Primate Eating Habits Revealed in First In-depth Analysis

Some people may have a hard time eating five servings of fruit a day, but primates, on the other hand, have not trouble at all, according to the most comprehensive study on primate eating habits ever preformed, which found that some monkeys consume five servings of fruit per hour and as many as 50 portions of fruit in a single day.

The study was conducted by researchers at the University of East Anglia (UEA), who focused on primates in Central and South America. The team compiled data from 290 primate dietary studies done over the past 42 years from researchers in 17 countries.

the UEA team focused on research that looked into the amount and diversity of fruit consumed by primates in neotropical forests, finding a link between body mass and fruit consumption. Larger primates consumed more fruit, while smaller ones tended to eat more insects.

The amount of fruit the primates consume gradually increases with the animals' size, peaking at medium-sized primates such as saki monkeys. But fruit intake then declines in favor of leaves in larger primates such as howler and woody spider monkeys.

"We examined dietary data to quantify how much different primate species feed on fruit, leaves and insects -- particularly in relation to their body size. We found that different species vary widely in the amount and diversity of fruits that they eat, as well as the overall contribution of fruit to their diets," said research leader Joseph Hawes from UEA's School of Environmental Sciences.

"We found that the diet of medium-sized primates is most likely to be dominated by fruits. Meanwhile smaller primates, which have high metabolic requirements, eat more insects as they provide a high-quality source of nutrients and calories. Larger monkeys eat a lot more foliage because their guts can tolerate high levels of cellulose and toxins -- which are unpalatable or indigestible to smaller primates."

Hawes said that many primate species can easily consume their "five a day" within an hour of active fruit foraging, with some species consuming between 45 and 50 pieces of fruit per day.

Their diets, however, may be a bit monotonous.

"One of the most surprising things that we found was that primates with wide geographic ranges do not necessarily consume a wider diversity of fruits as expected, perhaps because these species tend to be generalist feeders. Another surprise was that primates with higher prevalence of fruit in their diets were historically among the most poorly studied, meaning we still have a lot to learn about their importance as consumers and seed dispersers."

Hawes and his colleagues' research is published in the journal Oikos.