Western lowland gorilla holding newborn gorilla baby in exhibit Western lowland gorilla holding newborn gorilla baby in exhibit

Lester E. Fisher Center for the Study and Conservation of Apes

Chimpanzee holding lettuce in exhibit

The Lester E. Fisher Center for the Study and Conservation of Apes brings together primate experts and organizations from around the world to collaborate on groundbreaking research, conservation, education, and advocacy. The center leverages high-quality science to increase human understanding of primates, and to promote progressive care, management, and protections for these complex animals.

The Fisher Center conducts multidisciplinary research that:

  • advances knowledge of primate behavior, biology, and cognition
  • evaluates and enhances the welfare of primates in zoos and sanctuaries
  • conserves and protects wild primate populations and their ecosystems
  • provides unique training and educational opportunities for the next generation of primatologists

Areas of Focus

Progressive Primatology

Fisher Center scientists actively contribute to the study of primates (monkeys and apes). They approach their research with a comparative perspective—often conducting parallel studies with the gorillas, chimpanzees, and Japanese macaques at Lincoln Park Zoo— and prioritize studies that keep the primates’ natural social groups together at all times.

With more than 100 peer-reviewed publications on primate biology, behavior, and cognition, the Fisher Center is increasingly recognized as a leader in the field. In 2016, the center hosted the largest-ever primatology conference, which was attended by more 1,500 scientists from around the world.

Inside the Primate Mind

While much of the research at the Fisher Center focuses on behavior, its scientists are also very interested in cognition—what is going on inside the minds of primates. Using non-invasive techniques— such as monitoring their eye movements with infrared trackers and providing them with voluntary puzzles and touchscreen tests—Fisher Center scientists have gained new insight into how humanity’s closest relatives see the world around them, which can help guide their care in zoos and sanctuaries.

In 2010, Fisher Center scientists published a book, The Mind of the Chimpanzee, that remains the most contemporary collection of studies from respected scientists worldwide seeking to understand how chimpanzees think, learn, and feel.

Primate Welfare

The Fisher Center prioritizes studies that help advance the care and management of primates, even beyond zoos. For many years, it has partnered with Chimp Haven, the national chimpanzee sanctuary in Louisiana, in a unique collaboration to advance methods of welfare assessment for chimpanzees.

And in 2007, Lincoln Park Zoo created Project ChimpCARE, an initiative to help advance protections for chimpanzees in suboptimal conditions across the United States. Through this initiative, Fisher Center scientists contributed to changes in federal regulations that increased protections for chimpanzees nationwide.

Conservation in the Republic of Congo

While some Fisher Center researchers study the primates at Lincoln Park Zoo, others work deep in the rainforest of the Republic of Congo. Through a partnership with the Goualougo Triangle Ape Project, they leverage science to promote increased protections for the endangered gorilla and chimpanzee populations in and around the Nouabale-Ndoki National Forest.

By working with local communities and governments, as well as the logging industry itself, Fisher Center scientists are affecting change in logging practices in the Congo basin. This work has helped contribute to significant advances in conserving these unique ecosystems, such as the annexation of the Goualougo Triangle to the National Park in 2013.

Zoo scientist observing chimpanzees in exhibit

Research Internships

The Fisher Center offers opportunities for aspiring primatologists to gain valuable experience in a rigorous scientific environment and take part in a long-term program in behavioral science.

Learn More

Supporters

Arcus Foundation
Chauncey and Marion D. McCormick Family Foundation
Leo S. Guthman Foundation

