About two-thirds of cuckoo species, including all North American species, build nests and nurse their young; Only about 35% of cuckoo species raise their chicks parasitically. Most live in forests in tropical and temperate regions.
Nest parasitism is a special reproductive behavior in which birds lay eggs in the nests of other birds, and their adoptive parents incubate and raise the chicks. The great cuckoo is the most typical bird among the more than 80 species of nest parasitic birds. It can parasitize eggs in the nests of 125 other species of birds.
Nest parasitism behavior is manifested in: host selection. During the breeding period, the cuckoo looks for a host that is similar to the incubation and brooding periods, has basically the same feeding habits as the chicks, and has an egg shape and color that is easy to imitate. Most of them are bird-shaped. order birds. In terms of parasitism time, cuckoos often parasitize and lay eggs quickly before the host begins to incubate eggs, taking advantage of the host leaving the nest to go out. In late spring and early summer, they fly north. It does not make its own nests, nor does it incubate eggs. It lays an average of 2-10 eggs per year, but it places the eggs in the nests of thrushes and reeds, allowing these birds to carefully incubate them for it. And every time it flies to a nest, it only lays one.
The co-evolution of nest parasitism is reflected in the morphological characteristics of the host eggs. There is no obvious difference in the color, size, etc. of the parasites eggs. At the same time, the hosts blurred identification of eggs is also an aspect. The impact on the hosts reproduction is that the giant cuckoo often removes one of the hosts eggs before laying eggs, or pushes them all out of the nest, forcing the host to lay eggs again. Once the nest-parasitized chick hatches, it has the habit of pushing the foster relatives chick out of the nest, so that it can exclusively take care of the foster parent, thus reducing the hosts reproductive success rate.
