AN EXPERIMENTAL TEST OF THE CONTRASTING-COLOR HYPOTHESIS OF RED-BAND EFFECTS IN RED-WINGED BLACKBIRDS

We performed an experiment to investigate effects of red leg bands on the behavior of male Red-winged Blackbirds (Agelaius phoeniceus). We p resented models having either black, blue, or red leg bands to territo rial male Red-winged Blackbirds to test the hypothesis that any color of band that contrasts with the color of the legs makes an individual appear abnormal or unhealthy and therefore subject to attack. Overall, territorial males responded equally aggressively to the black- and bl ue-banded models, but spent more time at distances greater than 10 m, displayed at lower intensities, and took longer to attack when the mod el was given red bands. Thus, red bands appeared to make the model ini tially more threatening to territorial male Red-winged Blackbirds. The se results do not support the contrasting-color hypothesis and suggest that the effect of red bands is attributable to the bands matching th e color of the male's epaulets. The failure of the contrasting-color h ypothesis also leaves unresolved the different outcomes of one previou s experiment showing a negative effect of red bands, and two analyses of long-term banding studies that detected no effect of red bands.