Publications

  • Leinwand, J. G., Huskisson, S. M., Egelkamp, C. L., & Hopper, L. M. (2020). Within-and between-species variation in the responses of three primate species to a touchscreen gambling task. Learning and Motivation, 71, 101635.
  • Hansen, B. K., Hopper, L. M., Fultz, A. L., & Ross, S. R. (2020). Understanding the Behavior of Sanctuary-Housed Chimpanzees During Public Programs. Anthrozoös, 33(4), 481-495.
  • Huskisson, S. M., Jacobson, S. L., Egelkamp, C. L., Ross, S. R., & Hopper, L. M. (2020). Using a Touchscreen Paradigm to Evaluate Food Preferences and Response to Novel Photographic Stimuli of Food in Three Primate Species (Gorilla gorilla gorilla, Pan troglodytes, and Macaca fuscata). International Journal of Primatology, 41(1), 5-23.
  • Hopper, L. M. (2017). Social learning and decision making. In SJ Schapiro (Ed.), Handbook of Primate Behavior Management. (pp. 225-242). CRC Press, Taylor & Francis Group.
  • Ross, S. R., & Leinwand, J. G. 2020. A review of research in primate sanctuaries. Biology Letters, 16(4), 20200033. https://doi.org/10.1098/rsbl.2020.0033
  • Boesch, C., Kalan, A. K., Mundry, R., Arandjelovic, M., Pika, S., Dieguez, P., Ayimisin, E. A., Barciela, A., Coupland, C., Egbe, V. E., Eno-Nku, M., Michael Fay, J., Fine, D., Adriana Hernandez-Aguilar, R., Hermans, V., Kadam, P., Kambi, M., Llana, M., Maretti, G., Morgan, D., Murai, M., Neil, E., Nicholl, S., Ormsby, L.J., Orume, R., Pacheco, L., Piel, A., Sanz, C., Sciaky, L., Stewart, F.A., Tagg, N., Wessling, E.G., Willie, J. & Kühl, H. S. 2020. Chimpanzee ethnography reveals unexpected cultural diversity. Nature Human Behaviour, 1–7. https://doi.org/10.1038/s41562-020-0890-1
  • Fiore, A. M., Cronin, K. A., Ross, S. R., & Hopper, L. M. 2020. Food Cleaning by Japanese Macaques: Innate, Innovative or Cultural?. Folia Primatologica; International Journal of Primatology, 1–12. https://doi.org/10.1159/000506127
  • Norconk, M. A., Atsalis, S., Tully, G., Santillán, A. M., Waters, S., Knott, C. D., Ross, S. R., Shanee, S., & Stiles, D. 2020. Reducing the primate pet trade: Actions for primatologists. American Journal of Primatology, 82(1), e23079. https://doi.org/10.1002/ajp.23079
  • Earl, S. C., Hopper, L. M., & Ross, S. R. 2020. Same Space, Different Species: The Influence of Exhibit Design on the Expression of Zoo-Housed Apes’ Species-Typical Retiring Behaviors. Animals, 10(5), 836. https://doi.org/10.3390/ani10050836
  • Cronin, K. A., Tank, A., Ness, T., Leahy, M., & Ross, S. R. 2020. Sex and season predict wounds in zoo-housed Japanese macaques (Macaca fuscata): A multi-institutional study. Zoo Biology, Early View. https://doi.org/10.1002/zoo.21533
  • Cooksey, K., Sanz, C., Ebombi, T. F., Massamba, J. M., Teberd, P., Magema, E., Abea, G., Peralejo, J. S. O., Kienast, I., Stephens, C., & Morgan, D. 2020. Socioecological Factors Influencing Intergroup Encounters in Western Lowland Gorillas (Gorilla gorilla gorilla). International Journal of Primatology. https://doi.org/10.1007/s10764-020-00147-6
  • Musgrave, S., Lonsdorf, E., Morgan, D., Prestipino, M., Bernstein-Kurtycz, L., Mundry, R., & Sanz, C. 2020. Teaching varies with task complexity in wild chimpanzees. Proceedings of the National Academy of Sciences, 117(2), 969. https://doi.org/10.1073/pnas.1907476116
  • Campbell, T. P., Sun, X., Patel, V. H., Sanz, C., Morgan, D., & Dantas, G. 2020. The microbiome and resistome of chimpanzees, gorillas, and humans across host lifestyle and geography. The ISME Journal, 1–16. https://doi.org/10.1038/s41396-020-0634-2
  • Frankel, J. S., Mallott, E. K., Hopper, L. M., Ross, S. R., & Amato, K. R. 2019. The effect of captivity on the primate gut microbiome varies with host dietary niche. American Journal of Primatology 81(12), e23061. https://doi.org/10.1002/ajp.23061
