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 about Internships

Science Projects

Chimpanzees socializing at Chimp Haven
Enhancing Animal Welfare, At Zoos
A Zoo-sanctuary Partnership for Chimpanzees
A logging path cut through the African rainforest
In the Wild, Conserving Threatened Wildlife
Evaluating Logging Impacts in Congo
Zoo scientists setting up a motion-activated field camera in the African rainforest
At Zoos, Enhancing Animal Welfare
Goualougo Video Analysis Lab
A wild chimpanzee peering through the foilage
Conserving Threatened Wildlife, In the Wild
Monitoring Ape Behavior
Zoo scientists trekking through the African rainforest
In the Wild, Conserving Threatened Wildlife
Monitoring Ape Health
Chimpanzee in exhibit
At Zoos, Enhancing Animal Welfare
Project ChimpCARE
Chimpanzee in exhibit
Enhancing Animal Welfare, At Zoos
Studying How Primates Innovate and Learn
Zoo staff observing chimpanzees in exhibit
At Zoos, Enhancing Animal Welfare
Studying Primate Behavior
In the Wild, Helping People and Wildlife Coexist, Conserving Threatened Wildlife
The Goualougo Triangle Ape Project
Western lowland gorilla using a touchscreen computer in exhibit
At Zoos, Enhancing Animal Welfare
Using Technology to Study Primate Cognition
Zoo scientists at a field site in the African rainforest
In the Wild, Helping People and Wildlife Coexist
Working with Congolese Communities

Partners

Chimp Haven
Species Survival Plans
Gombe Stream Research Center
Goualougo Triangle Ape Project
International Primatological Society
Jane Goodall Institute
Japan Monkey Centre
Kumamoto Sanctuary
Katie Amato Lab, Northwestern University
Primate Research Institute – Kyoto University
Washington University in St. Louis
Wildlife Conservation Society

 

Supporters

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

Publications

  • Angley, L. P., Vale, G. L., & Cronin, K. A. (2024). The impact of care on chimpanzee welfare: A comprehensive review. Applied Animal Behaviour Science, 275, 106272. https://doi.org/10.1016/j.applanim.2024.106272
  • Leinwand, J. G., & Vale, G. L. (2023). Compassion fatigue in chimpanzee (Pan troglodytes) caregivers: Prevalence, contributing factors, and coping mechanisms. Journal of Zoological and Botanical Gardens, 5(1), Article 1. https://doi.org/10.3390/jzbg5010001 
  • Whiten, A., Harrison, R. A., McGuigan, N., Vale, G. L., & Watson, S. K. (2022). Collective knowledge and the dynamics of culture in chimpanzees. Philosophical Transactions of the Royal Society B, Biological Sciences, 377(1843), 20200321. https://doi.org/10.1098/rstb.2020.0321 
  • Teberd, P., Sanz, C., Zambarda, A., Kienast, I., Ebombi, T. F., Abea, G., Kunz, J., Judson, K., Stephens, C., & Morgan, D. (2023). Path to Acceptance and Refined Practices for Habituating Western Lowland Gorillas. Primates. https://doi.org/10.1007/s10329-023-01086-5.
  • Ross, S.R., Leinwand, J.G., & Hopper, L.M. (2022). Ethical considerations in conducting.primate cognition research. In B.L. Schwartz & M.J. Beran (Eds.), Primate cognitive studies (pp. 551-583). Cambridge: Cambridge University Press. doi:10.1017/9781108955836.022.
  • Leinwand, J.G., Fidino, M., Ross, S.R., & Hopper, L.M. (2022). Familiarity mediates apes’ attentional biases towards human faces. Proceedings of the Royal Society: B. 289:20212599 https://doi.org/10.1098/rspb.2021.2599.
