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  • 51.
    Elmhagen, Bodil
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Hellström, Peter
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Kindberg, Jonas
    Changes in vole and lemming fluctuations in northern Sweden 1960-2008 revealed by fox dynamics2011Ingår i: Annales Zoologici Fennici, ISSN 0003-455X, E-ISSN 1797-2450, Vol. 48, nr 3, s. 167-179Artikel i tidskrift (Refereegranskat)
    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.

  • 52.
    Elmhagen, Bodil
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Hersteinsson, Páll
    Norén, Karin
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Unnsteinsdottir, Ester R.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    From breeding pairs to fox towns: the social organisation of arctic fox populations with stable and fluctuating availability of food2014Ingår i: Polar Biology, ISSN 0722-4060, E-ISSN 1432-2056, Vol. 37, nr 1, s. 111-122Artikel i tidskrift (Refereegranskat)
    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.

  • 53.
    Elmhagen, Bodil
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Kindberg, Jonas
    Hellström, Peter
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    A boreal invasion in response to climate change?: Range shifts and community effects in the borderland between forest and tundra2015Ingår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 44, nr 1, s. 39-50Artikel i tidskrift (Refereegranskat)
    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.

  • 54.
    Elmhagen, Bodil
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Tannerfeldt, M.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Food-niche overlap between arctic and red foxes2002Ingår i: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 80, nr 7, s. 1274-1285Artikel i tidskrift (Refereegranskat)
    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.

  • 55.
    Elmhagen, Bodil
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Zoologisk ekologi.
    Tannerfeldt, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Zoologisk ekologi.
    Verucci, Paolo
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Zoologisk ekologi.
    The arctic fox (Alopex lagopus) : an opportunistic specialist.2000Ingår i: Journal of Zoology, Vol. 251, nr 2, s. 139-149Artikel i tidskrift (Refereegranskat)
    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.

  • 56.
    Erlandsson, Rasmus
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Limitations of a weaker competitor – Implications of territory quality on the reproductive output of a tundra specialistManuskript (preprint) (Övrigt vetenskapligt)
  • 57.
    Erlandsson, Rasmus
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Hasselgren, Malin
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Norén, Karin
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    The resource dispersion hypothesis – a test with a cyclic mesopredatorManuskript (preprint) (Övrigt vetenskapligt)
  • 58.
    Erlandsson, Rasmus
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Meijer, Tomas
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Wagenius, Sofie
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Indirect effects of prey fluctuation on survival of juvenile arctic fox (Vulpes lagopus): a matter of maternal experience and litter attendance2017Ingår i: Canadian Journal of Zoology, ISSN 0008-4301, E-ISSN 1480-3283, Vol. 95, s. 239-246Artikel i tidskrift (Refereegranskat)
    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.

  • 59.
    Erlandsson, Rasmus
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Norén, Karin
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Wallén, Johan
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Märkningen av fjällrävar förutsättning för effektiv och långsiktig forskning2015Ingår i: Härjedalen, ISSN 1103-9426, nr 27 augustiArtikel i tidskrift (Övrig (populärvetenskap, debatt, mm))
  • 60.
    Erlandsson, Rasmus
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Stoessel, Marianne
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Skånes, Helle
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Wennbom, Marika
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    An innovative use of orthophotos - possibilities to assess plant productivity from colour infrared aerial orthophotos2019Ingår i: Remote Sensing in Ecology and Conservation, ISSN 0034-429X, E-ISSN 2056-3485Artikel i tidskrift (Refereegranskat)
    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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  • 61. Frafjord, K.
    et al.
    Becker, D.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Interactions between Arctic and Red Foxes in Scandinavia - Predation and Aggression1989Ingår i: Arctic, ISSN 0004-0843, E-ISSN 1923-1245, Vol. 42, nr 4, s. 354-356Artikel i tidskrift (Refereegranskat)
  • 62. Geffen, E.
    et al.
    Kam, Michael
    Hefner, R.
    Hersteinsson, P.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Dalén, Love
    Naturhistoriska riksmuseet, Molekylärsystematik.
    Fuglei, E.
    Norén, Karin
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    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 canids2011Ingår i: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 20, nr 24, s. 5348-5358Artikel i tidskrift (Refereegranskat)
    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

  • 63. Geffen, Eli
    et al.
    Waidyaratne, Sitara
    Dalén, Love
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Zoologisk ekologi.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. 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.2007Ingår i: Mol Ecol, ISSN 0962-1083, Vol. 16, nr 20, s. 4241-55Artikel i tidskrift (Refereegranskat)
  • 64.
    Godoy, Erika
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Norén, Karin
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Mating patterns in an inbred Arctic carnivore2018Ingår i: Polar Biology, ISSN 0722-4060, E-ISSN 1432-2056, Vol. 41, nr 5, s. 945-951Artikel i tidskrift (Refereegranskat)
    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.

