Some species of Molothrus, a widely distinct genus of American birds, allied to our starlings, have parasitic habits like those of the cuckoo; and the species present an interesting gradation in the perfection of their instincts.

与我们的八哥近亲的美洲鸟类的一些物种具有像布谷鸟一样的寄生习性；并且该物种在其本能的完善方面呈现出有趣的渐变。