Lab members


The Diademed Sifaka

Study Site: Tsinjoarivo

Tsinjoarivo's Biodiversity




Mitchell Irwin

Mitch is currently a Professor in the Anthropology Department at NIU, where he has been a member of the faculty since 2012. He received his BSc from the University of Toronto, and his MA & PhD from the Interdepartmental Doctoral Program in Anthropological Sciences, Stony Brook University. He has been an NSERC postdoc at McGill University, and a visiting scholar at the University of Queensland, Australia. His research integrates primate behavior, ecology, and measures of physiological health to understand seasonality and the impacts of habitat change on wild lemurs. Mitch teaches Anthropology courses at NIU, including a study abroad program based at Tsinjoarivo (more detail here), and is an associate member of the Institute for the study of Energy, Sustainability and the Environment. He is one of three co-founders and a member of the board of directors of the NGO Sadabe, which promotes research, conservation and development at Tsinjoarivo.

Current Graduate Students


Edgar Villeda - MA Student

Edgar earned his BS in Anthropology from Appalachian State University in Fall 2021 and entered NIU’s MA program in Anthropology in Fall 2022. Previously he contributed to population density estimate research on lemurs at Betampona Strict Natural Reserve in Madagascar with Dr. Zach Farris. Edgar plans to conduct a study on the interaction between tannins and the gut microbiome of captive and wild Propithecus diadema and Eulemur fulvus across seasons and forest types. This investigation seeks to understand if these lemurs’ microbial community defends against tannins in their diet and contribue to health.


Tojo Andriamaminirina - MS Student

Tojo is a student at the University of Antananarivo. His fieldwork, completed in 2022, examines the habitat microstructure available to, and selected by, Hapalemur griseus in disturbed and undisturbed forest at Tsinjoarivo. This species appears to be quite adaptable, persisting even in disturbed forest fragments, but its actual microhabitat preferences have not been examined.


Casey Farmer - MA Student

Casey earned her BS in Animal Science from Cornell University in Spring 2019, and entered NIU's MA program in Anthropology in Fall 2021. She has completed behavioral, genetics, nutritional ecology, and energetics research (both her own and assisting others) at the Duke Lemur Center while working at Duke University with Dr. Charles Nunn. She conducted a non-invasive energetics study of Propithecus diadema at Tsinjoarivo investigating the roles of nutrition, activity, and seasonality on their energetic condition.


Maire O'Malley - MA Student

Maire earned her BS in Animal Science with a minor in Wildlife Biology and Management from the University of Kentucky, and entered NIU's MA program in Anthropology in Fall 2021. Previously, Maire has conducted research on captive primate welfare for the Chicago Zoological Society and created conservation-based educational content for the Dian Fossey Gorilla Fund. Maire is examining micronutrients in Hapalemur griseus foods at Tsinjoarivo, and their influence on food selection and conservation.


Koloina Rakotoarivelo - MS Student

Koloina, a student at the University of Antananarivo, completed her fieldwork in 2021 at Mahatsinjo. Her research revisits the ecological constraints model - the idea that within-group feeding competition limits the health of individuals, and therefore, group size. She collected data on three Propithecus diadema groups of varying size across multiple years, and will test whether activity budgets and daily travel distance correlate with group size.

Navoko Randriamahafaly - MS Student

Navoko, a student at the University of Antananarivo, is examining how Propithecus diadema groups respond to demographic instability. In 2019-20, two groups in the Mahatsinjo region suffered losses due to fosa predation, and Navoko is examining how the remaining individuals group flexibly in this small forest fragment with limited breeding opportunities.


Marie-Jeanne Razafiarivony - MS Student

Marie-Jeanne, a student at the University of Antananarivo, is examining niche overlap and coexistence between the larger, diurnal Propithecus diadema, and the smaller, nocturnal Avahi laniger, at Mahatsinjo. Her data will reveal to what extent competition between the species may contribute to extirpation in small forest fragments.


Elly Fahzad Soulaimana - MS Student

Elly, a student at the University of Antananarivo, is interested in the factors causing local extinction in small forest fragments. He reassessed and recensused eight forest fragments that had previously been censused in 2001 and is examining patterns of change in species richness and how these are linked with habitat attributes.

Henikaja Rasoaviarimanana - MS Student

Henikaja, a student at the University of Antananarivo, is interested in the factors affecting lemur community composition and the relative abundance of species and guilds. His fieldwork in 2019 involved an intensive census and habitat assessment in the Ambalaomby region. This represents the first lemur census in the eastern half of the new Tsinjoarivo-Ambalaomby Protected Area, and will be invaluable in understanding the diversity in habitat and fauna across the landscape.


Chloé Gherardi - PhD Student (co-advisor)

Chloé earned her BS in Biology with a minor in Natural History from McGill University, and completed NIU's MA program in Biological Sciences in 2021. Her thesis examined the nutritional ecology of Avahi laniger and Lepilemur mustelinus at Tsinjoarivo, and examined chemical niche separation among sympatric lemurs within this community.     


