Optimal Foraging
Optimal Foraging Behavior:
Optimal foraging is strictly behavioral ecology. In this kind of analysis
we look at the performance of a behavior. The assumption of the theory
of optimal foraging is that organisms will be energy maximizers or time
minimizers. Energy maximizers try to get the most energy out of an environment
and time minimizers try to get the energy they need in the least possible
time. Thus, any time energy is limiting, an approach such as this is very
useful. Some examples of variations of this are:
• Optimal diet problem
• Optimal patch use problem
• Optimal load size problem.
Crows and Welks:
One example is the crows that drop welks on the ground to crack open the
shells. The crow must make several decisions. Mostly, how high should
it fly before it drops the welk? If it flies high, they need to drop the
welk fewer times. But, the higher the crow flies, the more energy it spends.
It would be possible to theoretically calculate which height is the most
optimum to drop the welk based on the least energy expenditure. From this
theoretical estimate you an go out in the wild and estimate what is the
actual average height that a crow drops a welk. It turns out that the
height seen in the wild is the same as the theoretical best value.
Handling time:
Another common optimal foraging experiment is to look at the optimal size
of prey for a bird to get the most energy per time out of a system.
Central Place Foraging:
Birds are most known for this type of foraging theory. This is primarily
because birds have a nest and will then go out to forage. The idea is
that birds will bring back more or larger prey when they are away from
the nest than when they are near the nest.
Marginal Value Theorem:
As a bird begins to eat in a patch, the food density decreases. What point
should an individual leave a patch. How long will it take for an individual
to leave a patch. If there is a patch that is close to another, the bird
should leave sooner than if the patch is farther away. Thus, the use depends
on the patch gain and the rate of travel between patches.
An interesting video of Crow Feeding.
By Rob Nelson
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