Research
By training I am a behavioral ecologist, but in recent years I’ve become increasingly
interested in behavioral physiology, as well as in the effects of environmental
contaminants on behavior. Most of my research focuses on the evolutionary forces that
shape animal social interactions, particularly reproductive, parental and aggressive
behavior. I’m also interested in the evolution of life histories. I work with birds and fish
in both laboratory and field settings. Continue reading to learn more about some of the
projects I’m currently working on, as well as to download my curriculum vitae or PDF
files of some of my papers.
Lab
Current members of my research group include Maureen Manning (technician) and Caleb
Murphy (senior thesis student).
Projects
Behavioral endocrinology of dark-eyed juncos. Manipulations of plasma testosterone
(T) levels in male dark-eyed juncos (a socially monogamous, ground-nesting songbird)
have revealed myriad phenotypic effects (reviewed in Ketterson et al. 2001). With my
colleagues, Ellen Ketterson and Val Nolan at the Center for the Integrative Study of
Animal Behavior and the Department of Biology at Indiana University, I am currently
investigating the role of T in mediating female behavior and the potential for intersexual
conflict over optimal T-level expression. Field work for this project is conducted at the
University of Virginia’s Mountain Lake Biological Station, where I am also collaborating
with Amy Pedersen (Department of Biology, University of Virginia) and others on a
long-term study of rodent-junco population dynamics.
Phytoestrogen exposure in aquatic vertebrates. Phytoestrogens are a class of naturallyoccurring estrogenic compounds found in many plants, particularly soybeans and some
tree species. Significant phytoestrogen levels have been reported downstream from some
pulp and paper mills, but little is known about their effect on fish populations. I am in the
beginning stages of research on the behavioral consequences of phytoestrogen exposure
in fishes such as the fathead minnow (Pimephales promelas) and the fighting fish (Betta
splendens).
Aggressive behavior in male and female fighting fish. Male Betta splendens are widely
known for their stereotyped agonistic displays and often-fatal displays of aggression.
Females are also aggressive in a variety of inter- and intrasexual contexts. I am currently
investigating the effects that intensive natural and artificial selection on male behavior
have on female behavior, and ultimately, female fitness. This work will utilize a
combination of behavioral, physiological and classical genetics approaches with both
laboratory and field components. Visit the International Betta Congress to learn more
about these fish.
Incubation costs and life history tradeoffs in cavity-nesting birds. Most of what we
know about avian incubation behavior comes from correlative studies, rather than direct
manipulations of incubation conditions. Beginning in the fall of 2004, Dan Ardia (a
Darwin Fellow in the University of Massachusett’s Organismic and Evolutionary Biology
program) and I will begin a two-year project in which we will examine the costs and
consequences of incubation behavior in house wrens (Troglodytes aedon) through
experimental manipulations of the thermal environment, female condition, and maternal
effects. This field work will be conducted in and around Amherst, Massachusetts.
Peer-reviewed publications (as of 3/1/04)
*indicates undergraduate co-author
Clotfelter, E.D., O’Neal*, D.M., Gaudioso*, J.M, Casto, J.M., Parker-Renga, I.M.,
Snajdr, E.A., Duffy, D.L., Nolan, V. Jr. and Ketterson, E.D. In press. Consequences of
elevating plasma testosterone in females of a socially monogamous songbird: evidence of
constraint on male evolution? Hormones and Behavior.
Ingham*, R.R., Gesualdi*, D.A., Toth, C.R. and Clotfelter, E.D. In press. Effects of
genistein on growth and development of aquatic vertebrates. Bulletin of Environmental
Contamination and Toxicology.
Clotfelter, E.D. and Paolino*, A.D. 2003. Bystanders to contests between conspecifics
are primed for increased aggression in male fighting fish. Animal Behaviour 66: 343-347.
Whittingham, L.A., Dunn, P.O. and Clotfelter, E.D. 2003. Parental allocation of food to
nestling tree swallows: the influence of nestling behaviour, sex and paternity. Animal
Behaviour 65: 1203-1210.
Clotfelter, E.D., Schubert*, K.A., Nolan, V., Jr. and Ketterson, E.D. 2003. Mouth color
signals thermal state in nestling dark-eyed juncos. Ethology 109: 171-182.
Nolan, V., Jr., Ketterson, E.D., Cristol, D.A., Rogers, C.M., Clotfelter, E.D., Titus, R.C.,
Schoech, S.J. and Snajdr, E.A. 2002. Dark-eyed junco (Junco hyemalis). In The Birds of
North America, No. 716 (Poole, A. and Gill, F., Eds.). The Birds of North America, Inc.,
Philadelphia, PA.
Clotfelter, E.D., Nolan, V., Jr. and Ketterson, E.D. 2001. The effects of experimentally
elevated testosterone and food deprivation on food consumption and prey size
preferences in male dark-eyed juncos (Junco hyemalis). Ethology 107: 439-449.
Ketterson, E.D., Nolan, V. Jr., Casto, J.M., Buerkle, C.A., Clotfelter, E.D., Grindstaff,
J.A., Jones, K.J., Lipar, J.L., McNabb, F.M., Neudorf , D.L., Parker-Renga, I., Schoech,
S.J. and Snajdr, E. 2001. Testosterone, phenotype, and fitness: a research program in
evolutionary behavioral endocrinology. In Avian Endocrinology (Dawson, A. and
Chaturvedi, C.M., Eds.), pp. 19-40. Narosa: New Dehli.
Clotfelter, E.D., Whittingham, L.A. and Dunn, P.O. 2000. Laying order, hatching
asynchrony and nestling body mass in tree swallows (Tachycineta bicolor). Journal of
Avian Biology 31: 329-334.
Clotfelter, E.D. and Yasukawa, K. 1999a. The effect of aggregated nesting on red-winged
blackbird nest success and brood parasitism by brown-headed cowbirds. Condor 101:
729-736.
Clotfelter, E.D. and Yasukawa, K. 1999b. Impact of brood parasitism by brown-headed
cowbirds on the reproductive success of red-winged blackbirds. Condor 101: 105-114.
Clotfelter, E.D. and Yasukawa, K. 1999c. The function of early onset of nocturnal
incubation in the red-winged blackbird. Auk 116: 417-426.
Clotfelter, E.D., Yasukawa, K., and Newsome, R.D. 1999. The effects of prescribed
burning and habitat edges on brown-headed cowbird parasitism of red-winged blackbirds
in southern Wisconsin. Studies in Avian Biology 18: 275-281.
Clotfelter, E.D. 1998. What cues do brown-headed cowbirds use to locate red-winged
blackbird host nests? Animal Behaviour 55: 1181-1189.
Clotfelter, E.D. 1997. Red-winged blackbird parental investment following brood
parasitism by brown-headed cowbirds: is parentage important? Behavioral Ecology and
Sociobiology 41: 193-201.
Clotfelter, E.D. 1996. Mechanisms of facultative sex ratio variation in zebra finches
(Taeniopygia guttata). Auk 113: 441-449.
Clotfelter, E.D. 1995. Courtship displays and intrasexual competition in the bronzed
cowbird. Condor 97: 816-818.
Clotfelter, E.D. and Brush, T. 1995. Unusual parasitism by the bronzed cowbird. Condor
97: 814-815.