Assistant Professor
213 Kunkel


  • Ph.D., Arizona State University

Currently, I teach Human Physiology, General Biology 102, and Physiology of Extreme Animals. While most of my interests intersect with physiology at some level, I have a specific interest in animal behavior, and I hope to offer courses such as Behavioral Ecology in the near future.

Very broadly, I pursue research questions in organismal biology from physiological, evolutionary, and ecological perspectives. By combining field studies with lab-based experiments, my research examines the development of traits associated with both survival (e.g., immune function) and reproduction (e.g., ornamentation) and then quantifies these traits using a variety of techniques, including biochemical analyses, in vivo and in vitro immunological assays, and behavioral trials. Students interested in completing projects in my lab are more than welcome to contact me either by email or simply stopping by my office.

Project 1:

Carotenoids are red, orange, or yellow pigmentary molecules that vertebrates cannot synthesize de novo, but these molecules are very important to the organism, acting as antioxidants and improving immune function. Therefore, only high-quality individuals can allocate these physiologically useful molecules to the skin or feathers, where they can be used in colorful ornaments to honestly signal quality (as seen in many red or yellow birds, fish, and lizards). Currently, I am examining how access to carotenoids early in development affects coloration, tissue carotenoid levels, and behavior of juvenile and adult mallard ducks, which possess a beak that is pigmented by carotenoids and is used to attract females.

Project 2:

In the near future, I will be establishing a colony of nest boxes in the Easton area to examine how nutrition of parents and nestlings affects coloration of adult birds, nestlings, and even eggs. Because many pigments (including the carotenoids found in the skin of many adult and nestling birds, and biliverdin, which is a blue-green pigment found in eggshells) are antioxidants, these individuals may face a trade-off when allocating these molecules to pigmentary, rather than physiological, roles. By assessing immune function, reproductive investment, and nesting success, members of my lab and I will tease apart the roles these molecules play in shaping organismal quality.

List of publications:

Butler MW and KJ McGraw. 2012. Differential effects of early- and late-life access to carotenoids on adult immune function and ornamentation in mallard ducks (Anas platyrhynchos). PLoS ONE 7: e38043.

*Behbahaninia H, MW Butler, MB Toomey, and KJ McGraw. 2012. Food color preferences against a dark, textured background vary in relation to sex and age in house finches (Carpodacus mexicanus). Behaviour 149:51-65.

Butler MW and KJ McGraw. 2012. Developmental immune history affects adult immune function but not carotenoid-based ornamentation in mallard ducks. Functional Ecology 26:406-415.

Lambrechts MM, KL Wiebe, P Sunde, T Solonen, F Sergio, A Roulin, AP Møller, BC López, JA Fargallo, K-M Exo, G Dell’Omo, D Costantini, M Charter, MW Butler, GR Bortolotti, R Arlettaz, and E Korpimäki. 2012. Nest-box design for the study of diurnal raptors and owls is still an overlooked point in ecological, evolutionary and conservation studies: a review. Journal of Ornithology 153:23-34.

Butler MW, MB Toomey, KJ McGraw, and M Rowe. 2012. Ontogenetic immune challenges shape adult personality in mallard ducks. Proceedings of the Royal Society, B 279:326-333.

Butler MW and KJ McGraw. 2011. Past or present? Relative contributions of developmental and adult conditions to adult immune function and coloration in mallard ducks (Anas platyrhynchos). Journal of Comparative Physiology B 181:551-563.

Butler MW, MB Toomey, and KJ McGraw. 2011. How many color metrics do we need? Evaluating how different color-scoring procedures explain carotenoid pigment content in avian bare-part and plumage ornaments. Behavioral Ecology and Sociobiology 65:401-413.

Butler MW and KJ McGraw. 2010. Relationships between dietary carotenoids, body tissue carotenoids, parasite burden, and health state in wild mallard (Anas platyrhynchos) ducklings. Archives of Biochemistry and Biophysics 504:154-160.

Costantini D, M Rowe, MW Butler, and KJ McGraw. 2010. From molecules to living systems: historical and contemporary issues in oxidative stress and antioxidant ecology. Functional Ecology 24:950-959.

Toomey MB, MW Butler, and KJ McGraw. 2010. Immune-system activation depletes retinal carotenoids in house finches (Carpodacus mexicanus). Journal of Experimental Biology 213:1709-1716.

Toomey MB, MW Butler, MG Meadows, LA Taylor, HB Fokidis, and KJ McGraw. 2010. A novel method for quantifying the glossiness of animals. Behavioral Ecology and Sociobiology 64:1047-1055.

Butler MW, LL Leppert, and AM Dufty Jr. 2010. Effects of small increases in corticosterone levels on morphology, immune function, and feather development. Physiological and Biochemical Zoology 83:78-86.

Butler MW and KJ McGraw. 2009. Indoor housing during development affects moult, carotenoid circulation and beak colouration of mallard ducks (Anas platyrhynchos). Avian Biology Research 2:203-211.

Butler MW, BA Whitman, and AM Dufty Jr. 2009. Nest box temperature and hatching success of American kestrels varies with nest box orientation. The Wilson Journal of Ornithology 121:778-782.

Butler MW, JC Garvin, NT Wheelwright, and CR Freeman-Gallant. 2009. Ambient temperature, but not paternity, is associated with immune response in Savannah sparrows (Passerculus sandwichensis). The Auk 126:536-542.

Meadows, MG, MW Butler, NI Morehouse, LA Taylor, MB Toomey, KJ McGraw, and RL Rutowski. 2009. Iridescence: views from many angles. Journal of the Royal Society Interface 6:S107-S113.

Ghiradella, HT and MW Butler. 2009. Many variations on a few themes: a broader look at development of iridescent scales (and feathers). Journal of the Royal Society Interface 6:S243-S251.

McGraw KJ, EA *Tourville, and MW Butler. 2008. A quantitative comparison of the commonly used methods for extracting carotenoids from avian plasma. Behavioral Ecology and Sociobiology 62:1991-2002.

Butler MW and AM Dufty Jr. 2007. Nestling immunocompetence is affected by captivity but not investigator handling. The Condor 109:920–928.

Butler M and A Johnson. 2004. Are melanized feather barbs stronger? Journal of Experimental Biology 207:285-293.

* denotes undergraduate author