  • Cronin, K., & Ross, S. 2019. A cautionary note on the use of behavioural diversity (H-Index) in animal welfare science. Animal Welfare, 28, 157–164. https://doi.org/10.7120/09627286.28.2.157
  • Egelkamp, C. L., Jacobson, S. L., Cronin, K. A., Wagner, K. E., Ross, S. R., & Hopper, L. M. 2019. A Comparison of Sequential Learning Errors Made by Apes and Monkeys Reveals Individual but not Species Differences in Learning. International Journal of Comparative Psychology, 32. Retrieved from https://escholarship.org/uc/item/024578f5
  • Egelkamp, C. L., & Ross, S. R. Egelkamp, C. L., & Ross, S. R. 2019. A review of zoo-based cognitive research using touchscreen interfaces. Zoo Biology, 38(2), 220–235. https://doi.org/10.1002/zoo.21458
  • Ross, S. R., Hansen, B. K., Hopper, L. M., & Fultz, A. 2019. A unique zoo-sanctuary collaboration for chimpanzees. American Journal of Primatology 81(5): e22941
  • Hopper, L. M., Egelkamp, C. L., Fidino, M., & Ross, S.R. 2019. An assessment of touchscreens for testing primate food preferences and valuations. Behavior Research Methods, 51(2), 639–650. https://doi.org/10.3758/s13428-018-1065-0
  • Plenderleith, L. J., Liu, W., Learn, G. H., Loy, D. E., Speede, S., Sanz, C.M., Morgan, D.B., Bertolani, P., Hart, J.A., Hart, T.B., Hahn, B.H., Sharp, P. M. 2019. Ancient Introgression between Two Ape Malaria Parasite Species. Genome Biology and Evolution, 11(11), 3269–3274. https://doi.org/10.1093/gbe/evz244
  • Bibollet-Ruche, F., Russell, R. M., Liu, W., Stewart-Jones, G. B. E., Sherrill-Mix, S., Li, Y., … Hahn, B. H. 2019. CD4 receptor diversity in chimpanzees protects against SIV infection. Proceedings of the National Academy of Sciences, 201821197. https://doi.org/10.1073/pnas.1821197116
  • ManyPrimates, Altschul, D.M., Beran, M.J., Bohn, M., Call, J., DeTroy, S., Duguid, S.J., Egelkamp, C.E., Fichtel, C., Fischer, J., Flessart, M., Hanus, D., Haun, D.B.M., Haux, L.M., Hernandez-Aguilar, R., Herrmann, E., Hopper, L.M., Joly, M., Kano, F., Keupp, S., Melis, A.P., Rodrigo, A.M., Ross, S.R., Sánchez-Amaro, A., Sato, Y., Schmitt, V., Schweinfurth, M.K., Seed, A.M., Taylor, D., Völter, C.J., Warren, E., & Watzek, J. 2019. Establishing an infrastructure for collaboration in primate cognition research. PLoS ONE, 14(10), e0223675. https://doi.org/10.1371/journal.pone.0223675
  • Saiyed, S. T., Hopper, L. M., & Cronin, K. A. 2019. Evaluating the Behavior and Temperament of African Penguins in a Non-Contact Animal Encounter Program. Animals, 9(6), 326. https://doi.org/10.3390/ani9060326
  • Bonnie, K. E., Bernstein-Kurtycz, L. M., Shender, M. A., Ross, S. R., & Hopper, L. M. 2019. Foraging in a social setting: a comparative analysis of captive gorillas and chimpanzees. Primates, 60(2), 125–131. https://doi.org/10.1007/s10329-018-00712-x
  • Jacobson, S.L., & Hopper, L.M. 2019. Hardly habitual: chimpanzees and gorillas show flexibility in their motor responses when presented with a causally-clear task. PeerJ, 7, e6195
  • Morgan, D. B. 2019. Impacts of Selective Logging and Associated Anthropogenic Disturbance on Intact Forest Landscapes and Apes of northern Congo. Frontiers in Forests and Global Change, 2. https://doi.org/10.3389/ffgc.2019.00028
  • Hopper, L. M., Fernandez-Duque, E., & Williams, L. E. 2019. Testing the weekend effect hypothesis: Time of day and lunar phase better predict the timing of births in laboratory-housed primates than day of week. American Journal of Primatology, e23026. https://doi.org/10.1002/ajp.23026
  • Jacobson, S. L., Kwiatt, A. C., Ross, S. R., & Cronin, K. A. 2019. The effects of cognitive testing on the welfare of zoo-housed Japanese macaques (Macaca fuscata). Applied Animal Behaviour Science, 212: 90–97. https://doi.org/10.1016/j.applanim.2018.12.014
