Foraging theory

Optimal Foraging Theory

Optimal foraging theory (OFT) is a model that helps predict how an animal behaves when searching for food. Although obtaining food provides the animal with energy, searching for and capturing the food require both energy and time. The animal wants to gain the most benefit (energy) for the lowest cost during foraging, so that it can maximize its fitness. OFT helps predict the best strategy that an animal can use to achieve this goal.

OFT is an ecological application of the optimality model. This theory assumes that the most economically advantageous foraging pattern will be selected for in a species through natural selection. When using OFT to model foraging behavior, organisms are said to be maximizing a variable known as the currency, such as the most food per unit time. In addition, the constraints of the environment are other variables that must be considered. Constraints are defined as factors that can limit the forager’s ability to maximize the currency. The optimal decision rule, or the organism’s best foraging strategy, is defined as the decision that maximizes the currency under the constraints of the environment. Identifying the optimal decision rule is the primary goal of the OFT.

Well how may this help with humans foraging?

What I find interesting about this theory is that it allows us to begin understanding foraging timings within what are called foraging zones. For us this could be the space of about 50m squared, a single woodland or even the front of a coast, it can also be linked with a single species of plant.

It seems that there is an optimal amount of time to be spent collecting a single species of plant from a single zone. Once over 30-40% of the plant material available in a single zone has been collected foraging speed and harvest size begins to slow down fairly dramatically. It therefore makes me think that a key to the most successful foraging for myself, as with animals, is little and often. This fits quite nicely with what I deem good foraging practice, pick up to 30% of what’s available at your foraging zone before quickly moving on to the next zone.

Don’t waste time picking the whole lot at one zone as you will be wasting time. It’s sometimes nice to work through a zone fairly systematically, following a line, like a lawn mower, but before you know it you’ve fully cleared a site and it’s taken you hours. Instead pick a little from here, a little from there and move on swiftly. Not only will you pick more and pick faster, you will leave a lot less impact on the zones and sites you’re picking from.

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