Many tropical herbivores alter their diets throughout the year in
response to different levels of food availability. Fruit bats, including Pteropus
samoensis Peale and Pteropus tonganus Quoy & Gaimard, are phytophagous
species that may increase their consumption of foods such as unripe fruit and
leaves in periods of low fruit diversity and volume. These periods include the
tropical dry season or following the frequent hurricanes that batter the Samoan
Archipelago. We examined the nutritional composition of leaves and immature
fruits and compared the levels of organic and mineral nutrients with those of
ripe fruit. We used principal components analysis (PCA) to examine patterns
of variation in nutrient components of leaves, unripe fruit, and ripe fruit, as
well as to compare the mean levels of nutrients. Overall, unripe fruit provided
levels of nutrients comparable with those of ripe fruit of the same species for
many organic and mineral components. Unripe fruit were only half as rich in
iron as ripe fruit, but unripe fruit had high levels of calcium compared with
ripe fruit of the same species. Leaves are often cited as a rich source of protein
for fruit bats, and our results were consistent with this suggestion. Leaves were
also found to be rich in zinc, manganese, and calcium. Therefore, flying foxes
and other herbivores probably do not avoid unripe fruits and leaves because of
their low nutrient levels. It may be that these famine foods are not normally
consumed because of the presence of secondary compounds, low concentrations
of palatable sugars, or a distasteful and hard pericarp on unripe fruits