  • Woods, J. M., Ross, S. R., & Cronin, K. A. 2019. The Social Rank of Zoo-Housed Japanese Macaques is a Predictor of Visitor-Directed Aggression. Animals, 9(6), 316. https://doi.org/10.3390/ani9060316
  • Hopper, L. M., & Torrance, A. W. 2019. User innovation: A novel framework for studying animal innovation within a comparative context. Animal Cognition, 22(6), 1185-1190
  • Hopper, L. M., Cronin, K. A., & Ross, S. R. 2018. A multi-institutional assessment of a short-form personality questionnaire for use with macaques. Zoo Biology, 37: 281-289. https://doi.org/10.1002/zoo.21439
  • Sherrill-Mix, S., McCormick, K., Lauder, A., Bailey, A., Zimmerman, L., Li, Y., … Bushman, F. D. 2018. Allometry and Ecology of the Bilaterian Gut Microbiome. MBio, 9(2), e00319-18. https://doi.org/10.1128/mBio.00319-18
  • Hansen, B., Fultz, A., Hopper, L., & Ross, S. 2018. An evaluation of video cameras for collecting observational data on sanctuary‐housed chimpanzees (Pan troglodytes). Zoo Biology, 37(3), 156–161. https://doi.org/10.1002/zoo.21410
  • Adamescu, G. S., Plumptre, A. J., Abernethy, K. A., Polansky, L., Bush, E. R., Chapman, C. A., … Beale, C. M. 2018. Annual cycles are the most common reproductive strategy in African tropical tree communities. Biotropica. Retrieved from http://eprints.whiterose.ac.uk/129767/
  • Egelkamp, C.L., & Hopper, L.M. 2018. Behavioral and cognitive research. In W. Trevathan (Ed.). The International Encyclopedia of Biological Anthropology. John Wiley and Sons, Inc. (in press)
  • Hopper, L. M., van de Waal, E., & Caldwell, C. A. 2018. Celebrating the continued importance of “Machiavellian Intelligence” 30 years on. Journal of Comparative Psychology, 132(4), 427–431. https://doi.org/10.1037/com0000157
  • Watson, S. K., Vale, G. L., Hopper, L. M., Dean, L. G., Kendal, R. L., Price, E. E., … Whiten, A. 2018. Chimpanzees demonstrate individual differences in social information use. Animal Cognition, (Early View). https://doi.org/10.1007/s10071-018-1198-7
  • Antonioni, A., Pereda, M., Cronin, K. A., Tomassini, M., & Sánchez, A. 2018. Collaborative hierarchy maintains cooperation in asymmetric games. Scientific Reports, 8(1), 5375. https://doi.org/10.1038/s41598-018-23681-z
  • Huskisson, S. M., & Chism, J. L. 2018. Emerging relationships in a new group of Western lowland gorillas Gorilla gorilla gorilla at Riverbanks Zoo & Garden, Columbia, SC. International Zoo Yearbook, 52(1), 1-11
  • Marrocoli, S., Gatiso, T. T., Morgan, D., Nielsen, M. R., & Kühl, H. 2018. Environmental Uncertainty and Self-monitoring in the Commons: A Common-pool Resource Experiment Framed Around Bushmeat Hunting in the Republic of Congo. Ecological Economics, 149, 274–284. https://doi.org/10.1016/j.ecolecon.2018.03.020
  • Cronin, K. A., Bethell, E. J., Jacobson, S. L., Egelkamp, C., Hopper, L. M., & Ross, S. R. 2018. Evaluating mood changes in response to anthropogenic noise with a response-slowing task in three species of zoo-housed primates. Animal Behavior and Cognition, 5(2), 209­–221. https://doi.org/10.26451/abc.05.02.03.2018
  • Fisken, F. A., Carlsen, F., Elder, M., Jongh, T. de, Pereboom, J. J. M., Pohl, B., Rietkerk, F., Ross, S.R., Taniguchi, A. 2018. Global population records and managed-programme updates for the great apes: short report. International Zoo Yearbook, 52(1), 212–226. https://doi.org/10.1111/izy.12206
  • Finestone, E. M., Brown, M. H., Ross, S. R., & Pontzer, H. 2018. Great ape walking kinematics: Implications for hominoid evolution. American Journal of Physical Anthropology, 166(1), 43–55. https://doi.org/10.1002/ajpa.23397
