What Are Frugivores?

Frugivores are animals whose diet is wholly or mostly fruit. They are a specialized subset of herbivores, and obligate frugivores get almost all of their calories from fruit. Familiar examples include Jamaican fruit bats, flying foxes, toucans and hornbills, orangutans, and the maned wolf of South America, whose fruit-rich diet helps disperse seeds across tropical forests.

Frugivores are animals that thrive entirely or predominantly on fruits and fruit-like plant parts. They sit within the broader category of herbivores, but unlike a typical leaf-eater, a frugivore gets the bulk of its calories from ripe fruit. Many herbivores and omnivores nibble fruit when it is around, and studies suggest roughly one in four mammals eats fruit as part of its diet. Only a smaller group, however, builds its life around it. The Jamaican fruit bat, the giant flying foxes of Asia and Australasia, and even some fish in the family Characidae (the pacus and tambaqui of the Amazon) are hardcore frugivores.

How Frugivores Help In Seed Dispersal

Many evolutionary biologists believe frugivory evolved through ‘mutualism’ to facilitate seed dispersal. Mutualism is an interaction in which both partners benefit, and in the fruit-eating process the plant and the frugivore each gain something. Frugivores subsist by eating fruit; when they eat the fruit (seeds included) and then travel to a new spot, they spread those seeds in their droppings, where many later germinate. Scientists argue that this kind of mutualism has helped flowering plants (angiosperms) diversify since the Cretaceous, when fleshy fruits first became widespread roughly 80 million years ago.

Frugivory Vs Granivory

In contrast to granivory, a form of seed predation in which the animal chews and digests the seeds along with the fruit, frugivory leaves the seeds intact from mouth to droppings. Interestingly, most of this mutualism is concentrated in the tropics, where fruit-producing plants are plentiful all year round.

How Plants Have Adapted To Attract Frugivores

To encourage seed dispersal, fruit-producing plants have evolved a suite of adaptations that attract frugivores. Many fruits sport bright colors and pleasing aromas to flag themselves to passing eaters. Fruit pulp is also rich in water and carbohydrates, while being low in lipids and proteins, which makes it an easy, quick-energy meal. Seeds, in turn, have adapted to survive inside the digestive systems of frugivores for extended periods. Many seeds actually become more permeable to water after passing through the digestive system of frugivores, which gives them a better shot at germination. Some mistletoe seeds will even start germinating inside the gut of a bird that has just eaten the fruit.

How Frugivores Have Adapted Themselves To Survive On Fruits

Like plants, frugivores have evolved a few adaptations of their own to be efficient seed dispersers. Their digestive systems are tuned to process large amounts of fruit without grinding up the seeds inside. Some fruit-eating birds have a notably short intestine, allowing them to pass seeds through quickly. Other frugivores have short gut-retention times for the same reason, so seeds come out the other end whole and viable. The Jamaican fruit bat, for example, can move a fig seed from mouth to dropping in as little as 15 to 20 minutes, which is part of why it is such an effective forest regenerator.

Examples Of Frugivorous Animals

Birds get the lion’s share of attention from researchers working on frugivory, and for good reason: they are some of the most efficient seed dispersers on the planet. A long-running study by ecologists Bette Loiselle and John Blake of the University of Missouri-St. Louis, working in Costa Rican wet forest, showed how the local extinction of seed-dispersing frugivorous birds can sharply reduce seed viability and the spread of the plants that depend on them. Hornbills, aracaris, cotingas and toucans are some of the most familiar examples of frugivorous birds. Hornbills alone are known to carry seeds from more than 700 plant species, and toucans regularly disperse seeds over distances of several kilometers. Some frugivorous birds lean heavily on fruit only during the nesting season, when they need a steady stream of carbohydrates, and when the supply of preferred fruits runs out they will resort to acrid, bitter berries that other animals avoid.

Mammals count as frugivores when they reliably move seeds around in the course of eating fruit. The maned wolf (Chrysocyon brachyurus) of the South American grasslands is a textbook example. Despite being a canid, roughly half of its diet is plant matter, and the single most important food item is a tomato-like fruit called lobeira, or “wolf apple” (Solanum lycocarpum). The Portuguese name lobeira literally means “fruit of the maned wolf,” which gives you some idea of how tightly the two are linked. Many researchers consider the maned wolf one of the most important mammalian seed dispersers on the continent.

Among primates, orangutans are heavyweight frugivores. Ripe fruit makes up roughly 65 percent of what they eat day to day, and in a good fruiting season that figure can climb closer to 90 percent. When fruit is scarce they fall back on flowers, leaves, honey, insects, bark and vines. Owl monkeys (genus Aotus) of Central and South America are another well-studied primate frugivore, with fruit making up anywhere from a fifth to nearly nine-tenths of the diet depending on the species, the habitat and the season. They prefer small, ripe fruits and often forage in large-crown trees in search of them.

Significance Of Frugivores

Plants colonize new ground largely through seed dispersal, so losing a region’s frugivores can knock an entire ecosystem off balance and, in time, drive plant species to extinction. This is especially clear in the tropics, where 60 to 90 percent of tree species rely on animals to move their seeds and where the loss of even a single large fruit-eater can ripple through the forest. In the Amazon, for instance, overfishing of large fruit-eating fish like the tambaqui (Colossoma macropomum) has reduced populations of some species by around 90 percent, leaving a clear seed-dispersal gap in flooded forests. Similarly, ecologists have shown that losing a single large monkey species can reshape plant communities, because monkeys carry seeds over long distances that smaller frugivorous birds simply cannot match.