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How do animals learn which foods are nutritious or poisonous?

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Two wild horses graze on tall grass in the open prairie of Theodore Roosevelt National Park, with rolling badlands visible in the background. — Feeding behaviour Wild horses graze in the Badlands of North Dakota.

Animals learn to identify nutritious or poisonous foods primarily through individual experience and associative learning, which links sensory inputs like taste and smell to post-feeding outcomes.1

Learning Nutritional Value

Animals often balance their nutrient intake by associating specific flavors with positive or negative physiological effects. When an animal experiences a deficiency, it may develop an increased preference for flavors associated with needed nutrients, such as protein or carbohydrates. Conversely, they can learn to reject foods that lack essential components, such as specific amino acids or vitamins, through aversion learning.1

Avoiding Poisonous Foods

To avoid toxins, many species employ a strategy of sampling novel foods in small quantities. If the food causes illness, the animal associates the distress with the flavor of that food and subsequently excludes it from its diet. This aversion can be powerful; in mammals, strong aversions to flavors can be conditioned even when the onset of illness is delayed by several hours. While some food preferences are innate, individual learning allows animals to refine their diet based on the specific palatability and safety of items encountered in their environment.12