| 1. |
- Andren, Henrik, et al.
(författare)
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Season rather than habitat affects lynx survival and risk of mortality in the human-dominated landscape of southern Sweden
- 2022
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Ingår i: Wildlife Biology. - : Wiley. - 0909-6396 .- 1903-220X. ; 2022
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Tidskriftsartikel (refereegranskat)abstract
- Landscapes are mosaics of habitat associated with different risks and resources, including human activities, which can affect individual survival in wildlife. Different relationships between habitat characteristics and human-caused and natural mortality can result in attractive sinks. We used individual-based data from 97 Eurasian lynx Lynx lynx monitored for 160 exposure-years to link adult survival and the risk of mortality to home range habitat characteristics in the human-dominated landscape of southern Sweden. Human-caused mortality (i.e. legal hunting, poaching and vehicle accidents) dominated mortality causes (24 out of 37 deaths). We did not detect any strong effects of habitat characterises explaining the variation in mortality risk in lynx. Although the density of roe deer affects several aspects of lynx ecology, we could not detect any effects of roe deer density on lynx survival, probably because roe deer density was sufficiently high in our study area. Instead, seasonal variation was the main factor influencing mortality in lynx. Mortality was highest during the hunting season for lynx (16 February-31 March), as well as during autumn and winter, probably because lynx poaching occurs opportunistically during the hunting season for moose and roe deer. We did not find any indication that human activity created attractive sinks for lynx, since there were no contrasting patterns between human-caused and natural mortality in terms of habitat characteristics. One explanation for the limited influence of the home range characteristics may be that lynx in our study died from multiple causes. Therefore, it is less likely that one or a few habitat characteristics could explain the risk of mortality at the home range scale. There is strong evidence that lynx can coexist with humans in multi-use and human-dominated landscapes, even without large protected areas, if the management regimes are favourable.
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| 2. |
- Berteaux, Dominique, et al.
(författare)
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Harmonizing circumpolar monitoring of Arctic fox : benefits, opportunities, challenges and recommendations
- 2017
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Ingår i: Polar Research. - : Norwegian Polar Institute. - 0800-0395 .- 1751-8369. ; 36:suppl. 1
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 3. |
- Cockerill, Christopher Alan, 1994-, et al.
(författare)
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That’s so Last Season: Unraveling the Genomic Cost of fur farming in Arctic Foxes
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Humans have relied on animal fur for thousands of years, yet fur farming only began relatively recently during the mid-19th Century. Little is known of this incipient domestication process or the genomic consequences involved. It is hypothesized that domestication involves processes such as founder effects, population bottlenecks and low population size, which, when combined with intense artificial selection, lead to inbreeding, a limited genepool and reduced fitness. The arctic fox (Vulpes lagopus) is one such species that has been farmed intensively since the early 1900s and has been artificially selected for economic phenotypes. We investigated the origin of these lineages and the genomic consequences of intense farming by comparing the genomes of farmed and wild arctic foxes from across their range. Our research reveals signatures of recent inbreeding through long Runs of Homozygosity (ROH) and reduced genomic variation in Fennoscandian farm foxes relative to the wild Fennoscandian population. We identified a coastal ecotype origin for all farmed arctic foxes, as opposed to the other main, inland, lemming ecotype, placing them phylogenetically close to the wild Icelandic population. The depleted genome-wide heterozygosity and increased recent inbreeding in farm fox lineages is consistent with a heavy cost of domestication, shedding light on the demographic history and genomic consequences of human manipulation. We highlight the need for increased genomic investigations into fur farm populations to understand the incipient domestication process and uncover the cost of intense farming. The genomic consequences of domestication must be considered in the management of fur farm populations, with actionable steps needed to prevent descendants of escaped farm foxes from polluting the gene pool in the wild through introgression.
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| 4. |
- Dalén, Love, et al.