  • Strindberg, S., Maisels, F., Williamson, E. A., Blake, S., Stokes, E. J., Aba’a, R., … Wilkie, D. S. 2018. Guns, germs, and trees determine density and distribution of gorillas and chimpanzees in Western Equatorial Africa. Science Advances, 4(4), eaar2964. https://doi.org/10.1126/sciadv.aar2964
  • Kozma, E. E., Webb, N. M., Harcourt-Smith, W. E. H., Raichlen, D. A., D’Août, K., Brown, M. H., Finestone, E.M., Ross, S.R., Aerts, P., Pontzer, H. 2018. Hip extensor mechanics and the evolution of walking and climbing capabilities in humans, apes, and fossil hominins. Proceedings of the National Academy of Sciences, 201715120. https://doi.org/10.1073/pnas.1715120115
  • Altschul, D. M., Hopkins, W. D., Herrelko, E. S., Inoue-Murayama, M., Matsuzawa, T., King, J. E., Ross, S.R., Weiss, A. 2018. Personality links with lifespan in chimpanzees. ELife, 7, e33781. https://doi.org/10.7554/eLife.33781
  • Saiyed ST, Liubicich RC, Fidino M, Ross SR. 2018. Stillbirth rates across three ape species in accredited American zoos. American Journal of Primatology. 2018; e22870. https://doi.org/10.1002/ajp.22870
  • Hopper, L. M., & Cronin, K. A. 2018. What Did You Get? What Social Learning, Collaboration, Prosocial Behaviour, and Inequity Aversion Tell Us About Primate Social Cognition. In L. D. Di Paolo, F. Di Vincenzo, & F. De Petrillo (Eds.), Evolution of Primate Social Cognition (pp. 13–26). Cham: Springer International Publishing. https://doi.org/10.1007/978-3-319-93776-2_2
  • Cronin, K.A. & Hopper, L.M. 2017. A comparative perspective on helping and fairness. In J. Sommerville & J. Decety (Eds.), Frontiers in Developmental Science Series: Social Cognition. (pp. 26-45). Psychology Press, Taylor & Francis Group, London
  • Hopper, L.M. 2017. Andrew Whiten. In J. Vonk & T. Shackelford (Eds.), Encyclopedia of Animal Cognition and Behavior (pp. 1-5). Cham: Springer International Publishing
  • Ang, M. Y. L., Shender, M. A., & Ross, S. R. 2017. Assessment of behavior and space use before and after forelimb amputation in a zoo-housed chimpanzee (Pan troglodytes). Zoo Biology 36: 5–10
  • Jacobson, S. L., Freeman, H. D., Santymire, R. M., & Ross, S. R. 2017. Atypical experiences of captive chimpanzees (Pan troglodytes) are associated with higher hair cortisol concentrations as adults. Royal Society Open Science, 4(12), 170932. https://doi.org/10.1098/rsos.170932
  • van Leeuwen, E.J.C., Mundry, R., Cronin, K.A., Bodamer, M. & Haun, D.B.M. 2017. Chimpanzee culture extends beyond matrilineal family units. Current Biology, 27: R588-R590
  • Hopper, L. M. 2017. Cognitive research in zoos. Current Opinion in Behavioral Sciences, 16, 100–110. https://doi.org/10.1016/j.cobeha.2017.04.006
  • Cronin, K.A. 2017. Comparative studies of cooperation: Collaboration and prosocial behavior in animals. In J. Call, G.B. Burghardt, I. Pepperberg, C.T. Snowdon, & T. Zental (Eds.), APA Handbook of Comparative Psychology. (pp. 915-929). American Psychological Association, Washington, D.C.
  • Howard, L. H., Wagner, K. E., Woodward, A. L., Ross, S. R., & Hopper, L. M. 2017. Social Models Enhance Apes’ Memory for Novel Events. Scientific Reports, 7, 40926
  • Cronin, K. A., Jacobson, S. L., Bonnie, K. E., & Hopper, L. M. 2017. Studying primate cognition in a social setting to improve validity and welfare: a literature review highlighting successful approaches. PeerJ, 5, e3649
  • Vale, G., Flynn, E., Kendal, J., Rawlings, B., Hopper, L., Schapiro, S., Lambeth, S., Kendal, R. 2017. Testing differential use of payoff-biased social learning strategies in children and chimpanzees. Proceedings of the Royal Society: Biological Sciences
  • van Leeuwen, E.J.C., Cronin, K.A., & Haun, D.B.M. 2017. Tool use for corpse cleaning in chimpanzees. Scientific Reports, 7, 44091. https://doi.org/10.1038/srep44091