  • 65.
    Granquist, Sandra
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi. Marine and Freshwater Research Institute, Iceland.
    Esparza-Sala, Rodrigo
    Hauksson, Erlingur
    Karlsson, Olle
    Jónsdóttir, Ingibjörg G.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Prey consumption of Harbour seals (Phoca vitulina) in north western Iceland: Comparing DNA metabarcoding and morphological analysesManuskript (preprint) (Övrigt vetenskapligt)
    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.

  • 66.
    Granquist, Sandra M.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Marine and Freshwater Research Institute, Iceland; The Icelandic Seal Center, Iceland.
    Esparza-Salas, Rodrigo
    Hauksson, Erlingur
    Karlsson, Olle
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Fish consumption of harbour seals (Phoca vitulina) in north western Iceland assessed by DNA metabarcoding and morphological analysis2018Ingår i: Polar Biology, ISSN 0722-4060, E-ISSN 1432-2056, Vol. 41, nr 11, s. 2199-2210Artikel i tidskrift (Refereegranskat)
    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.

  • 67. Granquist, Sandra M.
    et al.
    Nilsson, Per Åke
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    From Eco-Tourism to Ego-Tourism: Fluctuations in Human View on Nature over Time2019Ingår i: Athens Journal of Tourism, E-ISSN 2241-8148, Vol. 6, nr 3, s. 195-210Artikel i tidskrift (Refereegranskat)
    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.

  • 68.
    Götherström, Anders
    et al.
    Stockholms universitet, Humanistiska fakulteten, Institutionen för arkeologi och antikens kultur, Arkeologiska forskningslaboratoriet.
    Collins, M. J.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Lidén, Kerstin
    Stockholms universitet, Humanistiska fakulteten, Institutionen för arkeologi och antikens kultur, Arkeologiska forskningslaboratoriet.
    Bone preservation and DNA amplification2002Ingår i: Archaeometry, ISSN 0003-813X, E-ISSN 1475-4754, Vol. 44, nr 3, s. 395-404Artikel i tidskrift (Refereegranskat)
    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.

  • 69.
    Haage, Marianne
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Elmhagen, Bodil
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Maran, Tiit
    An experimental approach to the formation of diet preferences and individual specialisation in European mink2017Ingår i: European Journal of Wildlife Research, ISSN 1612-4642, E-ISSN 1439-0574, Vol. 63, nr 2, s. 1-8, artikel-id 34Artikel i tidskrift (Refereegranskat)
    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.

  • 70.
    Haage, Marianne
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Bergvall, Ulrika A.
    Maran, Tiit
    Kiik, Kairi
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Situation and context impacts the expression of personality: The influence of breeding season and test context2013Ingår i: Behavioural Processes, ISSN 0376-6357, E-ISSN 1872-8308, Vol. 100, s. 103-109Artikel i tidskrift (Refereegranskat)
  • 71.
    Haage, Marianne
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Maran, Tiit
    Alm Bergvall, Ulrika
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Elmhagen, Bodil
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Evolutionary maintenance of personality – a field experiment on survival and personalityIngår i: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939Artikel i tidskrift (Refereegranskat)
  • 72.
    Haage, Marianne
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Maran, Tiit
    Alm Bergvall, Ulrika
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Elmhagen, Bodil
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    The influence of spatiotemporal conditions and personality on survival in reintroductions-evolutionary implications2017Ingår i: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 183, nr 1, s. 45-56Artikel i tidskrift (Refereegranskat)
    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.

  • 73.
    Haage, Marianne
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Pasanen-Mortensen, Marianne
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Sidorovich, Vadim
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Elmhagen, Bodil
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    American mink in north-eastern Europe – abundances, population trends and dynamics in relation to the red fox and otterManuskript (preprint) (Övrigt vetenskapligt)
  • 74.
    Hasselgren, Malin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Eide, Nina E.
    Erlandsson, Rasmus
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Flagstad, Øystein
    Landa, Arild
    Wallén, Johan
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Norén, Karin
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Genetic rescue in an inbred Arctic fox (Vulpes lagopus) population2018Ingår i: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 285, nr 1875, artikel-id 20172814Artikel i tidskrift (Refereegranskat)
    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.

