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Wilkinson, C., Vigués, J., Stoessel, M., Vinka, M., Angerbjörn, A. & Norén, K. (2024). Phase-dependent red fox expansion into the tundra: implications for management. Journal of Wildlife Management, 88(4), Article ID e22569.
Open this publication in new window or tab >>Phase-dependent red fox expansion into the tundra: implications for management
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2024 (English)In: Journal of Wildlife Management, ISSN 0022-541X, E-ISSN 1937-2817, Vol. 88, no 4, article id e22569Article in journal (Refereed) Published
Abstract [en]

Expansion of boreal species into tundra ecosystems is a consequence of climate change and human exploitation that threatens local species through increased predation, competition, and pathogen transmission. Under these circumstances, efficient control of expanding boreal species may be necessary, but the efficiency of such action depends on understanding the ecological influences of expansion. The red fox (Vulpes vulpes) is expanding into the tundra across the Arctic. In Scandinavia, red foxes threaten local tundra species and communities including the endangered Arctic fox (V. lagopus). The ecological dynamics in the tundra are influenced by small rodent cycles (classified into different phases based on seasonal abundance fluctuations), which can affect red fox expansion, distribution, and abundance. We used a 17-year (2004–2020) dataset from the tundra in Sweden, consisting of raw snow track data, to test how cyclic prey influenced red fox distribution and abundance, and subsequently red fox control. The winter abundance of red fox was influenced by small rodent phase, with higher abundance during high prey availability (i.e., increased number of prey numbers) with no support for a time lag between red fox and small rodent abundance. This suggests that high prey availability attracts red foxes to the tundra and that higher immigration from the boreal zone can be expected in response to increased prey abundances. There was no relationship between red fox control and small rodent availability, but control was influenced by red fox abundance during the previous year, which highlights an opportunistic control strategy. We recommend an adaptive management strategy where authorities include small rodent dynamics in the planning and execution of red fox control.

Keywords
boreal invasion, control strategies, rodent cycle, Vulpes vulpes
National Category
Zoology Ecology
Identifiers
urn:nbn:se:su:diva-227797 (URN)10.1002/jwmg.22569 (DOI)001175584100001 ()2-s2.0-85186604095 (Scopus ID)
Available from: 2024-04-10 Created: 2024-04-10 Last updated: 2024-04-29Bibliographically approved
Wallén, J., Norén, K., Angerbjörn, A., Eide, N. E., Landa, A. & Flagstad, Ø. (2023). Context-dependent demographic and genetic effects of translocation from a captive breeding project. Animal Conservation, 26(3), 412-423
Open this publication in new window or tab >>Context-dependent demographic and genetic effects of translocation from a captive breeding project
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2023 (English)In: Animal Conservation, ISSN 1367-9430, E-ISSN 1469-1795, Vol. 26, no 3, p. 412-423Article in journal (Refereed) Published
Abstract [en]

Translocations are a widespread approach to conserve threatened populations. Given the rapid decline and genetic deterioration of many natural populations, translocations are expected to become even more common in the future. The success of translocations is, however, dependent on multiple context-dependent factors, such as demographic and genetic status, habitat quality and animal behaviour. The Scandinavian arctic fox (Vulpes lagopus) exists in a small, fragmented population that is demographically vulnerable and exposed to inbreeding depression. In the early 2000 s, releases of arctic foxes from the Norwegian Captive Breeding Programme were initiated with the purpose of reintroducing populations to formerly inhabited areas and promoting connectivity. Since 2008/2009, 61 foxes have been released in Junkeren, Norway to re-establish an unoccupied area. We used a combination of field observations and microsatellite genotyping from the release site and two neighbouring subpopulations to investigate (i) the probability of establishment and reproduction for released foxes at the release site and in neighbouring subpopulations, and (ii) the impact on litter size and genetic composition in the recipient populations. Results showed that 18% of the released foxes were established at the release site, or in neighbouring subpopulations and 11.5% reproduced successfully. The extent of post-release dispersal into neighbouring subpopulations was also relatively high (11.5%). During the study period, the number of litters more than doubled in the subpopulations with released foxes contributing 29.5% to this increase, but no clear effect of immigration on litter size was found. There was a slight increase in genetic variation in one of the subpopulations, and a significant decline in genetic divergence between subpopulations. We conclude that despite extensive releases, demographic and genetic effects were highly context-dependent. This study highlights the challenges of reinforcement programmes in small populations and reintroductions to unoccupied sites, especially for highly mobile species in a fragmented landscape. 

