The impact of brood parasitism on host fitness in common pochards and tufted ducks.

摘要

To better understand the role that avian conspecific brood parasitism plays in the evolution of host life-histories, I studied the patterns of occurrence of brood parasitism, its impact on host fitness, and how hosts respond to parasitism for two species of diving duck (Common Pochard and Tufted Duck) breeding on Engure Marsh, Latvia. Using a combination of observation and experimentation, I concluded that the frequency of brood parasitism's occurrence is dependent, in part, on host to parasite ratio. Further, when presented with the opportunity, parasites may select higher quality hosts which maximize the probability of a parasite's egg being successful. From the host's perspective, brood parasitism had no detectable impact on clutch size, nest success, hatching success, duckling recruitment, or adult survival. As would be predicted from these results, hosts did not discriminate against eggs laid in the nest by parasites. Results are consistent with many studies on waterfowl, other precocial birds, and fish, suggesting brood parasitism's impact may be consistent among many vertebrate taxa with similar parental care patterns. More research on more diverse fauna are needed to confirm this generality.