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  • 51.
    Elmhagen, B.odil
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    The applicability of metapopulation theory to large mammals2001In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 94, no 1, p. 89-100Article in journal (Refereed)
    Abstract [en]

    Metapopulation theory has become a common framework in conservation biology and it is sometimes suggested that a metapopulation approach should be used for management of large mammals. However. it has also been suggested that metapopulation theory would not be applicable to species with long generations compared to those with short ones. In this paper, we review how and on what empirical ground metapopulation terminology liar, been applied to insects, small mammals and large mammals, The review showed that the metapopulation term sometimes was used for population networks which only fulfilled the broadest possible definition of a metapopulation, i.e. they were subpopulations connected by migrating individuals. We argue that the metapopulation concept should be reserved for networks that also show some kind of metapopulation dynamics. Otherwise it applies to almost all populations and loses its substance. We found much empirical support for metapopulation dynamics in both insects and small mammals, but not in large mammals. A me possible reason is the methods used to confirm the existence of metapopulation dynamics, For insects and small mammals, the common approach is to study population turnover through patch occupancy data. Such data is difficult to obtain for large mammals, since longer temporal scales need to be covered to record extinctions and colonizations. Still, many populations of large mammals are exposed to habitat fragmentation and the resulting subpopulations sometimes have high risks of extinction. If there is migration between the subpopulations, the metapopulation framework could provide valuable information on their population dynamics. We suggest that a metapopulation approach can be interesting for populations of large mammals. when there are discrete breeding subpopulations and when these subpopulations have different growth rates and demographic fates. Thus, a comparison of the subpopulations' demographic fates, rather than subpopulation turnover, can be a feasible alternative for studies of metapopulation dynamics in large mammals.

  • 52.
    Elmhagen, Bodil
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Berteaux, Dominique
    Burgess, Robert M.
    Ehrich, Dorothee
    Gallant, Daniel
    Henttonen, Heikki
    Ims, Rolf A.
    Killengreen, Siw T.
    Niemimaa, Jukka
    Norén, Karin
    Stockholm University, Faculty of Science, Department of Zoology.
    Ollila, Tuomo
    Rodnikova, Anna
    Sokolov, Alexandrs A.
    Sokolova, Natasha A.
    Stickney, Alica A.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Homage to Hersteinsson and Macdonald: climate warming and resource subsidies cause red fox range expansion and Arctic fox decline2017In: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 36, no suppl. 1, article id 3Article, review/survey (Refereed)
    Abstract [en]

    Climate change can have a marked effect on the distribution and abundance of some species, as well as their interspecific interactions. In 1992, before ecological effects of anthropogenic climate change had developed into a topical research field, Hersteinsson and Macdonald published a seminal paper hypothesizing that the northern distribution limit of the red fox (Vulpes vulpes) is determined by food availability and ultimately climate, while the southern distribution limit of the Arctic fox (Vulpes lagopus) is determined by interspecific competition with the larger red fox. This hypothesis has inspired extensive research in several parts of the circumpolar distribution range of the Arctic fox. Over the past 25 years, it was shown that red foxes can exclude Arctic foxes from dens, space and food resources, and that red foxes kill and sometimes consume Arctic foxes. When the red fox increases to ecologically effective densities, it can cause Arctic fox decline, extirpation and range contraction, while conservation actions involving red fox culling can lead to Arctic fox recovery. Red fox advance in productive tundra, concurrent with Arctic fox retreat from this habitat, support the original hypothesis that climate warming will alter the geographical ranges of the species. However, recent studies show that anthropogenic subsidies also drive red fox advance, allowing red fox establishment north of its climate-imposed distribution limit. We conclude that synergies between anthropogenic subsidies and climate warming will speed up Arctic ecosystem change, allowing mobile species to establish and thrive in human-provided refugia, with potential spill-over effects in surrounding ecosystems.

  • 53.
    Elmhagen, Bodil
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Borgström, Sara
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Boyd, Emily
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. University of Reading, England.
    Cousins, Sara A. O.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Dalen, Love
    Ehrlén, Johan
    Stockholm University, Faculty of Science, Department of Physical Geography. Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Ermold, Matti
    Hambäck, Peter A.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Hedlund, Johanna
    Stockholm University, Faculty of Science, Department of Zoology.
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Jaramillo, Fernando
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Lagerholm, Vendela K.
    Stockholm University, Faculty of Science, Department of Zoology. Swedish Museum of Natural History, Sweden.
    Lyon, Steve W.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Moor, Helen
    Stockholm University, Faculty of Science, Stockholm Resilience Centre.
    Nykvist, Björn
    Stockholm University, Faculty of Science, Stockholm Resilience Centre. Stockholm University, Stockholm Environment Institute.
    Pasanen-Mortensen, Marianne
    Stockholm University, Faculty of Science, Department of Zoology.
    Plue, Jan
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Prieto, Carmen
    Stockholm University, Faculty of Science, Department of Physical Geography.
    van der Velde, Ype
    Stockholm University, Faculty of Science, Department of Physical Geography. Wageningen University & Research Center, Netherlands.
    Lindborg, Regina
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Interacting effects of change in climate, human population, land use, and water use on biodiversity and ecosystem services2015In: Ecology & Society, E-ISSN 1708-3087, Vol. 20, no 1, article id UNSP 23Article in journal (Refereed)
    Abstract [en]

    Human population growth and resource use, mediated by changes in climate, land use, and water use, increasingly impact biodiversity and ecosystem services provision. However, impacts of these drivers on biodiversity and ecosystem services are rarely analyzed simultaneously and remain largely unknown. An emerging question is how science can improve the understanding of change in biodiversity and ecosystem service delivery and of potential feedback mechanisms of adaptive governance. We analyzed past and future change in drivers in south-central Sweden. We used the analysis to identify main research challenges and outline important research tasks. Since the 19th century, our study area has experienced substantial and interlinked changes; a 1.6 degrees C temperature increase, rapid population growth, urbanization, and massive changes in land use and water use. Considerable future changes are also projected until the mid-21st century. However, little is known about the impacts on biodiversity and ecosystem services so far, and this in turn hampers future projections of such effects. Therefore, we urge scientists to explore interdisciplinary approaches designed to investigate change in multiple drivers, underlying mechanisms, and interactions over time, including assessment and analysis of matching-scale data from several disciplines. Such a perspective is needed for science to contribute to adaptive governance by constantly improving the understanding of linked change complexities and their impacts.

  • 54.
    Elmhagen, Bodil
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Eide, Nina E.
    Norén, Karin
    Stockholm University, Faculty of Science, Department of Zoology.
    Killengreen, Siw T.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Wallén, Johan
    Stockholm University, Faculty of Science, Department of Zoology.
    Åtgärdsprogram för fjällräv, 2017–2021 (Vulpes lagopus): Hotkategori: Starkt hotad EN2017Report (Other academic)
  • 55.
    Elmhagen, Bodil
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Hellström, Peter
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Kindberg, Jonas
    Changes in vole and lemming fluctuations in northern Sweden 1960-2008 revealed by fox dynamics2011In: Annales Zoologici Fennici, ISSN 0003-455X, E-ISSN 1797-2450, Vol. 48, no 3, p. 167-179Article in journal (Refereed)
    Abstract [en]

    Cyclic dynamics with extensive spatial synchrony has long been regarded as characteristic of key herbivores at high latitudes. This contrasts to recent reports of fading cycles in arvicoline rodents in boreal and alpine Fennoscandia. We investigate the spatio-temporal dynamics of boreal red fox and alpine arctic fox in Sweden as a proxy for the dynamics of their main prey, voles and Norwegian lemming, respectively. We analyse data from five decades, 1960-2008, with wavelets and autocorrelation approaches. Cyclic dynamics were identified with at least one method in all populations (arctic fox n = 3, red fox n = 6). The dynamics were synchronous between populations, or coupled with a 1-yr lag, in 8 of 13 pairwise comparisons. Importantly though, the dynamics were heterogeneous in space and time. All analytical approaches identified fading cycles in the three arctic fox populations and two northern red fox populations. At least one method identified similar patterns in three southern red fox populations. Red fox dynamics were cyclic in the 1970s primarily, while arctic fox dynamics was cyclic until the late 1980s or early 1990s. When cyclic, 4-yr cycles dominated in arctic fox and northern red fox, whilst 3-4-yr cycles was found in southern red foxes. Significant cyclic regimes reappeared in the 1990s or 2000s in two red fox populations and one arctic fox population. Cycles and regionally coupled dynamics appeared associated in northern arctic and red foxes. This study supports accumulating evidence which suggests that cyclic and synchronous patterns in the dynamics of lemmings and voles are nonstationary in space and time. Furthermore, the similar patterns of change in both fox species indicate that persistence of cycles is governed by similar mechanisms in lemmings and voles.