(författare)
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Population history and genetic structure of a circumpolar species : the arctic fox
- 2005
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Ingår i: Biological Journal of the Linnean Society. - : Oxford University Press (OUP). - 0024-4066 .- 1095-8312. ; 84:1, s. 79-89
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Tidskriftsartikel (refereegranskat)abstract
- The circumpolar arctic fox Alopex lagopus thrives in cold climates and has a high migration rate involving long-distance movements. Thus, it differs from many temperate taxa that were subjected to cyclical restriction in glacial refugia during the Ice Ages. We investigated population history and genetic structure through mitochondrial control region variation in 191 arctic foxes from throughout the arctic. Several haplotypes had a Holarctic distribution and no phylogeographical structure was found. Furthermore, there was no difference in haplotype diversity between populations inhabiting previously glaciated and unglaciated regions. This suggests current gene flow among the studied populations, with the exception of those in Iceland, which is surrounded by year-round open water. Arctic foxes have often been separated into two ecotypes: ‘lemming’ and ‘coastal’. An analysis of molecular variance suggested particularly high gene flow among populations of the ‘lemming’ ecotype. This could be explained by their higher migration rate and reduced fitness in migrants between ecotypes. A mismatch analysis indicated a sudden expansion in population size around 118 000 BP, which coincides with the last interglacial. We propose that glacial cycles affected the arctic fox in a way opposite to their effect on temperate species, with interglacials leading to short-term isolation in northern refugia.
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| 5. |
- Ehrich, Dorothee, et al.
(författare)
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Documenting lemming population change in the Arctic : Can we detect trends?
- 2020
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 49:3, s. 786-800
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Tidskriftsartikel (refereegranskat)abstract
- Lemmings are a key component of tundra food webs and changes in their dynamics can affect the whole ecosystem. We present a comprehensive overview of lemming monitoring and research activities, and assess recent trends in lemming abundance across the circumpolar Arctic. Since 2000, lemmings have been monitored at 49 sites of which 38 are still active. The sites were not evenly distributed with notably Russia and high Arctic Canada underrepresented. Abundance was monitored at all sites, but methods and levels of precision varied greatly. Other important attributes such as health, genetic diversity and potential drivers of population change, were often not monitored. There was no evidence that lemming populations were decreasing in general, although a negative trend was detected for low arctic populations sympatric with voles. To keep the pace of arctic change, we recommend maintaining long-term programmes while harmonizing methods, improving spatial coverage and integrating an ecosystem perspective.
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| 6. |
- Gauthier, Gilles, et al.
(författare)
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Taking the beat of the Arctic : are lemming population cycles changing due to winter climate?
- 2024
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : Royal Society. - 0962-8452 .- 1471-2954. ; 291:2016
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Tidskriftsartikel (refereegranskat)abstract
- Reports of fading vole and lemming population cycles and persisting low populations in some parts of the Arctic have raised concerns about the spread of these fundamental changes to tundra food web dynamics. By compiling 24 unique time series of lemming population fluctuations across the circumpolar region, we show that virtually all populations displayed alternating periods of cyclic/non-cyclic fluctuations over the past four decades. Cyclic patterns were detected 55% of the time (n = 649 years pooled across sites) with a median periodicity of 3.7 years, and non-cyclic periods were not more frequent in recent years. Overall, there was an indication for a negative effect of warm spells occurring during the snow onset period of the preceding year on lemming abundance. However, winter duration or early winter climatic conditions did not differ on average between cyclic and non-cyclic periods. Analysis of the time series shows that there is presently no Arctic-wide collapse of lemming cycles, even though cycles have been sporadic at most sites during the last decades. Although non-stationary dynamics appears a common feature of lemming populations also in the past, continued warming in early winter may decrease the frequency of periodic irruptions with negative consequences for tundra ecosystems.
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| 7. |
- Johansson, Örjan, et al.
(författare)
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Identification errors in camera-trap studies result in systematic population overestimation
- 2020
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Reliable assessments of animal abundance are key for successful conservation of endangered species. For elusive animals with individually-unique markings, camera-trap surveys are a benchmark standard for estimating local and global population abundance. Central to the reliability of resulting abundance estimates is the assumption that individuals are accurately identified from photographic captures. To quantify the risk of individual misidentification and its impact on population abundance estimates we performed an experiment under controlled conditions in which 16 captive snow leopards (Panthera uncia) were camera-trapped on 40 occasions and eight observers independently identified individuals and recaptures. Observers misclassified 12.5% of all capture occasions, resulting in systematically inflated population abundance estimates on average by one third (mean +/- SD = 35 +/- 21%). Our results show that identifying individually-unique individuals from camera-trap photos may not be as reliable as previously believed, implying that elusive and endangered species could be less abundant than current estimates indicate.
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| 8. |
- Johansson, Örjan, et al.