Vololona Rahalinarivo - PhD student (co-supervised with Dr. Jeannot Randrianasy)

Vololona is a primatology student within the "Anthropobiologie et Développement Durable" Mention, Faculty of Sciences, University of Antananarivo. During her DEA degree her fieldwork focused on dwarf lemurs at Tsinjoarivo. Her dissertation will examine the impacts of environmental factors on brown lemur activity patterns and cathemerality.

Past Postdoctoral Associates


Dr Tim Bransford - Postdoc

Tim earned his PhD in Evolutionary Anthropology from Rutgers University in 2019. His doctoral work was a study of how mother orangutans use behavioral and physiological strategies to modulate their energy budget and nutritional status across periods of infant development. Tim is working on two main lemur projects. The first is the influence of seasonality, nutrition and energetics on the ranging patterns of diademed sifakas and brown lemurs, and the second is the establishment of botanical plots for long-term monitoring at Tsinjoarivo. Tim started a faculty position in Fall 2020 at Eckerd College. [website]

Past Graduate Students


Georginot Harizo Rijamanalina - Masters student (co-advised)

Zo completed his masters degree in 2020 at the University of Antananarivo ("Anthropobiologie et Développement Durable" Mention, Faculty of Sciences). His fieldwork, conducted in 2018, examined the group geometry of diademed sifakas in intact and fragmented forest, and how inter-individual distances varied according to activity.


Chazal Tatamoniaina Vololontsoa - Masters student (co-advised)

Tatamo earned her masters degree in 2019 from the University of Antananarivo ("Anthropobiologie et Développement Durable" Mention, Faculty of Sciences). Her fieldwork, conducted in 2018, examined the social tolerance of mother diademed sifakas and how tolerance varied across food types and between groupmates.


Emma Thurau - MA student

Emma graduated from California State University, Los Angeles in 2017 with a B.A. in Anthropology. She has studied in Costa Rica and the Los Angeles Zoo, conducted labwork in lemur genetics, and volunteered for the Madagascar Biodiversity Partnership in Summer 2017 (conducting fieldwork at Kianjavato). She conducted MA fieldwork in 2018 and defended her MA thesis in 2019, a study of tannins and their effects on protein availability to diademed sifakas. Emma is currently a PhD student in the New York Consortium in Evolutionary Primatology in New York. [website]


Amanda Hamrick - MA student

Amanda graduated from the University of Minnesota in 2017 with a BSc in Ecology, Evolution and Behavior and a BA in Anthropology. She has studied in Kenya (examining effects of takeovers on De Brazza's monkey) and Panama, and completed a study of European Starlings. Amanda conducted fieldwork in 2018, examining the depletion of feeding patches in diademed sifakas during the lean season.


Shallu Prasher - MA Student

Shallu graduated from the University of Toronto in 2015 with a BSc in Biology and Anthropology. She conducted fieldwork at the Duke Lemur Center in 2018, examining the spatial distribution of Lemur catta scentmarks in relation to ecological and social factors in multiple natural habitat enclosures, and defended her MA in 2019.


Katie Heffernan - PhD Student (co-advisor)

Katie earned her bachelors in Biology at University of Wisconsin - Parkside in 2009, and then received a M.S. with a specialization in Human Anatomical Sciences in 2011 from Northern Illinois University. Her PhD thesis, which she defended in 2019, focuses on dental macrowear in diademed sifakas, how it is impacted by habitat change, and whether it influences reproduction and infant survival. Katie is currently a faculty member at Richard Bland College of William and Mary University. [website]


Amanda DuBour - MA Student

Amanda graduated from the University of South Florida in 2015 with a BS and began her MA work at NIU in Fall 2015. She completed fieldwork in 2016 - a study of nutrient intakes and balancing in the red-bellied lemur (Eulemur rubriventer) at Tsinjoarivo, and defended her MA in 2017.


Laurie Spencer - MA Student

Laurie earned her BS in Biological Sciences at DePaul University, and entered NIU's MA program in Anthropology in 2012. She has worked as an animal keeper and research intern at the Lincoln Park Zoo. Laurie conducted her MA fieldwork in 2014, measuring the incidence of Cryptosporidium and Giardia parasites in lemurs, livestock and humans at Tsinjoarivo, and defended her MA in 2017. Her lab analyses combined traditional microscopy techniques with immunofluorescence. In January 2017 Laurie began her PhD research in the Dept. of Biological Sciences [researchgate]


Kim Foreit - MA Student

Kim graduated from Loyola University with a BS in Anthropology in 2010. She has previously worked as a Reseach Intern and the Lincoln Park Zoo, both in data collection on captive apes and digitizing wild chimp data from Gombe. Her MA thesis, completed in 2016, examined subtle manifestations of female dominance in bamboo lemurs (Hapalemur griseus) - specifically focusing on leadership of group movements, group geometry, and displacements.