  • Hopper, L.M., Lake, B.R., Leinwand, J.G., Fultz, A., & Ross, S.R. (2022). Assessing chimpanzees’ fluency of movement: applications for monitoring health and welfare. Applied Animal Behaviour Science. 250: 105612. https://doi.org/10.1016/j.applanim.2022.105612.
  • Kano, F., Furuichi, T., Hashimoto, C., Krupenye, C., Leinwand, J.G., Hopper, L.M., Martin, C., Otsuka, R., & Tajima, T. (2022). What is unique about the human eye? Comparative image analysis on the external eye morphology of human and nonhuman great apes. Evolution and Human Behavior. https://doi.org/10.1016/j.evolhumbehav.2021.12.004.
  • Ross, S.R., Joshi, P.B., Terio, K.A., & Gamble, K.C. (2022). A 25-Year Retrospective Review of Mortality in Chimpanzees (Pan troglodytes) in Accredited U.S. Zoos from a Management and Welfare Perspective. Animals, 12(15). https://doi.org/10.3390/ani12151878.
  • Vale GL, Coughlin C, Brosnan SF. (2022) The importance of thinking about the future in culture and cumulative cultural evolution. Phil. Trans. R. Soc. B 20210349.
  • Vale, GL. Williams, L., Neal Webb, S, Schapiro, SJ & Brosnan, S.F (in press). Female squirrel monkeys’ (Saimiri boloviensis) responses to inequity in a group context; testing a link between cooperation and inequity responses. Animal Behaviour.
  • Huskisson, S.M., Ross, S.R. & Hopper, L.M. Do zoo visitors induce attentional bias effects in primates completing cognitive tasks?. Anim Cogn 24, 645–653 (2021). https://doi.org/10.1007/s10071-020-01445-5.
  • Hopper LM, Gulli RA, Howard LH, Kano F, Krupenye C, Ryan AM & Paukner A (2021). The application of non-invasive, restraint-free eye-tracking methods for use with nonhuman primates. Behavior Research Methods, 53, 1003-1030.
  • Leeds, A., Boyer, D., Ross, S. R., & Lukas, K. E. (2021). Patterns of wounding in mixed-sex social groups of western lowland gorillas (Gorilla gorilla gorilla). Applied Animal Behaviour Science, 236, 105226.
  • Che-Castaldo, J., Havercamp, K., Watanuki, K., Matsuzawa, T., Hirata, S., & Ross, S. R. (2021). Comparative survival analyses among captive chimpanzees (Pan troglodytes) in America and Japan. PeerJ, 9, e11913.
  • Osuna‐Mascaró, A. J., Ortiz, C., Stolz, C., Musgrave, S., Sanz, C. M., Morgan, D. B., & Fragaszy, D. M. (2021). Dexterity and technique in termite fishing by chimpanzees (Pan troglodytes troglodytes) in the Goualougo Triangle, Republic of Congo. American Journal of Primatology, 83(1), e23215.
  • Pontzer, H., Brown, M. H., Wood, B. M., Raichlen, D. A., Mabulla, A. Z., Harris, J. A., … & Ross, S. R. (2021). Evolution of water conservation in humans. Current Biology, 31(8), 1804-1810.
  • Hopper, L. M., Allritz, M., Egelkamp, C. L., Huskisson, S. M., Jacobson, S. L., Leinwand, J. G., & Ross, S. R. (2021). A Comparative Perspective on Three Primate Species’ Responses to a Pictorial Emotional Stroop Task. Animals 11(3), 588.
  • Hopper, L. M. (2021). Leveraging Social Learning to Enhance Captive Animal Care and Welfare. Journal of Zoological and Botanical Gardens, 2(1), 21-40.
  • Leinwand, J. G., Moyse, J. A., Hopper, L. M., Leahy, M., & Ross, S. R. (2021). The use of biofloors in great ape zoo exhibits. Journal of Zoo and Aquarium Research, 9(1), 41-48.
