Foraging in the domestic pig, sus scrofa

Author: Arielle Layman

Introduction

Optimal foraging theory uses theories of natural selection to interpret organisms’ feeding strategies. It predicts that animals that maximize caloric intake while minimizing costs will increase their fitness (Stephens, 2007). When applying the theory to an organism, three factors, which are called assumptions, must be considered:

1. Decision Assumptions
   1. What is the organism’s goal in foraging? For example, is it looking to maximize nutrient intake or prevent starvation?
2. Currency Assumptions
   1. How will the organism compare choices?
3. Constraint Assumptions
   1. What limits does the organism face? For instance, what is available and what is safe to eat? (Stephens, 1986)

The predictions of optimal foraging theory vary greatly depending on the organism studied. An herbivore may have to weigh the risk of being preyed upon while against the nutritional benefit of the food. A carnivore may have to choose between a high-risk high-gain scenario, such as attacking large but difficult to subdue prey, and a low-risk low-gain scenario, such as consuming easy to attack but less substantial prey. Optimal foraging theory can therefore be divided into two main questions: how long should an herbivore stay in a food patch and which prey should a carnivore consume? (Stephens, 1986).

Often, a forager’s decisions are dependent on those of another forager, and social foraging theories apply. For example, a bee may perform a dance to show its hive the location of nectar (Kamil, 1987) or predators may hunt in packs (Giraldeau, 2000)

The domestic pig, Sus scrofa domestica , is an interesting organism to study in the light of optimal foraging theory. It is an omnivore that faces few constraints—it is preyed upon by few predators and has a varied diet— so it has many foraging options (Watson, 2004). Comparing its behavior to its undomesticated predecessor, the wild boar ( Sus scrofa ), provides a unique perspective on the evolution of foraging.