Safidy Rasolonjatovo - MS Student (co-advisor)

Safidy earned her masters degree in the Department of Animal Biology at the University of Antananarivo; her main supervisor was Dr Lydia Rabetafika. Her fieldwork was completed in 2014, and her thesis focused on the group movements, group leadership and expression of female dominance in multiple groups of diademed sifaka.


Maharavo Razafindraseta - MS Student (co-advisor)

Maha is a student in the Department of Animal Biology at the University of Antananarivo; his main supervisor is Dr Lydia Rabetafika. He completed fieldwork with Dr Irwin in 2014, focusing on parasite transmission in three lemur species (diademed sifakas, brown lemurs and bamboo lemurs). In the field he quantified the positional behavior of lemurs during defecation and the pathways for contamination of vegetation; his labwork will quantify the helminth parasites found in each species.


Brandon Semel - MA Student

Brandon earned his bachelors of Science in Environmental Science and Evolutionary Anthropology at Duke University in 2013, and earned his MA degree at NIU in 2015. He had previously trained in Madagascar with an SIT study abroad program, conducted independent research at Makira, and worked as a teaching assistant for Operation Wallacea study abroad programs. Brandon's MA thesis work tested hypotheses for the function of geophagy in diademed sifakas and brown lemurs at Tsinjoarivo - a project incorporating nutritional ecology, parasitology and behavioral ecology. [researchgate]


Molly Fitzpatrick - MA Student

Molly completed fieldwork at Tsinjoarivo in 2013 and earned her MA degree in 2014. Her study examined two groups of bamboo lemur (Hapalemur griseus), quantifying their diet, cyanide consumption and parasite load.

Graduate Student Committees, Past and Present

Sandratra Rakotoanosy (MS, University of Antananarivo 2021) -- "Evaluation des Impacts de l’Environnement sur la Croissance des Enfants de Bas Âge dans le Nouvelle Aire Protégée de Tsinjoarivo Ambalaomby"

Jessie Birckelbaw (MA, NIU 2021) -- "Dominance or Leverage? An Analysis of Female Power in Captive Varecia"

Brenna Ritchie (MS, NIU 2021) -- "The Gut Microbiome of Hapalemur griseus griseus and Propithecus diadema: A Comparative Study Between Wild and Captive Lemur Species"

Caitlin Bemis (MA, NIU 2018) -- "Prehensility in hominins: Anatomy of a “precision grip” in fossil and living primates"

Margaret Buehler (MA, NIU 2016) -- "Inter-sexual Social Interactions in Cebus capucinus"

Jessica Ritsche (MA, NIU 2016) -- "Do Folivores Deplete Patches? Feeding Ecology of Costa Rican Mantled Howlers (Alouatta palliata)"

Xiaoying Zhong (MA, NIU 2016) -- "The phylogeny of Homo erectus"

Anna Kordek (MA, NIU 2014) -- "Stress and Behavior of Male Bonobos in Groups of Varied Sex Ratio"

Sylvia Orellana (MA, NIU 2014) -- "Balancing the Scales: Diurnal Temporal Variation in the Feeding and Foraging Patterns of Saguinus fuscicollis"

Holiarimino Vololonoro (DEA, University of Antananarivo, 2011) -- "Étude comparative des activités du Hapalemur griseus griseus (Link, 1795) entre la forêt fragmentée et la forêt continue de Tsinjoarivo-Ambatolampy Madagascar"

Jean-Elvis Rakotomalala (DEA, University of Antananarivo, 2010) -- "Impact de la Fragmentation des Habitats Naturels et des Activites Humaines sur les Populations Lémuriennes de la Forêt Classée d'Ankadivory (Tsinjoarivo)"

Undergraduate Advisees, Past and Present

Bugs Craig (BA, NIU; 2022, labwork funded by NIU's Student Engagement Fund - examining alkaloid prevalence in lemur foods)

Sarah Naughton (BS, NIU; 2020, labwork funded by NIU's Student Engagement Fund - examining macronutrient content of bamboo lemur foods)

James Mogan (BS/BA, NIU; 2017-18; fieldwork conducted during Study Abroad program followed by labwork and undergraduate honors thesis)

Meredith Keeley (Independent Field Study 2014; graduate of Queen's University of Charlotte, NC, USA)

Kim Lein (BA, NIU, 2013; Kim, a USOAR grant recipient and advisee of Dr Irwin, conducted a study of the spatial dynamics of scentmarking in diademed sifakas and bamboo lemurs)

Kathryn Olson (BS, NIU, 2013; Kathryn, a URAP grant recipient, conducted a study of the helminth parasites of diademed sifakas at Tsinjoarivo)