scholarly journals 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

BMC Zoology ◽  
2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Karl Frafjord
Keyword(s):  
Continuous Light ◽  
Summer Season ◽  
Infrared Detection ◽  
The Arctic ◽  
Southern Population ◽  
The South ◽  
Active Season ◽  
The North ◽  
Light Levels ◽  
Southern Norway

Abstract 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.

scholarly journals Anomalous azimuthal variations with 360° periodicity of Rayleigh phase velocities observed in Scandinavia

2020 ◽  
Vol 224 (3) ◽  
pp. 1684-1704
Author(s):  
Alexandra Mauerberger ◽  
Valérie Maupin ◽  
Ólafur Gudmundsson ◽  
Frederik Tilmann
Keyword(s):  
Seismic Anisotropy ◽  
Broad Band ◽  
Shear Velocity ◽  
Velocity Variation ◽  
The South ◽  
Study Region ◽  
Lithospheric Thickness ◽  
Phase Velocities ◽  
The North ◽  
Southern Norway

SUMMARY We use the recently deployed ScanArray network of broad-band stations covering most of Norway and Sweden as well as parts of Finland to analyse the propagation of Rayleigh waves in Scandinavia. Applying an array beamforming technique to teleseismic records from ScanArray and permanent stations in the study region, in total 159 stations with a typical station distance of about 70 km, we obtain phase velocities for three subregions, which collectively cover most of Scandinavia (excluding southern Norway). The average phase dispersion curves are similar for all three subregions. They resemble the dispersion previously observed for the South Baltic craton and are about 1 per cent slower than the North Baltic shield phase velocities for periods between 40 and 80 s. However, a remarkable sin(1θ) phase velocity variation with azimuth is observed for periods >35 s with a 5 per cent deviation between the maximum and minimum velocities, more than the overall lateral variation in average velocity. Such a variation, which is incompatible with seismic anisotropy, occurs in northern Scandinavia and southern Norway/Sweden but not in the central study area. The maximum and minimum velocities were measured for backazimuths of 120° and 300°, respectively. These directions are perpendicular to a step in the lithosphere–asthenosphere boundary (LAB) inferred by previous studies in southern Norway/Sweden, suggesting a relation to large lithospheric heterogeneity. In order to test this hypothesis, we carried out 2-D full-waveform modeling of Rayleigh wave propagation in synthetic models which incorporate a steep gradient in the LAB in combination with a pronounced reduction in the shear velocity below the LAB. This setup reproduces the observations qualitatively, and results in higher phase velocities for propagation in the direction of shallowing LAB, and lower ones for propagation in the direction of deepening LAB, probably due to the interference of forward scattered and reflected surface wave energy with the fundamental mode. Therefore, the reduction in lithospheric thickness towards southern Norway in the south, and towards the Atlantic ocean in the north provide a plausible explanation for the observed azimuthal variations.

‘Take it from the top’: northern conceptions about identity in the western Arctic and beyond

Polar Record ◽  
2012 ◽  
Vol 48 (3) ◽  
pp. 222-229 ◽  
Author(s):  
Suzanne Robinson
Keyword(s):  
Northwest Territories ◽  
The Arctic ◽  
The South ◽  
Research Project ◽  
The North ◽  
The World ◽  
Western Arctic ◽  
Student Researchers

ABSTRACTDuring the last decades the Arctic has become more central on the world stage. However, despite increased interest how much do people really know about ‘the north’ and the ‘northern people’? The aim of this article is to chronicle a research project by students, who saw themselves as northerners, that used video to capture northerners’ definitions of the north, as well as asking the community about what they wanted newcomers and southern Canada to know about the north. The group also embarked on a new discipline of northerners studying ‘the south’. 43 students interviewed 95 people in the Beaufort Delta, Northwest Territories and 25 people in Edmonton, Alberta. The student researchers’ responses and that of their interviewees are some of the most direct messages on how northerners view their identity and that of their fellow southern Canadians. This project created a video tool to share, educate, and commence a dialogue between people about the north straight from the source.

scholarly journals The Middle Jurassic of western and northern Europe: its subdivisions, geochronology and correlations

2003 ◽  
Vol 1 ◽  
pp. 61-73 ◽  
Author(s):  
John H. Callomon
Keyword(s):  
North Sea ◽  
Middle Jurassic ◽  
The Arctic ◽  
The South ◽  
Temperate Latitude ◽  
The North ◽  
Biotic Diversity ◽  
The Pacific ◽  
Shelf Seas ◽  
Two Factors