  • 56.
    Elmhagen, Bodil
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Hersteinsson, Páll
    Norén, Karin
    Stockholm University, Faculty of Science, Department of Zoology.
    Unnsteinsdottir, Ester R.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    From breeding pairs to fox towns: the social organisation of arctic fox populations with stable and fluctuating availability of food2014In: Polar Biology, ISSN 0722-4060, E-ISSN 1432-2056, Vol. 37, no 1, p. 111-122Article in journal (Refereed)
    Abstract [en]

    Food availability can impact group formation in Carnivora. Specifically, it has been suggested that temporal variation in food availability may allow a breeding pair to tolerate additional adults in their territory at times when food abundance is high. We investigate group occurrence and intraspecific tolerance during breeding in a socially flexible canid, the arctic fox (Vulpes lagopus). We compare Iceland and Sweden where resource conditions differ considerably. A breeding pair was the most common social unit in both populations, but as predicted, groups were more frequent where food abundance varied substantially between years (Sweden: 6 %) than where food availability was stable (Iceland: ≤2 %). Within Sweden, supplemental feeding increased group occurrence from 6 to 21 %, but there was no effect of natural variation in lemming (Lemmus lemmus) availability since group formation was rare also at lemming highs. Thus, additional factors appeared to influence the trade-off between intraspecific territoriality and tolerance. We report two cases where related females showed enduring social relationships with good-neighbour strategies. Related females also engaged in alloparental behaviour in a ‘fox town’ with 31 foxes (4 adults, 3 litters). In contrast, when unrelated foxes bred close to each other, they moved or split their litters during summer, presumably because of territorial conflict. We suggest that fluctuating food availability is linked to group formation in this Arctic carnivore, but also when food availability increases, additional factors such as relatedness, alloparental benefits, competition and predator defence appear necessary to explain group formation.

  • 57.
    Elmhagen, Bodil
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Kindberg, Jonas
    Hellström, Peter
    Stockholm University, Faculty of Science, Department of Zoology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    A boreal invasion in response to climate change?: Range shifts and community effects in the borderland between forest and tundra2015In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 44, no 1, p. 39-50Article in journal (Refereed)
    Abstract [en]

    It has been hypothesized that climate warming will allow southern species to advance north and invade northern ecosystems. We review the changes in the Swedish mammal and bird community in boreal forest and alpine tundra since the nineteenth century, as well as suggested drivers of change. Observed changes include (1) range expansion and increased abundance in southern birds, ungulates, and carnivores; (2) range contraction and decline in northern birds and carnivores; and (3) abundance decline or periodically disrupted dynamics in cyclic populations of small and medium-sized mammals and birds. The first warm spell, 1930-1960, stands out as a period of substantial faunal change. However, in addition to climate warming, suggested drivers of change include land use and other anthropogenic factors. We hypothesize all these drivers interacted, primarily favoring southern generalists. Future research should aim to distinguish between effects of climate and land-use change in boreal and tundra ecosystems.

  • 58.
    Elmhagen, Bodil
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Tannerfeldt, M.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Food-niche overlap between arctic and red foxes2002In: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 80, no 7, p. 1274-1285Article in journal (Refereed)
    Abstract [en]

    Arctic foxes (Alopex lagopus) in Fennoscandia have retreated to higher altitudes on the mountain tundra, possibly because of increased competition with red foxes (Vulpes vulpes) at lower altitudes. In this study we compare summer food niches of the two species in mountain tundra habitat. Arctic foxes consumed lemmings more often than red foxes did, while red foxes consumed field voles and birds more often. Yet despite substantial variation in the diet of each species among summers, food-niche overlaps between the species were consistently high in most summers, as arctic and red foxes responded similarly to temporal changes in prey availability. Occurrences of field voles and birds in fox scats were negatively Correlated with altitude, while the occurrences of lemmings tended to increase with altitude. Since arctic foxes bred at higher altitudes than red foxes, the differences between arctic and red fox diets were better explained by altitudinal segregation than by differences between their fundamental food niches. Arctic foxes should therefore endeavour to use the more productive hunting grounds at the lower altitudes of their former range, but interference competition with red foxes might decrease their access to these areas, and consequently cause a decrease in the size of in their realised niche.

  • 59.
    Elmhagen, Bodil
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. Zoologisk ekologi.
    Tannerfeldt, Magnus
    Stockholm University, Faculty of Science, Department of Zoology. Zoologisk ekologi.
    Verucci, Paolo
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology. Zoologisk ekologi.
    The arctic fox (Alopex lagopus) : an opportunistic specialist.2000In: Journal of Zoology, Vol. 251, no 2, p. 139-149Article in journal (Refereed)
    Abstract [en]

    Reliable and abundant resources are likely to favour specialisation, while unpredictable environmental variation should favour a generalist strategy. The rodent population cycles of northern latitudes can be seen as both predictable and unpredictable, depending on the scale in time and space. The arctic fox (Alopex lagopus) is an opportunistic carnivore, but paradoxically, it seems to function as a specialist on fluctuating rodent (Arvicolinae) populations in most inland areas. We have studied the dietary response of arctic foxes in Sweden during five years of varying abundance of Norwegian lemming (Lemmus lemmus), and how these changes influenced reproductive success of the foxes. The arctic fox population on mainland Fennoscandia is threatened by extinction and the situation has deteriorated during the 1980´s and 90´s, due to an absence of lemming peaks. Our results showed that in all years, lemming was the main prey for arctic foxes, with in total 85% frequency of occurrence in summer faeces (scats). Bird remains (mainly Passeriformes) were present in 34% of the scats, reindeer (Rangifer tarandus) in 21%, voles and shrews in 4% and hares (Lepus timidus) in 2% of the scats. The occurrences of lemming, bird and larger mammal (reindeer and hare) remains in the scats varied significantly between years. Temporal variations within summer seasons and dietary differences between subareas, indicated that arctic foxes fed opportunistically on the alternative prey types, when available. Den occupancy rates were positively correlated with lemming population densities during the previous winter, indicating a strong numerical response. We conclude that from a functional aspect, the arctic fox in Sweden is a lemming specialist, since lemming is the main prey and their abundance is the best predictor of arctic fox reproductive success. At the same time, other prey are used opportunistically in relation to their availability.

  • 60.
    Erlandsson, Rasmus
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Limitations of a weaker competitor – Implications of territory quality on the reproductive output of a tundra specialistManuscript (preprint) (Other academic)
  • 61.
    Erlandsson, Rasmus
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Hasselgren, Malin
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Norén, Karin
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    The resource dispersion hypothesis – a test with a cyclic mesopredatorManuscript (preprint) (Other academic)
  • 62.
    Erlandsson, Rasmus
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. Norwegian Institute for Nature Research, Norway.
    Hasselgren, Malin
    Stockholm University, Faculty of Science, Department of Zoology.
    Norén, Karin
    Stockholm University, Faculty of Science, Department of Zoology.
    Macdonald, David
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Resources and predation: drivers of sociality in a cyclic mesopredator2022In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 198, no 2, p. 381-392Article in journal (Refereed)
    Abstract [en]

    In socially flexible species, the tendency to live in groups is expected to vary through a trade-off between costs and benefits, determined by ecological conditions. The Resource Dispersion Hypothesis predicts that group size changes in response to patterns in resource availability. An additional dimension is described in Hersteinsson's model positing that sociality is further affected by a cost-benefit trade-off related to predation pressure. In the arctic fox (Vulpes lagopus), group-living follows a regional trade-off in resources' availability and intra-guild predation pressure. However, the effect of local fluctuations is poorly known, but offers an unusual opportunity to test predictions that differ between the two hypotheses in systems where prey availability is linked to intra-guild predation. Based on 17-year monitoring of arctic fox and cyclic rodent prey populations, we addressed the Resource Dispersion Hypothesis and discuss the results in relation to the impact of predation in Hersteinsson's model. Group-living increased with prey density, from 7.7% (low density) to 28% (high density). However, it remained high (44%) despite a rodent crash and this could be explained by increased benefits from cooperative defence against prey switching by top predators. We conclude that both resource abundance and predation pressure are factors underpinning the formation of social groups in fluctuating ecosystems.

  • 63.
    Erlandsson, Rasmus
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Meijer, Tomas
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Wagenius, Sofie
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Indirect effects of prey fluctuation on survival of juvenile arctic fox (Vulpes lagopus): a matter of maternal experience and litter attendance2017In: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 95, p. 239-246Article in journal (Refereed)
    Abstract [en]

    Reproductive experience affects juvenile survival in a wide range of species with possible links to differences in foraging capacity and predation. Using supplementary feeding, we aimed to limit direct effect of prey abundance to investigate indirect effects of small-rodent availability and maternal experience on juvenile summer survival rates in an endangered population of arctic fox (Vulpes lagopus (L., 1758)). We used data spanning 7 years, included a complete small-rodent cycle, comprising 49 litters and 394 cubs. The effect of small-rodent abundance on juvenile survival depended on maternal breeding experience. Cubs born by first-time-breeding females had lower survival rate when small-rodent abundance was low compared with juveniles born to experienced mothers who remained unaffected. It was unlikely due to starvation, as physical condition was unrelated to survival. Instead, we favour the explanation that intraguild predation was an important cause of mortality. There was a negative relationship between survival and amount of time cubs were left unattended, suggesting that parental behaviour affected predation. We propose that a prey switch related to small-rodent abundance caused fluctuations in intraguild predation pressure and that inexperienced females were less able to cope with predation when small rodents were scarce.

