Research exhibits orangutans’ eating habits

<p class="p1">Erin R. Vogel from the Department of Anthropology speaks at the Food Sciences Building on Cook campus.<span class="s1"></p>
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Erin R. Vogel from the Department of Anthropology speaks at the Food Sciences Building on Cook campus.

Erin R. Vogel and her colleagues took to the Borneo rainforests of Southeast Asia in 2003 to explore how ecology and diet affected the energy states of a species of orangutans.

Vogel, assistant professor in the Department of Anthropology, led a nutritional science seminar about orangutan nutrition and energetics yesterday in the Food Sciences Building on Cook Campus.

Vogel has been conducting research on orangutans in Indonesia with the Center for the Advanced Study of Hominid Paleobiology for the past several decades. 

Vogel said primate ecologists, including herself, focus their research on how primates utilize food to survive, particularly in environments where a fluctuation in food availability is often seen. 

“I am very interested in food because it can influence all aspects of life,” Vogel said. “Food can be the difference between life and death. It can influence history, it can have dramatic effects on social behavior and it also has an effect on the types of morphologies we observe.”

Vogel said she studied birds as an undergraduate student, and by chance her advisor invited her to do a study on primates.

“After that, I kind of just fell in love with it,” she said.

Vogel said she actively promotes biodiversity and sustainable management with an interest in exploring how ecology and diet affect energy states and reproduction. 

Her primary research goals are to determine what has led to changes in primate behavior and to bridge the fields of behavioral science, psychology and physiology in order to understand diet selection, she said. 

 “Obviously, we can’t just go and ask the orangutans what they prefer to eat,” Vogel said.

Vogel’s research in Borneo involved the observation of orangutans’ food preferences and comparing those choices to food availability as well as physiological and behavioral effects, she said. 

The researchers concluded after 30,000 hours of focal data collection from 2003-2010 that the orangutans are less efficient foragers and have less energy storage at times when fruit is scarce, Vogel said. 

Orangutans only have natural habitats in Indonesia and Malaysia, she said. They are mostly frugivorous animals: Meaning they prefer fruit, but may also feed on leaves, insects and meat. 

She said the Borneo rainforest is considered to be a very challenging environment for frugivores because of its unpredictable and usually scarce supply of fruit. 

“Long periods of fruit unavailability can last from two to eight years,” Vogel said. “Primates have evolved behavioral, morphological and physiological mechanisms to cope with more challenging food choices.” 

During low fruiting periods, the orangutans spend less time traveling between patches, staying in one place and eating for longer periods of time until nothing is left.

Vogel said the orangutans also compensate for fruit scarcity by falling back on less preferable food options such as leaves, flowers and bark.

“These food items are available year round and tend to be of low nutritional quality,” Vogel said. “It is not surprising that they prefer to feed on fruit, because if we look at the total energy gain per patch, we find that they are selecting food that has the highest energy gains.” 

Vogel’s third research goal is to study how primate behavior can inform us about human processes and vice versa.

Paul Breslin, professor in the Department of Nutritional Sciences, sees a possible correlation between the food-gathering strategies of orangutans and the eating habits of humans, he said.

“All animals forage unless we are anchored to a rock,” Breslin said. “We [humans] forage in urban environments, too, including restaurants, supermarkets and bodegas. Fluctuating fruit availability is part of the world in which orangutans must forage.”

Vogel and her colleagues used standard protein requirements for humans in order to estimate whether the apes were getting enough protein from their diet, she said. 

“In terms of protein, we see a slight decrease in percentage of energy coming from [the orangutan’s] diet when fruit is scarce,” she said. 

Fruit also provides the orangutans more calories and a higher percentage of lipids. 

Vogel said very few studies have actually focused on energetics, and how it relates to frugivorous primate population density.

“I think the fact that [orangutans] are able to use a variety of methods to cope with this fruit scarcity is amazing,” Vogel said. “All of these different areas suggest really unique adaptations for coping with it.”

Sarah Hassanien, a graduate student, came to the seminar as a requirement for her school and found Vogel’s studies both interesting and relevant to her own research in biochemistry. 

“I am personally interested in comparing low and high fruit seasons to humans,” Hassanien said. “The animal sciences, exercise sciences — every science seems to be connected under one giant umbrella.”

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