Fruit Bats

Two Fruit Bats resting in the tree.

Photo: Jeff@adobe

Fruit Bats of American Samoa

Fruit bats are among the most distinctive animals in American Samoa, especially for visitors from regions where bats are typically smaller and less visible. Three species of bats inhabit the islands: two large fruit bats (Pteropus samoensis and P. tonganus) and a small insect-eating bat (Emballonura semicaudata).

The Large Fruit Bats

The two fruit bat species are particularly striking due to their size, with wingspans reaching up to 3 feet. They are active both day and night, making them a unique sight in the Samoan sky.

• Pteropus samoensis (pe'a vao), commonly known as the Samoan fruit bat, is found only in the Samoan Archipelago and Fiji. Although it once existed in Tonga, it is now extinct there.

• Pteropus tonganus (pe'a fanua), known by several names, including the Insular, White-naped, or Tongan fruit bat, has a broader range, found from Papua New Guinea to the Cook Islands.

Observing Fruit Bats

In American Samoa, fruit bats can be seen flying, feeding, or roosting in trees. Despite overlapping in size (adults weighing 300-600 grams), the two species can be distinguished from a distance based on their flight and silhouette:

• Pe'a vao has a triangular shape with scalloped, opaque wings. Its flight is relaxed, with slower wing beats and a tendency to soar on rising warm air currents during the day.

• Pe'a fanua, by contrast, appears more cross-like, with narrower wings and more pronounced neck and head. It has faster wing beats, shallower strokes, and tends to fly in a direct path at dawn or dusk.

 

Fruit bats taking care of their young.

NPS

Close-Up Characteristics

Though identifying the bats from afar is challenging, closer inspection reveals more distinguishing features:

• Pe'a vao often displays a white or yellowish triangular patch from the forehead to the back of the head, or it may have a grayish head. Its neck and shoulders are russet brown, with the rest of its body appearing dustier in color.

• Pe'a fanua has a black head and body, contrasted by a creamy yellow band on its neck that extends slightly below the shoulders, giving the appearance of a cape. This feature gives rise to the name white-naped fruit bat, although the color is more cream than white.

Social Behavior

The two species of fruit bats exhibit quite different social behaviors:

• Pe'a fanua forms large roosting colonies during the day, with groups ranging from hundreds to thousands of bats. These colonies are typically organized by reproductive status, with bachelor males, clusters of females defended by a male (suggesting a harem mating system), or groups of females with young. Individuals tend to be faithful to their roosts, returning to their colonies after foraging.

• In contrast, pe'a vao roosts singly or in pairs. Males typically roost on exposed or dead branches on ridge tops, while females roost in more covered positions on forest slopes. This behavior suggests a monogamous mating system, with females often seen roosting with their young.

Reproductive Care

Both species demonstrate remarkable care for their young. Pregnancy lasts approximately 5 months in both, and after birth, it takes at least 3 more months before the young are weaned. Even after they are capable of flight, juveniles may continue to receive parental care, possibly until they reach adult size or reproductive maturity.

• Pe'a vao typically gives birth between April and June, while pe'a fanua births occur year-round but are most common from January to August.

In American Samoa, the sight of a mother fruit bat carrying her young during flight is a testament to the close bond these creatures share and their careful nurturing of the next generation.