What Do Flying Foxes Eat? Their Diet of Fruit and Nectar

Flying foxes eat primarily fruit and nectar, supplemented by pollen, leaves, and occasionally insects when their preferred foods run low. These large bats, all members of the genus Pteropus, are among the most fruit-dependent mammals on Earth, with some species recorded feeding on well over 70 plant species across dozens of families. But calling them “fruit bats” undersells the complexity of their diets, which shift with geography, season, and the specific nutritional demands of breeding and lactation.

Fruit Is the Foundation, and Figs Are King

Across their range from Australia to Madagascar to the islands of the Pacific, flying foxes are overwhelmingly frugivorous. Two species studied in Samoa, the Samoan flying fox and the Tongan flying fox, fed on over 78 plant species from 39 families throughout their range, and interacted with roughly 59 percent of the forest tree species in their study area for fruit or flower resources. Six plant families were particularly important: Sapotaceae, Myrtaceae, Moraceae, Combretaceae, Fabaceae, and Sapindaceae.¹ These bats were not eating everything available; they chose a nonrandom subset of the local fruit species and showed a clear preference for fruits from primary forest over secondary growth.

Among all the fruit they eat, figs deserve special mention. A study of the island flying fox in Peninsular Malaysia using genetic analysis of droppings found that figs were the most abundant plant taxon detected in every single month of sampling.² Figs fruit year-round in many tropical environments, which makes them a reliable fallback when other species are out of season. Flying foxes do not typically swallow whole fruits. They crush ripe fruit in their mouths, swallow the juice and soft pulp, and spit out the remaining fibrous material. Small seeds, especially from figs, often pass through the digestive tract intact.

Nectar Specialists and Pollen Feeders

Not all flying foxes are equally focused on fruit. Australia’s little red flying fox is better described as a specialist nectarivore. Analysis of its diet revealed 204 plant species, dominated by floral products from the family Myrtaceae. A small number of widely occurring eucalypts and paperbarks, particularly from the genera Corymbia, Eucalyptus, and Melaleuca, turned out to be the major diet species that regularly drive the enormous aggregations this species is known for.³ When eucalypts bloom heavily, camps of little red flying foxes can swell into the hundreds of thousands practically overnight.

Nectar feeding is more common across the genus than the “fruit bat” label suggests. Flying foxes visit flowers for energy-rich nectar, and in doing so their fur picks up large amounts of pollen. They then groom and ingest much of this pollen, which provides a meaningful source of protein that fruit alone cannot supply. This is not incidental; it is a nutritional strategy that helps offset one of the biggest challenges of a fruit-heavy diet.

The Protein Problem

Fruit and nectar are loaded with sugars but poor in protein and certain minerals. Research on the grey-headed flying fox found that when fed an apple diet, the bat had to consume about 3.2 times as much dry matter to meet its nitrogen requirement as it would need to meet its energy requirement alone. In other words, these bats eat far more food than they need for calories just to scrape together enough protein.⁴ The surplus energy gets burned off as heat, a metabolic cost of having to overeat just to survive on dilute food.

This protein gap explains why flying foxes do not live on fruit and nectar alone. Evaluation of native food plants for a critically endangered island flying fox confirmed the pattern: fruit and nectar cover energy needs, but they fall short on protein and essential minerals during demanding life periods like pregnancy and lactation. Flying foxes likely compensate by supplementing with pollen and foliage, meaning they need a diverse array of plant species to meet all their nutritional requirements.⁵

Leaves, Insects, and Other Supplements

Leaf-eating in flying foxes is more widespread than most people realize, and it appears to be driven largely by calcium. In feeding trials with wild-caught Tongan fruit bats, about 83 percent of the animals consumed available leaves. Males ate them more frequently and in greater quantities than females, and bats that ate leaves regularly consumed up to 46 percent more calcium than those that did not.⁶ Flying foxes do not eat leaves the way a herbivore would, though. They typically chew the leaves, extract the juices, and spit out the fibrous wad, a behavior called leaf fractionation.

