Behavioral responses of nesting female dark‐eyed juncos Junco hyemalis to hetero‐ and conspecific passerine preen oils

Several studies have suggested a greater role for olfactory cues in avian social interactions than previously recognized, but few have explicitly investigated the effect of odor on parental behavior. We present results from a preliminary study in which we applied hetero‐ and conspecific preen gland secretions, which are known to contain volatile compounds, to the nests and eggs of incubating female dark‐eyed juncos Junco hyemalis . The responses to these two conditions were compared to the responses of females whose nests were treated with their own preen oil as a control condition, and to females whose nests were treated with the vehicle only. We found that females significantly reduced incubation bout length, a form of parental care, in response to alien secretions, more so if they came from a heterospecific than a conspecific. Females did not reduce incubation bout length in response to their own preen oil or to a vehicle‐only control. These results suggest that odors in the nest may influence avian parental care. However, the behavioral change was only temporary and had no effect on later hatching success. In our study population, brood parasitism by brown‐headed cowbirds is common, but resulting nest abandonment is rare; juncos are frequently able to successfully breed even with cowbird nestlings in their nests. Thus, we suggest that more extreme behavioral responses to alien odor, such as nest abandonment or egg ejection, may not be adaptive and should not be expected.