We propose a fundamental geographic distribution for the wolverine ( Gulo gulo (L., 1758)) based on the hypothesis that the occurrence of wolverines is constrained by their obligate association with persistent spring snow cover for successful reproductive denning and by an upper limit of thermoneutrality. To investigate this hypothesis, we developed a composite of MODIS classified satellite images representing persistent snow cover from 24 April to 15 May, which encompasses the end of the wolverine’s reproductive denning period. To investigate the wolverine’s spatial relationship with average maximum August temperatures, we used interpolated temperature maps. We then compared and correlated these climatic factors with spatially referenced data on wolverine den sites and telemetry locations from North America and Fennoscandia, and our contemporary understanding of the wolverine’s circumboreal range. All 562 reproductive dens from Fennoscandia and North America occurred at sites with persistent spring snow cover. Ninety-five percent of summer and 86% of winter telemetry locations were concordant with spring snow coverage. Average maximum August temperature was a less effective predictor of wolverine presence, although wolverines preferred summer temperatures lower than those available. Reductions in spring snow cover associated with climatic warming will likely reduce the extent of wolverine habitat, with an associated loss of connectivity.

Summary1. More than a quarter of the world's carnivores are threatened, often due to multiple and complex causes. Considerable research efforts are devoted to resolving the mechanisms behind these threats in order to provide a basis for relevant conservation actions. However, even when the underlying mechanisms are known, specific actions aimed at direct support for carnivores are 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 fox Vulpes lagopus L., including yearly surveys of 600 fox dens covering 21 000 km 2 . These surveys showed that the population was close to extinction in 2000, with 40-60 adult animals left. However, the population subsequently showed a fourfold increase in size.3. During this time period, conservation actions through supplementary feeding and predator removal were implemented in several regions across Scandinavia, encompassing 79% of the area. To evaluate these actions, we examined the effect of supplemental winter feeding and red fox control applied at different intensities in 10 regions. A path analysis indicated that 47% of the explained variation in population productivity could be attributed to lemming abundance, 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 fluctuations but also shows that red foxes severely impact the viability of arctic foxes. This study also highlights the importance of implementing conservation actions on extensive spatial and temporal scales, with geographically dispersed actions to scientifically evaluate the effects. We note that population recovery was only seen in regions with a high intensity of management actions. 5. Synthesis and applications. The present study demonstrates that carnivore population declines may be reversed through extensive actions that target specific threats. Fennoscandian arctic fox is still endangered, due to low population connectivity and expected climate impacts on the distribution and dynamics of lemmings and red foxes. Climate warming is expected to contribute to both more irregular lemming dynamics and red fox appearance in tundra areas; however, the effects of climate change can be mitigated through intensive management actions such as supplemental feeding and red fox control.

The southern Norwegian wolverine (Gulo gulo) population was considered functionally extinct in the 1960s but has partly recovered in recent years. Proper management of this population is highly dependent on reliable estimates of critical population parameters such as population size, sex ratio, immigration rate, and reproductive contribution from immigrants. We report on a large-scale population monitoring project assessing these parameters through genetic tagging of individuals, with feces as the source of DNA. Sixty-eight different individuals were detected among 147 successfully genotyped samples collected in 2000 and 2001. Sixty of these individuals were represented in the 2001 sample, which may be considered a minimum estimate of the population size. Almost 50% of these animals were sampled only once, however, indicating that the true population size may be markedly higher. Accordingly, a capture-recapture estimate based on the observed resampling rates suggested a population size of 89 wolverines (95% confidence interval [CI] = 74-104), which is approximately 35% higher than an estimate of 64 obtained from the number of active natal dens (95% CI = 46-95; p = 0.08). Indirect estimates of dispersal distances inferred from mother-offspring relationships suggested that wolverine males have the ability to disperse up to 500 km, a distance exceeding anything previously reported in the literature. Dispersal distances of more than 100 km were detected for females. Bayesian clustering analysis and subsequent assessment of individual relationships suggest that immigrants from northern Scandinavia have contributed and still contribute to the southern Norwegian gene pool, counteracting genetic erosion and reducing the risk of inbreeding depression. Additional sampling efforts will be undertaken during the coming years to allow for observations of population trends, immigration rate, and reproductive variance among individuals. Such data will provide an important basis for the design of an appropriate conservation plan for this small and vulnerable population. Historia de Colonización y Monitoreo No Invasivo de una Población Reestablecida de Gulo gulo Resumen: La población sureña de Gulo gulo se consideraba funcionalmente extinta en la década de 1960 pero se ha recuperado parcialmente en años recientes. El manejo adecuado de esta población depende, en gran medida, de estimaciones confiables de parámetros poblacionales críticos como por ejemplo el tamaño poblacional, la proporción de sexos, la tasa de inmigración y la contribución reproductiva de inmigrantes. Reportamos un proyecto de monitoreo poblacional a gran escala que evaluó estos parámetros por medio del marcaje genético de individuos, con heces como la fuente de ADN. Se detectaron 68 individuos diferentes entre 147 muestras de genotipos identificados exitosamente y colectadas en 2000 y 2001. Sesenta de estos individuos estuvieron representados en la muestra de 2001, lo que puede considerarse como una estimación §Current Noninvasive Monitoring of Wolverines 677 ...

Different monitoring approaches collect data that can measure progress toward achieving global environmental indicators. These indicators can: (1) Audit management actions; (2) Inform policy choices; and (3) Raise awareness among the public and policy makers. We present a generic, empirically

Wolverine (Gulo gulo) numbers in Scandinavia were significantly reduced during the early part of the century as a result of predator removal programmes and hunting. Protective legislation in both Sweden and Norway in the 1960s and 1970s has now resulted in increased wolverine densities in Scandinavia. We report here the development of 15 polymorphic microsatellite markers in wolverine and their use to examine the population sub-structure and genetic variability in free-ranging Scandinavian wolverine populations as well as in a sample of individuals collected before 1970. Significant subdivision between extant populations was discovered, in particular for the small and isolated population of southern Norway, which represents a recent recolonization. Overall genetic variability was found to be lower than previously reported for other mustelids, with only two to five alleles per locus and observed heterozygosities (H(O)) ranging from 0.269 to 0.376 across the examined populations, being lowest in southern Norway. Analysis of the mitochondrial DNA control region revealed no variation throughout the surveyed populations. As the historical sample did not show higher levels of genetic variability, our results are consistent with a reduction in the genetic variation in Scandinavian wolverines that pre-dates the demographic bottleneck observed during the last century. The observed subdivision between populations calls for management caution when issuing harvest quotas, especially for the geographically isolated south Norwegian population.