| 1. |
- Aguirre, A. Alonso, et al.
(författare)
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Field anesthesia of wild arctic fox (Alopex lagopus) cubs in the Swedish lapland using medetomidine-ketamine-atipamezole
- 2000
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Ingår i: Journal of zoo and wildlife medicine. - 1042-7260 .- 1937-2825. ; 31:2, s. 244-246
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Tidskriftsartikel (refereegranskat)abstract
- A safe and effective anesthetic regime for use in arctic fox (Alopex lagopus) cubs was developed. During July 1996, six free-ranging 6-8-wk-old cubs were captured near their den in Vindelfjallen Nature Reserve, Sweden. Medetomidine and ketamine HCl, followed by atipamezole, were selected for the anesthetic trial because of the well-documented safety and efficacy of this drug combination in a broad range of species. The dosage regimen used was 50 mu g/kg medetomidine combined with 2.5 mg/kg ketamine followed by reversal with 250 mu g/kg atipamezole. induction was rapid, with a mean induction time of 1 min and 32 sec (range: 58-150 sec). The cubs were anesthetized for a mean time of 18 +/- 5 min (range: 13-25 min). Serially recorded heart rate, respiratory rate, temperature, and pulse oximetry were stable throughout the anesthetic period for all cubs. Anesthetic depth was suitable for safe handling and minor clinical procedures, including venipuncture. Following atipamezole, all cubs were standing within 12 +/- 7 min (range: 5-24 min) and fully recovered at 27 +/- 5 min (range: 19-36 min). This information will be useful for future captive breeding and management programs involving the endangered arctic fox.
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| 2. |
- Aguirre, A. A., et al.
(författare)
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Health evaluation of arctic fox (Alopex lagopus) cubs in Sweden
- 2000
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Ingår i: Journal of zoo and wildlife medicine. - 1042-7260 .- 1937-2825. ; 31:1, s. 36-40
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Tidskriftsartikel (refereegranskat)abstract
- Hematologic. serum biochemistry, and serum cortisol reference ranges were established and tonsil/rectal bacterial and fecal parasite examinations were performed on 21 wild arctic fox (Alopex lagopus) cubs during July 1996. Several of the hematologic and serum biochemistry values fell within normal ranges for other wild canids or domestic dogs of the same age class. Serum alanine transaminase and creatine phosphokinase values were significantly higher in the youngest cubs. Proteus vulgaris and Escherichia coli were isolated from both tonsilar and rectal swabs of several cubs in all dens. The most common gastrointestinal parasite ova were Toxascaris leonina (59%), Isospora spp. (52%), Uncinaria stenocephala (33%), and Capillaria spp. (26%). Prevalence of T. leonina differed significantly between dens and between age groups. Hematologic and serum biochemistry values and degree of parasitism may be indicators of health, stress, and nutritional status of arctic foxes.
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| 3. |
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| 4. |
- 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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| 5. |
- Angerbjörn, Anders, et al.
(författare)
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Geographical and temporal patterns of lemming population dynamics in Fennoscandia
- 2001
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Ingår i: Ecography. - 0906-7590 .- 1600-0587. ; 24:3, s. 298-308
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Tidskriftsartikel (refereegranskat)abstract
- There is a long-lasting debate in ecology on cyclicity, synchrony and time lags of lemming population fluctuations. We have analysed 137 yr of previously published population data on the Norwegian lemming Lemmus lemmus in ten geographic regions of Fennoscandia. The dominating pattern was synchronous 4-yr cycles. There was no support for the hypothesis of a north-south gradient in cycle length. However. we found periods of prolonged interruptions in the cyclicity, which were more common in northern areas. Wa found a high degree of synchrony between regions. with only a weak relationship to distance, The observed pattern in lemming population dynamics was more consistent with effects from extrinsic factors, such as climate. than intrinsic factors. such as dispersal.
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| 6. |
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| 7. |
- Angerbjörn, Anders, et al.