  • Jacobson, SL, Hopper, LM, Shender, MA, Ross, SR, Leahy, M & McNernie, J. 2017. Zoo visitors’ perceptions of chimpanzee welfare are not affected by the provision of artificial environmental enrichment devices in a naturalistic exhibit. Journal of Zoo and Aquarium Research, 5(1), 56–61
  • Wagner, K.E., Hopper, L.M., & Ross, S.R. 2016. Asymmetries in the production of self-directed behaviour by chimpanzees and gorillas during a computerized cognitive test. Animal Cognition. 19(2), 343-350
  • Freeman, H.D., Ross, SR, Weiss, A. 2016. Atypical Early Histories Predict Lower Extraversion in Captive Chimpanzees. Developmental Psychobiology 58: 519-527
  • Hopper, L.M., Shender, M.A., & Ross, S.R. 2016. Behavioral research as physical enrichment for captive chimpanzees. Zoo Biology 35(4), 293-297
  • Jacobson S, Ross SR and Bloomsmith MA. 2016. Characterizing abnormal behavior in a large population of zoo-housed chimpanzees: Prevalence and potential influencing factors. PeerJ 4:e2225 https://doi.org/10.7717/peerj.2225
  • Beran, M.J., Hopper, L.M., de Waal, F.B.M., Sayers, K., Brosnan, S.F. 2016. Chimpanzee food preferences, associative learning, and the origins of cooking. Learning & Behavior: 44, 103-108
  • Kühl, H. S. Kuhl, H. S., Kalan, A. K., Arandjelovic, M., Aubert, F., D’Auvergne, L., Goedmakers, A., Jones, S., Kehoe, L., Regnaut, S., Tickle, A., Ton, E., van Schijndel, J., Abwe, E. E., Angedakin, S., Agbor, A., Ayimisin, E. A., Bailey, E., Bessone, M., Bonnet, M., Brazolla, G., Buh, V. E., Chancellor, R., Cipoletta, C., Cohen, H., Corogenes, K., Coupland, C., Curran, B., Deschner, T., Dierks, K., Dieguez, P., Dilambaka, E., Diotoh, O., Dowd, D., Dunn, A., Eshuis, H., Fernandez, R., Ginath, Y., Hart, J., Hedwig, D., Ter Heegde, M., Hicks, T. C., Imong, I., Jeffery, K. J., Junker, J., Kadam, P., Kambi, M., Kienast, I., Kujirakwinja, D., Langergraber, K., Lapeyre, V., Lapuente, J., Lee, K., Leinert, V., Meier, A., Maretti, G., Marrocoli, S., Mbi, T. J., Mihindou, V., Moebius, Y., Morgan, D., Morgan, B., Mulindahabi, F., Murai, M., Niyigabae, P., Normand, E., Ntare, N., Ormsby, L. J., Piel, A., Pruetz, J., Rundus, A., Sanz, C., Sommer, V., Stewart, F., Tagg, N., Vanleeuwe, H., Vergnes, V., Willie, J., Wittig, R. M., Zuberbuehler, K.,Boesch, C. 2016. Chimpanzee stone throwing and accumulation: evidence for a phylogenetic origin of ritual sites. Sci. Rep. 6, 22219; doi: 10.1038/srep22219
  • Beran, M.J., Hopper, L.M., de Waal, F.B.M., Brosnan, S.F., & Sayers, K. 2016. Chimpanzees, cooking, and a more comparative psychology. Learning & Behavior 44, 118-121
  • van Leeuwen, E.J.C., Mulenga, I.C., Bodamer, M. & Cronin, K.A. 2016. Chimpanzees’ responses to the dead body of a nine-year old group member. American Journal of Primatology. 78: 914-922
  • Ross SR and Shender MA. 2016. Daily travel distances of zoo-housed chimpanzees and gorillas: Implications for welfare assessments and space requirements. Primates 57: 395-401
  • Bonnie KE, Ang MY and Ross SR. 2016. Effects of crowd size on exhibit use by and behavior of chimpanzees (Pan troglodytes) and Western lowland gorillas (Gorilla gorilla) at an accredited zoo. Applied Animal Behaviour Science 178: 102-110
  • Cronin, K.A., West, V., & Ross, S.R. 2016. Investigating the relationship between welfare and rearing young in captive chimpanzees (Pan troglodytes). Applied Animal Behaviour Science 181, 166-172
  • Sanz, C. M., Morgan, D. B., & Hopkins, W. D. 2016. Lateralization and performance asymmetries in the termite fishing of wild chimpanzees in the Goualougo Triangle, Republic of Congo. American Journal of Primatology, online early view, http://doi.org/10.1002/ajp.22574
