Not all brood parasites kill all of their host's offspring outright.

并非所有的寄生虫都会直接杀死宿主的所有后代。

This retaliatory adaptation can fuel an evolutionary arms race where brood parasites evolve eggs that closely mimic their host's.

这种报复性适应可能会引发一场进化军备竞赛，在这种竞赛中，寄生虫会进化出与宿主非常相似的卵。

Unless the brood parasite kills all of the host's young, it may be best to simply foster the imposter.

除非寄生虫杀死了宿主的所有幼崽，否则最好简单地培养冒名顶替者。

In fact, hosts will often drive adult brood parasites away from their nests, and many take their defenses further.

事实上， 宿主通常会将成虫寄生虫赶出它们的巢穴，而且许多寄生虫会采取更进一步的防御措施。

By depositing their eggs into a stranger's nest, brood parasites are able to shift the major costs of parenting onto others.

通过将卵产在陌生人的巢穴中，寄生虫能够将育儿的主要成本转嫁给其他人。

In fact, studies have shown that those hosts that reject parasitic eggs less frequently can visually distinguish between their eggs and a brood parasite's.

事实上，研究表明那些拒绝寄生虫卵的频率较低的宿主可以在视觉上区分它们的卵和寄生虫的卵。