| 1. |
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| 2. |
- Angerbjörn, Anders, et al.
(författare)
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Carnivore conservation in practice : replicatedmanagement actions on a large spatial scale
- 2013
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 50:1, s. 59-67
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Tidskriftsartikel (refereegranskat)abstract
- More than a quarter of the world’s carnivores are threatened, often due to multiple andcomplex causes. Considerable research efforts are devoted to resolving the mechanisms behindthese threats in order to provide a basis for relevant conservation actions. However, evenwhen the underlying mechanisms are known, specific actions aimed at direct support for carnivoresare difficult to implement and evaluate at efficient spatial and temporal scales.2. We report on a 30-year inventory of the critically endangered Fennoscandian arctic foxVulpes lagopus L., including yearly surveys of 600 fox dens covering 21 000 km2. These surveysshowed that the population was close to extinction in 2000, with 40–60 adult animalsleft. However, the population subsequently showed a fourfold increase in size.3. During this time period, conservation actions through supplementary feeding and predatorremoval were implemented in several regions across Scandinavia, encompassing 79% of thearea. To evaluate these actions, we examined the effect of supplemental winter feeding andred fox control applied at different intensities in 10 regions. A path analysis indicated that47% of the explained variation in population productivity could be attributed to lemmingabundance, whereas winter feeding had a 29% effect and red fox control a 20% effect.4. This confirms that arctic foxes are highly dependent on lemming population fluctuationsbut also shows that red foxes severely impact the viability of arctic foxes. This study also highlightsthe importance of implementing conservation actions on extensive spatial and temporalscales, with geographically dispersed actions to scientifically evaluate the effects. We note thatpopulation recovery was only seen in regions with a high intensity of management actions.5. Synthesis and applications. The present study demonstrates that carnivore populationdeclines may be reversed through extensive actions that target specific threats. Fennoscandianarctic fox is still endangered, due to low population connectivity and expected climate impactson the distribution and dynamics of lemmings and red foxes. Climate warming is expected tocontribute to both more irregular lemming dynamics and red fox appearance in tundra areas;however, the effects of climate change can be mitigated through intensive managementactions such as supplemental feeding and red fox control.
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| 3. |
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| 4. |
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| 5. |
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| 6. |
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| 7. |
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| 8. |
- Bergqvist, Göran, et al.
(författare)
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Effects of female body mass and climate on reproduction in northern wild boar
- 2018
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Ingår i: Wildlife Biology. - : Wiley. - 0909-6396 .- 1903-220X.
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Tidskriftsartikel (refereegranskat)abstract
- Mammalian life history strategies depend on climate conditions. Hence, reproductive parameters may vary regionally, and knowledge on such patterns are important for sustainable management. Wild boar research has been biased towards south and central Europe. Here we investigate the effects of mother's carcass mass, season and climate (summer temperature and precipitation as well as January temperature) on pregnancy rate and litter size in 601 free-ranging female wild boar from hemiboreal Sweden, close to the north border of wild boar distribution range in Europe. Pregnancy rate was on average 33.4 +/- 1.94% (mean +/- SE), whereas average litter size of pregnant females was 4.7 +/- 0.12. Pregnancy rate was highest during the seasonal reproduction peak in winter and spring, and both pregnancy rate and litter size increased significantly with increasing female body mass. The probability of a female being pregnant exceeded 50% when carcass mass exceeded 58 kg, equivalent to a live mass of 113 kg, and litter size increased by one for each 16 kg increase in female carcass mass. We found no significant effects of temporal variations in climate, and suggest that such variations were not sufficiently large to affect wild boar reproduction. Alternatively, the reproductive strategy of wild boar may be adjusted to prevailing regional climate conditions. In that case, other life history traits, such as mortality, may be more sensitive to short-term climate fluctuations. Wild boar management needs to take temporal variations in reproduction, as well as in resource availability, into consideration when deciding on prudent management actions.
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| 9. |
- Dalén, Love, et al.
(författare)
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DNA analysis on fox faeces and competition induced niche shifts
- 2004
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Ingår i: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 13:8, s. 2389-2392
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Tidskriftsartikel (refereegranskat)abstract
- Interference competition can force inferior competitors to change their distribution patterns. It is, however, possible that the dominant competitor poses a higher threat during certain times of the year, for example during reproduction. In such cases, the inferior competitor is expected to change its distribution accordingly. We used a molecular species identification method on faeces to investigate how the spatial overlap between arctic and red foxes changes between seasons. The results show that arctic and red foxes are sympatric during winter, but allopatric in summer as arctic foxes retreat to higher altitudes further from the tree-line during the breeding season
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| 10. |
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| 11. |
- Dalén, Love, et al.
