People / Research / Analyses / Volunteers / Potential Students


research_diagramAs a primate dietary ecologist, I am interested in the factors that influence food acquisition and diet selection in non-human primates. In particular, I am interested in how primates have adapted to maximize energy intake, in face of variable environments. I answer research questions revolving around diet selection and energy acquisition in non-human primates by examining the behavior, morphology, and physiology of my study animals within an ecological context.

juni_joram_m_berlowitzFor my dissertation research, I took an economic approach to gain an understanding of the ecological basis of aggression in white-faced capuchin monkeys (Cebus capucinus). I continued my research on capuchins during my first postdoctoral position and studied the functional significance of the M/L cone opsin polymorphism in New World primates. In 2004, I started a long-term field project at the Tuanan Research Station examining both the proximate and ultimate mechanisms of diet selection and energy acquisition in wild orangutans. My current research focuses on examining the interaction between behavior, morphology, physiology and diet in wild orangutans. Below, I describe a few of my past, present, and future foci.

Learn more about the Tuanan Orangutan Research Project (TORP)

Read more about our USAID funded projectPromoting Sustainable Forest Management & Biodiversity through Research & Education Partnerships.


  • Non-invasive methods to evaluate orangutan health and skeletal muscle wasting in wild orangutans: cytokine, isotopes, and 3 MH (with Dr. Lyle Moldawer, Dr. Ricardo Ungaro, Dr. John Rathmacher, Dr. Brooke Crowley, and Alysse Moldawer )
  • Cognitive foraging, seed dispersal, and the role of wild orangutans in forest regeneration (with Shauhin Alavi)
  • The energetic costs of motherhood in wild orangutans (with Timothy Bransford and Maria van Noordwijk)
  • Home range quality and health and the influence of logging in wild orangutans (with Alysse Moldawer)
  • Protein balance in captive and rehabilitated orangutans (with Liz Ballare)
  • Diet and energetics is released orangutans (with Didik Prasetyo)
  • The relationship between protein balance, hunger, orangutans health, and food availability in wild orangutans living in a peat swamp habitat (with Dr. Robin Bernstein, Dr. Maria van Noordwijk, and Dr. Cheryl Knott)
  • Nutritional balancing in wild orangutans (with Dr. Jessica Rothman and Dr. David Raubenheimer)
  • Variation in nutritional composition of orangutan diets in two peat swamp habitats (with Dr. Mark Harrison)
  • The effect of fruit availability on foraging behavior in wild orangutans in a peat swamp habitat
  • Integration of long-term research and environmental education in the Kapuas River region, Central Kalimantan, Indonesia
  • The relationship between jaw form and food mechanics in Sumatran and Bornean orangutans (see below for details) (with Dr. Andrea Taylor, Dr. Serge Wich, Ms. Astri Zulfa, and Dr. Nathaniel Dominy)
  • Sex differences in food mechanics in wild orangutans (with Dr. Andrea Taylor, Dr. Serge Wich, Dr. Michael Larson, Ms. Astri Zulfa, and Dr. Nathaniel Dominy)
  • Understanding geographic variation in orangutan diet selection (with C.P. van Schaik, S. Wich, N. Dominy, C. Knott, M. Harrison, M. Bastian, A. Marshall, S. Utami Atmoko, T, Mitra-Setia)



fruit_leafMy current research (and some of my past research) primarily focuses on the proximate and ultimate factors that affect diet selection in non-human primates. I am examining urinary indicators of health and nutritional in wild orangutans and how these indicators relate back to diet selection and environmental factors. Above you will see some of my newest projects revolving around this topic. Below are some of the published studies in which we have examined various aspects of diet selection and consequences of foraging decisions.


Vogel, E.R., Crowley, B.E. , Knott, C.D., Blakely, M.D. , Larsen, M., Dominy, N.J. A method for measuring nitrogen balance in  free ranging primates. In press. International Journal of Primatology.

Lucas, P.W., Constantino, P.J., Vogel, E.R., Chalk, J., Talebi, M., Wagner, M. Measuring the toughness of primate foods and its ecological value. In press. International Journal of Primatology.

Crowley, B.E. , Thorén, S., Rasoazanabary, E., Vogel, E.R., Barrett, M.A., Zohdy, S., Blanco, M.B., McGoogan, K.C., Arrigo-Nelson, S.J., Irwin, M.T., Wright, P.C., Radespiel, U., Godfrey, L.R., Koch, P.L., and Dominy, N.J. In press. Geographic isotopic variation in mouse lemur (Microcebus) populations. Journal of Biogeography.

