
    • Seasonal variation in the thermal responses to changing environmental temperature in the world's northernmost land bird 

      Nord, Andreas; Folkow, Lars (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-01-10)
      Arctic homeotherms counter challenges at high latitudes using a combination of seasonal adjustments in pelage/plumage, fat deposition and intricate thermoregulatory adaptations. However, there are still gaps in our understanding of their thermal responses to cold, particularly in Arctic birds. Here, we have studied the potential use of local heterothermy (i.e. tissue cooling that can contribute to ...
    • Shifting mirrors: adaptive changes in retinal reflections to winter darkness in Arctic reindeer 

      Stokkan, Karl-Arne; Folkow, Lars; Dukes, Juliet; Neveu, Magella; Hogg, Chris R; Siefken, Sandra Katharina Christiane; Dakin, Steven C; Jeffery, Glen (Journal article; Tidsskriftartikkel; Peer reviewed, 2013-12-22)
      Arctic reindeer experience extreme changes in environmental light from continuous summer daylight to continuous winter darkness. Here, we show that they may have a unique mechanism to cope with winter darkness by changing the wavelength reflection from their tapetum lucidum (TL). In summer, it is golden with most light reflected back directly through the retina, whereas in winter it is deep ...