Her dissertation research focused on the hormonal control of mating behavior in Japanese quail.
[1] In her early research using the Japanese quail, Adkins-Regan performed a number of fundamental experiments on the mechanisms of sexual differentiation of behavior in birds, which have a ZW sex determination system.
Her work demonstrated that, unlike what is observed in mammalian sexual differentiation, female-typical reproductive behavior can be activated in both male and female Japanese quail by estrogen treatment.
Thus, the absence of male-type sexual behavior in adult females would result from their early exposure to endogenous estrogens, a process that would be experimentally reproduced in males by the injection of exogenous estradiol.
In the socially-monogamous zebra finches, she performed a series of parallel experiments demonstrating the effects of steroid hormones on the development sexually differentiated behaviors in these songbirds.