(författare)
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Predator-prey relationships : Arctic foxes and lemmings
- 1999
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Ingår i: Journal of Animal Ecology. - : Wiley. - 0021-8790 .- 1365-2656. ; 68:1, s. 34-49
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Tidskriftsartikel (refereegranskat)abstract
- 1. The number of breeding dens and litter sizes of arctic foxes Alopex lagopus were recorded and the diet of the foxes was analysed during a ship-based expedition to 17 sites along the Siberian north coast. At the same time the cyclic dynamics of coexisting lemming species were examined. 2. The diet of arctic foxes was dominated by the Siberian lemming Lemmus sibiricus (on one site the Norwegian lemming L. lemmus), followed by the collared lemming Dicrostonyx torquatus. 3. The examined Lemmus sibiricus populations were in different phases of the lemming cycle as determined by age profiles and population densities. 4. The numerical response of arctic foxes to varying densities of Lemmus had a time lag of 1 year, producing a pattern of limit cycles in lemming-arctic fox interactions, Arctic fox litter sizes showed no time lag, but a linear relation to Lemmus densities. We found no evidence for a numerical response to population density changes in. Dicrostonyx. 5. The functional or dietary response of arctic foxes followed a type II curve for Lemmus, but a type III response curve for Dicrostonyx. 6. Arctic foxes act as resident specialist for Lemmus and may increase the amplitude and period of their population cycles. For Dicrostonyx, on the other hand, arctic foxes act as generalists which suggests a capacity to dampen oscillations.
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| 8. |
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| 9. |
- Barth, Lukas, et al.
(författare)
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Are Norwegian lemmings Lemmus lemmus avoided by arctic Alopex lagopus or red foxes Vulpes vulpes? A feeding experiment
- 2000
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Ingår i: Wildlife Biology. ; 6:2, s. 101-109
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Tidskriftsartikel (refereegranskat)abstract
- Arctic fox Alopex lagopus and red fox Vulpes vulpes are close relatives with similar niche demands in the Holarctic. Where they are sympatric, they compete for territories, dens and food. Seat analyses from Fennoscandia have shown different proportions of lemmings and voles in the diets of the two fox species suggesting food partitioning. However, it was not clear if this was due to different food preferences or distinct habitat use. Since the arctic fox is an endangered species in Fennoscandia, it is important to know whether the superior, north spreading red fox can oust it from the tundra habitat, or if food specialisation may prevent displacement. In a feeding experiment at the Lycksele Zoo in northern Sweden, we compared the food preferences of two arctic and two red foxes. Our results show that the four individuals responded similarly to a variety of food items, and particularly that the two species were not distinct in their food preferences concerning lemmings and voles. However, the foxes had considerable individual predilections. Therefore, in the wild, the unequal proportions of lemmings and voles found in seats may reflect different habitat use for hunting.
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| 10. |
- Dalén, Love, et al.
(författare)
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Is the endangered Fennoscandian arctic fox (Alopex lagopus) population genetically isolated?
- 2002
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Ingår i: Biological Conservation. - 0006-3207 .- 1873-2917. ; 105:2, s. 171-178
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Tidskriftsartikel (refereegranskat)abstract
- The arctic fox population in Fennoscandia is on the verge of going extinct after not being able to recover from a severe bottleneck at the end of the 19th century. The Siberian arctic fox population, on the other hand, is large and unthreatened. In order to resolve questions regarding gene flow between, and genetic variation within the populations, a 294 bp long part of the mitochondrial hypervariable region 1 was sequenced. This was done for 17 Swedish, 15 Siberian and two farmed foxes. Twelve variable nucleotide sites were observed, which resulted in 10 different haplotypes. Three haplotypes were found in Sweden and seven haplotypes were found in Siberia. An analysis of molecular variance showed a weak, but significant, differentiation between the populations. No difference in haplotype diversity was found between the populations. A phylogenetic analysis revealed that the three Swedish haplotypes were not monophyletic compared to the Siberian haplotypes. These results indicate a certain amount of gene flow between the two populations. both before and after the bottleneck. Restocking the Fennoscandian population with arctic foxes from Siberia might therefore be a viable option.
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