Food Habits of Arctic Foxes (Alopex Lagopus) on the Western Coast of Svalbard

Food habits of arctic foxes (Alopex lagopus) on the western coast of Svalbard were studied in the years 1986-89. Faeces (n=1018) were collected mostly in summer, and food remains were recorded both at dens and elsewhere in the region. The foxes were opportunistic in their hunting and feeding habits, utilizing a wide variety of available food items. Alcids (mainly little auks and Brunnich's guillemot), gulls (mainly kittiwakes), and fulmars were the major foods in summer. The consumption of alcids by fox families was correlated with availability near the den. In winter, fulmars and, in one region, seals were important foods. Some regional differences in food consumption were found. A change in diet was observed when a litter of pups moved from one den to another (2 of 3 cases). Differences in food habits between years also were found at the same den (4 of 5 cases). Foxes frequently cached food by scatter hoarding, placing only a single item in each cache.Key words: arctic fox, Alopex lugopus, food habits, prey species, food caching, SvalbardOn a étudié les habitudes alimentaires du renard arctique (Alopex lagopus) sur la côte ouest du Svalbard au cours des années allant de 1986 à 1989. On a recueilli les fèces (n = 1018) surtout en été, et on a consigné les débris de nourriture à la fois dans les terriers et ailleurs dans la région. Les renards se montraient opportunistes dans leurs façons de chasser et de se nourrir, et faisaient usage d'une vaste gamme d'aliments à leur portée. Les alcidés (surtout le petit pingouin et la marmette de Brünnich), les mouettes (surtout la mouette à trois doigts) et les fulmars étaient les sources principales de nourriture estivale. La consommation d'alcidés par les familles de renards était corrélée avec leur disponibilité à proximité du terrier. En hiver, les fulmars et, dans un certain endroit, les phoques constituaient une source importante de nourriture. On a trouvé certaines différences régionales dans la consommation alimentaire. On a observé un changement dans le régime lorsqu'une portée de renardeaux se déplaçait d'un terrier à un autre (dans 2 cas sur 3). On a aussi enregistré des différences dans les habitudes alimentaires d'une année à l'autre au même terrier (dans 4 cas sur 5). Les renards cachaient fréquemment la nourriture en l'éparpillant, ne mettant qu'un élément dans chaque cache.Mots clés; renard arctique, Alopex lugopus, habitudes alimentaires, espèces-proies, cache alimentaire, Svalbar

The influence of night length: Activity of the northern bat Eptesicus nilssonii under conditions of continuous light in midnight sun compared to a southern population

Background - Nearly all insectivorous bats (Chiroptera) are strictly nocturnal, flying and feeding only between sunset and sunrise despite lower insect availability than by day, most likely to avoid predation by diurnal birds. This may represent a great challenge to bats living north of the Arctic Circle, which are exposed to bright nights in the period of the midnight sun. The northern bat Eptesicus nilssonii was studied at different latitudes in Norway (69, 66 and 58°N) by three techniques; visual counts of exits from and returns to roosts, infrared detection with a datalogger and an ultrasound data recorder, to reveal how their activity varied across latitude, season, and night, as well as across light levels. How does a nocturnal bat adjust to perpetual light and what light levels are tolerated? Results -In the north the bats’ active season lasted 2.5 months, 1.5 months shorter than in the south. The bats only flew in 3-4 weeks of midnight sun, and hardly ever left the roost until the sun went behind a hill in the evening. In addition, the timing of their nightly hunting was highly influenced by the darkness of the sky, and they very rarely flew in light levels above 200 foot-candles (FC). As the night became darker than twilight from early August, the bats restricted their activity to between sunset and sunrise. This was the normal situation in southern Norway, where the bats tracked sunset and sunrise throughout the entire season. Those bats appeared to prefer light levels below 100-50 FC and hence, also did fly in twilight conditions. Conclusions - The willingness to fly in twilight by the southern population may be a prerequisite to the northern bat’s survival in the land of the midnight sun. These bats must accept short nights in the first part of their summer season and must be willing to fly in light levels 2-4 times higher than in the south. Most likely, this depends on a reduced predation risk and good abundance of insects at night

Population dynamics of an island population of water voles Arvicola amphibius (Linnaeus, 1758) with one major predator, the eagle owl Bubo bubo (Linnaeus, 1758), in northern Norway