Insects round out the diet for some species, though they are a minor component. Captive and wild observations suggest that insects become part of the diet primarily when fruit and vegetation are scarce during dry seasons. Flying foxes are not active insect hunters in the way that microbats are, but they will eat insects they encounter on fruit or flowers, and some species appear to seek them out opportunistically when protein is hard to come by.

Finding Food by Smell

Flying foxes rely heavily on their sense of smell to locate and evaluate food. Experiments with the little golden-mantled flying fox and the greater musky fruit bat showed that both species could accurately distinguish between an empty dish and one containing fruit using odor alone, even when they could not see or touch the food. More impressively, they could tell ripe fruit from unripe fruit of the same species purely by smell.⁷

A separate study reinforced how central smell is to foraging. When offered whole guava, mashed guava without its original shape, and an artificial fruit that looked and felt like real guava, the bats responded to the real and mashed fruit even in total darkness. The fake fruit, despite looking right, was ignored even when lit. Odor, not vision, acted as the primary cue for finding food.⁸ This makes sense for animals that forage at night in dense forest canopy, where vision is limited but chemical signals from ripe fruit carry far on the wind.

Seed Dispersal Over Extraordinary Distances

Because flying foxes swallow small seeds and travel long distances before defecating, they are powerful seed dispersers. In Madagascar, seeds from several fig species showed increased germination success after passing through a flying fox’s gut compared to unhandled seeds. GPS tracking revealed that bats traveled 3 to 5 kilometers within a few hours after feeding, and sometimes retained seeds for over 24 hours. The researchers calculated that just 11 tracked bats could potentially disperse seeds across roughly 58,000 hectares over 45 days of tracking, moving seeds up to 20 kilometers from the parent tree.⁹

This dispersal ability matters most in fragmented landscapes. Flying foxes can carry seeds from intact forest into deforested or degraded areas, jump-starting forest regrowth in places where wind or smaller animals would never reach. On Pemba Island off the coast of Tanzania, the Pemba flying fox similarly improved germination rates for fig and mango seeds that passed through its digestive system.¹⁰ For island ecosystems with limited wildlife, flying foxes may be among the only animals capable of moving large seeds between forest fragments.

Pollinating the Durian

The relationship between flying foxes and durian is one of the more economically significant bat-plant partnerships on Earth. In Southeast Asia, durian is a multi-billion-dollar crop, and bats are its primary pollinators. An experiment on durian trees in Malaysia found that flowers accessible to flying foxes produced more mature fruit, with the number of flying fox visits having a positive effect on fruit set.¹¹ In Sulawesi, Indonesia, flowers that were accessible to bats had significantly higher fruit set compared with flowers that were completely closed to animal visitors or that could only be visited by insects.¹² In both studies, bats outperformed insects as pollinators for this crop.

Durian flowers open at night and produce large quantities of nectar, a near-perfect match for a nocturnal animal with a sweet tooth and a large body that can push its face deep into the flower. The irony is that flying foxes are often persecuted for raiding fruit orchards in the same regions where they are quietly sustaining the pollination of one of the most valued crops.

Urban Foraging and Crop Conflicts

Flying foxes have increasingly been turning up in cities, and their diet in urban areas looks different from what they eat in the wild. Tracking of the grey-headed flying fox showed that human-modified landscapes sustain a large proportion of the population year-round, with bats that roosted in major urban environments relying on different dominant plant species than those in non-urban areas.¹³ Urban parks, botanic gardens, and street trees planted with native flowering species offer a year-round food supply that wild forest, with its boom-and-bust flowering cycles, does not always provide.

In Thailand, GPS-tracked Lyle’s flying foxes mostly foraged in farmland, plantations, and gardens, feeding on a highly diverse diet of 34 food plant species that included both exotic crops and native plants depending on availability.¹⁴ This flexible diet is a double-edged sword. It helps flying foxes survive in human-dominated landscapes, but it also puts them in direct conflict with orchardists. Mango, lychee, and other commercial fruit crops become targets, and the resulting persecution is a serious conservation threat for several flying fox species. Preserving native vegetation near orchards could reduce conflict by giving bats an alternative food source, as the Thai study’s authors suggested.