(författare)
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Population structure in a critically endangered arctic fox population : does genetics matter?
- 2006
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Ingår i: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 15:10, s. 2809-2819
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Tidskriftsartikel (refereegranskat)abstract
- The arctic fox (Alopex lagopus) in Scandinavia is classified as critically endangered after having gone through a severe decline in population size in the beginning of the 20th century, from which it has failed to recover despite more than 65 years of protection. Arctic foxes have a high dispersal rate and often disperse over long distances, suggesting that there was probably little population differentiation within Scandinavia prior to the bottleneck. It is, however, possible that the recent decline in population size has led to a decrease in dispersal and an increase in population fragmentation. To examine this, we used 10 microsatellite loci to analyse genetic variation in 150 arctic foxes from Scandinavia and Russia. The results showed that the arctic fox in Scandinavia presently is subdivided into four populations, and that the Kola Peninsula and northwest Russia together form a large fifth population. Current dispersal between the populations seemed to be very low, but genetic variation within them was relatively high. This and the relative F-ST values among the populations are consistent with a model of recent fragmentation within Scandinavia. Since the amount of genetic variation is high within the populations, but the populations are small and isolated, demographic stochasticity seems to pose a higher threat to the populations' persistence than inbreeding depression and low genetic variation.
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| 12. |
- Dalerum, Fredrik, et al.
(författare)
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Distribution, morphology and use of arctic fox dens in Sweden
- 2002
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Ingår i: Wildlife Biology. ; 8:3, s. 185-192
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Tidskriftsartikel (refereegranskat)abstract
- Seventy-seven arctic fox dens in Vindelfjällen, Northern Sweden, are described with regard to distribution, morphology and fox use. The density of dens in the area was 1 den / 21 km2 and dens were more spaced than random. The dens were situated at a mean altitude ( sd) of 915 74 m.a.s.l., were on average 3.5 1.88 km from nearest tree line, had a mean number of 44 32 den openings and a mean area of 277 237 m2. During the 21 year study period, 31 dens were used by arctic foxes and 10 by red foxes. Number of den openings, den area, altitude and distance to nearest tree line explained 36 % of arctic fox den use (p < 0.001) and 21 % of red foxes use of arctic fox dens during the study period (p = 0.01). Arctic foxes used dens at higher altitude (p = 0.03) and further away from forest than red foxes did (p = 0.03), and tended to breed in dens with more den openings (p = 0.08). Arctic foxes used some breeding dens more frequently than others (p = 0.002). Among the breeding dens, both den use and litter size were positively related to den area (den use: p = 0.04; litter size: p < 0.001). Successful breeding dens for arctic foxes in Sweden thus appear to be characterised by large size and many openings, and they are situated far away from forest at relatively high altitudes.
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| 13. |
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| 14. |
- Elmhagen, Bodil, et al.
(författare)
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A boreal invasion in response to climate change? : Range shifts and community effects in the borderland between forest and tundra
- 2015
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 44:1, s. 39-50
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 15. |
- Elmhagen, Bodil, 1973-, et al.
(författare)
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Changes in vole and lemming fluctuations in northern Sweden 1960-2008 revealed by fox dynamics
- 2011
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Ingår i: Annales Zoologici Fennici. - : Finnish Zoological and Botanical Publishing Board. - 0003-455X .- 1797-2450. ; 48:3, s. 167-179
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 16. |
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| 17. |
- Elmhagen, Bodil, et al.
(författare)
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Food-niche overlap between arctic and red foxes
- 2002
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Ingår i: Canadian Journal of Zoology. - 0008-4301 .- 1480-3283. ; 80, s. 1274-1285
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 18. |
- Elmhagen, Bodil, et al.
(författare)
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From breeding pairs to fox towns : the social organisation of arctic fox populations with stable and fluctuating availability of food
- 2014
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Ingår i: Polar Biology. - : Springer Science and Business Media LLC. - 0722-4060 .- 1432-2056. ; 37:1, s. 111-122
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 19. |
- Elmhagen, Bodil, et al.
