Meeting Abstract
Though multiple studies have explored the effects of stress on symmetrical growth in birds over short periods of time, there have been comparatively fewer long-term measurements of how stress affects asymmetrical growth, particularly in birds of prey. Fluctuating asymmetry (FA) is known to occur as a product of poor early-life conditions and experience with persistent stressors. One way to quantify stress in birds is to measure corticosterone (CORT) in feathers. Birds deposit CORT into their feathers when first growing the feathers as nestlings and also during molt, but they cannot deposit CORT after that feather is grown. We examined FA in juvenile birds, from four species, admitted to the Illinois Raptor Center either as orphaned nestlings or for rehabilitation and concurrently measured CORT in feathers. We also measured levels of lead in the blood of each bird to explore a possible link between toxicology and stress or symmetrical growth. Finally, we explored additional downstream consequences, such as parasite prevalence in birds with varying degrees of asymmetry. We found that for juvenile birds, feather CORT showed a positive, linear relationship with asymmetry. However, there was no significant relationship between CORT and asymmetry in adult birds. Blood lead levels were significantly correlated with fluctuating asymmetry, and fluctuating asymmetry was a significant predictor of parasite prevalence for all species. Overall, our findings add to the existing body of evidence that early-life stressors can have long-lasting consequences for birds.
