A more dramatic female behavior that Tinbergen did not disuss is egg cannibalism. Females often attack males' nests and eat eggs or developing young. This benefits the female because she gets a nutritious meal and eliminates the eggs of her rivals. It appears that cannibalistic females are very successful in mating with males whose nests they have previously raided. Egg cannibalism, however, is always detrimental to the male's reproductive success. Not surprisingly, males have evolved several types of behavior to deter egg cannibalism. Males frequently attack marauding females with vigorous bites and threatening displays. A male may also distract cannibalistic females by feeding outside his territory. Finally, because egg cannibals often travel in roving gangs, males often court single females while avoiding females in groups.