  • 64.
    Erlandsson, Rasmus
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Norén, Karin
    Stockholm University, Faculty of Science, Department of Zoology.
    Wallén, Johan
    Stockholm University, Faculty of Science, Department of Zoology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Märkningen av fjällrävar förutsättning för effektiv och långsiktig forskning2015In: Härjedalen, ISSN 1103-9426, no 27 augustiArticle in journal (Other (popular science, discussion, etc.))
  • 65.
    Erlandsson, Rasmus
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Stoessel, Marianne
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Skånes, Helle
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Wennbom, Marika
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    An innovative use of orthophotos - possibilities to assess plant productivity from colour infrared aerial orthophotos2019In: Remote Sensing in Ecology and Conservation, E-ISSN 2056-3485, Vol. 5, no 4, p. 291-301Article in journal (Refereed)
    Abstract [en]

    Studies of ecological processes should focus on a relevant spatial scale, as crude spatial resolution will fail to detect small scale variation which is of potentially critical importance. Remote sensing methods based on multispectral satellite images are used to assess primary productivity and aerial photos to map vegetation structure. Both methods are based on the principle that photosynthetically active vegetation has a characteristic spectral signature. Yet they are applied differently due to technical differences. Satellite images are suitable for calculations of vegetation indices, for example Normalized Difference Vegetation Index (NDVI). Colour infrared aerial photography was developed for visual interpretation and never regarded for calculation of indices since the spectrum recorded and post processing differ from satellite images. With digital cameras and improved techniques for generating colour infrared orthophotos, the implications of these differences are uncertain and should be explored. We tested if plant productivity can be assessed using colour infrared aerial orthophotos (0.5 m resolution) by applying the standard NDVI equation. With 112 vegetation samples as ground truth, we evaluated an index that we denote rel‐NDVIortho in two areas of the Fennoscandian mountain tundra. We compared the results with conventional SPOT5 satellite‐based NDVI (10 m resolution). rel‐NDVIortho was related to plant productivity (Northern area: P = <0.001, R2 = 0.73; Southern area: P = <0.001, R2 = 0.39), performed similar to SPOT5 satellite NDVI (Northern area: P = <0.001, R2 = 0.76; Southern area: P = <0.001, R2 = 0.40) and the two methods were highly correlated (cor = 0.95 and cor = 0.84). Despite different plant composition, the results were consistent between areas. Our results suggest that vegetation indices based on colour infrared aerial orthophotos can be a valuable tool in the remote sensing toolbox, offering a high‐spatial resolution proxy for plant productivity with less signal degradation due to atmospheric interference and clouds, compared to satellite images. Further research should aim to investigate if the method is applicable to other ecosystems.

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  • 66.
    Fjellström, Markus
    et al.
    Stockholm University, Faculty of Humanities, Department of Archaeology and Classical Studies, Archaeological Research Laboratory.
    Eriksson, Gunilla
    Stockholm University, Faculty of Humanities, Department of Archaeology and Classical Studies, Archaeological Research Laboratory.
    Angerbjorn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Lidén, Kerstin
    Stockholm University, Faculty of Humanities, Department of Archaeology and Classical Studies, Archaeological Research Laboratory.
    Approaching historic reindeer herding in Northern Sweden by stable isotope analysis2020In: Journal of Nordic Archaeological Science, ISSN 1650-1519, Vol. 19, p. 63-75Article in journal (Refereed)
    Abstract [en]

    A strong cultural connection exists between reindeer and modern Sámi identityand economy. Reindeer domestication is, however, a rather late event, andthere are many Sámi who live off resources other than reindeer herding. Theuse of stable isotope analysis on historic reindeer from different geographicareas can contribute to analysing both the processes involved in reindeer domesticationand different environmental utilization by the Sámi. In this study,reindeer bones from six different sites in northern Sweden, ranging in datefrom the 11th to the 20th century, were analysed for stable isotopes to studyhow reindeer have been utilized in various historic contexts – settlements,offering sites and a marketplace. The stable isotope analysis demonstrateddifferent practices in utilization of reindeer, such as foddering. Foddering issuggested to have caused the elevated δ15N values found in reindeer at theoffering sites Vindelgransele and Unna Saiva, as well as at the settlementVivallen. The analysis further indicates that the offering sites were used bysingle Sámi groups. An important outcome of our study is that the biologyof reindeer in Sápmi was culturally influenced by the Sámi even before thereindeer was domesticated.

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  • 67. Frafjord, K.
    et al.
    Becker, D.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Interactions between Arctic and Red Foxes in Scandinavia - Predation and Aggression1989In: Arctic, ISSN 0004-0843, E-ISSN 1923-1245, Vol. 42, no 4, p. 354-356Article in journal (Refereed)
  • 68. Geffen, E.
    et al.
    Kam, Michael
    Hefner, R.
    Hersteinsson, P.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Dalén, Love
    Naturhistoriska riksmuseet, Molekylärsystematik.
    Fuglei, E.
    Norén, Karin
    Stockholm University, Faculty of Science, Department of Zoology.
    Adams, J. R.
    Vucetich, J.
    Meier, T. J.
    Mech, L. D.
    von Holdt, B. M.
    Stahler, D. R.
    Wayne, R. K.
    Kin encounter rate and inbreeding avoidance in canids2011In: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 20, no 24, p. 5348-5358Article in journal (Refereed)
    Abstract [en]

    Mating with close kin can lead to inbreeding depression through the expression of recessive deleterious alleles and loss of heterozygosity. Mate selection may be affected by kin encounter rate, and inbreeding avoidance may not be uniform but associated with age and social system. Specifically, selection for kin recognition and inbreeding avoidance may be more developed in species that live in family groups or breed cooperatively. To test this hypothesis, we compared kin encounter rate and the proportion of related breeding pairs in noninbred and highly inbred canid populations. The chance of randomly encountering a full sib ranged between 1–8% and 20–22% in noninbred and inbred canid populations, respectively. We show that regardless of encounter rate, outside natal groups mates were selected independent of relatedness. Within natal groups, there was a significant avoidance of mating with a relative. Lack of discrimination against mating with close relatives outside packs suggests that the rate of inbreeding in canids is related to the proximity of close relatives, which could explain the high degree of inbreeding depression observed in some populations. The idea that kin encounter rate and social organization can explain the lack of inbreeding avoidance in some species is intriguing and may have implications for the management of populations at risk

  • 69. Geffen, Eli
    et al.
    Waidyaratne, Sitara
    Dalén, Love
    Stockholm University, Faculty of Science, Department of Zoology. Zoologisk ekologi.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology. Zoologisk ekologi.
    Vila, Carles
    Hersteinsson, Pall
    Fuglei, Eva
    White, Paula A
    Goltsman, Michael
    Kapel, Christian M O
    Wayne, Robert K
    Sea ice occurrence predicts genetic isolation in the Arctic fox.2007In: Mol Ecol, ISSN 0962-1083, Vol. 16, no 20, p. 4241-55Article in journal (Refereed)
  • 70.
    Godoy, Erika
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Norén, Karin
    Stockholm University, Faculty of Science, Department of Zoology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Mating patterns in an inbred Arctic carnivore2018In: Polar Biology, ISSN 0722-4060, E-ISSN 1432-2056, Vol. 41, no 5, p. 945-951Article in journal (Refereed)
    Abstract [en]

    Mating patterns are highly context-dependent and the outcome of selection pressures formed by ecological factors, inbreeding levels and access to available partners. In small and inbred populations, matings are limited by high kin encounter rates and access to mates. In this paper, we use background pedigree data to investigate mating patterns and inbreeding avoidance in an isolated and critically endangered Arctic fox (Vulpes lagopus) population. Empirical data showed avoidance of matings within natal family. Based on 35 documented matings, we only recorded two full-sibling matings and these occurred between individuals from different natal families. Matings between second-order relatives, however, occurred to the same extent as between unrelated individuals. To test how this influenced the population development of inbreeding (f), we simulated scenarios of random mating, exclusion of natal family and exclusion of individuals in already existing pair bonds. The observed development of inbreeding did not correspond the expected scenario of random mating (linear regression, r2 = 0.354, P = 0.20), but showed a comparable outcome as the simulated development of discriminating natal family (linear regression, r2 = 0.980, P < 0.001). We conclude that behavioural, pre-copulatory inbreeding avoidance strategies occur in this population and that exclusion of mating with natal family causes a slower increase in inbreeding levels compared to random mating. This study demonstrates how long-term monitoring, pedigree construction and simulations can generate information valuable for an in-depth understanding of both conservation genetics and behavioural ecology in threatened populations.