  • 75.
    Hasselgren, Malin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Dussex, Nicolas
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Swedish Museum of Natural History, Sweden.
    von Seth, Johanna
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Swedish Museum of Natural History, Sweden.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Dalén, Love
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Norén, Karin
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Genomic consequences of inbreeding and outbreeding in an endangered carnivoreManuskript (preprint) (Övrigt vetenskapligt)
    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.

  • 76.
    Hellström, Peter
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Lindberg, Peter
    Göteborgs universitet.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Numerical responses and population decline of an avian predator dependent on cyclic preyManuskript (preprint) (Övrigt vetenskapligt)
    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.

  • 77.
    Hellström, Peter
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Nyström, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Functional responses of rough-legged buzzards in a multi-prey system2014Ingår i: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 174, nr 4, s. 1241-1254Artikel i tidskrift (Refereegranskat)
    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.

  • 78.
    Hellström, Peter
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Ecology.
    Nyström, Jesper
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Ecology.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Ecology.
    Predation patterns on Norwegian lemmings and grey-sided voles2007Ingår i: Abstracts V European Congress of Mammalogy: Hystrix Italian Journal of Mammalogy, (n.s.) Vol 1-2, Supp. (2007), 2007, s. 101-Konferensbidrag (Refereegranskat)
  • 79. Henden, J-A
    et al.
    Yoccoz, Nigel G
    Ims, Rolf A
    Bårdsen, B-J
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Phase-dependent effect of conservation efforts in cyclically fluctuating populations of Arctic fox (Vulpes lagopus).2009Ingår i: Biological Conservation, ISSN 0006-3207, E-ISSN 1873-2917, Vol. 142, s. 2586-2592Artikel i tidskrift (Refereegranskat)
    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.

  • 80.
    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
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Strength of asymmetric competition between predators in food webs ruled by fluctuating prey: the case of foxes in tundra2010Ingår i: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 119, nr 1, s. 27-34Artikel i tidskrift (Refereegranskat)
    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.

  • 81.
    Herfindal, Ivar
    et al.
    Norwegian University of Science and Technology.
    Linnell, John D. C.
    Norwegian Institute for Nature Research.
    Elmhagen, Bodil
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    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
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Population persistence in a landscape context: the case of endangered arctic fox populations in Fennoscandia2010Ingår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 33, nr 5, s. 932-941Artikel i tidskrift (Refereegranskat)
    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

  • 82. Hersteinsson, P.
    et al.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Frafjord, K.
    Kaikusalo, A.
    The Arctic Fox in Fennoscandia and Iceland - Management Problems1989Ingår i: Biological Conservation, ISSN 0006-3207, E-ISSN 1873-2917, Vol. 49, nr 1, s. 67-81Artikel i tidskrift (Refereegranskat)
    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.

  • 83. Johansson, Linda
    et al.
    Mangi, Anna-Carin
    Norén, Karin
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Spillningsinventering av fjällräv i Norrbottens län 2009: Genetisk kartläggning av spillning insamlad vid prioriterade fjällrävslyor2009Rapport (Övrigt vetenskapligt)
  • 84. Kaikusalo, A.
    et al.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    The Arctic Fox Population in Finnish Lapland During 30 Years, 1964-931995Ingår i: Annales Zoologici Fennici, ISSN 0003-455X, E-ISSN 1797-2450, Vol. 32, nr 1, s. 69-77Artikel i tidskrift (Refereegranskat)
    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.

  • 85.
    Lagerholm, Vendela K.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Swedish Museum of Natural History, Sweden; University of St Andrews, UK.
    Norén, Karin
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. University of California Davis, USA.
    Ehrich, Dorothee
    Ims, Rolf A.
    Killengreen, Siw T.
    Abramson, Natalia I.
    Niemaa, Jukka
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Henttonen, Heikki
    Dalén, Love
    Run to the hills: gene flow among mountain areas leads to low genetic differentiation in the Norwegian lemming2017Ingår i: Biological Journal of the Linnean Society, ISSN 0024-4066, E-ISSN 1095-8312, Vol. 121, nr 1, s. 1-14Artikel i tidskrift (Refereegranskat)
    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.

