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  • 1. Berteaux, Dominique
    et al.
    Angerbjörn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Erlandsson, Rasmus
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Norén, Karin
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    White, Paula A.
    Harmonizing circumpolar monitoring of Arctic fox: benefits, opportunities, challenges and recommendations2017Ingår i: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 36, nr suppl. 1, artikel-id 2Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The biodiversity working group of the Arctic Council has developed pan-Arctic biodiversity monitoring plans to improve our ability to detect, understand and report on long-term change in Arctic biodiversity. The Arctic fox (Vulpes lagopus) was identified as a target of future monitoring because of its circumpolar distribution, ecological importance and reliance on Arctic ecosystems. We provide the first exhaustive survey of contemporary Arctic fox monitoring programmes, describing 34 projects located in eight countries. Monitored populations covered equally the four climate zones of the species’ distribution, and there were large differences between populations in long-term trends, multi-annual fluctuations, diet composition, degree of competition with red fox and human interferences. Den density, number of active dens, number of breeding dens and litter size were assessed in almost all populations, while projects varied greatly with respect to monitoring of other variables indicative of population status, ecosystem state or ecosystem function. We review the benefits, opportunities and challenges to increased integration of monitoring projects. We argue that better harmonizing protocols of data collection and data management would allow new questions to be addressed while adding tremendous value to individual projects. However, despite many opportunities, challenges remain. We offer six recommendations that represent decisive progress toward a better integration of Arctic fox monitoring projects. Further, our work serves as a template that can be used to integrate monitoring efforts of other species, thereby providing a key step for future assessments of global biodiversity.

  • 2.
    Choi, Seoyun
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Grocutt, Emma
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Erlandsson, Rasmus
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Angerbjorn, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Parent personality is linked to juvenile mortality and stress behavior in the arctic fox (Vulpes lagopus)2019Ingår i: Behavioral Ecology and Sociobiology, ISSN 0340-5443, E-ISSN 1432-0762, Vol. 73, nr 12, artikel-id 162Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Life history theory predicts that individuals will differ in their risk-taking behavior according to their expected future fitness. Understanding consequences of such individual variation within a behavioral trait is crucial in explaining potential trade-offs between different traits and in predicting future dynamics in changing environments. Here, we studied individuals in a wild arctic fox population to explore if (1) individual variation in risk-taking behaviors of adult arctic foxes and in stress-dealing behaviors of their juveniles exist and are consistent over time to verify the existence of personality traits; (2) those behavioral traits in adults and juveniles are correlated; (3) they can explain fitness-related components (i.e., juvenile physical condition, mortality rate). We presented simple field experiments assessing behavioral traits by observing adult reactions toward approaching observers, and juvenile behaviors while trapping. Through the experiments, we found highly consistent individual variation of adults in vigilance and boldness levels, and more flexible juvenile behavioral traits categorized as investigating, passive, and escaping. The offspring of bolder adults exhibited more investigating behaviors and were less passive than the offspring of shy adults. Juvenile physical condition was not related to their mortality nor any behavioral traits of either parents or themselves. Lastly, highly investigating and active juveniles with bold parents had significantly lower mortality rates. This shows that interactions between parent personality and juvenile behavioral traits affect a fitness-related component in the life history of individuals. Significance statement The recent surge of interest in consistent individual difference in behavior, also called as animal personality, has already focused on its fitness consequences, but few studies have investigated the interactions between parent and offspring personality, and their ecological consequences. Moreover, this has rarely been studied in wild canids. The arctic fox is a charismatic species showing wide individual variation in behaviors. They live in highly fluctuating tundra ecosystems providing different selection regimes, making it even more eco-evolutionarily intriguing. Yet, few studies looked into behavioral traits and their importance in this system. While introducing simple methods to improve personality research in the wild, we provide a unique example of how variation in both parents and their juveniles collectively works for group dynamics in a cyclic population. This provides a firm basic for understanding behavior-mediated dynamics and opens up broader questions on how fluctuating environments exert varying pressures on individual differences.

  • 3.
    Erlandsson, Rasmus
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Spatial and temporal population dynamics in the mountain tundra – mesopredator and prey2019Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    It is well known that competition, predation and fluctuating food resources can have strong effect on individual fitness and population dynamics. The complexity of natural systems can make it complicate to disentangle those processes, but environments with relatively simple food webs, and strong cyclic population dynamics offer contrasting conditions resembling experimental treatments. This thesis concerns the spatial and temporal implications of fluctuations in small rodent abundance on two trophic levels in a highly cyclic ecosystem, the Scandinavian mountain tundra. The first two chapters focus on plant biomass and spatiotemporal distribution in the Norwegian lemming (Lemmus lemmus), while the three last papers focus on the direct and indirect effects of small rodent fluctuations and territory quality on reproductive success, juvenile survival and group living in a lemming specialist mesopredator, the arctic fox (Vulpes lagopus). By developing, validating and applying a novel application of aerial photos for remote sensing of plant biomass (Chapter I), we found that food availability predicted lemming distribution during population peaks, but that they were more habitat specific during increase years when intraspecific competition was lower (Chapter II). Arctic fox reproduction is tightly connected to small rodent abundance but the effects of geographical variation in food availability is less well known. We used 17 years of population surveys of an arctic fox subpopulation in mid Sweden (Helagsfjällen) to investigate potential effects. During small rodent increase years, we found that arctic fox litter sizes were smaller in territories of intermediate plant productivity, compared to both more and less productive territories (Chapter III). This could be an effect of limited food availability together with increased presence of red foxes (Vulpes vulpes), a stronger and potentially lethal competitor. However, when small rodents peaked, and competition would be expected to decrease, we saw no effect of territory productivity. Based on a smaller data set concerning juvenile summer survival, we found that the mortality rate among juveniles born by first time breeding arctic fox females were more sensitive to low small rodent prey abundance (Chapter IV). We explain it with an increased predation pressure from top-predators that switch from small rodents to alternative prey when small rodents decline, as suggested by an observed positive effect on juvenile survival by adult presence on den sites. Arctic foxes are socially flexible, and several adults can share a den with the resident pair, potentially increasing juvenile survival and help in territorial defence. Returning to the 17-year data set, we tested the Resource Dispersion Hypothesis predicting that increased resource availability should increase group size (Chapter V). We found support for this prediction as group living increased during the small rodent peak phase. However, it remained unexpectedly high during the decrease phase, when resources are scarce. This could however be related to increased predation pressure, and an increasing benefit of group living.

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  • 4.
    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)
  • 5.
    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)
  • 6.
    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.

  • 7.
    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))
  • 8.
    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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  • 9.
    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.

  • 10.
    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.

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