Food intake, feeding rhythm, and body mass regulation in Svalbard rock ptarmigan.
Food intake (FI), feeding activity (FA), and body mass (BM) were recorded continuously throughout a 13-mo period in Svalbard rock ptarmigan kept under natural conditions of light and ambient temperature at Svalbard (79 degrees N). FI was persistently high from March until August, including the period when daylight is continuous, whereas it was low from November until January, when it is permanently dark. From August until November, BM doubled, while FI dropped to one-third. BM fell rapidly from mid-November until April despite a doubling of FI from February until March. From August until mid-November and from February until mid-April FA occurred mainly during the light period of the day. From late November until February and from mid-April until August intermittent FA occurred continuously. It is suggested that the seasonal changes in BM are not determined by FI alone but depend heavily on seasonal changes in locomotor activity as reflected in FA.
D000818:Animals; D001717:Birds / Q000502:physiology*; D001835:Body Weight; D002940:Circadian Rhythm; D004435:Eating; D010507:Periodicity; D012621:Seasons