Meeting Abstract
Morphological and physiological traits are often predictive of reproductive performance, and researchers make inferences about how behavior operates to shape those relationships. However, it is rare that we understand exactly how those traits translate to reproductive success, as this involves detailed information about individual behavior, and its physiological basis, that can be difficult to obtain. We deployed proximity loggers on breeding barn swallows (Hirundo rustica erythrogaster) to test how experimentally manipulating male ventral plumage color affects social interactivity, reproductive success, and aspects of physiology including testosterone and stress-induced corticosterone. First clutch eggs were collected for a record of paternity pre-manipulation and adult swallows were tagged with Encounternet proximity loggers. Tags recorded close proximity interactions for two days both before and after half of the males in the network had their ventral plumage experimentally darkened. Physiological data were collected pre- and post-manipulation for nearly all individuals. Two years of experimental data show that a male’s social interactivity changed proportionally to his change in plumage color. Males who experienced a greater shift in color (pale to dark), a larger, positive change in testosterone levels, and a dampened stress-induced corticosterone response had a larger, positive change in the number of interactions with their social mate post-manipulation compared to pre-manipulation. Changes in male-male interactions were not directly related to the phenotype manipulation or changes in physiology.
