Meeting Abstract
Avian plumage maintenance is expected to be costly in terms of allocation to uropygial gland antibacterial secretions as well as the time spent preening. However, the extent to which or whether feather maintenance costs compete with reproductive demands to impact offspring survival and quality is largely unknown. Resources permitting, zebra finches can breed in the same season in which they hatch. Thus, the rate at which birds develop secondary sexual traits should be a meaningful index of offspring quality. In order to manipulate feather bacteria loads, breeders were cage-housed and treated 3 times weekly with 0.5% chlorhexidine suspended in saline, saline only or handling only. Bacterial samples were collected prior to treatment assignment, and at 3 stages in the nesting cycle: during incubation, after hatching, and after fledging. We predicted that treatment with chlorhexidine would result in lower colony forming units across the reproductive cycle, higher hatchling survival, and more rapid offspring development. All of these predictions were met. Collectively, our results indicate that feather bacteria impaired reproductive performance. To assay possible costs of combatting feather bacteria, we also considered treatment and breeding stage effects on adult uropygial gland volume, and time spent preening.