  • 71.
    Granquist, Sandra
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology. Marine and Freshwater Research Institute, Iceland.
    Esparza-Sala, Rodrigo
    Hauksson, Erlingur
    Karlsson, Olle
    Jónsdóttir, Ingibjörg G.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Prey consumption of Harbour seals (Phoca vitulina) in north western Iceland: Comparing DNA metabarcoding and morphological analysesManuscript (preprint) (Other academic)
    Abstract [en]

    Understanding ecological relationships between humans and marine predators is challenging, but crucial for the implementation of sustainable management practices. Comprehensive estimation of pinniped diet is essential for assessing their interaction with commercial fisheries as well as to increase knowledge on ecological interactions and food webs. In Iceland, salmonid fisheries are economically important and harbour seals are often culled in the vicinity of salmon estuaries to prevent potential seal predation on salmonid stocks. There is a lack of information on harbour seal diet, and due to uncertainty of the accuracy of methods traditionally used to estimate harbour seal diet (e.g. hard-part analysis of faeces) it is necessary to improve analysis methods. In this study, we investigated the diet of harbour seals hauling out in an estuary area in north western Iceland between June and September of 2010 and 2011 by DNA analysis of prey in faeces using DNA barcoding. The results were compared to previously published results from morphological analysis. Our results showed that harbour seals mainly consumed sand eels, flatfishes, gadoids, herring and capelin. Species consumed by the seals were at large in agreement with species availability in the area. The results from molecular and morphological analysis were similar in regards of important prey species. However the species diversity was lower in the morphological analysis and 37.5% of the samples included prey items that were unidentifiable in the morphological analysis. Notably, despite salmon, trout and char availability in the study area, neither of the methods found evidence of salmonids in the harbour seal diet. Since the main reason for culling harbour seals in Iceland is to reduce predation on salmonids, the finding that salmonids are not important prey species is important in terms of management implications, especially in the light of a recent severe decline in the Icelandic harbour seal population.

  • 72.
    Granquist, Sandra M.
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. Marine and Freshwater Research Institute, Iceland; The Icelandic Seal Center, Iceland.
    Esparza-Salas, Rodrigo
    Hauksson, Erlingur
    Karlsson, Olle
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Fish consumption of harbour seals (Phoca vitulina) in north western Iceland assessed by DNA metabarcoding and morphological analysis2018In: Polar Biology, ISSN 0722-4060, E-ISSN 1432-2056, Vol. 41, no 11, p. 2199-2210Article in journal (Refereed)
    Abstract [en]

    Understanding ecological relationships between humans and marine predators is crucial for the implementation of sustainable management practices. Comprehensive estimation of pinniped diet is essential for assessing interaction with fisheries and often has an important conservational value. Due to uncertainty regarding the accuracy of methods traditionally used to estimate harbour seal (Phoca vitulina) diet it is necessary to improve analysis methods. We investigated the diet of harbour seals hauling out in an estuary area in north-western Iceland between May and August of 2010 and 2011 by genetic (molecular) analysis of prey in faeces using DNA metabarcoding. The results were compared to previously published results from morphological analysis. Our results showed that species consumed were mainly sandeels (Ammodytes sp.), flatfishes (Pleuronectidae), gadoids (Gadidae), herring (Clupea harengus) and capelin (Mallotus villosus). The results from molecular and morphological analyses were similar in regards to important prey species, but species diversity was lower in the morphological analysis and 38% of the samples included prey items that were unidentifiable in the morphological analysis. Notably, despite Atlantic salmon (Salmo salar), brown trout (Salmo trutta) and Arctic char (Salvelinus alpinus) availability in the study area, neither of the methods found evidence of salmonids in the harbour seal diet. Recently, a severe decline has been observed in the Icelandic harbour seal population. Since the main reason for culling harbour seals in Iceland is to reduce predation on salmonids, findings presented in this paper have essential conservation implications and suggest that culling needs to be reassessed.

  • 73. Granquist, Sandra M.
    et al.
    Nilsson, Per Åke
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    From Eco-Tourism to Ego-Tourism: Fluctuations in Human View on Nature over Time2019In: Athens Journal of Tourism, E-ISSN 2241-8148, Vol. 6, no 3, p. 195-210Article in journal (Refereed)
    Abstract [en]

    Human view on nature has fluctuated over time, depending on contemporary knowledge and beliefs. In recent centuries, the view has shifted from an instrumental to an existential apprehension of nature. This development has contributed to the emergence of nature-based tourism. By using nature-based tourism as an example, we explore trends and tendencies concerning use and views of nature. Today, it is regarded politically correct to consider nature based on ethical standpoints deriving from scientific research results, which have been addressed as cornerstones to cope with negative anthropogenic effects on nature. However, concurrently with the emerging existentialism and individualism in society, these ethical standpoints have been questioned, which can potentially create a trend where people act against political correctness. We explore how this affects the human view on nature, and debate the emergence of a trend towards a more individualistic consumptive nature-based tourism, called ego-tourism, as well as how this trend may affect tourism and wildlife conservation.

  • 74.
    Götherström, Anders
    et al.
    Stockholm University, Faculty of Humanities, Department of Archaeology and Classical Studies, Archaeological Research Laboratory.
    Collins, M. J.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Lidén, Kerstin
    Stockholm University, Faculty of Humanities, Department of Archaeology and Classical Studies, Archaeological Research Laboratory.
    Bone preservation and DNA amplification2002In: Archaeometry, ISSN 0003-813X, E-ISSN 1475-4754, Vol. 44, no 3, p. 395-404Article in journal (Refereed)
    Abstract [en]

    The use of ancient DNA has increased during the past two decades in several scientific disciplines. However, the underlying mechanism of DNA degradation in bone tissue are poorly understood. Here we address the importance of hydroxyapatite and collagen for DNA preservation in bone. We used two series of bones and teeth, one set of modern experimentally degraded bovid bones and one set of ancient horse bones/teeth. From these samples, we measured crystallinity, DNA presence and extracted collagen. The mtDNA fragments, parts of cytochrome b and the D-loop were amplified and sequenced. Our results show that presence of DNA was strongly related to the crystallinity in the hydroxyapatite and to the amount of collagen. This suggests that the hypothesis that hydroxyapatite has a crucial role in DNA preservation in calcified tissue is valid; and hydroxyapatite and collagen can be used to indicate whether DNA is present in the material. This is what would be expected if DNA is adsorbed to and stabilized by hydroxyapatite in calcified tissue, and collagen is part of the complex system that preserves DNA in bone tissue. Further, since collagen is the preferred material for radiocarbon dating, such bones may be a starting-point for a DNA analysis.

  • 75.
    Haage, Marianne
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Elmhagen, Bodil
    Stockholm University, Faculty of Science, Department of Zoology.
    Maran, Tiit
    An experimental approach to the formation of diet preferences and individual specialisation in European mink2017In: European Journal of Wildlife Research, ISSN 1612-4642, E-ISSN 1439-0574, Vol. 63, no 2, p. 1-8, article id 34Article in journal (Refereed)
    Abstract [en]

    Individual dietary specialisation can occur within populations even when average diets suggest that the population has a generalist feeding strategy. Individual specialisation may impact fitness and has been related to demographic traits, ecological opportunity, competition, learning and animal personality. However, the causation and formation of individual specialisation are not fully understood. Experiments on animals raised in controlled environments provide an opportunity to examine dietary preferences and learning largely independent from variation in lifetime experiences and ecological opportunity. Here, we use a feeding experiment to examine individual specialisation and learning in captive bred European mink (Mustela lutreola) in an Estonian conservation programme. In a series of cafeteria experiments, animals could choose between one familiar food item (Baltic herring Clupea harengus membras) and two initially novel ones (noble crayfish Astacus astacus and house mouse Mus musculus). In general, mice were rarely eaten whilst crayfish consumption increased over time and fish decreased. At the individual level, there was a mix of generalists and crayfish or fish specialists, and the individuals differed in learning time in relation to novel prey. Our results indicate that individual variation in innate preferences and learning both contributes to individual diet specialisation. The differences in learning indicate individual variation in behavioural plasticity, which in turn can be related to personality. This could be of concern in conservation, as personality has been shown to affect survival in translocations.

  • 76.
    Haage, Marianne
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Bergvall, Ulrika A.
    Maran, Tiit
    Kiik, Kairi
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Situation and context impacts the expression of personality: The influence of breeding season and test context2013In: Behavioural Processes, ISSN 0376-6357, E-ISSN 1872-8308, Vol. 100, p. 103-109Article in journal (Refereed)
  • 77.
    Haage, Marianne
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Maran, Tiit
    Alm Bergvall, Ulrika
    Stockholm University, Faculty of Science, Department of Zoology.
    Elmhagen, Bodil
    Stockholm University, Faculty of Science, Department of Zoology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Evolutionary maintenance of personality – a field experiment on survival and personalityIn: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939Article in journal (Refereed)
  • 78.
    Haage, Marianne
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Maran, Tiit
    Alm Bergvall, Ulrika
    Stockholm University, Faculty of Science, Department of Zoology.
    Elmhagen, Bodil
    Stockholm University, Faculty of Science, Department of Zoology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    The influence of spatiotemporal conditions and personality on survival in reintroductions-evolutionary implications2017In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 183, no 1, p. 45-56Article in journal (Refereed)
    Abstract [en]

    Personality exists in non-human animals and can impact fitness. There is, however, a shortage of empirical studies in certain areas within the field, and fundamental evolutionary theory on personality remains largely untested. For example, little is known on how variation in personality is maintained over evolutionary time. Theory suggests that fluctuating selection pressures due to spatiotemporal variation in conditions, e.g. food availability, is a possible mechanism and a few studies have shown that the success of different personality types varies with spatiotemporal conditions. However, it remains unknown whether different mechanisms can maintain personality within a species. Here we use a reintroduction programme for the critically endangered European mink (Mustela lutreola) to test whether multiple personality trait domains (boldness, exploration and sociability) affected survival in two different years and islands. This was done through pre-release personality tests and post-release radio-tracking monitoring. Survival was positively correlated with boldness, whereas the relationship with exploration was either negative or positive depending on year/island. The results show a complex relationship between personality and survival and suggest that exploration can be maintained over evolutionary time via spatiotemporal variation in conditions. However, in contrast to exploration, boldness did not vary spatiotemporally and sociability had no impact on survival. This indicates that different personality trait domains might be maintained by different mechanisms. To date, personality has been studied primarily within behavioural sciences, but through empirical findings we highlight the importance of personality also in ecology and conservation biology.