  • 86.
    Lagerholm, Vendela K.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Swedish Museum of Natural History, Sweden.
    Sandoval-Castellanos, Edson
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Swedish Museum of Natural History, Sweden.
    Ehrich, Dorothee
    Abramson, Natalia I.
    Nadachowski, Adam
    Kalthoff, Daniela C.
    Germonpre, Mietje
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Stewart, John R.
    Dalén, Love
    On the origin of the Norwegian lemming2014Ingår i: Molecular Ecology, ISSN 0962-1083, E-ISSN 1365-294X, Vol. 23, nr 8, s. 2060-2071Artikel i tidskrift (Refereegranskat)
    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.

  • 87.
    Larm, Malin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Brundin, Erika
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Stålhandske, Thomas
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Arctic Fox Responses to Tourism Activity2020Ingår i: Journal of Wildlife Management, ISSN 0022-541X, E-ISSN 1937-2817, Vol. 84, nr 4, s. 821-828Artikel i tidskrift (Refereegranskat)
    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.

  • 88.
    Larm, Malin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Elmhagen, Bodil
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Granquist, Sandra M.
    Brundin, Erika
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    The role of wildlife tourism in conservation of endangered species: Implications of safari tourism for conservation of the Arctic fox in Sweden2018Ingår i: Human Dimensions of Wildlife, ISSN 1087-1209, E-ISSN 1533-158X, Vol. 23, nr 3, s. 257-272Artikel i tidskrift (Refereegranskat)
    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.

  • 89.
    Larsson, Petter
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Swedish Museum of Natural History, Sweden.
    von Seth, Johanna
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Swedish Museum of Natural History, Sweden.
    Hagen, Ingerid J.
    Götherström, Anders
    Stockholms universitet, Humanistiska fakulteten, Institutionen för arkeologi och antikens kultur.
    Androsov, Semyon
    Germonpre, Mietje
    Bergfeldt, Nora
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Swedish Museum of Natural History, Sweden.
    Fedorov, Sergey
    Eide, Nina E.
    Sokolova, Natalia
    Berteaux, Dominique
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Flagstad, Øystein
    Plotnikov, Valeri
    Norén, Karin
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Díez-del-Molino, David
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Swedish Museum of Natural History, Sweden.
    Dussex, Nicolas
    Stanton, David W. G.
    Dalén, Love
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Swedish Museum of Natural History, Sweden.
    Consequences of past climate change and recent human persecution on mitogenomic diversity in the arctic fox2019Ingår i: Philosophical Transactions of the Royal Society of London. Biological Sciences, ISSN 0962-8436, E-ISSN 1471-2970, Vol. 374, nr 1788, artikel-id 20190212Artikel i tidskrift (Refereegranskat)
    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?'

  • 90.
    Le Vaillant, Maryline
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Erlandsson, Rasmus
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Elmhagen, Bodil
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Hörnfeldt, Birger
    Eide, Nina E.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Spatial distribution in Norwegian lemming Lemmus lemmus in relation to the phase of the cycle2018Ingår i: Polar Biology, ISSN 0722-4060, E-ISSN 1432-2056, Vol. 41, nr 7, s. 1391-1403Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Competition between individuals of the same or different species affects spatial distribution of organisms at any given time. Consequently, a species geographical distribution is related to population dynamics through density-dependent processes. Small Arctic rodents are important prey species in many Arctic ecosystems. They commonly show large cyclic fluctuations in abundance offering a potential to investigate how landscape characteristics relates to density-dependent habitat selection. Based on long-term summer trapping data of the Norwegian lemming (Lemmus lemmus) in the Scandinavian Mountain tundra, we applied species distribution modeling to test if the effect of environmental variables on lemming distribution changed in relation to the lemming cycle. Lemmings were less habitat specific during the peak phase, as their distribution was only related to primary productivity. During the increase phase, however, lemming distribution was, in addition, associated with landscape characteristics such as hilly terrain and slopes that are less likely to get flooded. Lemming habitat use varied during the cycle, suggesting density-dependent changes in habitat selection that could be explained by intraspecific competition. We believe that the distribution patterns observed during the increase phase show a stronger ecological signal for habitat preference and that the less specific habitat use during the peak phase is a result of lemmings grazing themselves out of the best habitat as the population grows. Future research on lemming winter distribution would make it possible to investigate the year around strategies of habitat selection in lemmings and a better understanding of a fundamental actor in many Arctic ecosystems.