Keywords
conservation, immigration, translocation, genetic variation, demography, arctic fox, Vulpes lagopus, captive breeding, conservation breeding
National Category
Genetics Zoology Ecology
Identifiers
urn:nbn:se:su:diva-213112 (URN)10.1111/acv.12831 (DOI)000888793400001 ()2-s2.0-85142366898 (Scopus ID)
Available from: 2022-12-21 Created: 2022-12-21 Last updated: 2023-09-28Bibliographically approved
Vigués, J., Norén, K., Wilkinson, C., Stoessel, M., Angerbjörn, A. & Dalerum, F. (2022). Abundance, predation, and habitat associations of lemming winter nests in northern Sweden. Ecosphere, 13(6), Article ID e4140.
Open this publication in new window or tab >>Abundance, predation, and habitat associations of lemming winter nests in northern Sweden
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2022 (English)In: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 13, no 6, article id e4140Article in journal (Refereed) Published
Abstract [en]

Spatially synchronous fluctuations of animal populations have profound ecological consequences, especially in northern latitudes. Spatially coupled fluctuations are often seen in small rodent populations, albeit with local and regional variations. While both resource limitation and predation influence rodent dynamics, their relative importance for generating spatial variation is less clear, particularly during winter. In this study, we quantify spatial variation in winter abundance of the Norwegian lemming (Lemmus lemmus) across three ecologically connected mountain areas in northern Sweden and evaluate whether the relative strength of bottom-up and top-down regulation influences such variation. Our data included observations of predated and nonpredated winter nests as well as environmental characteristics of nest locations and nest predation. While the direction of annual changes in lemming nest abundance was perfectly synchronized among the three areas, there were differences in nest abundance, potentially caused by contrasting amplitudes of temporal fluctuations in lemming winter populations. Mustelid predation was positively associated with decreasing lemming populations but did not differ in occurrence among the three areas. Lemming nests were predominantly observed in meadows, whereas areas prone to flooding and close to the tree line were underrepresented. Mustelid predation was most common close to the tree line, but not associated with geomorphological characteristics related to snow depth. We suggest that the observed differences in lemming winter abundances were caused by variations in the relative strength of bottom-up and top-down regulation in the three mountain areas. We encourage further studies evaluating how the relative strength of different processes influence local population regulation, and how such processes influence spatial variation in animal population dynamics at different spatial scales.

Keywords
microtine rodents, Norwegian lemming, population cycles, population synchrony, spatial variation
National Category
Biological Sciences
Identifiers
urn:nbn:se:su:diva-207420 (URN)10.1002/ecs2.4140 (DOI)000814111900001 ()
Available from: 2022-07-27 Created: 2022-07-27 Last updated: 2022-07-27Bibliographically approved
Zimova, M., Moberg, D., Mills, L. S., Dietz, A. J. & Angerbjörn, A. (2022). Colour moult phenology and camouflage mismatch in polymorphic populations of Arctic foxes. Biology Letters, 18(11), Article ID 20220334.
Open this publication in new window or tab >>Colour moult phenology and camouflage mismatch in polymorphic populations of Arctic foxes
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2022 (English)In: Biology Letters, ISSN 1744-9561, E-ISSN 1744-957X, Vol. 18, no 11, article id 20220334Article in journal (Refereed) Published
Abstract [en]

Species that seasonally moult from brown to white to match snowy backgrounds become conspicuous and experience increased predation risk as snow cover duration declines. Long-term adaptation to camouflage mismatch in a changing climate might occur through phenotypic plasticity in colour moult phenology and or evolutionary shifts in moult rate or timing. Also, adaptation may include evolutionary shifts towards winter brown phenotypes that forgo the winter white moult. Most studies of these processes have occurred in winter white populations, with little attention to polymorphic populations with sympatric winter brown and winter white morphs. Here, we used remote camera traps to record moult phenology and mismatch in two polymorphic populations of Arctic foxes in Sweden over 2 years. We found that the colder, more northern population moulted earlier in the autumn and later in the spring. Next, foxes moulted earlier in the autumn and later in the spring during colder and snowier years. Finally, white foxes experienced relatively low camouflage mismatch while blue foxes were mismatched against snowy backgrounds most of the autumn through the spring. Because the brown-on-white mismatch imposes no evident costs, we predict that as snow duration decreases, increasing blue morph frequencies might help facilitate species persistence.