Nomadic Movements and Why Distance Matters for Diet

Flying foxes are not sedentary animals that commute to the same trees each night. They are genuinely nomadic, and the distances they cover are staggering. Satellite tracking of three Australian species found that individuals traveled enormous distances each year: the black flying fox covered roughly 1,400 to 1,900 kilometers annually, the grey-headed flying fox about 2,300 to 2,600 kilometers, and the little red flying fox between 3,800 and 6,000 kilometers.¹⁵ These movements are not migrations along fixed routes. Individual bats wander with little uniformity in direction, apparently tracking shifting flowering and fruiting events across the landscape.

This nomadism is a direct consequence of diet. A nectar specialist like the little red flying fox has to follow eucalypt blooms as they sweep across the continent, because no single location offers flowers year-round. In urban areas, where planted gardens provide more consistent resources, some flying foxes appear to settle for longer stays and commute shorter distances to forage.¹⁶ The reliable “fast food” of cities may be changing the movement ecology of these animals in ways researchers are still working to understand.

Diet Breadth in the Tropics Versus the Subtropics

Not all flying fox species eat the same breadth of foods. A comparison of diet data across the genus suggested a geographic pattern: flying foxes in the tropics, where specific plants fruit abundantly and for long periods, tend to be more specialized. Species at the subtropical edges of the genus’s range, where food shortages occur irregularly and less predictably, tend to have broader diets.¹⁷ The Ryukyu flying fox in Japan, living at the northern limit of the genus, exemplifies this flexibility. It eats a wider range of plant species and plant parts than its tropical cousins, presumably because it cannot afford to be choosy in an environment where resources are patchier.

Plant Toxins and Mineral Licks

The fruits, young leaves, and flower parts that flying foxes eat often contain toxic or otherwise harmful plant compounds. Research on fruit-eating bats in the Amazon found evidence that pregnant and lactating bats visited mineral licks not primarily for the minerals themselves, but to buffer the effects of these secondary plant compounds, which they ingest in large quantities during periods of high energy demand.¹⁸ In other words, eating clay-rich soil or water may help bats neutralize the toxins that come bundled with their food. This detoxification strategy has been documented in other fruit-eating animals and suggests that the diet of flying foxes is not as simple as eating ripe fruit off a tree. Managing the chemical hazards in their food is an ongoing physiological challenge.

Teeth Built for Juice Extraction

The way flying foxes eat, crushing fruit and spitting out the fiber, has left an evolutionary mark on their teeth. A comparative study of dental morphology found that frugivory led to convergent dental specializations in flying foxes and in the unrelated leaf-nosed bats of the New World. Key adaptations for fruit eating include reduced canine robustness, specialized premolars, and labial displacement of molar cusps. Gaps between the teeth appear to help with handling fruit and ejecting fibrous byproducts during chewing.¹⁹ These are not the sharp, piercing teeth of an insect-eating bat. They are flattened, broad structures designed to extract maximum juice from fibrous tropical fruits.

Captive Diets and What Goes Wrong

Getting the diet right for flying foxes in zoos and wildlife rehabilitation is harder than it looks. A survey of metabolic bone disease across zoological parks found that captive flying foxes are vulnerable to nutritional imbalances, in part because their wild diets are so complex and difficult to replicate. In the wild, flying foxes meet their needs through a rotating buffet of dozens of fruit, flower, and leaf species. In captivity, they often receive a simplified diet of commercially available fruits, which tend to be bred for sugar content rather than nutritional completeness.²⁰ Without adequate calcium and vitamin D, metabolic bone disease develops, weakening the skeleton and eventually making flight impossible.

Heat Events and Their Connection to Food

Extreme heat is an emerging and devastating threat to flying foxes, and it intersects with diet in a grim way. During the Australian summer of 2019-2020, an estimated minimum of 72,175 flying foxes died in heat events across southeastern Australia, and another 2,612 died in pup abandonment events. These were the highest recorded mortality figures for Australian flying foxes in a single summer.²¹ When temperatures climb past roughly 42°C, flying foxes cannot thermoregulate effectively and begin dying in their roost camps. Because these mass die-offs hit during the breeding season, they can remove both adults and dependent young from the population simultaneously. For species that already struggle with habitat loss and reduced food availability, extreme heat pushes them closer to a demographic tipping point where the population cannot replace its losses.