  • 79.
    Haage, Marianne
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Pasanen-Mortensen, Marianne
    Stockholm University, Faculty of Science, Department of Zoology.
    Sidorovich, Vadim
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Elmhagen, Bodil
    Stockholm University, Faculty of Science, Department of Zoology.
    American mink in north-eastern Europe – abundances, population trends and dynamics in relation to the red fox and otterManuscript (preprint) (Other academic)
  • 80.
    Hasselgren, Malin
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Eide, Nina E.
    Erlandsson, Rasmus
    Stockholm University, Faculty of Science, Department of Zoology.
    Flagstad, Øystein
    Landa, Arild
    Wallén, Johan
    Stockholm University, Faculty of Science, Department of Zoology.
    Norén, Karin
    Stockholm University, Faculty of Science, Department of Zoology.
    Genetic rescue in an inbred Arctic fox (Vulpes lagopus) population2018In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 285, no 1875, article id 20172814Article in journal (Refereed)
    Abstract [en]

    Isolation of small populations can reduce fitness through inbreeding depression and impede population growth. Outcrossing with only a few unrelated individuals can increase demographic and genetic viability substantially, but few studies have documented such genetic rescue in natural mammal populations. We investigate the effects of immigration in a subpopulation of the endangered Scandinavian arctic fox (Vulpes lagopus), founded by six individuals and isolated for 9 years at an extremely small population size. Based on a long-term pedigree (105 litters, 543 individuals) combined with individual fitness traits, we found evidence for genetic rescue. Natural immigration and gene flow of three outbred males in 2010 resulted in a reduction in population average inbreeding coefficient (f), from 0.14 to 0.08 within 5 years. Genetic rescue was further supported by 1.9 times higher juvenile survival and 1.3 times higher breeding success in immigrant first-generation offspring compared with inbred offspring. Five years after immigration, the population had more than doubled in size and allelic richness increased by 41%. This is one of few studies that has documented genetic rescue in a natural mammal population suffering from inbreeding depression and contributes to a growing body of data demonstrating the vital connection between genetics and individual fitness.

  • 81.
    Hasselgren, Malin
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Dussex, Nicolas
    Stockholm University, Faculty of Science, Department of Zoology. Swedish Museum of Natural History, Sweden.
    von Seth, Johanna
    Stockholm University, Faculty of Science, Department of Zoology. Swedish Museum of Natural History, Sweden.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Dalén, Love
    Stockholm University, Faculty of Science, Department of Zoology.
    Norén, Karin
    Stockholm University, Faculty of Science, Department of Zoology.
    Genomic consequences of inbreeding and outbreeding in an endangered carnivoreManuscript (preprint) (Other academic)
    Abstract [en]

    Loss of genetic variation through genetic drift and inbreeding is a major threat to small and isolated populations. Although previous studies have generally used genetically verified pedigrees to document effects of inbreeding and gene flow, these often fail to capture the whole inbreeding history. Also, empirical support for a link between genomic inbreeding and fitness is scarce. By sequencing complete genomes of 23 Scandinavian arctic foxes (Vulpes lagopus) born before and after an immigration event, we here look into the genomic consequences of inbreeding and genetic rescue. We found a significant difference, with 18% higher genome-wide heterozygosity and 81% lower genomic inbreeding in immigrant F1 compared to native individuals. However, more distant descendants of immigrants (F2, F3) did not show the same pattern. We also found that foxes surviving their first year generally had higher heterozygosity and lower inbreeding than non-survivors. Finally, pedigree-based inbreeding correlated with, but underestimated, genomic inbreeding levels. Our results demonstrate a fundamental link between genetic variation and fitness, the transient nature of genetic rescue, and that inbreeding is even more severe than captured from a genetically verified pedigree. Our results have important implications in conservation biology as inbreeding depression can be detected in populations lacking a pedigree.

  • 82.
    Hasselgren, Malin
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Dussex, Nicolas
    Stockholm University, Faculty of Science, Department of Zoology. Swedish Museum of Natural History, Sweden.
    von Seth, Johanna
    Stockholm University, Faculty of Science, Department of Zoology. Swedish Museum of Natural History, Sweden.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Olsen, Remi-André
    Stockholm University, Science for Life Laboratory (SciLifeLab). Stockholm University, Faculty of Science, Department of Biochemistry and Biophysics.
    Dalén, Love
    Norén, Karin
    Stockholm University, Faculty of Science, Department of Zoology.
    Genomic and fitness consequences of inbreeding in an endangered carnivore2021In: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 30, no 12, p. 2790-2799Article in journal (Refereed)
    Abstract [en]

    Reduced fitness through genetic drift and inbreeding is a major threat to small and isolated populations. Although previous studies have generally used genetically verified pedigrees to document effects of inbreeding and gene flow, these often fail to capture the whole inbreeding history of the species. By assembling a draft arctic fox (Vulpes lagopus) genome and resequencing complete genomes of 23 additional foxes born before and after a well-documented immigration event in Scandinavia, we here look into the genomic consequences of inbreeding and genetic rescue. We found a difference in genome-wide diversity, with 18% higher heterozygosity and 81% lower F-ROH in immigrant F1 compared to native individuals. However, more distant descendants of immigrants (F2, F3) did not show the same pattern. We also found that foxes with lower inbreeding had higher probability to survive their first year of life. Our results demonstrate the important link between genetic variation and fitness as well as the transient nature of genetic rescue. Moreover, our results have implications in conservation biology as they demonstrate that inbreeding depression can effectively be detected in the wild by a genomic approach.

  • 83.
    Hellström, Peter
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Lindberg, Peter
    Göteborgs universitet.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Numerical responses and population decline of an avian predator dependent on cyclic preyManuscript (preprint) (Other academic)
    Abstract [en]

    Specialist predators per definition show numerical responses to changes in food supply. Numerical responses are broadly divided into a reproductive response, where reproductive output increases with increased food supply, and an aggregative response caused by breeding suppression and movements. Numerical responses are crucial for understanding predator-prey relations, and also for appropriate management of predator populations. Declining populations of keystone herbivores (voles and lemmings) have been described as a widespread pattern in Europe. Negative effects of dampened small mammal cycles on numerical responses, and thereby population dynamics, have been predicted but so far demonstrated for relatively few specialist predators. We therefore monitored relationships between a common sub-arctic avian predator, the rough-legged buzzard Buteo lagopus, and small rodents in NW Sweden for 19 years (1970-1978 and 2001-2010, 369 observed breeding attempts). Rough-legged buzzards were food-limited and exhibited aggregative and reproductive responses to current rodent abundance in both study periods, but with a weaker coupling in recent years. Density of breeding pairs in rodent peak years was 32-50 % lower in the 2000s than in the 1970s. Further, reproductive output was lower in the 2000s, possibly preventing a population increase. Mean clutch size decreased with 0.77 eggs/clutch (from 4.53 to 3.73, an 18 % reduction), and mean number of fledglings per breeding attempt decreased with 1.08 juveniles/pair (from 3.88 to 2.80, a decrease of 28%). Hatching success and brood survival did not change between 1970s and 2000s, which suggests that reproductive output is constrained by clutch size, rather than by nestling mortality. The observed changes in reproductive parameters support a long-term change in food supply at the onset of breeding as the causal factor. Our study demonstrates the link between predator-prey theory and the declining population-paradigm of conservation biology, illustrating how estimation of numerical responses can be used to predict the outcome of perturbations to predator-prey systems.

