Seasonal variations in the food consumption of woodchucks (Marmota monax).
Food consumption of 155 woodchucks ( Marmota monax ) was measured immediately after capture to determine whether a seasonal rhythm obtained in feeding of a natural population. Food intake of adults was lowest in March. It reached a maximum in May, then declined through the summer; some individuals increased food intake temporarily in late autumn. Comparative ata from a laboratory colony showed that a similar rhythm occurred under conditions of constant temperature and photoperiod. Variability in food consumption axima associated with different age groups, considered in the context of vailable life history information, suggested that the rhythm had a period omewhat less than 1 year.
Seasonal changes of food and water consumption and urine production of the marmot, Marmota flaviventris.
In early spring, food and water consumption and the excretion and clearances of urine and solutes reached maximal rates. Water consumption exceeded food intake and urine production and plasma osmolality was lowest. Toward early and late summer, water intake decreased faster than food consumption and urine production. Urea excretion and clearances diminished with food consumption, while creatinine clearance decreased only slightly. Plasma osmolality increased. The data are consistent with rehydration soon after hibernation is completed, followed by a period of weight gain and dehydration in preparation for the next prolonged period of hibernation.
Die Populationsdynamik Von Canthocampt Us Staphylinus (Jurine) (Copepoda, Harpacticoida) Im Litoral Des Bodensees
The population dynamics of Canthocamptus staphylinus in the littoral zone of Lake Constance are described (fig. 2). Adult animals aestivate as cysts. The main part of the population emerges from the cysts in autumn. During the resting stage and the first spell after emerging, mortality is very low (fig. 3). Reproduction, expressed as numbers of ovigerous females, begins in November and reaches its maximum in January. The new generation becomes adult in May/June and encysts without previous reproduction. According to Sarvala (1979) it may be possible, that in littoral populations dormancy is induced by long day periods and temperatures of over 12° C (figs. 1, 2). In the profundal zone C. staphylinus also forms cysts, however, both light and temperature are not likely to induce this stage in depths of over 60 m.