Vigilance

One thing that many animals do when feeding is to remain vigilant. Most animals don't have eyes in the backs of their heads, so they must periodically stop eating to scan the area for predator using vision, smell, or sound.

Think of a duck that has potential predators under the water (snapping turtle) and above (raptors). Ducks cannot be vigilant for raptors while their head is underwater looking for food, nor be vigilant for underwater predators without looking under water. The result is that an increase in predation threat reduces feeding in ducks.

When wolves, having previously been absent for 50 years, were re-introduced to Yellowstone Park, greater elk (Cervus elaphe) and bison (Bison bison) females
responded by increasing their vigilance while decreasing their foraging. This response was especially pronounced in breeding female elk with calves.