Ganzhorn, J.U., Arrigo-Nelson, S., Boinski, S., Bollen, A., Carrai, V., Derby, A., Donati, G., Koenig, A., Kowalewski, M., Lahann,P., Norscia, I., Polowinsky, S.Y., Schwitzer, C., Stevenson, P.R., Talebi, M.G., Tan, C., Vogel, E.R., Wright, P.C. 2009. Possible fruit protein effects on primate communities in Madagascar and the Neotropics. PLoS ONE. 4(12): e8253.

lab_suppliesVogel, E.R., Haag, L., Mitra-Setia, T., van Schaik, C.P.and Dominy, N.J. 2009. Foraging and ranging behavior during a fallback episode: Hylobates albibarbis and Pongo pygmaeus wurmbii compared. American Journal of Physical Anthropology. 140:716–726.

Ross, C.F., Washington, R.L., Eckhardt, A., Reed, D.A., Vogel, E.R., Dominy, N.J., Machanda, Z.P. 2009. Ecological consequences of scaling of chew cycle duration and daily feeding time in Primates. Journal of Human Evolution 56:570-585.

van Schaik, C.P, van Noordwijk, M.A. Vogel, E.R. 2009. Ecological sex differences in wild orangutans. Wich, S.A., Utami Atmoko, S., Mitra Setia, T., van Schaik, C.P. (eds). Orangutans: Geographic Variation in in Behavioral Ecology and Conservation. Oxford University Press. pp. 256-268.

Harrison, M.E. , Vogel, E.R., Morrogh-Bernard, H.C., van Noordwijk, M.A. 2009. Methods for calculating dietary composition compared: A case study using orangutans. American Journal of Primatology 71:353–358.

Panger, M., Perry, S., Rose, L.M, Gros-Louis, J., Vogel, E., MacKinnon, K., Baker, M. 2002.


orangutans2_treefruit_seedsmap_indonesiamandiblesfcn_morph_graphMy collaborators and I are examining the proximate mechanisms of diet selection in Bornean and Sumatran orangutans. We have explored the mechanical properties of orangutan foods in relationship to foods consumed by chimpanzees and human foragers to deepen our understanding of why jaw morphology and molar enamel thickness vary across hominoids. We seek to understand the factors that have selected for craniodental morphological variation among hominoids by examining variation in diet selection in an ecological context. In another study funded by the L.S.B. Leakey Foundation, we are comparing the mechanical properties of foods consumed by Bornean and Sumatran orangutans. Bornean orangutans have relatively more robust mandibles compared to Sumatran orangutans. Here we propose to test if there is a relationship between the observed differences in masticatory morphology and the mechanical properties of foods consumed by wild Bornean and Sumatran orangutans. Our data are important for understanding variation between co-existing hominin species that lived 2.0-3.0 million years ago: the robust-jawed and mega-toothed Paranthropus and the more gracile Australopithecus. If we can demonstrate that variation in these same morphological traits is related to variation in the percentage of tough/hard food items in the diets of different populations of orangutans, than we can more reasonably infer that anatomical differences between hominins reflect differences in the types of food items included in their diets.


Vogel, E.R., Haag, L., Mitra-Setia, T., van Schaik, C.P.and Dominy, N.J. 2009. Foraging and ranging behavior during a fallback episode: Hylobates albibarbis and Pongo pygmaeus wurmbii compared. American Journal of Physical Anthropology. 140:716–726.

Dominy, N.J., Vogel, E.R., Yeakel, J.D. , Constantino, P., Lucas, P.W. 2008. The mechanical properties of plant underground storage organs and implications for the adaptive radiation and resource partitioning of early hominins. Evolutionary Biology 35(3): 157-175.

Taylor, A.B., Vogel, E.R., & Dominy, N.J. 2008. Masticatory biomechanics and food mechanical properties in large-bodied hominoids. Journal of Human Evolution. 55(4): 604-616.

Vogel E.R., van Woerden J.T., Lucas, P.W., Utami Atmoko, S.S., van Schaik C.P, & Dominy N.J. 2008. Functional ecology and evolution of hominoid molar enamel: Pan troglodytes schweinfurthii and Pongo pygmaeus wurmbii. Journal of Human Evolution 55(1): 60-74.


map_bw_tuanangeo_var_graph1geo_var_graph2The objective of this project is to understand the mechanisms that contribute to geographic variation in orangutan (Pongo pygmaeus s.l. [or P. abelii and P. pygmaeus s.s.]) diet selection using principles derived from optimal foraging theory (OFT) and to establish the degree to which food choice in orangutans has a cultural basis. Orangutans are an ideal species for testing principles derived from optimal foraging theory because they are often solitary and foraging decisions are unlikely to be influenced by other individuals. For this study, five wild populations in Borneo and Sumatra will be compared and three hypotheses will be tested. Testing of the first and second hypotheses will determine if orangutans select food species or particular food items in concordance with the predictions of OFT. If food selection cannot be explained by ecological principles, the physical characteristics of food items will be quantified to test if physical properties of foods, such as toughness, promote innovative foraging techniques. Testing of the third hypothesis will determine if orangutans develop innovative foraging behaviors in response to variations in food availability.


