Figure 1. Aggressive behavior of sparrows subjected to simulated territorial intrusion during breeding and non-breeding season.

Male song sparrows (n = 8/group) in their territory were exposed to a caged conspecific male decoy in addition to a recorded male song playbacks in breeding season, spring (SE) and non-breeding season, autumn (AE). As controls (AC, SC), a white-crowned sparrow decoy and recorded songs were used. Behavior of a subject was recorded for number of songs, number of flight, closest approach to the decoy (meters; m), and time spend within 5-m of the decoy. Kruskal-Wallis 1-way ANOVA followed by Mann-Whitney U test; significant at * p<0.05, ** p<0.01 between experimental conditions of the same season, or at † p<0.05 between seasons under same experimental conditions. Results are shown in mean±SEM.