  • Huskisson SM, Egelkamp CL, Jacobson SL, Ross SR & Hopper LM (2021). Primates’ food preferences predict their food choices even under uncertain conditions. Animal Behavior and Cognition, 8(1), 69-96.
  • Lester, J. D., Vigilant, L., Gratton, P., McCarthy, M. S., Barratt, C. D., Dieguez, P., … & Arandjelovic, M. (2021). Recent genetic connectivity and clinal variation in chimpanzees. Communications biology, 4(1), 1-11.
  • Barratt, C. D., Lester, J. D., Gratton, P., Onstein, R. E., Kalan, A. K., McCarthy, M. S., … & Kühl, H. (2021). Quantitative estimates of glacial refugia for chimpanzees (Pan troglodytes) since the Last Interglacial (120,000 BP). American Journal of Primatology, e23320.
  • Harris, D. J., Ndolo Ebika, S. T., Sanz, C. M., Madingou, M. P., & Morgan, D. B. (2021). Large trees in tropical rain forests require big plots. Plants, People, Planet, 3(3), 282-294.
  • Doelling, C.R., Cronin, K.A., Ross, S.R., & Hopper, L.M. (2021). The relationship between personality, season, and wounding receipt in zoo-housed Japanese macaques (Macaca fuscata): a multi-institutional study. American Journal of Primatology, 83(12), e23332.
  • Huskisson, S.M., Doelling, C.R., Ross, S.R., & Hopper, L.M. (2021). Assessing the potential impact of zoo visitors on the welfare and cognitive performance of Japanese macaques. Applied Animal Behaviour Science, 243, 10543.
  • Ross, SR, Lake BR, Fultz, A & Hopper LM (2021). An evaluation of thermal imaging as a welfare monitoring tool for captive chimpanzees. Primates, 62(6), 919-927.
  • Amato, K. R., Chaves, Ó. M., Mallott, E. K., Eppley, T. M., Abreu, F., Baden, A. L., … & Zeng, Y. (2021). Fermented food consumption in wild nonhuman primates and its ecological drivers. American journal of physical anthropology.
  • 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.
  • 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 https://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
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  • Chelluri, G.I., Ross, S.R. and Wagner, K.E. 2013. Behavioral correlates and welfare implications of informal interactions between caretakers and zoo-housed chimpanzees and gorillas. Applied Animal Behaviour Science 147: 306-315
  • S. E. Henley, M. A. Shender, K. E. Wagner, S. R. Ross 2013. Behavioral development in a new group of bachelor gorillas (Gorilla gorilla gorilla). American Journal of Primatology. 75(S1), 77
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  • Margulis, S.W., Atsalis, S., Bellem, A., Wielebnowski, N. 2007. Assessment of reproductive behavior and hormonal cycles in geriatric Western Lowland gorillas. Zoo Biology, 26: 117-139
  • Morgan, D.B. and Sanz, C.M. 2007. Best Practice Guidelines for Reducing the Impact of Commercial Logging on Great Apes in Western Equatorial Africa. Gland, Switzerland: IUCN SSC Primate Specialist Group (PSG). 32 pp
  • Beck, B., Walkup, K., Rodrigues, M., Unwin, S., Travis, D. and Stoinski, T. 2007. Best Practice Guidelines for the Re-introduction of Great Apes. IUCN/SSC Primate Specialist Group, Gland, Switzerland
  • Sanz, C.M. and Morgan, D.B. 2007. Chimpanzee tool technology in the Goualougo Triangle, Republic of Congo. Journal of Human Evolution, 52(4): 420-433
  • Snowdon, C.T. & Cronin, K.A. 2007. Cooperative breeders do cooperate. Behavioural Processes, 76: 138-141
