Ovivore

Ovivores are animals that feed on eggs as a meaningful part of their diet. In fact, the term ‘ovivore’ derives from the Latin words ovum, meaning ‘egg’, and vorare, meaning ‘to devour’.¹

Depending on the predator’s size, mouthparts, habitat, and foraging strategy, ovivores may consume many kinds of animal eggs, including bird, reptile, amphibian, and fish eggs, as well as eggs laid by insects and other invertebrates.

However, the dependence of these animals on eggs may vary. While some ovivores are highly specialized for egg-eating, others may be opportunistic, feeding on eggs only when they are available.

Eggs as Prey

Eggs are a highly nutritious food source because they are designed to support the growth of embryos. They are also often laid in clutches, making them a concentrated source of nutrition. Moreover, unlike mobile prey, eggs are stationary, with no chance of fleeing or hiding once a predator finds them.

However, they are not easy to obtain. Eggs are typically seasonal and unpredictable, and many are protected by hard or leathery shells that can be difficult to crack or swallow. Their location can also make them hard to access. Eggs may be hidden in nests, buried underground, placed high in trees or cliffs, laid inside cavities, or even attached to underwater surfaces. Additionally, parent animals may guard their eggs and fiercely attack predators, distract them, or mob them to drive them away.

Types

Ovivores are grouped under 3 broad categories based on how strongly they depend on eggs in their diet.

1. Specialist Ovivores: They are highly adapted to eating eggs and typically rely on them heavily. 
2. Frequent Ovivores: They are generalist predators that regularly seek out eggs during nesting, breeding, or spawning seasons. However, they also feed on other food sources.
3. Opportunistic Ovivores: They are broad-diet animals that consume eggs only when they are available, but do not depend on them as a major food source.

Adaptations

These animals have different anatomical and behavioral adaptations that help them locate, access, and consume eggs.

• Specialist egg-eating snakes have flexible jaws and expandable throats that allow them to swallow eggs whole, while their reduced teeth help keep the shell intact until it is inside the body. Once swallowed, bony projections in the neck region crack the shell in the esophagus.²
• Birds use their sharp beaks to crack open the eggs. They also use their memory to locate nests.
• Mammals typically have a strong sense of smell, which they use to detect eggs. They then use their jaws to break them open.
• Fish generally consume eggs that remain exposed in spawning areas.
• Insects and other invertebrates typically target small, soft, exposed, or damaged eggs that larger predators usually ignore.

Ecological Role

Ovivores play an important role in food webs because they affect how many eggs survive to hatch. By feeding on eggs, they directly affect the reproductive success of egg-laying animals. This pressure can also shape nesting behaviors, such as hiding eggs, guarding nests, laying eggs in safer places, or producing higher quantities of eggs.³

However, egg predation is not necessarily harmful. As a part of the food web, it helps transfer energy from eggs to predators. However, it becomes a concern when ovivores become unusually abundant in a particular habitat, or they target vulnerable species with small populations, leading to an alarming decrease in their numbers.⁴