Research - Early-life stress
Non-Parental Chick Maltreatment in the Nazca Booby (Galapagos)
One of the most compelling features of human child abuse is its intergenerational nature. While this “cycle of violence” has been extensively documented, little is known regarding the mechanism of intergenerational transmission. At our study site on Isla Española, Galápagos, all Nazca booby chicks are visited by non-parental adult visitors (NAVs) who display parental, aggressive, and/or sexual behavior toward chicks. We have found that the degree ofvictimization during NAV events as a nestling is strongly correlated with future NAV behavior as an adult, reminiscent of the "cycle of violence" in human biology. Maltreatment is stressful for chicks, and results in long-term changes to glucocorticoid regulation, and anxiety-related behaviors. This is one the longest studies of the effects of early-life natural stressors in a wild animal.
Long-term effects of early-life glucocorticoid exposure in wild sparrows
Stressors that elicit a physiological stress response early in life can have long-term impacts on an animal's behavior, physiology, and fitness. Understanding of such “programming” effects has broad implications for human health, captive animal health and productivity, and for managing wildlife populations. However, the persistence of programming effects over the lifespan of animals, especially for wild species, and their relevance for natural systems is not well established. In this study we manipulate glucocorticoids in wild House Sparrow nestlings, and track changes in behavior, growth, physiology, survival, and reproduction over time. We have found that nestling body condition is negatively impacted by glucocorticoids, but that sparrows can make up for poor early growth by accelerating later growth. However, this compensation comes at a cost to adult anti-predator behavior and long-term survival.
This work was funded by a National Science Foundation Dissertation Improvement Grant, a National Science Foundation Graduate Research Fellowship, an American Ornithologists' Union Research Award, the Centre d'Etudes Biologiques de Chize, and a Fyssen Foundation postdoctoral fellowship.