The palaeogeographic settings of Denmark and East Greenland during the Middle Jurassic are outlined. They lay in the widespread epicontinental seas that covered much of Europe in the post-Triassic transgression. It was a period of continuing eustatic sea-level rise, with only distant connections to world oceans: to the Pacific, via the narrow Viking Straits between Greenland and Norway and hence the arctic Boreal Sea to the north; and to the subtropical Tethys, via some 1200 km of shelf-seas to the south. The sedimentary history of the region was strongly influenced by two factors: tectonism and climate. Two modes of tectonic movement governed basinal evolution: crustal extension leading to subsidence through rifting, such as in the Viking and Central Grabens of the North Sea; and subcrustal thermal upwelling, leading to domal uplift and the partition of marine basins through emergent physical barriers, as exemplified by the Central North Sea Dome with its associated volcanics. The climatic gradient across the 30º of temperate latitude spanned by the European seas governed biotic diversity and biogeography, finding expression in rock-forming biogenic carbonates that dominate sediments in the south and give way to largely siliciclastic sediments in the north. Geochronology of unrivalled finesse is provided by standard chronostratigraphy based on the biostratigraphy of ammonites. The Middle Jurassic saw the onset of considerable bioprovincial endemisms in these guide-fossils, making it necessary to construct parallel standard zonations for Boreal, Subboreal or NW European and Submediterranean Provinces, of which the NW European zonation provides the primary international standard. The current versions of these zonations are presented and reviewed.

scholarly journals Arctic Thunder: A Novel by R. Feagan

2011 ◽  
Vol 1 (1) ◽  
Author(s):  
Sandy Campbell
Keyword(s):  
Point Of View ◽  
The Arctic ◽  
The South ◽  
Traffic Light ◽  
Basketball Players ◽  
University Of Alberta ◽  
The North ◽  
Western Arctic ◽  
Turn Over ◽  
The University

Feagan, Robert. Arctic Thunder: A Novel. Toronto: Dundurn Press, 2010. Print. St. Albert is a small city, just north of Edmonton in Central Alberta.  In the opening pages of this book, thirteen-year-old Mike Watson and his team, the St. Albert Rams, win the Alberta Bantam Provincial box lacrosse championship.  Then his father, an RCMP officer, announces that they’ve been posted to Inuvik, which Mike describes as a place “somewhere inside the Arctic Circle and makes winter in St. Albert seem like summer”. The author, Robert Feagan, who lives in St. Albert, but spent much of his youth in RCMP posts across the Canadian Western Arctic, does a good job of presenting the struggles of a thirteen year old boy from the South trying to fit into the largely Inuit and Dene community in Inuvik. The story is definitely told from the point of view of a “white kid from the South”, except that Mike is part Zulu, so he sort of looks like he might fit in. Mike finds that teenagers are teenagers everywhere and when he goes to school he meets: the bully, the nerd whom everyone avoids and the super athletes, who in this case compete in the Arctic Games.  There is even a beautiful female nemesis, Gwen, who is one of the best basketball players Mike has every encountered. While well written and engaging, Feagan sometimes becomes a little didactic in educating the reader about the North.  Characters occasionally launch into unnaturally detailed explanations about things northern. Much of the tension between characters is also resolved too neatly.  Most of the core characters acquire self-understanding, turn over new leaves, and apologize to each other within a very few pages.  Much more realistic is the portrayal of the typical teenager, Mike, whispering a “Thank-you” to his Mom, long after she’s out of earshot. Through the course of the book, Mike (and the reader) come to appreciate what Inuvik, with its single traffic light and one retail store, has to offer.  Feagan works in a sensitive treatment of the role of the elders in the community and the healthy effects of living close to the land.  Of course, lacrosse, which no one plays in Inuvik, is an important thread through the story. Adult readers should not be put off by the fact that this is a young adult novel; it is a good Arctic read for anyone. Highly recommended: 4 out of 4 starsReviewer: Sandy Campbell Sandy is a Health Sciences Librarian at the University of Alberta, who has written hundreds of book reviews across many disciplines.  Sandy thinks that sharing books with children is one of the greatest gifts anyone can give. 

