omnivory

Omnivory is a feeding strategy in which an organism obtains energy and nutrients from more than one trophic level, typically by consuming both plant matter and animal matter. In practice, many omnivores supplement their diet with detritus, fungi, or microorganisms. The term applies to both the diet of individual species (omnivore) and to patterns in food webs, where consumers feed across multiple trophic levels rather than feeding only on organisms at one level.

Common omnivores include humans, bears, raccoons, pigs, crows, and many fish and insect species. Some omnivores are facultative, meaning they primarily rely on one type of food but readily switch to others when availability changes; others are obligate omnivores who consistently include a mixed diet.

Ecological implications: Omnivory increases the connectance of food webs by linking producers, herbivores, and carnivores. It can stabilize energy flow and predator–prey dynamics by offering alternative prey, but it also complicates predictions of population dynamics and can facilitate the transfer of energy, nutrients, or contaminants across trophic levels.

Evolution and measurement: Omnivory arises where resources vary in availability. It is a continuum from specialists who occasionally eat non-preferred food to generalists whose diet includes substantial amounts from multiple levels. Diet breadth, trophic level range, and omnivory indices are used to quantify the degree of omnivory in ecological studies.