Keywords
arctic fox, camouflage, climate change, phenological mismatch, seasonal moult, snow cover
National Category
Biological Sciences
Identifiers
urn:nbn:se:su:diva-212594 (URN)10.1098/rsbl.2022.0334 (DOI)000885609900004 ()36382371 (PubMedID)2-s2.0-85141974088 (Scopus ID)
Available from: 2022-12-13 Created: 2022-12-13 Last updated: 2022-12-13Bibliographically approved
Barrio, I. C., Angerbjörn, A. & Jónsdóttir, I. S. (2022). Developing common protocols to measure tundra herbivory across spatial scales. Arctic Science, 8(3), 638-679
Open this publication in new window or tab >>Developing common protocols to measure tundra herbivory across spatial scales
2022 (English)In: Arctic Science, ISSN 2368-7460, Vol. 8, no 3, p. 638-679Article in journal (Refereed) Published
Abstract [en]

Understanding and predicting large-scale ecological responses to global environmental change requires comparative studies across geographic scales with coordinated efforts and standardized methodologies. We designed, applied, and assessed standardized protocols to measure tundra herbivory at three spatial scales: plot, site (habitat), and study area (landscape). The plot-and site-level protocols were tested in the field during summers 2014–2015 at 11 sites, nine of them consisting of warming experimental plots included in the International Tundra Experiment (ITEX). The study area protocols were assessed during 2014–2018 at 24 study areas across the Arctic. Our protocols provide comparable and easy to implement methods for assessing the intensity of invertebrate herbivory within ITEX plots and for characterizing vertebrate herbivore communities at larger spatial scales. We discuss methodological constraints and make recommendations for how these protocols can be used and how sampling effort can be optimized to obtain comparable estimates of herbivory, both at ITEX sites and at large landscape scales. The application of these protocols across the tundra biome will allow characterizing and comparing herbivore communities across tundra sites and at ecologically relevant spatial scales, providing an important step towards a better understanding of tundra ecosystem responses to large-scale environmental change. 

Keywords
ecological monitoring, Herbivory Network, Interactions Working Group (IWG), International Tundra Experiment (ITEX), standardized protocol
National Category
Ecology
Identifiers
urn:nbn:se:su:diva-212048 (URN)10.1139/as-2020-0020 (DOI)000928440900005 ()2-s2.0-85117316995 (Scopus ID)
Available from: 2022-12-01 Created: 2022-12-01 Last updated: 2023-03-14Bibliographically approved
Cockerill, C. A., Hasselgren, M., Dussex, N., Dalén, L., von Seth, J., Angerbjörn, A., . . . Norén, K. (2022). Genomic Consequences of Fragmentation in the Endangered Fennoscandian Arctic Fox (Vulpes lagopus). Genes, 13(11), Article ID 2124.
Open this publication in new window or tab >>Genomic Consequences of Fragmentation in the Endangered Fennoscandian Arctic Fox (Vulpes lagopus)
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2022 (English)In: Genes, E-ISSN 2073-4425, Vol. 13, no 11, article id 2124Article in journal (Refereed) Published
Abstract [en]

Accelerating climate change is causing severe habitat fragmentation in the Arctic, threatening the persistence of many cold-adapted species. The Scandinavian arctic fox (Vulpes lagopus) is highly fragmented, with a once continuous, circumpolar distribution, it struggled to recover from a demographic bottleneck in the late 19th century. The future persistence of the entire Scandinavian population is highly dependent on the northernmost Fennoscandian subpopulations (Scandinavia and the Kola Peninsula), to provide a link to the viable Siberian population. By analyzing 43 arctic fox genomes, we quantified genomic variation and inbreeding in these populations. Signatures of genome erosion increased from Siberia to northern Sweden indicating a stepping-stone model of connectivity. In northern Fennoscandia, runs of homozygosity (ROH) were on average ~1.47-fold longer than ROH found in Siberia, stretching almost entire scaffolds. Moreover, consistent with recent inbreeding, northern Fennoscandia harbored more homozygous deleterious mutations, whereas Siberia had more in heterozygous state. This study underlines the value of documenting genome erosion following population fragmentation to identify areas requiring conservation priority. With the increasing fragmentation and isolation of Arctic habitats due to global warming, understanding the genomic and demographic consequences is vital for maintaining evolutionary potential and preventing local extinctions.

