Sökning: "winter behaviour"

Visar resultat 11 - 15 av 52 avhandlingar innehållade orden winter behaviour.

1. 11. Observations of water vapour in the middle atmosphere

   Författare :Stefan Lossow; Jörg Gumbel; Jacek Stegman; Daniel R. Marsh; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; water vapour; mesosphere; stratosphere; dynamics; Odin satellite; limb sounding; microwave; tropics; polar winter; Meteorology; Meteorologi; meteorologi; Meteorology;

   Sammanfattning : Water vapour is the most important greenhouse gas and plays a fundamental role in the climate system and for the chemistry of the Earth's atmosphere. This thesis presents observations of water vapour in the middle atmosphere with a particular focus on the mesosphere. LÄS MER

3. 12. Cycles of voles, predators, and alternative prey in boreal Sweden

   Författare :Birger Hörnfeldt; S. Erlinge; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; 3-4 year cycles; Clethrionomys glareolus; Clethrionomys rufocanus; Microtus agrestis; snap-trapping; rate of change; population regulation; delayed density-dependence; time-lag mechanism; seasonality; predation; food; predator avoidance; foraging behaviour; Aegolius funereus; nest boxes; numerical response; nomadism; Vulpes vulpes; Sarcoptes scabiei vulpes; Lepus timidus; Francisella tularensis; Tetraonidae; hunting statistics; zooekologi; Animal Ecology;

   Sammanfattning : Bank voles, grey-sided voles, and field voles had synchronous 3-4 year density cycles with variable amplitudes which averaged about 200-fold in each species. Cycles of vole predators (red fox and Tengmalm's owl), and their (foxes') alternative prey (mountain hare and forest grouse) lagged behind the vole cycles. LÄS MER

4. 13. The behaviour of mica-rich aggregates under the temperate climate conditions

   Författare :Evgeny Novikov; Luleå tekniska universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Geoteknik; Soil Mechanics;

   Sammanfattning : In regions of temperate climate the destructive influence of frost action such as frost heave in winter and thaw weakening in spring are the main contributors to severe deterioration of the pavement structure. A number of studies on construction aggregates and field observations of road failures, especially caused by seasonal fluctuations of temperature, have revealed a negative influence of unbound mica-rich rock aggregates on the service life of road construction. LÄS MER

5. 14. Effects of winter-feeding on reindeer’s future ability to utilize natural pastures

   Författare :Heidi Rautiainen; Sveriges lantbruksuniversitet; Sveriges lantbruksuniversitet; []
   Nyckelord :LANTBRUKSVETENSKAPER; AGRICULTURAL SCIENCES;

   Sammanfattning : Winter feeding of reindeer (Rangifer tarandus tarandus) has become an increasingly common management action in reindeer husbandry in Sweden, Finland, and Norway when natural grazing resources are unavailable due to the loss of grazing grounds, disturbances, and icing events. In the short term, feeding increases survival and reproduction, but the long-term effects on reindeer’s ability to utilize natural pastures have not been investigated. LÄS MER

7. 15. Seasonal variations in general activity, behaviour and cutaneous glandular structures in reindeer (Rangifer tarandus L.)

   Författare :Torgny Mossing; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Androgen; Cervidae; dermal glands; locomotor activity olfactory communicatiorL pheromones; photoperiod; rein deer; rut; seasonal variations;

   Sammanfattning : The locomotor activity of the reindeer is separated into a diurnal and a nocturnal phase which, in turn, consists of a  number of short-term activity bursts. The onset and termination  of diurnal and nocturnal activity are largely in synchrony  with sunrise and sunset. LÄS MER