(författare)
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Homage to Hersteinsson and Macdonald : climate warming and resource subsidies cause red fox range expansion and Arctic fox decline
- 2017
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Ingår i: Polar Research. - : Norwegian Polar Institute. - 0800-0395 .- 1751-8369. ; 36:suppl. 1
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Forskningsöversikt (refereegranskat)abstract
- Climate change can have a marked effect on the distribution and abundance of some species, as well as their interspecific interactions. In 1992, before ecological effects of anthropogenic climate change had developed into a topical research field, Hersteinsson and Macdonald published a seminal paper hypothesizing that the northern distribution limit of the red fox (Vulpes vulpes) is determined by food availability and ultimately climate, while the southern distribution limit of the Arctic fox (Vulpes lagopus) is determined by interspecific competition with the larger red fox. This hypothesis has inspired extensive research in several parts of the circumpolar distribution range of the Arctic fox. Over the past 25 years, it was shown that red foxes can exclude Arctic foxes from dens, space and food resources, and that red foxes kill and sometimes consume Arctic foxes. When the red fox increases to ecologically effective densities, it can cause Arctic fox decline, extirpation and range contraction, while conservation actions involving red fox culling can lead to Arctic fox recovery. Red fox advance in productive tundra, concurrent with Arctic fox retreat from this habitat, support the original hypothesis that climate warming will alter the geographical ranges of the species. However, recent studies show that anthropogenic subsidies also drive red fox advance, allowing red fox establishment north of its climate-imposed distribution limit. We conclude that synergies between anthropogenic subsidies and climate warming will speed up Arctic ecosystem change, allowing mobile species to establish and thrive in human-provided refugia, with potential spill-over effects in surrounding ecosystems.
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| 20. |
- Elmhagen, Bodil, et al.
(författare)
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Implications of climate and land-use change for landscape processes, biodiversity, ecosystem services, and governance
- 2015
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 44, s. s1-S5
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Tidskriftsartikel (refereegranskat)abstract
- This introduction to the Special Issue summarizes the results of 14 scientific articles from the interdisciplinary research program Ekoklim at Stockholm University, Sweden. In this program, we investigate effects of changing climate and land use on landscape processes, biodiversity, and ecosystem services, and analyze issues related to adaptive governance in the face of climate and land-use change. We not only have a research focus on the 22 650 km(2) Norrstrom catchment surrounding lake Malaren in south-central Sweden, but we also conduct research in other Swedish regions. The articles presented here show complex interactions between multiple drivers of change, as well as feedback processes at different spatiotemporal scales. Thus, the Ekoklim program highlights and deals with issues relevant for the future challenges society will face when land-use change interacts with climate change.
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| 21. |
- Elmhagen, Bodil, et al.
(författare)
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Interacting effects of change in climate, human population, land use, and water use on biodiversity and ecosystem services
- 2015
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Ingår i: Ecology and Society. - 1708-3087. ; 20:1
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Tidskriftsartikel (refereegranskat)abstract
- Human population growth and resource use, mediated by changes in climate, land use, and water use, increasingly impact biodiversity and ecosystem services provision. However, impacts of these drivers on biodiversity and ecosystem services are rarely analyzed simultaneously and remain largely unknown. An emerging question is how science can improve the understanding of change in biodiversity and ecosystem service delivery and of potential feedback mechanisms of adaptive governance. We analyzed past and future change in drivers in south-central Sweden. We used the analysis to identify main research challenges and outline important research tasks. Since the 19th century, our study area has experienced substantial and interlinked changes; a 1.6 degrees C temperature increase, rapid population growth, urbanization, and massive changes in land use and water use. Considerable future changes are also projected until the mid-21st century. However, little is known about the impacts on biodiversity and ecosystem services so far, and this in turn hampers future projections of such effects. Therefore, we urge scientists to explore interdisciplinary approaches designed to investigate change in multiple drivers, underlying mechanisms, and interactions over time, including assessment and analysis of matching-scale data from several disciplines. Such a perspective is needed for science to contribute to adaptive governance by constantly improving the understanding of linked change complexities and their impacts.
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| 22. |
- Elmhagen, Bodil, 1973-
(författare)
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Interference competition between arctic and red foxes.
