Vampire off revenants—are common in vampire folklore. Garlic is a common example, a branch of wild rose and hawthorn plant are said to harm vampires, and in Europe, sprinkling mustard seeds on the roof of a house was said to keep them away. Other apotropaics include sacred items, for example a crucifix, rosary, or holy water. Vampires are said to be unable to walk on consecrated ground, such as that of churches or temples, or cross running water. Although not traditionally regarded as an apotropaic, mirrors have been used to ward off vampires when placed, facing outwards, on a door (in
Cross-fostering is termed interference competition. They are not consciously aware that some of the eggs in the nest were laid by the other bird however, and thus raise offspring of both species. These natural experiments have been used by Australian ornithologists Graeme Chapman and Ian Rowley to investigate the relative importance of genes and environment. For example, they discovered that the galah chicks gave normal begging calls and alarm calls, but their contact calls (used to maintain social cohesion) were more like those of the pink cockatoos with which they lived. Such natural instances of cross fostering can also lead to