  • 84.
    Hellström, Peter
    et al.
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Nyström, Jesper
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Functional responses of rough-legged buzzards in a multi-prey system2014In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 174, no 4, p. 1241-1254Article in journal (Refereed)
    Abstract [en]

    The functional response is a key element of predator–prey interactions. Basic functional response theory explains foraging behavior of individual predators, but many empirical studies of free-ranging predators have estimated functional responses by using population-averaged data. We used a novel approach to investigate functional responses of an avian predator (the rough legged-buzzard Buteo lagopus Pontoppidan, 1763) to intra-annual spatial variation in rodent density in subarctic sweden, using breeding pairs as the sampling unit. the rough-legged buzzards responded functionally to norwegian lemmings (Lemmus lemmus l. 1758), grey-sided voles (Myodes rufocanus Sundevall, 1846) and field voles (Microtus agrestis L. 1761), but different rodent prey were not utilised according to relative abundance. the functional response to norwegian lemmings was a steep type II curve and a more shallow type III response to grey-sided voles. the different shapes of these two functional responses were likely due to combined effects of differences between lemmings and grey-sided voles in habitat utilisation, anti-predator behaviour and size-dependent vulnerability to predation. Diet composition changed less than changes in relative prey abundance, indicating negative switching, with high disproportional use of especially lemmings at low relative densities. Our results suggest that lemmings and voles should be treated separately in future empirical and theoretical studies in order to better understand the role of predation in this study system.

  • 85.
    Hellström, Peter
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. Ecology.
    Nyström, Jesper
    Stockholm University, Faculty of Science, Department of Zoology. Ecology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology. Ecology.
    Predation patterns on Norwegian lemmings and grey-sided voles2007In: Abstracts V European Congress of Mammalogy: Hystrix Italian Journal of Mammalogy, (n.s.) Vol 1-2, Supp. (2007), 2007, p. 101-Conference paper (Refereed)
  • 86. Henden, J-A
    et al.
    Yoccoz, Nigel G
    Ims, Rolf A
    Bårdsen, B-J
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology, Department of Animal Ecology.
    Phase-dependent effect of conservation efforts in cyclically fluctuating populations of Arctic fox (Vulpes lagopus).2009In: Biological Conservation, ISSN 0006-3207, E-ISSN 1873-2917, Vol. 142, p. 2586-2592Article in journal (Refereed)
    Abstract [en]

    Predator populations with demographic cycles driven by multi-annual cycles of their key prey resourcecan be expected to be ‘‘cyclic phase sensitive” to management actions. We explored this by means ofmodelling in the case of the highly endangered Fennoscandian arctic fox population which is driven by4-year population cycles in small rodent prey. By using a model in which the management actionimproved arctic fox vital rate through increased resource availability, we show that arctic fox populationgrowth was most improved when management action was applied in the increase and decrease phase ofthe cycle. Except in the low phase of the cycle, the growth rate was more affected when the managementaction worked through improved reproduction than improved survival. There was a synergistic effect tobe gained by performing management action during multiple phases during a demographic cycle. Thuswe recommend that arctic fox conservation programs ought to be continuous in time, but with the highestintensities of management action in the phases of the cycle in which the target population is mostprone to respond.

  • 87.
    Henden, John-André
    et al.
    University of Tromsø, Norway.
    Ims, Rolf Anker
    University of Tromsø, Norway.
    Yoccoz, Nigel G
    University of Tromsø, Norway.
    Hellström, Peter
    Stockholm University, Faculty of Science, Department of Zoology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Strength of asymmetric competition between predators in food webs ruled by fluctuating prey: the case of foxes in tundra2010In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 119, no 1, p. 27-34Article in journal (Refereed)
    Abstract [en]

    In food webs heavily influenced by multi-annual population fluctuations of key herbivores, predator species may differ in their functional and numerical responses as well as their competitive ability. Focusing on red and arctic fox in tundra with cyclic populations of rodents as key prey, we develop a model to predict how population dynamics of a dominant and versatile predator (red fox) impacted long-term growth rate of a subdominant and less versatile predator (arctic fox). We compare three realistic scenarios of red fox performance: (1) a numerical response scenario where red fox acted as a resident rodent specialist exhibiting population cycles lagging one year after the rodent cycle, (2) an aggregative response scenario where red fox shifted between tundra and a nearby ecosystem (i.e. boreal forest) so as to track rodent peaks in tundra without delay, and (3) a constant subsidy scenario in which the red fox population was stabilized at the same mean density as in the other two scenarios. For all three scenarios it is assumed that the arctic fox responded numerically as a rodent specialist and that the mechanisms of competition is of a interference type for space, in which the arctic fox is excluded from the most resource rich patches in tundra. Arctic fox is impacted most by the constant subsidy scenario and least by the numerical response scenario. The differential effects of the scenarios stemmed from cyclic phase-dependent sensitivity to competition mediated by changes in temporal mean and variance of available prey to the subdominant predator. A general implication from our result is that external resource subsidies (prey or habitats), monopolized by the dominant competitor, can significantly reduce the likelihood for co-existence within the predator guild. In terms of conservation of vulnerable arctic fox populations this means that the likelihood of extinction increases with increasing amount of subsidies (e.g. carcasses of large herbivores or marine resources) in tundra and nearby forest areas, since it will act to both increase and stabilize populations of red fox.

  • 88.
    Herfindal, Ivar
    et al.
    Norwegian University of Science and Technology.
    Linnell, John D. C.
    Norwegian Institute for Nature Research.
    Elmhagen, Bodil
    Stockholm University, Faculty of Science, Department of Zoology.
    Andersen, Roy
    Norwegian Institute for Nature Research.
    Eide, Nina E
    Norwegian Institute for Nature Research.
    Frafjord, Karl
    Tromsö University.
    Henttonen, Heikki
    Metla - Finnish Forest Research Institute.
    Kaikusalo, Asko
    Metla - Finnish Forest Research Institute.
    Mela, Matti
    Metsähallitus - Finnish Park and Forestry Service.
    Tannerfeldt, Magnus
    Swedish Polar Research Secretariat.
    Dalén, Love
    Swedish Museum of Natural History.
    Strand, Olav
    Norwegian Institute for Nature Research.
    Landa, Arild
    Norwegian Institute for Nature Research.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Population persistence in a landscape context: the case of endangered arctic fox populations in Fennoscandia2010In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 33, no 5, p. 932-941Article in journal (Refereed)
    Abstract [en]

    Anthropogenic fragmentation of habitat and populations is recognized as one of the most important factors influencing loss of biodiversity. Since it is difficult to quantify demographic parameters in small populations, we need alternative methods to elucidate important factors affecting the viability of local populations. The Fennoscandian arctic fox inhabits a naturally fragmented alpine tundra environment, but historic anthropogenic impacts have further fragmented its distribution. After almost 80 yr of protection, the population remains critically endangered. Both intrinsic factors (related to the isolation and size of sub-populations) and extrinsic factors (related to environmental conditions influencing patch quality and interspecific competition) have been proposed as explanations for the lack of population growth. To distinguish between these hypotheses, we conducted a spatially explicit analysis that compares areas where the species has persisted with areas where it has become locally extinct. We used characteristics of the fragments of alpine tundra habitat and individual arctic fox breeding dens (including both currently active dens and historically active dens) within the fragments to evaluate the importance of habitat characteristics and connectivity in explaining variation in persistence within a fragment. The number of reproductive events in a fragment was related to the size of the fragment, but not more than expected following a 1:1 relationship, suggesting little effect of fragment size on the relative number of reproductions. The likelihood of a den being used for breeding was positively associated with factors minimising interspecific competition as well as increasing within-fragment connectivity. These results support the idea that the failure of Fennoscandian arctic fox to recover is caused by demographic factors that can be related to fine-scale Allee or Allee-like effects, as well as environmental influences related to increased competition and exclusion by red foxes

  • 89. Hersteinsson, P.
    et al.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Frafjord, K.
    Kaikusalo, A.
    The Arctic Fox in Fennoscandia and Iceland - Management Problems1989In: Biological Conservation, ISSN 0006-3207, E-ISSN 1873-2917, Vol. 49, no 1, p. 67-81Article in journal (Refereed)
    Abstract [en]

    The arctic for Alopex lagopus was an important fur animal in Fennoscandia until the 1920s when numbers crashed, and in spite of total protection for over half a century has not recovered and is now regarded as vulnerable.

    In Iceland, on the other hand, the species is well established and can withstand heavy exploitation by man, being regarded as vermin and hunted at all seasons.

    In this paper we review the latest available information on the status of the arctic fox in the Nordic countries, both with regard to minimum sizes and fluctuations in population, and various factors which have been suggested as the cause of the non-recovery of the population in Fennoscandia. These include fewer available large mammal carcasses due to the near-disappearance of the wolf, increased competition with the red fox, increased predation by red foxes on arctic foxes, etc.

    The views that arctic foxes are an important predator on sheep in Iceland at present, and that foxhunting alone in its present form is capable of significantly reducing the population there, are challenged.

    At present there is insufficient information to make sound management programmes for the arctic fox populations in Fennoscandia and Iceland. Suggestions are made concerning those factors which need to be explored so that workable management programmes can be put into effect in the two regions.

