Foraging Strategies

When observing foragers in their natural habitats, it is obvious that species have developed sometimes very specific ways of ingesting food to extract the necessary nutrients for survival and reproduction.

This is partly because food is typically distributed within a close geographical area and within a timeframe, whether it is a fruit that ripens at a specific season or a herd of zebras crossing a lion's hunting ground. Therefore, foraging strategies must take this heterogeneous distribution into account: some animals constantly consume a large amount of food with little nutritional values, such as cows grazing on grass, while others are able to ingest large quantities of food punctually with large fasting times in between, such as large snakes eating large prey three to four times a year.

Competition is also a strong factor pressuring species to find specific ecological niches, where their foraging strategy will not be challenged and would still provide the nutrients for survival.

Despite the large variation in foraging strategies, foragers' strategies usually fall into two broad categories:

• "Searching": the forager actively roams a foraging patch looking for specific preys. This strategy incurs an energetic cost due to traveling, but can sharply increase the probability of finding a prey that satisfies the forager's need. Of course, if the forager feeds on static prey (like plants and trees), then this strategy is their only way of feeding and the choice of the foraging patch is extremely important to avoid wasting energy on a low prey density location. This strategy is also typical of endotherms, animals able to generate their own body heat.

• "Ambush", also called "Sit and Wait": as the name suggests, the forager stays in the same location waiting for a mobile prey to appear. While this strategy minimizes the expenditure of energy, the potential energy gain is directly proportional to the density of preys in the foraging patch. This strategy is often associated with ectotherms, which gather heat from an external source such as the sunlight.

Other foraging strategies can be associated with the process the forager consumes their prey.

• Predators, or "True Predators", usually hunt other animals, consuming the entirety of the prey providing a large amount of energy that we will allow to survive for a long period of time.

• Herbivores, or "Grazers" when it comes to feeding on grass, typically get their energy from eating plants and other photosynthetic organisms. They usually consumes only a fraction of their prey (rarely fruit, leaves, stems and roots altogether for example) which allow regeneration. Due to the lower nutritional values of these preys, herbivores have to allocate more time for foraging activities to meet their needs.

• Parasites gathers nutrients from a live host organism, either feeding from the host itself or from the food they themselves ingest.