  • 91.
    Lidén, Kerstin
    et al.
    Stockholms universitet, Humanistiska fakulteten, Institutionen för arkeologi och antikens kultur. Stockholms universitet, Humanistiska fakulteten, Institutionen för arkeologi och antikens kultur, Arkeologiska forskningslaboratoriet. Stockholms universitet, Humanistiska fakulteten, Centrum för evolutionär kulturforskning.
    Angerbjörn, A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Dietary change and stable isotopes: a model of growth and dormancy in cave bears1999Ingår i: Proceedings of the Royal Society of London Series B-Biological Sciences, Vol. 266, nr 1430, s. 1779-1783Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In order to discuss dietary change over time by the use of stable isotopes, it is necessary to sort out the underlying processes in isotopic variation. Together with the dietary signal other processes have been investigated, namely metabolic processes, collagen turnover and physical growth. However, growth and collagen turnover time have so far been neglected in dietary reconstruction based on stable isotopes. An earlier study suggested that cave bears (Ursus spelaeus) probably gave birth to cubs during dormancy. We provide an estimate of the effect on stable isotopes of growth and metabolism and discuss collagen turnover in a population of cave bears. Based on a quantitative model, we hypothesized that bear cubs lactated their mothers during their first and second winters, but were fed solid food together with lactation during their first summer. This demonstrates the need to include physical growth, metabolism and collagen turnover in dietary reconstruction. Whereas the effects of diet and metabolism are due to fractionation, growth and collagen turnover are dilution processes.

  • 92.
    Lilja Öqvist, Elin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Granquist, Sandra M.
    Burns, Georgette Leah
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Seal watching: An investigation of codes of conduct2018Ingår i: Tourism in Marine Environments, ISSN 1544-273X, E-ISSN 2169-0197, Vol. 13, nr 1, s. 1-15Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Seal watching as a form of wildlife tourism is becoming increasingly popular worldwide. Behavioral changes caused by the presence of tourists could lead to negative consequences for seal welfare and may affect reproduction and survival. Therefore, managing seal-watching activities to ensure future protection and conservation is important. Codes of conduct or guidelines for how to behave around animals are one way to regulate wildlife watching and are often easier and quicker to implement than laws. Codes explaining the consequences for wildlife if the code is not followed appeal to the moral obligation of tourists and thereby increase incentives to act appropriately. This study focused on analyzing the content of codes of conduct for seal watching. Codes of conduct (n = 33) accessible on the internet during the time of study were analyzed. Results show that in many areas where seal watching occurs there are no regulations or guidelines. The content and detail of the codes varied and the information was often insufficient to offer adequate protection of seals. Few of the codes were developed in cooperation with scientists or stated that the content was based on research. Further, a majority of the codes did not explain the consequences for wildlife if the code was not followed. More research on seals and the tourists watching them is needed to better understand the effects of tourism and how disturbance could be minimized. Meanwhile, developing an international code of conduct (with local additions) built on existing knowledge in the field could be one option to increase protection and ensure conservation of these animals. The results presented in this article could assist the development of such a code of conduct.

  • 93.
    Lindenfors, Patrik
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Dalén, Love
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    A monophyletic origin of delayed implantation and its implications2003Ingår i: Evolution, ISSN 0014-3820, E-ISSN 1558-5646, Vol. 57, s. 1952-1956Artikel i tidskrift (Refereegranskat)
  • 94. Machín, Paula
    et al.
    Fernández-Elipe, Juan
    Hungar, Johannes
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Klaassen, Raymond H. G.
    Aguirre, José
    The role of ecological and environmental conditions on the nesting success of waders in sub-Arctic Sweden2019Ingår i: Polar Biology, ISSN 0722-4060, E-ISSN 1432-2056, Vol. 42, nr 8, s. 1571-1579Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Waders that breed in the sub-Arctic are one of the groups most threatened by climate change. At the same time, wader breeding success also can vary as a function of fluctuations in the numbers of predators and rodents (an alternative prey for the predators). How climate change could influence these foodweb interactions remains poorly studied. In this study, we analysed the effects of ecological (e.g. vole/lemming and predator abundance) and environmental factors (e.g. snow cover) on the breeding success of waders in sub-Arctic Lapland. We monitored more than 500 wader nests during six breeding seasons, which spanned a full rodent cycle and one year of exceptionally late snow melt. Nest predation rate, and thus wader breeding success, did not vary as a function of predator or rodent abundance. However, predation rate was exceptionally high in the year with a late snow melt. More variability in climate is expected for the future, where more precipitation and cold spring temperatures resulting in late snow melt will be more frequent, influencing the rodent and predator numbers, and therefore wader breeding success in the sub-Arctic. Snow would limit the number of open areas for nesting and hence predators would then be able to find these nests more easily. Additionally, predators might concentrate their efforts on alternative prey if snow has reduced their capacity to find other food sources. And, ultimately, changes in the rodent fluctuations could affect the final outcome of predators.

