Competition is a -/- interaction that occurs when individuals of different species compete for a resource that limits the survival and reproduction of each species, e.g., a leopard and a lion in a forest or grassland. Brood parasitism or the laying of one's eggs in the nest of another individual, is a reproductive strategy whereby parasites foist the cost of rearing their offspring onto another individual, the host, e.g., a cuckoo laying eggs in a crow's nest. Mutualism is an interspecific interaction that benefits both species (+/+), e.g., fungi and roots of a higher plant in mycorrhizae. Commensalism is the interaction in which one species benefits and the other is neither harmed nor benefited, e.g., a cattle egret and a cattle in a field.