Common cuckoo

It has a grayish, slender body and a long tail, the plumage resembling that of a sparrowhawk.

An excerpt from the article 20 facts about Common cuckoo
The legs are relatively short compared to the rest of the body. The underside of the body is decorated with grayish-white stripes that form grooves. Males are dark gray from the throat to the thorax area. In both sexes, the iris, eye socket, base of the bill and feet are yellow.