Summary
We performed an experiment to investigate effects of red leg bands on the behavior of male Red-winged Blackbirds (Agelaius phoeniceus). We presented models having either black, blue, or red leg bands to territorial 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 blue-banded models, but spent more time at distances greater than 10 m, displayed at lower intensities, and took longer to attack when the model was given red bands. Thus, red bands appeared to make the model initially more threatening to territorial male Red-winged Blackbirds. These results do not support the contrasting-color hypothesis and suggest that the effect of red bands is attributable to the bands matching the color of the male's epaulets. The failure of the contrasting-color hypothesis also leaves unresolved the different outcomes of one previous experiment showing a negative effect of red bands, and two analyses of long-term banding studies that detected no effect of red bands.
Methodology
We conducted this experiment in three cattail marshes located within 40 km of the Queen's University Biological Station in eastern Ontario from 26 April to 22 May 1990. We presented territorial males with a male Red-winged Black- bird model given red, blue, or black bands. Approximately half the territorial males were "naive," never having been exposed previously to a model blackbird and not used in other experiments. The remaining "experienced" males were also part of another experiment in which we clipped either the black feathers that are used by males to conceal their epaulets, causing the epaulets to be permanently exposed ("experienced- clipped"), or an equivalent number of contour feathers that did not alter the males' appearance ("experienced-controls"). In the course of these treatments these males had been captured using model blackbirds and song playbacks. Although those models did not have leg bands, previous experience with a model blackbird could reduce the males' aggression in subsequent exposures (Hansen and Rohwer 1986). Therefore, we analyzed their responses separately from those of naive males.