Northern Illinois University
Department of Anthropology
College of Liberal Arts and Sciences

Professor Irwin is a biological anthropologist specializing in primate ecology and behavior. His research focuses on the ecological adaptations of Madagascar's lemurs and how habitat disturbance affects the ecology, behavior and health of individuals and populations. He has studied feeding ecology, nutrition, body mass and condition and parasitology and is also interested in how Madagascar's abiotic and biotic environment has influenced the evolution of key lemur traits such as low activity levels, cathemerality and female dominance. Professor Irwin has an ongoing field project in Tsinjoarivo, eastern Madagascar and co-founded an NGO, SADABE, dedicated to promoting research, conservation and development.

Selected Publications

Irwin MT, Rahalinarivo V, Ramorasata B, Raharison JL, Ranaivoarisoa JF, Gherardi CNM, Rothman JM (2025) More choosy for minor foods: Diet, seasonality and food selection in sympatric frugivorous and folivorous lemurs. Ecology and Evolution 15:e71069.

Rahalinarivo V*, Rakotomanana HF, Randrianasy J, Ranaivoarisoa JF, Ramorasata B, Raharison JL, Irwin MT (2023) Activity budgets and seasonal activity shifts in sympatric lemurs: Increased lean season effort in a cathemeral frugivore contrasts with energy conservation in a diurnal folivore. American Journal of Primatology. DOI: 10.1002/ajp.23556

Morelli TL, Smith AB, Mancini AN, Balko EA, Borgerson C, Dolch R, Farris Z, Federman S, Golden CD, Holmes S, Irwin M, Jacobs RL, Johnson S, King T, Lehman S, Louis, Jr. EE, Murphy A, Randriahaingo HNT, Randrianarimanana HLL, Ratsimbazafy J, Razafindratsima OH, Baden AL (2020) The fate of Madagascar's rainforest habitat. Nature Climate Change 10:89-96.

Irwin MT, Samonds KE, Raharison JL, Junge RE, Mahefarisoa KL, Rasambainarivo F, Godfrey LR, Glander KE (2019) Morphometric signals of population decline in diademed sifakas occupying degraded rainforest habitat in Madagascar. Scientific Reports 9:8776. DOI:10.1038/s41598-019-45426-2

Tecot SR†, Irwin MT†, Raharison JL (2019) Variation in fecal cortisol levels across habitats and seasons in Propithecus diadema. Conservation Physiology 7(1):coz001. DOI:10.1093/conphys/coz001 (†co-first authors)

Irwin MT, Raharison JL, Junge RE, Chapman CA, Rothman JM (2017) Minerals in the foods and diet of diademed sifakas: Are they nutritional challenges? American Journal of Primatology. DOI: 10.1002/ajp.22623 (featured article)

Irwin MT, Raharison JL, Raubenheimer D, Chapman CA, Rothman JM (2015) The nutritional geometry of resource scarcity: Effects of lean seasons and habitats on nutrient intakes and balancing in a wild sifaka. Plos One 10(6):e0128046. doi:10.1371/journal.pone.0128046

Irwin MT, Raharison JL, Raubenheimer D, Chapman C, Rothman J (2014) Nutritional correlates of the lean season: Effects of seasonality and frugivory on the nutritional ecology of diademed sifakas. American Journal of Physical Anthropology 153:78-91.

Pontzer H, Raichlen DA, Gordon AD, Schroepfer-Walker KK, Hare BA, O'Neill MC, Muldoon KM, Dunsworth HM, Wood BM, Isler K, Burkart J, Irwin M, Shumaker RW, Lonsdorf EV, Ross SR (2014) Primate energy expenditure and life history. Proceedings of the National Academy of Sciences (USA) 111:1433-1437.

Schwitzer C, Mittermeier RA, Johnson SE, Donati G, Irwin M, Peacock H, Ratsimbazafy J, Razafindramanana J, Louis Jr. EE, Chikhi L, Colquhoun IC, Tinsman J, Dolch R, LaFleur M, Nash S, Patel E, Randrianambinina B, Rasolofoharivelo T, Wright PC (2014) Averting lemur extinctions amid Madagascar's political crisis. Science 343:842-843.

Crowley BE, Godfrey LR, Irwin MT (2011) A glance to the past: Subfossils, staple isotopes, seed dispersal and lemur species loss in southern Madagascar. American Journal of Primatology 73:25-37.

Groeneveld LF, Blanco MB, Raharison JL, Rahalinarivo V, Rasolarison RM, Kappeler PM, Godfrey LR, Irwin MT (2010) MtDNA and nDNA corroborate existence of sympatric dwarf lemur species at Tsinjoarivo, eastern Madagascar. Molecular Phylogenetics and Evolution 55:833-845.

Irwin MT, Junge RE, Raharison JL, Samonds KE (2010) Variation in physiological health of Diademed Sifakas across intact and fragmented forest at Tsinjoarivo, eastern Madagascar. American Journal of Primatology 72:1013-1025.

Irwin MT, Wright PC, Birkinshaw C, Fisher B, Gardner CJ, Glos J, Goodman SM, Loiselle P, Rabeson P, Raharison JL, Raherilalao MJ, Rakotondravony D, Raselimanana A, Ratsimbazafy J, Sparks J, Wilmé L, Ganzhorn JU (2010) Patterns of species change in anthropogenically disturbed forests of Madagascar. Biological Conservation 143:2351-2362.

Irwin MT, Raharison JL (2009) A review of the endoparasites of the lemurs of Madagascar. Malagasy Nature 2:66-93.

Irwin MT, Raharison JL, Wright PC (2009) Spatial and temporal variability in predation on rainforest primates: Do forest fragmentation and predation act synergistically? Animal Conservation 12:220-230.

Irwin MT (2008) Feeding ecology of diademed sifakas (Propithecus diadema) in forest fragments and continuous forest. International Journal of Primatology 29:95-115.

Irwin MT (2008) Diademed sifaka (Propithecus diadema) ranging and habitat use in continuous and fragmented forest: Higher density but lower viability in fragments? Biotropica 40:231-240.