Sökning: "body reserves"

Visar resultat 1 - 5 av 18 avhandlingar innehållade orden body reserves.

  1. 1. Nesting and migration in the introduced Canada goose in Sweden

    Författare :Göran Sjöberg; Catherine M. Lessells; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Species introductions; DNA fingerprinting; natal dispersal; breeding dispersal; bird migration; wintering areas; clutch size; laying date; body reserves; nest defence; waterfowl; Canada goose; Anatidae; Branta canadensis;

    Sammanfattning : The aim of the thesis was to document patterns in breeding and migration in Swedish Canada geese Branta canadensis, to explain these against the genetic and historical background of the population, and to test predictions of hypotheses pertaining to parental investment.The Canada goose population in Sweden was founded by the introduction of a few individuals in the 1930's. LÄS MER

  3. 2. Allocation of body resources to reproduction in butterflies

    Författare :Fredrik Stjernholm; Bengt Karlsson; Christer Wiklund; Jane K. Hill; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Biology; Zoology; Ecology; Butterflies; Reproduction; Life histories; Trade-offs; Resource use; Terrestrial; freshwater and marine ecology; Terrestisk; limnisk och marin ekologi;

    Sammanfattning : The life-history of an organism can be studied and understood in terms of acquisition and expenditure of resources. In butterflies, the use of resources for reproduction has been the focus of much research due to the possibility to easily quantify both the input of resources from different sources over the life-cycle as well as the partitioning of these resources to reproduction. LÄS MER

  4. 3. Costs and Tactics in the Evolution of Reproductive Effort

    Författare :Ingemar Jönsson; Biologiska institutionen; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; capital breeding; Falco tinnunculus; body mass; DEE; reproductive effort; reproductive costs; income breeding; Animal ecology; Djurekologi;

    Sammanfattning : This study focuses on various aspects of costs of reproduction and the evolution of energetic breeding tactics. It emphasizes the distinction between demographic costs of reproduction expressed already before current offspring have reached independence (prebreeding costs), and costs expressed only after offspring independence (postbreeding costs). LÄS MER

  5. 4. Bird orientation: external cues and ecological factors

    Författare :Johan Bäckman; Evolutionär ekologi; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; tracking radar; Emlen funnel.; Animal ecology; Djurekologi; oscillatory orientation; roosting flight; scatter; concentration; heading; cue calibration; light dependent; magnetoreception; subcutaneous fat stores; body condition; energetics; geomagnetic field; visual cues; orientation; birds; migration;

    Sammanfattning : Birds are generally capable of accurate orientation. In this thesis I present studies about the external cues and the ecological factors that influences bird orientation. A multitude of environmental cues are used to select and maintain a proper direction. LÄS MER

  7. 5. Fattening strategies in wintering passerines

    Författare :Kristjan Lilliendahl; Innes C Cathill; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Biology; Biologi; zoologisk ekologi; Animal Ecology;

    Sammanfattning : Stored fat is a main source of energy for birds in winter and it seems reasonable that fatter birds should survive better. Small birds wintering at high latitudes, however, carry less fat than their capacity permits, suggesting a predation cost of excessive fatness. LÄS MER