  • Sanz, C.M, Morgan, D.B., Strindberg, S., and Onononga, J.R. 2007. Distinguishing between the nests of sympatric chimpanzees and gorillas. Journal of Applied Ecology, 44(2): 263-272
  • Vreeman, V.M. and Ross, S.R. 2007. Do seasonal changes affect activity in captive chimpanzees (Pan troglodytes) and gorillas (Gorilla gorilla gorilla) living in a northern zoo?. American Journal of Primatology 69 (supplement 1): 89
  • Hopper, L.M., Spiteri, A., Lambeth, S.P., Schapiro, S.J., Horner, V. & Whiten, A. 2007. Experimental studies of traditions and underlying transmission processes in chimpanzees. Animal Behaviour.73, 1021-1032
  • Halloran, A.R., Broadfield, D., Ross, S.R. and Marshall, A. 2007. Exploring diachronic change in the group specific vocalizations of chimpanzees (Pan troglodytes). American Journal of Physical Anthropology (Suppl 44): 123-124
  • Hopkins, WD, Russel, J, Remkus, M, Freeman, H, & Schapiro, SJ. 2007. Handedness and grooming in chimpanzees (Pan troglodytes): Comparative analysis between findings in captive and wild individuals. International Journal of Primatology, 28, 1315-1326
  • Walsh, P.D., Breuer,T., Sanz, C.M., Morgan, D.B., and Doran-Sheehy, D. 2007. Potential for Ebola transmission between gorilla and chimpanzee social groups. American Naturalist, 169(5): 684-689
  • Melber, T.M., Lonsdorf, E.V. and Ross, S.R. 2007. Social learning of tool-use skills in captive chimpanzees (Pan troglodytes) and gorillas (Gorilla gorilla gorilla). American Journal of Primatology 69 (supplement 1): 100-101
  • Lonsdorf, E.V. 2007. The Role of Behavioral Research in the Conservation of Chimpanzees and Gorillas. Journal of Applied Animal Welfare Science, 10(1): 71-78
  • Freeman, H, Gosling, S. 2006. A review and meta-analysis of personality studies in non-human primates. American Journal of Primatology 68 (S1): 75
  • Lonsdorf, E.V., Ross, S.R. and Melber, T.N. 2006. An experimental, comparative approach to social learning of tool-use skills in chimpanzees (Pan troglodytes) and gorillas (Gorilla gorilla gorilla). International Journal of Primatology (supplement 1): 27
  • Ross, S.R. and Lukas, K.E. 2006. Attitudes and knowledge of visitors towards African apes at a North American Zoo. International Journal of Primatology (supplement 1): 27
  • 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
  • Bloomsmith, M.A., Ross, S.R., Bettinger, T., Clay, A.W. and Anderson, U. 2006. Cross-sectional study of the behavioral development of young male chimpanzees in twenty zoos. American Journal of Primatology 68 (supplement 1): 48
  • Travis, D.A., Hungerford, L., Engel, G.A., and Jones-Engel, L. 2006. Disease Risk Analysis: A Tool for Primate Conservation Planning and Decision Making. American Journal of Primatology: Special Topics Issue, 68: 855-867
  • Hopper, LM, Lambeth, SP, Schapiro, SJ, and Whiten, A. 2006. How do chimpanzees learn ‘Pan-pipes’ traditions?. International Journal of Primatology, 27(S1)
  • Hopkins, WD, Russell, J, Freeman, H, Reynolds, E, Griffis, C, and Leavens, DL. 2006. Lateralized scratching in chimpanzees (Pan troglodytes).Evidence of a Functional Asymmetry During Arousal. Emotion. 6, 553-559
  • Hostetter, AB, Russell, J, Freeman, H, and Hopkins, WD. 2006. Now you see me, now you don’t: evidence that chimpanzees understand the role of eyes in attention. Animal Cognition, 10, 55-62