  • 90. Johansson, Linda
    et al.
    Mangi, Anna-Carin
    Norén, Karin
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology, Animal Ecology.
    Spillningsinventering av fjällräv i Norrbottens län 2009: Genetisk kartläggning av spillning insamlad vid prioriterade fjällrävslyor2009Report (Other academic)
  • 91. Kaikusalo, A.
    et al.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    The Arctic Fox Population in Finnish Lapland During 30 Years, 1964-931995In: Annales Zoologici Fennici, ISSN 0003-455X, E-ISSN 1797-2450, Vol. 32, no 1, p. 69-77Article in journal (Refereed)
    Abstract [en]

    We have monitored the number of arctic foxes and microtine rodents in northern Finland for 30 years. Arctic fox densities were estimated by inventories at den sites, and microtine abundance by snap trapping. Time series analyses showed that the arctic fox population fluctuated widely but always close together with the microtines in a five year cycle. However, there was no time lag in the numerical response of foxes on microtines. The strong dependence on microtines was confirmed by analyses of faecal droppings and food remains at dens. In summer time microtines consisted in average of 45% of the diet and reindeer 30%, but during winters reindeer was the most important food source with 45% compared to 15% for microtines. There was a surprising positive correlation between number of voles and reindeer carcasses, suggesting competition or alternatively an external correlation from e.g. weather. Mean litter size of the arctic fox was also highly dependent on microtine abundance but decreased during the study period despite that food resources had not changed. Further, when microtines had high densities during two consecutive years, arctic foxes only responded to the first year. A feeding experiment resulted in an increase in number of red foxes but had no or little effect on arctic foxes. So, it is difficult to single out one explanation to the decline and second year effect. Food was probably not involved and we do not know if diseases and parasites have been involved. However, both competition and predation, primarily from the red fox, may be responsible together with climatic or weather changes.

  • 92. Keeling Hemphill, Elisa June
    et al.
    Flagstad, Øystein
    Jensen, Henrik
    Norén, Karin
    Stockholm University, Faculty of Science, Department of Zoology.
    Wallén, Johan Fredrik
    Stockholm University, Faculty of Science, Department of Zoology. Swedish Museum of Natural History, Sweden.
    Landa, Arild
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Eide, Nina E.
    Genetic consequences of conservation action: Restoring the arctic fox (Vulpes lagopus) population in Scandinavia2020In: Biological Conservation, ISSN 0006-3207, E-ISSN 1873-2917, Vol. 248, article id 108534Article in journal (Refereed)
    Abstract [en]

    The Arctic fox (Vulpes lagopus) population in Fennoscandia experienced a drastic bottleneck in the late 19th century as a result of high hunting pressure. In the 1990s, despite nearly 70 years of protection, the population showed no signs of recovery. In order to mitigate the population decline and facilitate re-establishment, conservation actions including supplementary feeding and red fox culling were implemented in 1998, followed by the reintroduction of foxes from a captive breeding programme, starting in 2006. A positive demographic impact of these actions is evident from a doubling of the population size over the past decade. We used genetic data collected in eight subpopulations between 2008 and 2015 to address whether the recent demographic recovery has been complemented by changes in genetic variation and connectivity between subpopulations. Our results show that genetic variation within subpopulations has increased considerably during the last decade, while genetic differentiation among subpopulations has decreased. A marked shift in metapopulation dynamics is evident during the study period, suggesting substantially increased migration across the metapopulation. This shift followed the recolonization of an extinct subpopulation through the release of foxes from the captive breeding programme and was synchronized in time with the implementation of supplementary feeding and red fox culling in stepping stone patches between core subpopulations in mid-Scandinavia. Indeed, the increase in genetic variation and connectivity in the Scandinavian arctic fox population suggests that metapopulation dynamics have been restored, which may indicate an increase in the long-term viability of the population.

  • 93.
    Lagerholm, Vendela K.
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. Swedish Museum of Natural History, Sweden; University of St Andrews, UK.
    Norén, Karin
    Stockholm University, Faculty of Science, Department of Zoology. University of California Davis, USA.
    Ehrich, Dorothee
    Ims, Rolf A.
    Killengreen, Siw T.
    Abramson, Natalia I.
    Niemaa, Jukka
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Henttonen, Heikki
    Dalén, Love
    Run to the hills: gene flow among mountain areas leads to low genetic differentiation in the Norwegian lemming2017In: Biological Journal of the Linnean Society, ISSN 0024-4066, E-ISSN 1095-8312, Vol. 121, no 1, p. 1-14Article in journal (Refereed)
    Abstract [en]

    The endemic Norwegian lemming (Lemmus lemmus) is an icon for cyclic species, famous since the Middle Ages for its enormous population outbreaks and mass movements. Although the drivers behind this cyclicity have been intensively investigated, virtually nothing is known about the extent to which long-distance dispersal during population peaks actually lead to gene flow among mountain tundra areas. In this article, we use nine microsatellite markers to address this question and analyse range-wide genetic diversity and differentiation between Fennoscandian sub-regions. The results revealed a high genetic variation with a surprisingly weak population structure, comparable to that of much larger mammals. The differentiation was mainly characterized as a genetic cline across the species' entire distribution, and results from spatial autocorrelation analyses suggested that gene flow occurs with sufficiently high frequency to create a genetic patch size of 100 km. Further, we found that for the equivalent distances, the southern sub-regions were genetically more similar to each other than those in the north, which indicates that the prolonged periods of interrupted lemming cyclicity recorded in the northern parts of Fennoscandia have led to increased isolation and population differentiation. In summary, we propose that mass movements during peak years act as pulses of gene flow between mountain tundra areas, and that these help to maintain genetic variation and counteract differentiation over vast geographic distances.

  • 94.
    Lagerholm, Vendela K.
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. Swedish Museum of Natural History, Sweden.
    Sandoval-Castellanos, Edson
    Stockholm University, Faculty of Science, Department of Zoology. Swedish Museum of Natural History, Sweden.
    Ehrich, Dorothee
    Abramson, Natalia I.
    Nadachowski, Adam
    Kalthoff, Daniela C.
    Germonpre, Mietje
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Stewart, John R.
    Dalén, Love
    On the origin of the Norwegian lemming2014In: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 23, no 8, p. 2060-2071Article in journal (Refereed)
    Abstract [en]

    The Pleistocene glacial cycles resulted in significant changes in species distributions, and it has been discussed whether this caused increased rates of population divergence and speciation. One species that is likely to have evolved during the Pleistocene is the Norwegian lemming (Lemmus lemmus). However, the origin of this species, both in terms of when and from what ancestral taxon it evolved, has been difficult to ascertain. Here, we use ancient DNA recovered from lemming remains from a series of Late Pleistocene and Holocene sites to explore the species' evolutionary history. The results revealed considerable genetic differentiation between glacial and contemporary samples. Moreover, the analyses provided strong support for a divergence time prior to the Last Glacial Maximum (LGM), therefore likely ruling out a postglacial colonization of Scandinavia. Consequently, it appears that the Norwegian lemming evolved from a small population that survived the LGM in an ice-free Scandinavian refugium.

  • 95.
    Larm, Malin
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Brundin, Erika
    Stockholm University, Faculty of Science, Department of Zoology.
    Stålhandske, Thomas
    Stockholm University, Faculty of Science, Department of Zoology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Arctic Fox Responses to Tourism Activity2020In: Journal of Wildlife Management, ISSN 0022-541X, E-ISSN 1937-2817, Vol. 84, no 4, p. 821-828Article in journal (Refereed)
    Abstract [en]

    As the interest for nature-based tourism activities increases, it is important to provide evidence-based guidelines for wildlife-human interactions to minimize the disturbance caused to wildlife. In Fennoscandia, the endangered arctic fox (Vulpes lagopus) is subject to increasing tourism interest and some regions recommend a minimum approach distance of 300 m, but the guidelines have not been scientifically validated. We conducted experimental human approaches towards arctic fox den sites to study activity and behavioral changes in response to the approaching observer. The first arctic foxes hid when approached within 300 m, but many had increased their vigilance already at the start distance of 500 m. At approximately 200 m, the hiding probability increased rapidly at dens disturbed and undisturbed by tourism activities. Arctic foxes at disturbed dens allowed the observer to approach more closely before they increased their vigilance and before they hid compared to foxes at undisturbed dens. We confirm that a minimum distance of 300 m might be sufficient for most arctic foxes to refrain from hiding, but a longer distance would be required to avoid causing any disturbance. We recommend a minimum approach distance of >= 300 m to be implemented in all Fennoscandian regions inhabited by the arctic fox.

  • 96.
    Larm, Malin
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Elmhagen, Bodil
    Stockholm University, Faculty of Science, Department of Zoology.
    Granquist, Sandra M.
    Brundin, Erika
    Stockholm University, Faculty of Science, Department of Zoology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    The role of wildlife tourism in conservation of endangered species: Implications of safari tourism for conservation of the Arctic fox in Sweden2018In: Human Dimensions of Wildlife, ISSN 1087-1209, E-ISSN 1533-158X, Vol. 23, no 3, p. 257-272Article in journal (Refereed)
    Abstract [en]

    There are both positive and negative impacts on wildlife associated with wildlife tourism. In Sweden, the endangered Arctic fox is subject to a growing tourist interest. In the Helags mountain region there are guided Arctic fox safari tours that provide visitors with information about the Arctic fox. A survey of five separate groups of visitors in the region revealed that knowledge about the status of Arctic foxes and awareness of the behavioral guidelines for Arctic fox encounters improved after participation in a safari tour and with increasing Arctic fox interaction. We propose a schematic model summarizing the diverse ways in which wildlife tourism affects wildlife and their relative importance for conservation. The Arctic fox population in Sweden is small and sensitive to disturbance, but the positive impacts of Arctic fox tourism seem to compensate for the negative and contribute to their conservation under the current level of tourism pressure.

