Loren Merrill, Madeleine F. Naylor, Merria Dalimonte, Sean McLaughlin, Tara E. Stewart, and Jennifer L. Grindstaff
Stress in early life can have long-lasting consequences. For instance, when young animals are exposed to stressors like malnourishment or disease, their appearance is often permanently impacted, along with their behaviours and cognitive abilities. Zebra finches are charismatic birds with bright beaks and boisterous songs, and are a model species for studying the short- and long-term effects of stress. The colour of a male’s beak and the quality of his song are thought to provide information to other birds about his condition: males want to know what sort of competitors other males are, and females want to know what sort of mate and father a male would be. In this study, we activated the immune systems of males during their early developmental period and then examined how early-life experience impacted the quality of their songs in adulthood. In previous work, we found that early-life challenges resulted in duller beaks, so we expected to find the same with respect to their songs. We were wrong. What we found instead was that males experiencing early-life immune activation had more complex songs. This meant that early-life challenge resulted in subpar beaks, but sexier songs. So what’s a girl to do? As part of this study we were interested in how females perceived males with different histories, and whether they preferred males with the duller beaks and dynamic songs, or males with the dapper beaks, and dismal songs. Our results suggested that these mixed messages may have confused the females, because we found some evidence that they favoured the males with duller beaks and more complex songs, but other evidence indicating they showed no preference. Stressful early-life environments may make males less attractive in some respects, but more attractive in others.
Image provided by authors.