  • 95.
    Meijer, Tomas
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Elmhagen, Bodil
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Eide, Nina
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Life history traits in a cyclic ecosystem– a field experiment on the arctic foxManuskript (preprint) (Övrigt vetenskapligt)
  • 96.
    Meijer, Tomas
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Elmhagen, Bodil
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Norén, Karin
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Dahlgren, Johan
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Reproductive strategy in a cyclic environmentManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The ability to maximize life-time reproductive output in relation to ecological variation in time and space is central for individual fitness. In cyclic environments the optimal litter size might vary over time depending on fluctuations in food abundance, offspring survival and their future fecundity. The arctic fox in Scandinavia is highly dependent on cyclic small rodents, such as lemmings and voles, for its reproduction. The arctic foxes can adjust their litter size in relation to small rodent phase, but this adjustment cannot be explained by food abundance only. In the rodent increase phase, litters are larger than expected from food abundance, while litters are smaller than expected in the decrease phase. In this paper, we studied how arctic fox litter size is associated with variation in the offspring reproductive value, specifically if the reproductive value is higher in the increase phase of the small rodent cycle. We followed the survival and fecundity, i.e. number of offspring, of 282 ear-tagged arctic foxes for a minimum of 4 years after birth in relation to small rodent phase. We found substantial variation in reproductive values, with a 3.2 times higher reproductive value for cubs born in the increase phase (0.74) compared to the decrease phase (0.23). The most pronounced difference in reproductive value between offspring born in different phases was caused by survival from birth to the end of their first year. Of the offspring born in the increase phase, 32% survived their first year compared to only 9% in the decrease phase. Our data supports that the observed phase dependent adjustment of arctic fox litter size has a demographic (and thereby an evolutionary) advantage by maximizing the number of offspring when the reproductive value is highest.

  • 97.
    Meijer, Tomas
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Mattsson, Roland
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen, Avdelningen för zoologisk ekologi.
    Osterman-Lind, Eva
    Fernandez-Aguilar, Xavier
    Gavier-Widen, Dolores
    Endoparasites in the endangered Fennoscandian population of arctic foxes (Vulpes lagopus)2011Ingår i: European Journal of Wildlife Research, ISSN 1612-4642, E-ISSN 1439-0574, Vol. 57, nr 4, s. 923-927Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Fennoscandian arctic fox (Vulpes lagopus) population is endangered due to overharvest and competition with the larger red fox (Vulpes vulpes). In this study, we have screened the population in Sweden for endoparasites by analysis of non-invasively faecal samples collected at reproductive dens during two summers, one with low food abundance (2008) and the other with high food abundance (2010). Eggs, larvae and oocysts of a total of 14 different endoparasites were identified with a species richness per inhabited den of 3.2 (CI95% +/- 0.48) in 2008 and 2.7 (CI95% +/- 0.72) in 2010. Capillariidae-like eggs was identified at 59% of the dens in 2008 and 57% in 2010 and Toxocara canis with 7% (2008) and 30% (2010); Toxascaris leonina with 93% (2008) and 65% (2010); Uncinaria stenocephala 65% (2008) and 39% (2010); Crenosoma vulpis 3% (2008) and 4% (2010); Trichuris sp. 7% (2008) and 4% (2010); Cystoisospora canis-like oocysts 28% (2008) and 26% (2010); Cystoisospora ohiensis-like oocysts 38% (2008) and 4% (2010); Eimeria sp. 7% (2008) and 9% (2010); Sarcocystis sp. 3% (2008) and 9% (2010); Taenia sp. 10% (2008) and 4% (2010); Mesocestoides sp. 3% (2008) and 0% (2010); Balantidium sp. 0% (2008) and 9% (2010) and Spiruroidea-like eggs 0% (2008) and 4% (2010). To our knowledge, Balantidium sp., Sarcocystis sp. and Trichuris sp. has never been described before in wild arctic foxes.

