[1][2] After receiving her doctoral degree, Ketterson was a postdoctoral scholar from 1974 to 1975 at Washington State University working with avian environmental physiologist James R.
[1] Ketterson and her trainees, with her longtime collaborator and partner Val Nolan, Jr., have conducted long-term field studies combined with experimental manipulation of free-living dark-eyed juncos at the Mountain Lake Biological Station in Virginia since the 1970s.
[10][11] Ketterson developed the experimental approach of manipulating levels of the hormone testosterone in free-living birds and comparing behavior, physiology, and fitness to controls in order to study the evolution of life history trade-offs.
[17] Her research has provided a mechanistic understanding of the fitness consequences of how animals allocate time and energy to competing demands (i.e. reproduction versus survival).
Later, her work explored whether hormones, which affect multiple target tissues simultaneously and mediate coordinated suites of traits, either constrain or potentiate adaptation.
[18][19] This work foreshadowed her interest in addressing limits to organisms' ability to respond to environmental change and the role of hormonally-mediated seasonal timing of behaviors (like reproduction, molt, and migration) in the generation and loss of biodiversity.
[27] The 2013 documentary film project, 'Ordinary Extraordinary Junco: Remarkable Biology from a Backyard Bird' highlights years of research conducted by Ketterson and her colleagues.