Meeting Abstract
In a wide variety of vertebrates, plasma glucocorticoid (CORT) levels rapidly increase in response to a stressor but the magnitude of the stress-induced CORT (SI-CORT) response can consistently vary among individuals. In Florida Scrub-Jays (Aphelocoma coerulescens) these individual differences in SI-CORT are repeatable throughout the adult lifespan (up to nine years) and are predictive of sex-specific differences in lifespan (lower SI-CORT males and higher SI-CORT females live longer). The specific causes for the differences in life-span associated with SI-CORT are not clear but, in general, the longer lived SI-CORT phenotypes have lower annual reproductive success. We investigated how SI-CORT phenotype influenced individual reproductive strategies and reproductive success using a novel “SmartFeeder” design that utilizes radio-frequency identification (RFID) technology to selectively provide live mealworms to specific individuals within a free-living population of Florida Scrub-Jays. Overall, supplemented jays raised more offspring to nutritional independence (~70 days old), however, this effect was only observed in males and females with moderate to high SI-CORT responses. Further, the effect of supplementation was strongest in pairs with two high SI-CORT individuals, but high SI-CORT jays paired with low SI-CORT jays showed no improvement over controls. Together, these data suggest that SI-CORT phenotype influences reproductive strategies in both male and female Florida scrub jays and annual reproductive success is heavily influenced by the interaction of SI-CORT phenotypes within a breeding pair.
