, Volume 152, Issue 2, pp 357–364 | Cite as

When carnivores are “full and lazy”

Behavioral Ecology


Are animals usually hungry and busily looking for food, or do they often meet their energetic and other needs in the 24 h of a day? Focusing on carnivores, I provide evidence for the latter scenario. I develop a model that predicts the minimum food abundance at which a carnivore reaches satiation and is released from time constraints. Literature data from five invertebrate and vertebrate species suggest that food abundances experienced in the field often exceed this threshold. A comparison of energetic demands to kill rates also suggests that carnivores often reach satiation: for the 16 bird and mammal species analyzed, this frequency is 88% (average across species). Because pressure of time would likely lead to trade-offs in time allocation and thus to a nonsatiating food consumption, these results suggest that carnivores are often released from time constraints.


Energy-time budgets Functional responses Kill rates Principle of stringency Time constraints 



I thank Carlos Martínez del Rio for discussions about foraging theory and physiological ecology. Richard Caldow is acknowledged for providing me with raw data and for comments on the manuscript. Further helpful comments came from Chris Carbone, Michael Kopp, John McNamara, Wolf Mooij, Richard Ostfeld, David Stephens, Jan van Gils, Martin Wikelski, and an anonymous reviewer.

Supplementary material

442_2006_654_MOESM1_ESM.doc (101 kb)
Kill Rates of Free-Ranging Carnivorous Birds and Mammals Compared to their Demands (DOC 101 kb)


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Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  1. 1.Section of Evolutionary Ecology, Department Biology IILudwig-Maximilians-UniversityMunichGermany
  2. 2.Laboratory of Ecological and Evolutionary Dynamics, Department of Biological and Environmental SciencesUniversity of HelsinkiHelsinkiFinland
  3. 3.Evolutionary Ecology Unit, Department of Biological and Environmental ScienceUniversity of JyväskyläJyväskyläFinland

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