  • Ross, S.R., Bettinger, T.M., and Bloomsmith, M.A. 2006. Patterns of wounding incidents in captive chimpanzee groups with adolescent males. International Journal of Primatology (supplement 1): 2
  • Melber, T.N., Lonsdorf, E.V., and Ross, S.R. 2006. The Lester E. Lester E. Fisher Center for the Study and Conservation of Apes: A new center for the advancement of research, conservation and education. American Journal of Primatology 68 (supplement 1):121
  • Lonsdorf, E.V. 2006. The role of the mother in the acquisition of tool-use skills in wild chimpanzees. Animal Cognition, 9: 36-46
  • Lonsdorf, E.V., Travis, D., Pusey, A.E. and Goodall, J. 2006. Using retrospective health data from the Gombe chimpanzee study to inform future monitoring efforts. American Journal of Primatology: Special Topics Issue on Disease Risk Analysis, 68: 897-908
  • Hopkins, WD, Cantalupo, C, Freeman, H, Russell, J, Kachin, M, and Nelson, E. 2005. Chimpanzees Are Right Handed When Recording Bouts Rather Than Frequencies in Hand Use. Laterality. 10, 121-130
  • Cronin, K.A., Kurian, A.V. & Snowdon, C.T. 2005. Cooperative problem solving in a cooperatively breeding primate. Animal Behaviour, 69: 133-142
  • Bloomsmith, M.A., Baker, K.C., Ross, S.R. and Lambeth, S.P. 2005. Early rearing conditions and captive chimpanzee behavior: Some surprising findings. Nursery Rearing of Nonhuman Primates in the 21st Century. Kluver Academic Publishers, New York, New York, 289-312
  • Hopkins, WD, Russell, J, Cantalupo, C, Freeman, H, and Shapiro, SJ. 2005. Factors influencing throwing in chimpanzees (Pan troglodytes). Journal of Comparative Psychology. 119, 363-370
  • Lonsdorf, E.V. 2005. Sex differences in the development of termite-fishing skills in wild chimpanzees (Pan troglodytes schweinfurthii) of Gombe National Park, Tanzania. Animal Behaviour, 70: 673-683
  • Hopkins, WD, Russell, J, Freeman, H, Buehler, N, Reynolds, E, and Shapiro, SJ. 2005. The distribution and development of handedness for manual gestures in captive chimpanzees (Pan troglodytes). Psychological Science, 16, 487-493
  • Lonsdorf, E.V. and Hopkins, W.D. 2005. Wild chimpanzees show population-level handedness for tool use. Proceedings of the National Academy of Sciences, 102: 12634-12638. https://www.pnas.org/cgi/content/abstract/0505806102
  • Ross, SR and Lukas, KE. 2005. Zoo Visitor Behavior at an African Ape Exhibit. Visitor Studies Today, 8(1): 4-12
  • Lukas, K.E. and Ross, S.R. 2005. Zoo visitor knowledge and attitudes towards gorillas and chimpanzees.. Journal of Environmental Education, 36(4): 33-48
  • Freeman, H, Cantalupo, C, Weiss, A, King, J, Hopkins, W. 2004. Association between personality and brain asymmetries in the limbic system of chimpanzees. American Journal of Primatology, 62 (S1): 105
  • Freeman, H, Cantalupo, C, Hopkins, WD. 2004. Asymmetries in the Hippocampus and Amygdala of Chimpanzees (Pan troglodytes). Behavioral Neuroscience. 118: 1460-1465
  • Russell, J, Freeman, H, Schapiro, S, Hopkins, W. 2004. Chimpanzee handedness: throwing out the first pitch. American Journal of Primatology, 62 (S1): 106
  • Maestripieri, D. and Ross, S.R. 2004. Maternal influences on infant behavioral development in western lowland gorillas. Advances in Psychology Research, 27: 96-112
  • Lonsdorf, E.V., Pusey, A.E. and Eberly, L. 2004. Sex differences in learning in chimpanzees. Nature, 428: 715-716
