Meeting Abstract
Ornamental traits function as signals to conspecifics, indicating status, fitness, condition, etc. However, elaborate ornaments are costly to produce and maintain, and honest-signaling theory predicts that only high quality individuals are able to produce exaggerated ornamental displays. Variation in ornamentation can be genetic or from environmental sources. In birds with structural coloration, plumage variation results from differences in energy allocated to feather growth due to environmental conditions during molt, and is an honest signal of condition since birds with large energy budgets can invest more in feather development. However, little is known about the consistency of ornamental signals throughout an individual’s lifetime, or more specifically, how signals differ between different plumages. Florida Scrub-jay (Aphelocoma coerulescens) juveniles are sexually dimorphic in the ultraviolet (UV) range, and UV brightness predicts social dominance, but not adult reproductive fitness. We combined observational and experimental approaches to test how environmental conditions and stress interact to affect structural coloration in Florida Scrub-jays across molts. We collected feathers from the same individuals in pre-basic (juvenile) and basic (adult) plumages and examined the effects of increased stress by administering corticosterone to yearlings during their first basic molt. Because most Florida Scrub-jays breed at 2-3 years of age, we also evaluated how consistency and relative brightness of UV coloration affected probability of breeding. Florida Scrub-jays are a Threatened species, and as their habitat continues to decline and degrade, it is important to understand how environmental changes affect plumage and reproductive fitness.
