The raven is a large all-black corvid bird. At maturity, the common raven averages 55-70 centimetres in size, and when spread the wings can be twice as long. Ravens are exceptionally intelligent animals and their mental abilities are in some parts at a level that only apes can surpass.
The cuckoo is long-tailed and slender. The cuckoo is 32-36 centimeters long, has a wing spacing of 54-60 cm and weighs about 120 g. The most common cuckoo is gray on the back, head and chest. The abdomen is white and black-streaked. A reddish-brown color form is quite common in females.