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, I investigate the relationship between arctic foxes Alopex lagopus and red foxes Vulpes vulpes in Swedish mountain tundra habitat (fjällen). The arctic fox population was severely reduced by hunting in the early 20th century. It has not recovered despite protection since 1928 and it is endangered, while the red fox population increased in 1930-1960.I found a high food niche overlap between arctic and red foxes and they responded similarly to changes in the prey base, indicating similar prey preferences. Hence, arctic and red foxes should compete for the same territories; more precisely the ones in low altitude areas close to the tree-line where prey abundance is relatively high. In the 19th century, arctic foxes bred in all tundra habitats. An analysis of present den use showed that arctic foxes have retreated to higher altitudes as they rarely used the lower parts of their former range. Instead, red foxes did. Arctic foxes were highly dependent on the availability of Norwegian lemmings Lemmus lemmus for reproduction, while red foxes at lower altitudes had better access to alternative prey.Interference competition imply that there are behavioural interactions between competing species, e.g. fighting or predation, but interactions can also be more subtle and imply that inferior species avoid encounters with stronger competitors by changing their habitat use. Red foxes are larger than arctic foxes. Hence, they have an advantage in direct fights and arctic foxes may either be driven away from their dens when red foxes establish in the vicinity, or they avoid habitats where they risk encounters with red foxes. I found that arctic foxes almost exclusively used dens situated farther than 8 km from inhabited red fox dens. In two out of three cases when they bred closer to red foxes, there was red fox predation on arctic fox cubs. Further, simulations of arctic fox avoidance of areas surrounding inhabited red fox dens in a spatially explicit population model, indicated that relatively small numbers of red foxes might have a large impact on arctic fox population size and distribution.Thus, the results of this thesis indicate that interference competition with red foxes has hampered arctic fox recovery after the initial population decline, by causing a substantial reduction in arctic fox habitat. Further, red foxes have taken over the most productive areas and remaining arctic fox habitats is of such low quality that it is uncertain whether it can maintain even a small arctic fox population.
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| 23. |
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| 24. |
- Elmhagen, Bodil, et al.
(författare)
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The arctic fox (Alopex lagopus) : an opportunistic specialist.
- 2000
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Ingår i: Journal of Zoology. - : Wiley. - 0952-8369 .- 1469-7998. ; 251:2, s. 139-149
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 25. |
- Elmhagen, Bodil, 1973-, et al.
(författare)
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Top predators, mesopredators and their prey : interference ecosystems along bioclimatic productivity gradients
- 2010
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Ingår i: Journal of Animal Ecology. - : Wiley. - 0021-8790 .- 1365-2656. ; 79:4, s. 785-794
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Tidskriftsartikel (refereegranskat)abstract
- 1. The Mesopredator Release Hypothesis (MRH) suggests that top predator suppression of mesopredators is a key ecosystem function with cascading impacts on herbivore prey, but it remains to be shown that this top-down cascade impacts the large-scale structure of ecosystems.2. The Exploitation Ecosystems Hypothesis (EEH) predicts that regional ecosystem structures are determined by top-down exploitation and bottom-up productivity. In contrast to MRH, EEH assumes that interference among predators has a negligible impact on the structure of ecosystems with three trophic levels.3. We use the recolonisation of a top predator in a three-level boreal ecosystem as a natural experiment to test if large-scale biomass distributions and population trends support MRH. Inspired by EEH, we also test if top-down interference and bottom-up productivity impact regional ecosystem structures.4. We use data from the Finnish Wildlife Triangle Scheme which has monitored top predator (lynx Lynx lynx), mesopredator (red fox Vulpes vulpes) and prey (mountain hare Lepus timidus) abundance for 17 years in a 200 000 km2 study area which covers a distinct productivity gradient.5. Fox biomass was lower than expected from productivity where lynx biomass was high, while hare biomass was lower than expected from productivity where fox biomass was high. Hence, where interference controlled fox abundance, lynx had an indirect positive impact on hare abundance as predicted by MRH. The rates of change indicated that lynx expansion gradually suppressed fox biomass.6. Lynx status caused shifts between ecosystem structures. In the “interference ecosystem”, lynx and hare biomass increased with productivity whilst fox biomass did not. In the “mesopredator release ecosystem”, fox biomass increased with productivity but hare biomass did not. Thus, biomass controlled top-down did not respond to changes in productivity. This fulfils a critical prediction of EEH.7. We conclude that the cascade involving top predators, mesopredators and their prey can determine large-scale biomass distribution patterns and regional ecosystem structures. Hence, interference within trophic levels has to be taken into account to understand how terrestrial ecosystem structures are shaped.
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