Predator–prey relationships are of great significance to ecosystems, and their effects on the population dynamics of voles and lemmings (Microtinae) in Boreal and Arctic environments have long been of particular interest. A simple ecosystem with one major prey and one major predator could be an ideal setting for a study of their interactions. This is the situation on several small islands on the coast of northern Norway just below the Arctic Circle, with populations of water voles Arvicola amphibius preyed upon by the eagle owl Bubo bubo. The population dynamics of the water vole was studied by trapping and tagging in 2003–2018, eagle owl pellets were collected for analyses, eagle owl breeding attempts were recorded, and some weather variables collected from official recordings. After having been introduced well into the study period, the number of sheep Ovis aries was also recorded. Water voles were the main prey of the eagle owl, with 89% occurrence in pellets, with an overrepresentation of adults and males. Both predation, sheep grazing and extreme weather events influenced the vole population. Predator exclusion, as happened in three summers due to an intensive radio tracking study, especially increased the number of surviving young (in particular from the early cohorts) and the mass of adults. Extreme weather events, such as flooding in summer and deeply frozen ground in winter, most significantly reduced vole populations. Sheep grazing may exacerbate the effects of predation. A similar multitude of factors may affect populations of other rodent species as well

Subfossil Records of the Arctic Fox (Alopex Lagopus) Compared to Its Present Distribution in Norway

We studied the prehistoric and historic distribution of arctic foxes in Norway by examining material and reports from archaeological excavations. A total of 44 arctic fox bones were found in 15 excavations, all of which were younger than 5000 years before present (B.P.). The majority of these sites was located within or close to the present distribution of arctic foxes. Additionally, 44 naturally deposited arctic fox bones were found in two excavations dated 36 000-28 000 and 13 000 B.P. respectively, indicating that the arctic fox also lived along the Norwegian coast in the Pleistocene. No arctic fox bone was dated to the period 9000-5000 B.P., and the species may have been rare or absent during this comparatively warm period. Since most bones (61%) were from the distal part of the limbs, the foxes may have been skinned elsewhere and transported to the site of deposition. Bones from red foxes were found in three excavations within the present distribution of arctic foxes, indicating that the arctic fox was relatively more abundant than red foxes during the late prehistoric and the historic periods in south Norway, but less abundant in north Norway.Key words: arctic fox, red fox, prehistoric and historic distributions, archaeological excavations, NorwayOn a étudié les distributions préhistorique et historique du renard arctique en Norvège, en examinant du matériel et des rapports provenant de fouilles archéologiques. Au total, 44 os de renard arctique ont été trouvés dans des fouilles effectuées sur 15 sites, et tous les os dataient de moins de 5000 ans avant le présent. La majorité de ces emplacements était située à l'intérieur ou près de la distribution actuelle du renard arctique. On a en outre trouvé 44 os de renard arctique déposés naturellement dans deux fouilles datées respectivement de 36 000 à 28 000 ans avant le présent et de 13 000 ans avant le présent, ce qui révèle que le renard arctique vivait aussi le long du rivage norvégien au cours du pléistocène. Aucun os de renard arctique n'a été daté de la période allant de 9000 à 5000 avant le présent et il est possible que l'espèce ait été rare ou absente au cours de cette période comparativement tempérée. Étant donné que la plupart des os (61 p. cent) proviennent de la partie distale des membres, il se peut que les renards aient été dépouillés ailleurs et transportés à l'emplacement où ils ont été déposés. On a trouvé des os de renard roux dans trois fouilles à l'intérieur de la distribution actuelle du renard arctique, ce qui révèle que ce dernier était relativement plus abondant que le renard roux en Norvège méridionale, à la fin de la période préhistorique et au cours de la période historique, mais moins abondant en Norvège septentrionale.Mots clés: renard arctique, renard roux, distributions préhistorique et historique, fouilles archéologiques, Norvèg

Vigilance in pre-nesting male geese: mate guarding or predator detection?

Several studies have concluded that vigilance decreases with group size. Two main hypotheses for vigilance in males have been proposed: 1) mate guarding (including protection of paternity) and 2) predator detection. Geese often live in large groups and are easy to observe. They are thus prime candidates for studies of male vigilance and agonistic behaviour. In this study, two species of pre-nesting geese were studied. Pink-footed Geese Anser brachyrhynchus were studied on their breeding grounds on Svalbard and in a spring staging area on the northwest coast of Norway, and Bean Geese A. fabalis were studied in a spring staging area in the north-eastern corner of Norway. Observations were made of pairs of geese during foraging bouts, recording foraging, vigilance and agonistic behaviour. Group size, distance between the male and female of a pair, and position in the group (one site only) were also recorded. Few significant relationships were found, the most striking one was that males were more vigilant at the edge of the group than in the centre. In some cases, a non-linear relation was found, i.e. between group size and vigilance in one area. Overall, hypothesis 2) was more strongly supported than hypothesis 1), but most likely the males were making the best of these conflicting interests. The near total absence of a group-size effect was not consistent with the predictions or with earlier findings, indicating that the relations may be more complex than previously suggested

Interactions between Arctic and Red Foxes in Scandinavia - Predation and Aggression

