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Activity rhythms in the Wood Mouse, Apodemus sylvaticus and the Bank Vole, Clethrionomys glareolus.



  • 1Simultaneous recordings were made of the feeding activities of the Wood Mouse (Apodemus sylvaticus) and the Bank Vole (Clethrionomys glareolus) in response to day-lengths of sixteen, twelve, and eight hours respectively.
  • 2The results are compared for amount of activity spent in feeding, pattern of distribution of activity during the daily cycle, nocturnal preference, and feeding behaviour.
  • 3The rhythms of both species are readily modifiable according to day-lengths and seem to vary in pattern as a function of their specific nocturnal preferenda and food habits.
  • 4The amount of activity outside the nest decreased considerably when food storing became a part of the species behaviour but was otherwise more or less constant.
  • 5Wood mice began storing food when the day-length was decreased from sixteen to twelve hours and bank voles when it was decreased from twelve to eight hours. The corresponding reductions in amount of activity (mean number of active periods per diel cycle) were of the same relative proportion for each species.
  • 6Progressive decreases in day-length produced parallel changes in nocturnal preference between the two species.
  • 7The results of other studies of activity rhythms in closely related species are compared with the data from the present investigation and certain theoretical discrepancies noted.
  • 8It is suggested that the role of activity rhythms in the community relations of the wood mouse and bank vole is an extremely critical one and that it is an important feature of any competition between them.
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