  • Maestripieri, D. and Ross, S.R. 2004. Sex differences in play among western lowland gorilla (Gorilla gorilla gorilla) infants: Implications for adult behavior and social structure. American Journal of Physical Anthropology, 123 (1): 52-61
  • Atsalis, S., Margulis, S.W., Bellem, A. and Wielebnowski, N. 2004. Sexual behavior and hormonal estrus cycles in captive aged lowland gorillas (Gorilla gorilla). American Journal of Primatology, 62: 123-132
  • Ross, S.R. 2003. A guide to caring for chimpanzees (book review). Zoo Biology, 22: 609-612
  • Hopkins, W.D., Stoinski, T.S., Lukas, K.E., Ross, S.R. and Wesley, M.J. 2003. Comparative Assessment of handedness for a coordinated bimanual task in chimpanzees (Pan), gorillas (Gorilla), and orangutans (Pongo). Journal of Comparative Psychology, 117(3): 302-308
  • Ross, S.R. 2003. North American regional studbook for the chimpanzee (Pan troglodytes). Lincoln Park Zoo, Chicago, Illinois
  • Bloomsmith, M., Kuhar, C., Baker, K., Lambeth, S., Brent, L., Ross, S. and Fritz, J. 2003. Primiparous chimpanzee mothers and their infants: Behavior, interactions, and success. Applied Animal Behavior Science, 84: 235-250
  • Margulis, S.W., Whitham, J.C. and Ogorzalek, K. 2003. Silverback male presence and group stability in gorillas (Gorilla gorilla). Folia Primatologica, 74: 92-96
  • Goodall, J. and Lonsdorf, E.V. 2002. Cultures in Chimpanzees. Oxford University Press Encyclopedia of Evolution
  • Maestripieri, D., Ross, S.K. and Megna, N.L. 2002. Mother-infant interactions in western lowland gorillas (Gorilla gorilla gorilla): Spatial relationships, communication, and opportunities for social learning. Journal of Comparative Psychology, 116(3): 219-227
  • Bloomsmith, M., Kuhar, C., Baker, K., Lambeth, S., Brent, L., Ross, S. and Fritz, J. 2001. Early interactions between primiparous chimpanzees and their infants. American Journal of Primatology, 54(1): 31
  • Ross, S.K. and Lukas, K.E. 2001. Exhibit use by great apes as part of a post-occupancy evaluation. American Journal of Primatology, 54(1): 31
  • Ross, S.K., Barger, N., Ganas, J., Lukas, K., Nichols, C., Megna, N., Stoinski, T. and Maestripieri, D. 2001. Maternal scaffolding of offspring behavior in western lowland gorillas. American Journal of Primatology, 54(1): 31
  • Baker, K.C., Bloomsmith, M.A., Ross, S.K., Lambeth, S.P. and Noble, P.L. 2001. The behavioral effects of control vs. passive exposure to joystick-controlled computer tasks intended as enrichment for chimpanzees. American Journal of Primatology, 54(1): 64
  • Bloomsmith, M.A., Ross, S.K. and Baker, K.C. 2000. Control over computer-assisted enrichment for socially housed chimpanzees. American Journal of Primatology, 51(1): 45
  • Bloomsmith, M.A., Baker, K.C., Ross, S.K. and Lambeth, S.P. 1998. Enlarging chimpanzee social groups: The behavioral course of introductions. American Journal of Primatology, 45: 171
  • Baker, KC and Ross, SK. 1998. Outdoor access: The behavioral benefits to chimpanzees. American Journal of Primatology, 45: 166
  • Gillespie, T.R., Lonsdorf, E.V., Canfield, E.P., Meyer, D.J., Nadler, Y., Raphael, J., Pusey, A.E., Pond, J., Pauley, J., Mlengeya, T., Travis, D.A. . Demographic and Ecological Affects on Patterns of Parasitism in Eastern Chimpanzees (Pan troglodytes schweinfurthii) in Gombe National Park, Tanzania. American Journal of Physical Anthropology, 143: 534-544.

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