Details

Autor(en) / Beteiligte

• Sundell, Janne
• Dudek, Dorota
• Klemme, Ines
• Koivisto, Elina
• Pusenius, Jyrki
• Ylönen, Hannu

Titel

Variation in Predation Risk and Vole Feeding Behaviour: A Field Test of the Risk Allocation Hypothesis

Ist Teil von

• Oecologia, 2004-03, Vol.139 (1), p.157-162

Ort / Verlag

Berlin: Springer-Verlag

Erscheinungsjahr

2004

Quelle

MEDLINE

Beschreibungen/Notizen

• Many prey animals experience temporal variation in the risk of predation and therefore face the problem of allocating their time between antipredator efforts and other activities like feeding and breeding. We investigated time allocation of prey animals that balanced predation risk and feeding opportunities. The predation risk allocation hypothesis predicts that animals should forage more in low- than in high-risk situations and that this difference should increase with an increasing attack ratio (i.e. difference between low- and high-risk situations) and proportion of time spent at high risk. To test these predictions we conducted a field test using bank voles (Clethrionomys glareolus) as a prey and the least weasel (Mustela nivalis nivalis) as a predator. The temporal pattern and intensity of predation risk were manipulated in large outdoor enclosures and the foraging effort and patch use of voles were measured by recording giving-up densities. We did not observe any variation in feeding effort due to changes in the level of risk or the proportion of time spent under high-risk conditions. The only significant effect was found when the attack ratio was altered: the foraging effort of voles was higher in the treatment with a low attack ratio than in the treatment with a high attack raio. Thus the results did not support the predation risk allocation hypothesis and we question the applicablity of the hypothesis to our study system. We argue that the deviation between the observed pattern of feeding behaviour of bank voles and that predicted by the predation risk allocation hypothesis was mostly due to the inability of risk. However, we also emphasise the difficulties of testing hypotheses under outdoor condition and with mammals capable of flexible behavioural patterns.