Bastian, M.L., Zweifel, N., Vogel, E.R., Wich, S.A., van Schaik, C.P. 2010. Diet traditions in wild orangutans. American Journal of Physical Anthropology. 143(2): 175-187.


capuchin_monkeycapuchin_monkey2spectrumdnaIn collaboration with Dr. Nathaniel Dominy (University of California – Santa Cruz) and Dr. Maureen Neitz (Medical College of Wisconsin), I examined if the energy intake rates on orange/red and/or dull-colored fruits differ between trichromatic and dichromatic group members, specifically adult females. This study was the first to use foraging data from a population of wild primates to test the hypothesis that M/L cone opsin polymorphisms are maintained by a heterozygous advantage for selecting fruits. For this study, I extracted genomic DNA from fecal samples and used PCR to amplify exons 3 and 5 of the M/L opsin gene. Contrary to the assumptions of previous theoretical and experimental studies, our analysis of C. capucinus foraging behavior showed that trichromats do not differ from dichromats in their fruit or energy acquisition rates. In addition, I am currently identifying the color vision phenotypes of wild Argentine Cebus apella. With Dr. Charles Janson and his graduate student Andrea Green (University of Montana), I am examining if visual phenotype has an effect on the detection of ecologically relevant prey and predators. I have recently completed the genetic analyses necessary to answer this question and we are presently combining these data with a behavioral data set. These experiments using realistic models will be the first to test the hypothesis that M/L cone opsin polymorphisms are maintained by frequency-dependant selection; that is, an advantage to dichromats in detecting the movement or color camouflage of prey and predators.


Talebi, M.G., Pope, T.R. Vogel, E.R., Neitz, M, and N.J. Dominy. 2006. Polymorphism of visual pigment genes in the muriqui (Primates, Atelidae). Molecular Ecology 15(2): 551- 558.

Vogel, E.R., Neitz, M., and Dominy, N.J. 2007. Effect of color vision phenotype on fruit and energy intake rates of wild white-faced capuchins, Cebus capucinus. Behavioral Ecology.18(2): 292-297.


capuchins1_09capuchins2_tr2coalition_fig1coalition_graph1Food competition is an important factor limiting primate group size and structuring social behavior. My doctoral dissertation focused on the ecology and intragroup aggression over food resources in white-faced capuchin monkeys (Cebus capucinus) in a Costa Rican dry forest. Using a novel “Focal Tree Method”, it was the first study of primate socioecology to examine resource availability on a scale that is both temporally and spatially relevant to the species under investigation. I focused on the ecological basis of aggression by evaluating the net benefit of access to a given resource, and the opportunity costs associated with foregoing alternative resources. I compared my findings to studies on other primate species and examined how differences in the potential for aggressive competition over food appear to affect the evolution of social structure in non-human primate species. As a more theoretical component to this research, I have been working together with game-theoreticians to model coalition formation processes among primates as a sequential game based on the resource holding potential of the players, the value of the resource, and the cost of fighting. We show that, given the primates’ strategic behavior, a variety of different coalition structures can emerge in equilibrium. The model is validated by my empirical data. We are currently working towards applying these models to human coalition formation in an evolutionary context. Following up on my dissertation research, I am currently examining how variation in digestive efficiency in Old World and New World arboreal monkeys translates into corresponding differences in diet, community structure and other socio-ecological variables among these two primate lineages.


Vogel, E.R. & Janson, C.H. 2011. Quantifying primate food abundance and distribution for socioecological studies: An objective consumer-centered method. International Journal of Primatology. 32: 737-752.

Stamatopoulos, G., Sengupta, A. Vogel, E. R., and C. H. Janson. 2009. A game-theoretic model of within-group coalition formation in non-human primates. Journal of Bioeconomics 11(2):165-183.

Vogel, E.R., Munch, S.B., & Janson, C.H. 2007. Understanding escalated aggression over food resources in white-faced capuchin moneys. Animal Behaviour 74:71-80.

Vogel, E.R. and Janson. 2007. Predicting the frequency of food related agonism in white-faced capuchin monkeys (Cebus capucinus), Using a novel focal tree method. American Journal of Primatology 69(5):533-550.

Janson, C.H. and Vogel, E.R. 2006. Estimating the effects of hunger on primate social ecology. In Hohmann, G., Robbins, M., and Boesch, C. (eds). Feeding Ecology in Apes and Other Primates. Cambridge University Press. pp. 285-312.

van Schaik, C.P., Pandit, S.A. & Vogel, E.R. 2006. Toward a general model for male-male coalitions in primate groups. In Kappeler, P.M. & van Schaik (eds) Cooperation in primates: comparative perspectives. Springer Verlag: Heidelberg. pp 151-171.

Vogel, E.R. 2005. Rank differences in energy intake rates in white-faced capuchin monkeys (Cebus capucinus): the effects of contest competition. Behavioral Ecology and Sociobiology 58: 333-344.

van Schaik, C.P., Pandit, S.A., Vogel, E.R. 2004. A model for within-group coalitionary aggression among males. Behavioral Ecology and Sociobiology 57:101-109.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s