Acta Biotheoretica

, Volume 38, Issue 1, pp 37–61 | Cite as

The value of fat reserves and the tradeoff between starvation and predation

There's a special providence in the fall of a sparrow Hamlet Act V sc ii
  • John M. McNamara
  • Alasdair I. Houston


It is shown that in a range of models, the probability that a forager dies from starvation is, to a good approximation, an exponential function of energy reserves. Using a time and energy budget for a 19g passerine, we explore the consequences, in terms of starvation and predation, of various levels of energy reserves. It is shown that there exists an optimal level L of reserves at which total mortality (starvation plus predation) is minimized. L increases when the environment deteriorates as a result of a decrease in either temperature or mean gross gain or an increase in the mean search time. The effect of combined deteriorations is greater than the sum of their individual effects. At L, the probability of predation is much higher than the probability of starvation. A simple analytic model suggests that this result will be fairly general, but also indicates conditions under which the result might not hold.


Exponential Function Optimal Level Individual Effect Energy Budget Total Mortality 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Kluwer Academic Publishers 1990

Authors and Affiliations

  • John M. McNamara
    • 1
  • Alasdair I. Houston
    • 2
  1. 1.School of MathematicsUniversity WalkBristol
  2. 2.Department of ZoologyEGIOxford

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