  • 97.
    Larm, Malin
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Erlandsson, Rasmus
    Stockholm University, Faculty of Science, Department of Zoology.
    Norén, Karin
    Stockholm University, Faculty of Science, Department of Zoology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Fitness effects of ecotourism on an endangered carnivore2020In: Animal Conservation, ISSN 1367-9430, E-ISSN 1469-1795, Vol. 23, no 4, p. 386-395Article in journal (Refereed)
    Abstract [en]

    Nature-based recreational and tourism activities can exert significant direct and indirect impacts on wildlife, through behavioral, physiological and distributional changes. Despite many studies demonstrating such changes, few attempts have been made to quantify the fitness consequences and evaluate their biological significance. Helagsfjallen in Sweden is a core area of the endangered Fennoscandian arctic foxVulpes lagopus, and a popular area for recreational tourism. Some dens in the area experience daily disturbance from tourism during the summer season, while others are virtually undisturbed. We used a long-term dataset (2008-2017) of 553 juveniles in 74 litters to investigate summer juvenile survival, which is an important fitness component for the arctic fox. We found that the mean juvenile survival rate increased from 0.56 at undisturbed dens to 0.83 at disturbed den during years of decreasing small-rodent abundance, where predation on the arctic fox is presumed to be highest. We suggest that the increased survival could be mediated by a human activity-induced predator refuge for the arctic foxes in close proximity of trails and mountain huts. Our study demonstrates a possible positive indirect effect of nature-based tourism on wildlife and is one of a few studies attempting to quantify this impact. It highlights the importance of context for how animals are affected by disturbance. We also demonstrate that studying how the effects of tourism activity vary depending on the context could provide opportunities for identifying the mechanisms behind these effects, which can be an important link between scientific research and the management of wildlife and tourism activities.

  • 98.
    Larm, Malin
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. Norwegian Institute for Nature Research (NINA), Norway.
    Hovland, Anne Lene
    Palme, Rupert
    Thierry, Anne-Mathilde
    Miller, Andrea L.
    Landa, Arild
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Eide, Nina E.
    Fecal glucocorticoid metabolites as an indicator of adrenocortical activity in Arctic foxes (Vulpes lagopus) and recommendations for future studies2021In: Polar Biology, ISSN 0722-4060, E-ISSN 1432-2056, Vol. 44, no 10, p. 1925-1937Article in journal (Refereed)
    Abstract [en]

    Measuring fecal glucocorticoid metabolites (fGCMs) is a widely used, non-invasive method for studies of stress in vertebrates. To study physiological responses in wild Arctic foxes (Vulpes lagopus) to perceived stressors such as fluctuating food availability, occurrence of competitors and predators and disturbance from human activities, a species-specific physiological validation of a method to evaluate adrenocortical activity is needed. Here we used 15 captive Arctic foxes (both males and females and juveniles and adults) to investigate fGCM concentrations following ACTH injection (physiological validation), or handling alone and compared them with their respective baseline concentrations prior to the treatments. A 5 alpha-pregnane-3ss,11ss,21-triol-20-one enzyme immunoassay measured significant fGCM increases following both treatments. The time lags to reach peak fGCM values were 9.3 +/- 1.3 h and 12.8 +/- 1.7 h for ACTH and handling treatment, respectively. Concentrations of fGCMs varied a lot between individuals, but not attributed to sex nor age of the foxes. However, we found a negative relationship between boldness and fGCM concentrations. Faecal glucocorticoid metabolites concentrations did not change significantly over a period of 48 h in samples kept at temperatures reflecting winter and summer means. This would allow the collection of samples up to two days old in the wild regardless of the season. We conclude that our successfully validated method for measuring fGCMs can be used as a non-invasive tool for studies exploring various stressors both in wild and captive Arctic foxes.

  • 99.
    Larm, Malin
    et al.
    Stockholm University, Faculty of Science, Department of Zoology.
    Norén, Karin
    Stockholm University, Faculty of Science, Department of Zoology.
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Temporal activity shift in arctic foxes (Vulpes lagopus) in response to human disturbance2021In: Global Ecology and Conservation, ISSN 2351-9894, Vol. 27, article id e01602Article in journal (Refereed)
    Abstract [en]

    The rapidly growing interest for nature-based recreational activities threaten biodiversity values and increases the disturbance caused to wildlife. Several studies have demonstrated spatial and temporal activity shifts of animals in response to human disturbance. However, most studies investigate effects on how animals use an area of high tourism disturbance, such as a tourist resort or hiking trail, and not the effects of human disturbance at a key site for the animal, such as a denning or breeding site. In this study, we use photos from remote camera monitoring of arctic fox (Vulpes lagopus) dens with the aim to investigate the effects of various levels of tourism disturbance on the diurnal activity pattern and vigilance of breeding adult arctic foxes at the den site. We find a temporal shift towards a higher daytime activity at the den in response to high intensity tourism (71 +/- 3.9% in disturbed areas compared with 53 +/- 6.2% in undisturbed areas), which stands in contrast to an increased nocturnality seen in studies of many other species, including another study of arctic foxes. We suggest that the difference could be explained by the higher cost of avoiding a key site for the animal, as in this study, compared with avoiding a more general human disturbance in an area within the distribution range of the animal, as in most other studies. Increased time spent avoiding the perceived threat of humans could compromise other important activities and have potential negative effects on e.g. hunting or provisioning for the juveniles. Human disturbance focused at a key site, such as a denning or breeding site, can thereby be expected to have larger consequences than what is observed in most studies of disturbance effects on wildlife. Based on observations of both tourists and arctic foxes during close encounters in an area of high intensity tourism, we also find that they both respond behaviorally to each other. The potential for positive or negative feedback mechanisms in such relationships between tourists and wildlife highlights the importance of considering both sides of the complex interaction to find a balance between preserving biodiversity and ensuring continued possibilities for recreation.

  • 100.
    Larsson, Petter
    et al.
    Stockholm University, Faculty of Science, Department of Zoology. Swedish Museum of Natural History, Sweden.
    von Seth, Johanna
    Stockholm University, Faculty of Science, Department of Zoology. Swedish Museum of Natural History, Sweden.
    Hagen, Ingerid J.
    Götherström, Anders
    Stockholm University, Faculty of Humanities, Department of Archaeology and Classical Studies.
    Androsov, Semyon
    Germonpre, Mietje
    Bergfeldt, Nora
    Stockholm University, Faculty of Science, Department of Zoology. Swedish Museum of Natural History, Sweden.
    Fedorov, Sergey
    Eide, Nina E.
    Sokolova, Natalia
    Berteaux, Dominique
    Angerbjörn, Anders
    Stockholm University, Faculty of Science, Department of Zoology.
    Flagstad, Øystein
    Plotnikov, Valeri
    Norén, Karin
    Stockholm University, Faculty of Science, Department of Zoology.
    Díez-del-Molino, David
    Stockholm University, Faculty of Science, Department of Zoology. Swedish Museum of Natural History, Sweden.
    Dussex, Nicolas
    Stanton, David W. G.
    Dalén, Love
    Stockholm University, Faculty of Science, Department of Zoology. Swedish Museum of Natural History, Sweden.
    Consequences of past climate change and recent human persecution on mitogenomic diversity in the arctic fox2019In: Philosophical Transactions of the Royal Society of London. Biological Sciences, ISSN 0962-8436, E-ISSN 1471-2970, Vol. 374, no 1788, article id 20190212Article in journal (Refereed)
    Abstract [en]

    Ancient DNA provides a powerful means to investigate the timing, rate and extent of population declines caused by extrinsic factors, such as past climate change and human activities. One species probably affected by both these factors is the arctic fox, which had a large distribution during the last glaciation that subsequently contracted at the start of the Holocene. More recently, the arctic fox population in Scandinavia went through a demographic bottleneck owing to human persecution. To investigate the consequences of these processes, we generated mitogenome sequences from a temporal dataset comprising Pleistocene, historical and modern arctic fox samples. We found no evidence that Pleistocene populations in mid-latitude Europe or Russia contributed to the present-day gene pool of the Scandinavian population, suggesting that postglacial climate warming led to local population extinctions. Furthermore, during the twentieth-century bottleneck in Scandinavia, at least half of the mitogenome haplotypes were lost, consistent with a 20-fold reduction in female effective population size. In conclusion, these results suggest that the arctic fox in mainland Western Europe has lost genetic diversity as a result of both past climate change and human persecution. Consequently, it might be particularly vulnerable to the future challenges posed by climate change. This article is part of a discussion meeting issue 'The past is a foreign country: how much can the fossil record actually inform conservation?'

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