(författare)
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Land sharing is essential for snow leopard conservation
- 2016
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Ingår i: Biological Conservation. - : Elsevier BV. - 0006-3207 .- 1873-2917. ; 203, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- Conserving large carnivores in an increasingly crowded planet raises difficult challenges. A recurring debate is whether large carnivores can be conserved in human used landscapes (land sharing) or whether they require specially designated areas (land sparing). Here we show that 40% of the 170 protected areas in the global range of the snow leopard (Panthera uncia) are smaller than the home range of a single adult male and only 4-13% are large enough for a 90% probability of containing 15 or more adult females. We used data from 16 snow leopards equipped with GPS collars in the Tost Mountains of South Gobi, Mongolia, to calculate home range size and overlap using three different estimators: minimum convex polygons (MCP), kernel utility distributions (Kernel), and local convex hulls (LoCoH). Local convex hull home ranges were smaller and included lower proportions of unused habitats compared to home ranges based on minimum convex polygons and Kernels. Intra-sexual home range overlap was low, especially for adult males, suggesting that snow leopards are territorial. Mean home range size based on the LoCoH estimates was 207 km(2) +/- 63 SD for adult males and 124 km(2) +/- 41 SD for adult females. Our estimates were 6-44 times larger than earlier estimates based on VHF technology when comparing similar estimators, i.e. MCP. Our study illustrates that protected areas alone will not be able to conserve predators with large home ranges and conservationists and managers should not restrict their efforts to land sparing. (C) 2016 Elsevier Ltd. All rights reserved.
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| 9. |
- Johansson, Örjan, et al.
(författare)
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Seasonal variation in daily activity patterns of snow leopards and their prey
- 2022
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- The daily and seasonal activity patterns of snow leopards (Panthera uncia) are poorly understood, limiting our ecological understanding and hampering our ability to mitigate threats such as climate change and retaliatory killing in response to livestock predation. We fitted GPS-collars with activity loggers to snow leopards, Siberian ibex (Capra sibirica: their main prey), and domestic goats (Capra hircus: common livestock prey) in Mongolia between 2009 and 2020. Snow leopards were facultatively nocturnal with season-specific crepuscular activity peaks: seasonal activity shifted towards night-sunrise during summer, and day-sunset in winter. Snow leopard activity was in contrast to their prey, which were consistently diurnal. We interpret these results in relation to: (1) darkness as concealment for snow leopards when stalking in an open landscape (nocturnal activity), (2) low-intermediate light preferred for predatory ambush in steep rocky terrain (dawn and dusk activity), and (3) seasonal activity adjustments to facilitate thermoregulation in an extreme environment. These patterns suggest that to minimise human-wildlife conflict, livestock should be corralled at night and dawn in summer, and dusk in winter. It is likely that climate change will intensify seasonal effects on the snow leopard's daily temporal niche for thermoregulation in the future.
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| 10. |
- Johansson, Örjan, et al.
(författare)
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Sex-specific seasonal variation in puma and snow leopard home range utilization
- 2018
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Ingår i: Ecosphere. - : Wiley. - 2150-8925. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Territory size is often larger for males than for females in species without biparental care. For large solitary carnivores, this is explained by males encompassing a set of female territories to monopolize their reproduction during mating (area maximization). However, males are expected to behave more like females outside of breeding, with their area utilization being dependent on the range required to secure food resources (area minimization). To examine how male and female solitary carnivores adjust their spatial organization during the year as key resources (mates and prey) change, we radio-collared 17 pumas (Puma concolor; nine males and eight females) and 14 snow leopards (Panthera uncia; seven males and seven females) and estimated home range size and overlap on two temporal scales (annual vs. monthly). Contrary to expectation, we found no evidence that males monopolized females (the mean territory overlap between females and the focal male during the mating season was 0.28 and 0.64 in pumas and snow leopards, respectively). Although male-male overlap of annual home ranges was comparatively high (snow leopards [0.21] vs. pumas [0.11]), monthly home range overlaps were small (snow leopards [0.02] vs. pumas [0.08]) suggesting strong territoriality. In pumas, both males and females reduced their monthly home ranges in winter, and at the same time, prey distribution was clumped and mating activity increased. In snow leopards, females showed little variation in seasonal home range size, following the seasonal stability in their primary prey. However, male snow leopards reduced their monthly home range utilization in the mating season. In line with other studies, our results suggest that female seasonal home range variation is largely explained by changes in food resource distribution. However, contrary to expectations, male territories did not generally encompass those of females, and males reduced their home ranges during mating. Our results show that male and female territorial boundaries tend to intersect in these species, and hint at the operation of female choice and male mate guarding within these mating systems.
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