Keywords
inbreeding, runs of homozygosity, bottleneck, fragmentation, mutational load, conservation
National Category
Biological Sciences
Identifiers
urn:nbn:se:su:diva-212504 (URN)10.3390/genes13112124 (DOI)000895270100001 ()
Available from: 2022-12-08 Created: 2022-12-08 Last updated: 2024-04-30Bibliographically approved
Erlandsson, R., Hasselgren, M., Norén, K., Macdonald, D. & Angerbjörn, A. (2022). Resources and predation: drivers of sociality in a cyclic mesopredator. Oecologia, 198(2), 381-392
Open this publication in new window or tab >>Resources and predation: drivers of sociality in a cyclic mesopredator
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2022 (English)In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 198, no 2, p. 381-392Article in journal (Refereed) Published
Abstract [en]

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

Keywords
Cooperative defence, Group-living, Group size, Intra-guild predation, Resource dispersion
National Category
Biological Sciences
Identifiers
urn:nbn:se:su:diva-202387 (URN)10.1007/s00442-022-05107-w (DOI)000749950700003 ()35112174 (PubMedID)
Available from: 2022-03-03 Created: 2022-03-03 Last updated: 2022-03-03Bibliographically approved
Ahlgren, H., Bro-Jørgensen, M. H., Glykou, A., Schmölcke, U., Angerbjorn, A., Olsen, M. T. & Lidén, K. (2022). The Baltic grey seal: A 9000-year history of presence and absence. The Holocene, 32(6), 569-577
Open this publication in new window or tab >>The Baltic grey seal: A 9000-year history of presence and absence
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2022 (English)In: The Holocene, ISSN 0959-6836, E-ISSN 1477-0911, Vol. 32, no 6, p. 569-577Article in journal (Refereed) Published
Abstract [en]

The grey seal (Halichoerus grypus) has been part of the Baltic Sea fauna for more than 9000 years and has ever since been subjected to extensive human hunting, particularly during the early phases of its presence in the Baltic Sea, but also in the early 20th century. In order to study their temporal genetic structure and to investigate whether there has been a genetically continuous grey seal population in the Baltic, we generated mitochondrial control region data from skeletal remains from ancient grey seals from the archaeological sites Stora Förvar (Sweden) and Neustadt (Germany) and compared these with modern grey seal data. We found that the majority of the Mesolithic grey seals represent haplotypes that is not found in contemporary grey seals, indicating that the Baltic Sea population went extinct, likely due to human overexploitation and environmental change. We hypothesize that grey seals recolonised the Baltic Sea from the North Sea. during the Bronze Age or Iron Age, and that the contemporary Baltic grey seal population is direct descendants of this recolonisation. Our study highlights the power of biomolecular archaeology to understand the factors that shape contemporary marine diversity. 

Keywords
aDNA, Baltic Sea, extirpation, Grey Seal, hunting, mitogenomes
National Category
Archaeology Genetics
Research subject
Archaeological Science; Genetics
Identifiers
urn:nbn:se:su:diva-189304 (URN)10.1177/09596836221080764 (DOI)000765316900001 ()2-s2.0-85126047611 (Scopus ID)
Funder
EU, Horizon 2020, 676154
Available from: 2021-01-19 Created: 2021-01-19 Last updated: 2022-06-08Bibliographically approved
Vigués, J., Menci, S., Wilkinson, C., Le Vaillant, M., Angerbjörn, A. & Norén, K. (2021). A beacon of dung: using lemming (Lemmus lemmus) winter nests and DNA analysis of faeces to further understand predator-prey dynamics in Northern Sweden. Polar Biology, 44(12), 2269-2276
Open this publication in new window or tab >>A beacon of dung: using lemming (Lemmus lemmus) winter nests and DNA analysis of faeces to further understand predator-prey dynamics in Northern Sweden
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2021 (English)In: Polar Biology, ISSN 0722-4060, E-ISSN 1432-2056, Vol. 44, no 12, p. 2269-2276Article in journal (Refereed) Published
Abstract [en]

