In this collaborative research project, a behavioral ecologist (K. A. Sullivan) and a physiological ecologist (W. W. Weathers) examine the relationship between foraging efficiency, social dominance, and survivorship in a small passerine bird, the yellow-eyed junco (Junco phaenotus). The study focuses on juvenile birds during the two-week period following the termination of adult care. During this period, juvenile mortality is high (42%) and body mass is a significant predictor of survival. The period of intense selection provides an opportunity to determine whether foraging efficiency and/or social dominance also affect survivorship, and hence fitness, as predicted by current theory. The study will provide insights concerning such diverse topics as how juvenile foraging efficiency affects the length of parental care, the energy costs and benefits of social dominance, the effect of microhabitat selection on daily energy expenditure, and population regulation by juvenile survivorship.
