Cuckoos (布谷鸟) are masters of cheating. When it comes to raising young, they don't spend the energy building a nest, protecting eggs or feeding children. Instead, the female passes these roles on to other birds. They don't raise their own young. Usually, they lay their eggs in the nests of other birds, fooling other birds into thinking the cuckoo eggs are theirs.
To succeed in doing this, a female cuckoo watches over her chosen nest to observe feeding times. When the host parent leaves its nest in search of food, the cuckoo quickly lays her eggs among those already in the nest. Sometimes, she will even destroy and remove one of the host's eggs to make room for her own.
Cuckoos are medium-sized birds with long tails, and often have gray or brown backs. When they hatch (孵化) and begin to grow in a host's nest, the difference between the two can be obvious to an onlooker. Often the cuckoo is twice the size of its foster parents, but still continues to receive food from them.
The cuckoo imposter (冒名顶替者) is usually the only baby bird that the host parent has to care for. This is because when the cuckoo hatches after around 11 days, it gets rid of all the other eggs in the nest. It will lift each egg onto its back before throwing them one by one over the edge of the nest. Even then, the non-biological parent will continue to treat it as one of its own.
Also, cuckoos have developed to produce eggs that are similar in color to their main hosts'. This reduces the chances of eggs being attacked. Female cuckoos have been known to take host birds' attention away after laying their eggs by producing a noise similar to Eurasian sparrow hawks, scaring birds away from returning to the nest and allowing time for the cuckoo to make her escape unnoticed.
