Does the house sparrow Passer domesticus represent a global model species for egg rejection behavior?

Conspecific brood parasitism (CP) is a facultative breeding tactic whereby females lay their eggs in the nests of conspecifics. In some species, potential hosts have evolved the ability to identify and reject foreign eggs from their nest. Previous studies suggest that the ubiquitous house sparrow Passer domesticus in Spain and South Africa employs both CP and egg rejection, while a population in China does not. Given the species' invasive range expansions, the house sparrow represents a potentially excellent global model system for parasitic egg rejection across variable ecological conditions. We examined the responses of house sparrows to experimental parasitism at three geographically distinct locations (in Israel, North America, and New Zealand) to provide a robust test of how general the findings of the previous studies are. In all three geographic regions egg rejection rates were negligible and not statistically different from background rates of disappearance of control eggs, suggesting that the house sparrow is not a suitable model species for egg rejection experiments on a global scale.