  • Pontzer H, Brown MH, Luke A, Dugas L, Schoeller D, Raichlen DA, Dunsworth H, Hare B, Schroepfer-Walker K, Thompson ME, Ross SR. 2016. Metabolic Acceleration and the Evolution of Human Brain Size and Life History. Nature doi:10.1038/nature17654
  • Meals LC, Ross SR, Eng C and Gamble KC. 2016. Prospective population management for Hepatitis B in the chimpanzee (Pan troglodytes) SSP population. Journal of Zoo and Wildlife Medicine 47(3): 711-716
  • Hopper, L.M., Freeman, H.D., & Ross, S.R. 2016. Reconsidering coprophagy as an indicator of negative welfare for captive chimpanzees. Applied Animal Behaviour Science. 176, 112-119
  • Ross, S.R., & Hopper, L.M. 2016. Seeking a deeper understanding of welfare-related behaviors. Connect. May 2016 Issue, 8-9
  • Cameron, K., Reed, T., Morgan, D., Ondzié, A., Sanz C., Kühl H., Olson S., Leroy E., Karesh, W. and Mundry, R. 2016. Spatial and Temporal Dynamics of a Mortality Event Among Central African Modeling Disease Spread in Apes. PLoS ONE 11(5):e0154505. doi:10.1371/journal.pone.0154505
  • Hopper, L.M. 2016. The individual and social drivers of primate innovation. PeerJ Preprints 4, e2276v1
    Cronin, K.A. 2016. Unnatural paradigm calls into question whether macaques’ social decisions represent empathy. Proceedings of the National Academy of Sciences.113 (10): E1331
  • Cronin, K.A., De Groot, E., & Stevens, J.M.G. 2015. Bonobos Show Limited Social Tolerance in a Group Setting: A Comparison with Chimpanzees and a Test of the Relational Model. Folia Primatologica, 86(3), 164–177
  • Hopper, L.M., Kurtycz, L.M., Ross, S.R., & Bonnie, K.E. 2015. Captive chimpanzee foraging in a social setting: a test of problem solving, flexibility, and spatial discounting. PeerJ 3, e833
  • Faughn C, Marrus N, Shuman J, Ross SR, Constantino J, Pruett JR, and Povinelli DJ. 2015. Chimpanzee Social Responsiveness Scale detects individual variation in social responsiveness for captive chimpanzees. Journal of Autism and Developmental Disorders 45(5): 1483-1488
  • Kendal, R.L., Hopper, L.M., Whiten, A., Brosnan, S.F., Lambeth, S.P., Schapiro, S.J., & Hoppitt, W. 2015. Chimpanzees copy dominant and knowledgeable individuals: implications for cultural diversity. Evolution & Human Behavior. 36, 65-72
  • Hopper, L.M., Tennie, C., Ross, S.R. & Lonsdorf, E.V. 2015. Chimpanzees create and modify probe-tools functionally: A study with zoo-housed chimpanzees. American Journal of Primatology 77(2), 162-170
  • Ndolo-Ebika, Sydney, Morgan, D., Sanz, C., Harris, D. 2015. Differences between trees and free-standing stranglers in Ficus in a Congolese forest. Plant Ecology and Evolution
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  • Ross, S.R., Wagner, K.E., Schapiro, S.J., Hau, J., and Lukas, K.E. 2011. Transfer and acclimatization effects on the behavior of two species of African great ape moved to a novel and naturalistic zoo environment. International Journal of Primatology, 32: 99-117
  • Heintz, M.R., Santymire, R.M., Parr, L.A., Lonsdorf, E.V. 2011. Validation of cortisol enzyme immunoassay and characterization of salivary cortisol circadian rhythm in chimpanzees (Pan troglodytes). American Journal of Primatology, 73: 1-6
  • Hopper, L.M. 2010. ‘Ghost’ experiments and the dissection of social learning in humans and animals. Biological Reviews. 85, 685-701
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  • Wallis, J. and Lonsdorf, E.V. 2010. A summary of recommendations for primate conservation education. American Journal of Primatology, 72: 441-444
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  • Meguerditchian, A., Calcutt, S.E., Lonsdorf, E.V., Ross, S.R., and Hopkins, W.D. 2010. Captive gorillas are right-handed for bimanual feeding. American Journal of Physical Anthropology, 141: 638-645
  • Ross, S.R. 2010. Chimpanzee (Pan troglodytes) Care Manual. Association of Zoos and Aquariums, Silver Spring, MD
