Meeting Abstract
To maximize lifetime reproductive success, animals must optimize allocation of time and energy to parental care and self-maintenance. In birds, incubation is crucial to maintain egg temperatures. Even small differences in mean temperature affect phenotypes critical to offspring survival, but incubation may diminish a parent’s time or energy available for self-maintenance. Large clutches are costly to warm, and may be a challenge for maintaining temperatures. Understanding parental behavior when faced with large clutch sizes, and how it affects egg temperatures, can provide insight into how parents cope with the parental care/self-maintenance tradeoff, and the effects on their offspring. To investigate this, we studied Wood Ducks, which are uniparental incubators with an average clutch size of 12 eggs, but nests reach >30 eggs due to conspecific brood parasitism. We manipulated clutch size in a box-nesting population and recorded hen incubation behavior along with temperatures of 7 artificial eggs within each nest during incubation. We found that as clutch size increased, hens took fewer, longer off-bouts, suggesting that hens can detect clutch size or associated temperatures and modulate their behavior. Clutch size was correlated negatively with mean nest temperature and positively with variation in mean temperature among eggs within a nest. Yet, hen mass loss during incubation did not differ. This suggests that hens shift investment towards self-maintenance (body mass) over parental care (egg temperature). Further, maintenance of optimal egg temperatures, which in turn affect offspring phenotype, may constrain the evolution of larger natural clutch sizes and be an overlooked cost of brood parasitism.