Seasonal change and microhabitat association of Arctic spider assemblages (Arachnida: Araneae) on Victoria Island (Nunavut, Canada)

2017 ◽  
Vol 149 (3) ◽  
pp. 357-371 ◽  
Author(s):  
Elyssa R. Cameron ◽  
Christopher M. Buddle
Keyword(s):  
Seasonal Change ◽  
Ecological Monitoring ◽  
High Arctic ◽  
The Arctic ◽  
Arctic Ecosystems ◽  
Active Season ◽  
The North ◽  
Arthropod Predators ◽  
Abundance And Diversity ◽  
Victoria Island

AbstractArctic ecosystems are characterised by a mosaic of distinct microhabitats, which play a key role in structuring biodiversity. Understanding species diversity in relation to these microhabitats, and how communities are structured seasonally, is imperative to properly conserve, monitor, and manage northern biodiversity. Spiders (Arachnida: Araneae) are dominant arthropod predators in the Arctic, yet the seasonal change in their communities in relation to microhabitat variation is relatively unknown. This research quantified how spider assemblages are structured seasonally and by microhabitat, near Cambridge Bay, Nunavut, Canada. In 2014, spiders were collected in 240 pan and pitfall traps placed in common microhabitat types (two wet and two dry) from 3 July to 11 August, the active season in the high Arctic. In total, 10 353 spiders from 22 species and four families were collected. Non-metric multidimensional scaling ordinations revealed that spider assemblages from wet habitats were distinct from those occurring in drier habitats, but that differences within each of those habitats were not evident. Abundance and diversity was highest in wet habitats and differed significantly from dry habitats; both these variables decreased seasonally. Spider assemblages in the north are structured strongly along moisture gradients, and such data informs planning for future ecological monitoring in the Arctic.

Logistic aspects of geological studies in the Ellsworth Mountains, Antarctica, 1979–80

Polar Record ◽  
1982 ◽  
Vol 21 (131) ◽  
pp. 147-159 ◽  
Author(s):  
John F. Splettstoesser ◽  
Gerald F. Webers ◽  
David B. Waldrip
Keyword(s):  
Austral Summer ◽  
Summer Season ◽  
The South ◽  
The North

The most ambitious field project of the 1979–80 austral summer season in Antarctica was conducted in the Ellsworth Mountains (Fig 1), when 42 scientists and technicians studied a variety of geological problems in an area which included both the Sentinel Range to the north and the Heritage Range to the south (Fig 2), from about 77°15'S to 80°30'S and 80°W to 87°30'W.

scholarly journals Northern agriculture: constraints and responses to global climate change

1996 ◽  
Vol 5 (3) ◽  
pp. 229-234 ◽  
Author(s):  
Timo J. N. Mela
Keyword(s):  
Effective Temperature ◽  
Global Climate ◽  
Growing Season ◽  
The Arctic ◽  
Northern Europe ◽  
The South ◽  
The North ◽  
Temperature Sum ◽  
High Yields ◽  
Cattle Rearing

In the northern circumpolar zone, the area between the 600°Cd and 1200°Cd isopleths of effective temperature sum above 5°C, the annual receipt of solar energy is limited by the low angle of radiation arriving at the earth’s surface. This is the primary cause of the climatic constraints observed in the zone, such as low temperatures, a short growing season, frosts during the growing season, long and cold winters and thick snow cover. In Finland, the length of the growing season varies from 180 days in the south (60°N) to 120 days in the north (70°N). Consequently, the growing time for crops from sowing to ripening is also short, which limits their ability to produce high yields. The most advanced forms of farming in the high-latitude zone are encountered towards the south in Northern Europe, central Siberia and the prairies of Canada, i.e. mainly in the phytogeographical hemiboreal zone where the effective temperature sum is higher than 1200°Cd. Conditions for agriculture then deteriorate gradually further north with the cooling of the climate, and this is reflected as an increase in cattle rearing at the expense of grain cultivation. In northern Europe farming is practised as far north as to the Arctic Circle, at about 66°N latitude. In North America, fields extend to about 55°N, In Asia, there are few fields north of 60°N. Finland is the most northern agricultural country in the world, with all its field area, about 2.5 million hectares, located north of latitude 60°N. Changes in the climate and atmospheric CO2 predicted for the future are likely to have a strong influence, either beneficial or disadvantageous, on the conditions for growth in northern areas where the annual mean temperature is 5°C or less.

Sign in / Sign up

Export Citation Format

Share Document