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  • Sanz, C., Schöning, C. Morgan, D. 2010. Chimpanzees prey on army ants with specialized tool set. American Journal of Primatology, 71:1’8
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  • Hopper, L.M. 2010. Deferred imitation in children and apes. Children imitate after a delay, but can apes ape in a similar fashion?. The Psychologist. 23, 294-297
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  • Ross, S.R., Ross, M.R., and Clark, A.B. 2010. Ethosearch: A comprehensive repository of ethograms for use in animal behavior research. Proceedings of the 7th International Conference on Methods and Techniques in Behavioral Research, 369 (abstract)
  • Milstein, M.S., S. E. Calcutt, S. R. Ross, K. E. Bonnie, E. V. Lonsdorf. 2010. Food-sharing in a variable environment among a group of zoo-housed chimpanzees (Pan troglodytes). American Journal of Primatology, 72: S1: 70
  • Freeman, H and Beer, J. 2010. Frontal Lobe Activation Mediates the Relation Between Sensation-Seeking and Cortisol Increases. Journal of Personality, 1497-1528
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  • Freeman, H, Gosling, S. 2010. Personality in non-human primates: A review and evaluation of past research. American Journal of Primatology. 71: 1-19
  • Ross, S.R., Milstein, M.S., Calcutt, S.E., Lonsdorf, E.V. 2010. Preliminary assessment of methods used to demonstrate nut cracking behavior to five captive chimpanzees (Pan troglodytes). Folia Primatologica, 81: 224-232
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  • Ross, S.R., and Vreeman, V.M. 2010. Project ChimpCARE: An assessment of privately-owned chimpanzees in the United States. American Journal of Primatology, 72: S1: 48
  • Cronin, K.A., Schroeder, K.K.S. & Snowdon, C.T. 2010. Prosocial behaviour emerges independent of reciprocity in cottontop tamarins. Proceedings of the Royal Society of London. Series B: Biological Sciences, 277: 3845-3851
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  • Lonsdorf, E.V., Ross, S.R., Linick, S.A., Milstein, M.S. and Melber, T.N. 2009. An experimental, comparative investigation of tool use in chimpanzees and gorillas. Animal Behaviour, 77: 1119-1126
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  • Ross, S.R., Lonsdorf, E.V., and Holmes, A.N. 2009. Interactions between indigenous wildlife and four species of zoo-housed apes in North America: Patterns of aggression and hunting. American Journal of Primatology, 71, Supplement 1: 34
  • Ross, S.R., Lonsdorf, E.V., and Holmes, A.N. 2009. Interactions Between Zoo-Housed Great Apes and Local Wildlife. American Journal of Primatology, 71: 458-465
  • Wroblewski, E.E., Murray, C.M., Keele, B.F., and Schumacher-Stankey, J.C. 2009. Male dominance rank and reproductive success in chimpanzees, Pan troglodytes schweinfurthii. Animal Behaviour, 77:873-885
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  • Margulis, S.W. 2008. Book review: Gorilla Society: Conflict, Compromise, and Cooperation Between the Sexes. American Journal of Physical Anthropology, 137: 241
  • Williams, J.M., Lonsdorf, E.V., Wilson, M.L., Schumacher-Stankey, J., Goodall, J, Pusey, A. E. 2008. Causes of death in the Kasekela chimpanzees of Gombe National Park, Tanzania. American Journal of Primatology, 70: 745-750
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  • Cranfield, M., Gaffikin, L., Minnis, R., Nutter, F., Rwego, I., Travis, D. and Whittier, C. 2006. Clinical Response to Decision Tree for the Mountain Gorilla (Gorilla beringeii) as a Model for Great Apes. American Journal of Primatology: Special Topics Issue, 68: 909-927
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