  • 98.
    Meijer, Tomas
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Norén, Karin
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    The impact of maternal experience on post-weaning survival in an endangered arctic fox population2011Ingår i: European Journal of Wildlife Research, ISSN 1612-4642, E-ISSN 1439-0574, Vol. 57, nr 3, s. 549-553Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Behavioural differences in parental care can influence offspring survival through variation in e.g. antipredator behaviour and ability to provide food. In a broad range of species, offspring survival has been found to be higher for experienced females compared to inexperienced first-time breeders. The increase in offspring survival for experienced females has mainly been explained by improved experience in providing food. In this paper, we have studied post-weaning juvenile survival in relation to maternal experience in an endangered population of arctic foxes (Vulpes lagopus) in Fennoscandia. For cubs raised by inexperienced and experienced females, the survival rate was 0.42 (CI 95% +/- 0.31) and 0.87 (CI 95% +/- 0.08), respectively. There was no difference in body condition between the cubs and no observations of starvation. We suggest that the difference in survival was due to lack of experience to one of the most common predators, the golden eagle (Aquila chrysaetos). Golden eagles were mainly observed on dens with litters where the females were inexperienced first-time breeders. From a conservation perspective, it is therefore important to increase adult survival through actions to enlarge the proportion of experienced breeders.

  • 99.
    Meijer, Tomas
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Norén, Karin
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Hellström, Peter
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Dalén, Love
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Estimating population parameters in a threatened arctic fox population using molecular tracking and traditional field methods2008Ingår i: Animal Conservation, ISSN 1469-1795, Vol. 11, nr 4, s. 330-338Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Comprehensive population parameter data are useful for assessing effective conservation actions. The Fennoscandian arctic fox Alopex lagopus is critically endangered and the population size is estimated at 120 individuals that are fragmented into four isolated populations. Here, we use molecular tracking and visual observations to estimate population size and survival in one of the populations on the Swedish mountain tundra during a year of low food availability. We collected 98 arctic fox faecal samples during the winter of 2006 and recorded visual observations of ear-tagged individuals during the summer of 2005 and 2006. The faecal samples were analysed for variation in nine microsatellite loci and matched to the genetic profiles of previously ear-tagged individuals from 2001 to 2005. During winter 2006, the minimum number alive was 12 individuals using visual observations, 30 using molecular tracking and 36 by combining the datasets. Population size was estimated through mark–recapture for the molecular tracking and visual observation datasets and through rarefaction analyses for molecular tracking data. The mark–recapture estimate for visual observations was uninformative due to the large confidence interval (CI) (i.e. 6–212 individuals). Based on the molecular tracking dataset combined with the minimum number alive for visual observations and molecular tracking, we concluded a consensus population size of 36–55 individuals. We also estimated the age-specific finite survival rate during 1 year (July 2005 to July 2006) by combining molecular tracking with visual observations. Juvenile survival on a yearly basis was 0.08 (95% CI 0.02–0.18) while adults had a survival of 0.59 (95% CI 0.39–0.82). Juveniles displayed a lower survival than the adults during autumn (P<0.01) whereas no age-specific survival difference during spring was found. The risk of negative effects due to the small population size and low juvenile survival is accordingly considerable.

  • 100. Moen, Jon
    et al.
    Aune, Karin.
    Edenius, Lars
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Potential effects of climate change on treeline position in the Swedish mountains2004Ingår i: Ecology & society, ISSN 1708-3087, E-ISSN 1708-3087, Vol. 9, nr 1, s. Article Number 16-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Climate change may strongly influence species distribution and, thus, the structure and function of ecosystems. This paper describes simulated changes in the position of the upper treeline in the Swedish mountains in response to predicted climate change. Data on predicted summer temperature changes, the current position of the treeline, and a digital elevation model were used to predict the position of the treeline over a 100-year timeframe. The results show the treeline advancing upward by 233-667 m, depending on the climate scenario used and location within the mountain chain. Such changes hypothetically caused a 75-85% reduction in treeless alpine heaths, with 60-93% of the remaining areas being scree slopes and boulder fields. For this change to occur, the migration rate of the trees would be in the order of 23-221 m yr(-1), which is well within published migration rates for wind-dispersed deciduous trees. The remaining alpine areas would be strongly fragmented. These drastic changes would influence all aspects of mountain ecosystems, including biodiversity conservation and human land-use patterns.

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