The hypothesis that predation is the cause of the regular small rodent population oscillations observed in boreal and Arctic regions has long been debated. Within this hypothesis, it is proposed that the most likely predators to cause these destabilizing effects are sedentary specialists, with small mustelids being possible candidates. One such case would be the highly specialized least weasel (Mustela nivalis) driving the Norwegian lemming (Lemmus lemmus) cycle in Fennoscandia. These predators are often elusive and therefore distribution data can only be based on field signs, which is problematic when various mustelid species are sympatric, such as weasels and stoats (Mustela erminea). Here we present the results of using mustelid faeces in predated winter lemming nests to correctly identify the predator and thus discern which species exerts the strongest predation pressure on lemming winter populations. Samples were obtained during different phases in the lemming cycle, spanning 6 years, to account for different prey densities. Faecal mitochondrial DNA extraction and amplification of a 400-bp fragment was successful in 92/114 samples (81%); the sequencing of these samples proved that most predation occurrences (83%) could be attributed to the least weasel. These findings support the hypothesis that weasels in particular show high specificity in predation and could therefore be candidates to driving the lemming cycle in this area. We conclude that DNA analysis of faecal remains around predated nests can be a useful tool for further investigations concerning predator-prey interactions in the tundra.

Keywords
Mustelid, Norwegian lemming, Rodent cycles, Faecal DNA, Non-invasive genetic sampling
National Category
Biological Sciences
Identifiers
urn:nbn:se:su:diva-200131 (URN)10.1007/s00300-021-02958-6 (DOI)000714317500001 ()
Available from: 2021-12-28 Created: 2021-12-28 Last updated: 2022-03-23Bibliographically approved
Meyer, N., Bollache, L., Galipaud, M., Moreau, J., Dechaume-Moncharmont, F.-X., Afonso, E., . . . Gilg, O. (2021). Behavioural responses of breeding arctic sandpipers to ground-surface temperature and primary productivity. Science of the Total Environment, 755, Article ID 142485.
Open this publication in new window or tab >>Behavioural responses of breeding arctic sandpipers to ground-surface temperature and primary productivity
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2021 (English)In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 755, article id 142485Article in journal (Refereed) Published
Abstract [en]

Most birds incubate their eggs, which requires time and energy at the expense of other activities. Birds generally have two incubation strategies: biparental where both mates cooperate in incubating eggs, and uniparental where a single parent incubates. In harsh and unpredictable environments, incubation is challenging due to high energetic demands and variable resource availability. We studied the relationships between the incubation behaviour of sandpipers (genus Calidris) and two environmental variables: temperature and a proxy of primary productivity (i.e. NDVI). We investigated how these relationships vary between incubation strategies and across species among strategies. We also studied how the relationship between current temperature and incubation behaviour varies with previous day's temperature. We monitored the incubation behaviour of nine sandpiper species using thermologgers at 15 arctic sites between 2016 and 2019. We also used thermologgers to record the ground surface temperature at conspecific nest sites and extracted NDVI values from a remote sensing product. We found no relationship between either environmental variables and biparental incubation behaviour. Conversely, as ground-surface temperature increased, uniparental species decreased total duration of recesses (TDR) and mean duration of recesses (MDR), but increased number of recesses (NR). Moreover, small species showed stronger relationships with ground-surface temperature than large species. When all uniparental species were combined, an increase in NDVI was correlated with higher mean duration, total duration and number of recesses, but relationships varied widely across species. Finally, some uniparental species showed a lag effect with a higher nest attentiveness after a warm day while more recesses occurred after a cold day than was predicted based on current temperatures. We demonstrate the complex interplay between shorebird incubation strategies, incubation behaviour, and environmental conditions. Understanding how species respond to changes in their environment during incubation helps predict their future reproductive success.

Keywords
Incubation strategy, Incubation recesses, Lag effects, NDVI, Incubation behaviour, Environmental conditions, Shorebird
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:su:diva-190033 (URN)10.1016/j.scitotenv.2020.142485 (DOI)000600786700010 ()33039934 (PubMedID)
Available from: 2021-02-24 Created: 2021-02-24 Last updated: 2022-03-04Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-5535-9086

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