, Volume 127, Issue 3, pp 215-227

Short-term rhythms in foraging behaviour of the common vole,Microtus arvalis

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access

Summary

  1. The common vole,Microtus arvalis, like other vole species, in captivity has a short-term activity rhythm in daytime, with a period of circa two hours. Trapping records show that this rhythm exists also in field conditions, with the population in synchrony to some degree; a correlation of trapping frequency with vole predation by kestrels indicates that it reflects the true natural behaviour.

  2. Lehmann's (1976) evidence inMicrotus agrestis that the short-term activity rhythm is essentially a feeding rhythm is supported for the common vole by separate recording of wheel running, feeding and nestbox occupation.

  3. The short-term rhythm is phase-locked to dawn. There is fair intraindividual constancy from day to day in the timing of meals, but interindividual variation causes a gradual breakdown of population synchrony in the course of the day, both in the field and in captive isolation.

  4. The frequency of the rhythm may be evolutionarily adjusted to metabolic demands of the species, as suggested by its dependence on body weight, but remains relatively invariant in the face of experimental (temperature) manipulation of metabolic expenditure. In the absence of food during the day, feeding attempts recur with the same timing as meals did before: periodic changes in satiety, related to food intake and digestion are insufficient to account for such changes in feeding motivation.

  5. The risk of being killed by a kestrel is lower for voles active in phase with the population majority than for voles out of phase with the population: there is safety in numbers. Numbers vary dramatically in vole populations, however, and the generality of predatory selection for prey synchrony remains to be tested.

  6. Foraging behaviour of the common vole is regulated by a circadian timing system even though feeding is spread evenly over night and day. The adaptive advantage of circadian entrustment with the timing of feeding motivation above meal timing by digestive processes is sought in the individual repetition of daily patterns as the optimal strategic answer to temporal day-to-day correlations in the environment.

Dedicated by the senior author to Professor Colin S. Pittendrigh on the occasion of his 60th birthday, with friendship and respect
We are grateful to Cor Dijkstra, Adriaan Rijnsdorp and Lourens Vuursteen for allowance to use their data on kestrel predation on voles, to Ludolf Smitt for the use of an experiment on vole feeding motivation, and to various other students for help in collecting the field data. The permission for field work in the Lauwersmeer land reclamation by the “Rijksdienst voor de IJsselmeerpolders” (R.IJ.P.) is greatly appreciated.