Arctic fox (Alopex lagopus) populations in Scandinavia are small and restricted to alpine regions, while red foxes (Vulpes vulpes) are common throughout both Norway and Sweden. The two species are similar in behaviour and diet, and thus competition between them is likely. This study provides seven observations of aggressive interactions between the two species. One adult arctic fox and one cub were killed by red foxes, one male arctic fox was chased away from his den, one female arctic fox and a cub fled into the den as a red fox approached, four cubs fled into the den as a red fox walked upon it and once a red fox walked upon the arctic fox den when no arctic foxes could be seen. Only on one occasion did an arctic fox succeed in chasing away a red fox. Red fox predation may prove to be limiting to the small arctic fox population in Scandinavia, and arctic foxes can be displaced from good dens and the most productive regions.Key words: arctic fox (Alopex lagopus), red fox (Vulpes vulpes), interactions, predation, aggression, field observations, ScandinaviaMots clés: renard polaire( Alopex lagopus), renard roux (Vulpes vulpes), interactions, prédation, agression, observations sur le terrain, Scandinavi

Influence of night length on home range size in the northern bat Eptesicus nilssonii

The northern bat Eptesicus nilssonii is widespread in Fennoscandia, with breeding populations well above the Arctic Circle. I studied this species at its extreme northern limit, at 69°N in Norway. I radio-tracked 17 bats from 2 maternity roosts during 2003–2006 to study the influence of the midnight sun and increasing lengths of darkness on activity (time spent out of roost) and home range size. Activity and home range was highly correlated with night length (light intensity); both increasing progressively with season. Bats were classified into 3 groups based on the time of the season they were tracked (basically July, August and September–October); short activity (average 1.57 h) and small home range (average 0.91 km2), medium activity (3.69 h) and medium-sized home range (4.58 km2), and long activity (4.80 h) and large home range (17.2 km2). Bats visited roosts several times during the night, and the duration of roost visits increased significantly by group. The number of periods out of roost increased from the first to the second group (1.45 vs. 2.36 flight periods per night), but insignificantly to the third group (2.37 flights). The most significant increase in activity and home range was associated with the first flight of juveniles in early August. These bats appeared to have a threshold level of around 1700 lux for activity out of roost, with little difference between light levels at emergence and return (the second group returned in significantly poorer light than they emerged in). Although the northern bat at this extreme latitude had adapted to the ambient light conditions, the bright nights under the midnight sun and the short season strongly reduced their window of opportunity for activity and may possibly reduce survival and reproductive success

Activity patterns of the soprano pipistrelle Pipistrellus pygmaeus throughout the year in southern Norway

Background - Most temperate bats are regular hibernators in the winter. Knowledge about the length of their active season and how they adjust their nightly activity throughout the season, is critical to conservation. The characteristics of these are likely to vary with climate as well as latitude. This study investigated the flight activity of the soprano pipistrelle Pipistrellus pygmaeus in Frafjord, a small valley in the south-western corner of Norway (58° 50′N 6° 18′E) with an oceanic climate. Results - Activity was recorded with an ultrasound recorder throughout April 2018 to June 2019 at one site, with supplemental recordings in March to June 2020, i.e., covering all months of the year. Recordings at other nearby sites were made in the summers (June–August) of 2016, 2017, 2019 and 2020, as well as some of the last days in December 2019 to the first days of January 2020. Overall, soprano pipistrelles were recorded flying in all months of the year, but very few in December–March. Regular activity was recorded from late April or early May until late October, and some recordings were also made in November. The highest numbers of recordings were made in August and September. Social calls, i.e. male song flights, were recorded from April to November, with the vast majority in August and September. Nearly all recordings were made between sunset and sunrise. Conclusions - The soprano pipistrelle in this region showed regular activity through 6–7 months of the year. It adjusted its activity to the changing night length throughout the year, closely following sunset and sunrise. It was rarely recorded flying before sunset and almost never after sunrise. Most activity was recorded in the middle of the night, and social calls also followed this trend closely. Harems in late summer and autumn were confirmed in a bat box, which was also used for winter hibernation

Influence of Reproductive Status: Home Range Size in Water Voles (Arvicola amphibius)

The relationship between home range and reproductive status of water voles (Arvicola amphibius) was studied by radio-tracking on an island off the coast of northern Norway in 2006–2009. The aim was to test assumptions about the species’ social structure relative to other microtines. Juveniles used fairly small ranges (about 400 m²), with no difference between males and females. Subadults, overwintered voles in April, had ranges similar to juveniles. Reproductively active males (mean 2774.0 m²) increased their range seven-fold relative to juvenile males, with ranges on average 3.3 times larger than adult females (mean 848.3 m²), which also expanded their range. Most litters were born in May and June, and as reproduction ceased in July adult males reduced their range whilst females did not. Body mass or year did not influence home range size. Overlap of home ranges varied, but could be extensive in both adult males and females. The water vole had a social structure similar to some Microtus species, but females appeared to be non-territorial and males perhaps conditioned territorial and non-territorial