Meeting Abstract
Nutritional deficiency often results in increased corticosterone levels in nestling birds and corticosterone, a metabolic and stress-related steroid hormone, is hypothesized to play a role in mediating begging behavior. Further, previous studies have found that corticosterone levels of nestlings are negatively correlated with parental nest attendance and provisioning rates. In this study we examined the relationship between adult provisioning and nestling glucocorticoid levels in a free-living species, the Florida scrub-jay (Aphelocoma coerulescens). We monitored parental activity at the nest immediately prior to blood sampling and found that nestling corticosterone levels varied as a function of parental provisioning rate and the time since their last feed. Counter to our predictions, higher provisioning rates and more recent feedings were associated with higher corticosterone levels in nestlings. These results suggest that either the act of feeding by parents, the process of digestion, sibling interactions, or some combination of the preceding resulted in increased baseline corticosterone levels in nestling Florida scrub-jays. These results indicate that some caution should be taken in interpreting elevated nestling baseline corticosterone levels as indicating “nutritional stress” or other distressed states in the absence of knowledge of the individual’s recent behavioral history.
