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For many species, the ability to rapidly adapt to changes in seasonality is essential for long-term survival. In the Arctic, seasonal moulting is a key life-history event that provides year-round camouflage and thermal protection. However, increased climatic variability of seasonal events can lead to phenological mismatch. In this study, we investigated whether winter-white (white morph) and winter-brown (blue morph) Arctic foxes (Vulpes lagopus) could adjust their winter-to-summer moult to match local environmental conditions. We used camera trap images spanning an eight-year period to quantify the timing and rate of fur change in a polymorphic subpopulation in south-central Norway. Seasonal snow cover duration and temperature governed the phenology of the spring moult. We observed a later onset and longer moulting duration with decreasing temperature and longer snow season. Additionally, white foxes moulted earlier than blue in years with shorter periods of snow cover and warmer temperatures. These results suggest that phenotypic plasticity allows Arctic foxes to modulate the timing and rate of their spring moult as snow conditions and temperatures fluctuate. With the Arctic warming at an unprecedented rate, understanding the capacity of polar species to physiologically adapt to a changing environment is urgently needed in order to develop adaptive conservation efforts. Moreover, we provide the first evidence for variations in the moulting phenology of blue and white Arctic foxes. Our study underlines the different intraspecific selective pressures that can exist in populations where several morphs co-occur, and illustrates the importance of integrating morph-based differences in future management strategies of such polymorphic species. camera trapping, camouflage, climate change, colour polymorphism, phenological mismatch, phenotypic plasticity

1. Emerging wildlife diseases often comeswith negative cultural and economic impact. Limiting disease spread is a recurrent goal and challenge, but the efficacy of various mitigationmeasures is rarely assessed. 2. Chronic wasting disease (CWD) is a lethal disease among cervids that was discovered among alpine reindeer (Rangifer tarandus) in the Nordfjella mountain range of Norway in 2016. After de-population, the entire range was fallowed to avoid re-emergence from environmental pathogen reservoirs. This involved installing perimeter fences in the alpine areas in order to keep reindeer from adjacent populations outside of the CWDrisk area, while other cervids (red deer Cervus elaphus, roe deer Capreolus capreolus and moose Alces alces) were likely to enter through the forested areas. 3. We used camera trapping and surveillance reports to assess the efficacy of the perimeter fences. All four species of cervids were documented inside the CWDrisk area. For reindeer, only 12.0% of observations were inside the CWDrisk area,while this was 28.7% for the other cervids. The higher proportion of observations outside of the fenced area indicate that fences provided a barrier and lowered the number of crossings also of red deer, roe deer and moose. 4. Fences do not provide complete barriers, andwe discuss practical solutions for how to avoid ‘intruders’ entering a given area, such as maintenance at critical points (e.g. river and road crossings) and height of fences (e.g. species variation in jumping; deep snow) to uphold their desired effect. 5. We argue that two fence lines with a buffer zone would be required when reintroduction of reindeer are planned in the CWD risk area after fallowing, similar to what has been suggested for other wildlife diseases.

1. Habitat fragmentation may affect species distributions through, for example, altered resource availability and shifts in species interactions. Fragmentation by roads has had negative impacts on Fennoscandian alpine ecosystems, with reduction of habitats and connectivity for alpine species. Concurrently, infrastructure development causes influx of subsidies through roadkills and litter, which may facilitate expansion of boreal scavenging species, such as the red fox Vulpes vulpes, which may intensify negative interactions with alpine species. Hence, understanding the impact of subsidies within marginal alpine areas is imperative for successful conservation and management of particularly vulnerable alpine species. 2. We used snow tracking and camera traps in three alpine tundra areas in Norway to investigate whether the presence of boreal scavengers was positively associated with highways during winter, and if this contrasted the pattern of a critically endangered alpine species, the Arctic fox Vulpes lagopus. In summer, artificial nests were used to assess whether predation risk was related to proximity to highways. 3. During winter, the occurrence of red foxes was higher close to highways and decreased with increasing distance to highways, while the arctic fox showed no discernible pattern. Red fox occurrence increased with the number of edible items of anthropogenic origin located along highways, whereas arctic fox occurrence decreased. 4. The overall predation risk of artificial nests during summer was high (>31.2%) and increased with proximity to the highway in the area with highest traffic volume. 5. Synthesis and applications. Highways crossing alpine areas may attract boreal scavengers, possibly connected to increased access to subsidies of anthropogenic origin. Litter and food waste dominated available subsidies along highways in our study, and prevailing mitigating measures directed at reducing roadkill and movement restrictions may not be applicable to reduce negative effects of littering. We recommend actions focusing on informational campaigns, improved garbage disposal facilities and routines, and imposing fines for littering, to reduce negative impacts on vulnerable species. This is likely needed to achieve goals of ‘no impact’ from the physical loss of habitats due to road development. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Spatial capture-recapture modelling (SCR) is a powerful tool for estimating densities, population size and space use of elusive animals. Here, we applied SCR modeling to non-invasive genetic sampling (NGS) data to estimate red fox (Vulpes vulpes) densities in two areas of boreal forest in central (2016 - 2018) and southern Norway (2017 - 2018). Estimated densities were overall lower in the northern study area (mean = 0.04 foxes per km2 [95%CI: 0.02-0.09] in 2016, 0.09 [0.05-0.18] in 2017 and 0.07 [0.04-0.13] in 2018) compared to the southern study area (0.16 [0.09-0.26] in 2017 and 0.10 [0.07-0.16] in 2018). We found a positive effect of forest cover on density in the northern, but not the southern study area. The absence of an effect in the southern area may reflect a paucity of evidence caused by low variation in forest cover, but could also be due to climatic differences (e.g., winter severity) between the two areas. Estimated mean home range size in the northern study area was 45 km2 [34-60] for females and 88 km2 [69-113] for males. Mean home range sizes were smaller in the southern study area (26 km2 [16-42] for females and 56 km2 [35-91] for males). In both study areas, detection probability was session-dependent and affected by sampling effort. This study highlights how SCR modeling in combination with NGS can be used to efficiently monitor red fox populations, and simultaneously incorporate ecological factors and estimate their effects on population density and space-use.

The Arctic fox (Vulpes lagopus L.) is listed as extinct in Finland, endangered in Sweden and critically endangered in Norway. Around 2000 there were only 40–60 adult individuals left, prompting the implementation of conservation actions, including a captive breeding programme founded from wild-caught pups. The initial breeding trials failed, probably because of stress among captive animals, and the programme was radically changed in 2005. Eight large enclosures within the species’ historical natural habitat were established, which had the positive effect of all pairs breeding in 2007. As of 2015, 385 pups (yearly average 37) were produced. In this ongoing programme, pups are released the winter (January–February) following their birth and have had an average first-year survival of 0.44. The release sites are prepared with artificial dens and a network of supplementary food dispensers, designed to work exclusively for the Arctic fox. After just four to seven years of releases, populations have been effectively re-established in three mountain areas where the species had been locally extinct. One of the newly re-established populations has become the largest population in Norway. Several other populations, including Swedish ones, have benefited considerably from successful immigration of released foxes. The number of wild-born pups that are descendants of released foxes has likely exceeded 600, and in 2014 50% of all free-living breeding pairs in mainland Norway included released foxes or their descendants. The Norwegian Arctic fox captive breeding programme has proven to be an important conservation action for the recovery of the Scandinavian Arctic fox population.